draft-ietf-cellar-ffv1-05.txt		draft-ietf-cellar-ffv1-06.txt
	cellar M. Niedermayer		cellar M. Niedermayer
	Internet-Draft		Internet-Draft
	Intended status: Informational D. Rice		Intended status: Informational D. Rice
	Expires: March 29, 2019		Expires: April 21, 2019
	J. Martinez		J. Martinez
	September 25, 2018		October 18, 2018
	FFV1 Video Coding Format Version 0, 1, and 3		FFV1 Video Coding Format Version 0, 1, and 3
	draft-ietf-cellar-ffv1-05		draft-ietf-cellar-ffv1-06
	Abstract		Abstract
	This document defines FFV1, a lossless intra-frame video encoding		This document defines FFV1, a lossless intra-frame video encoding
	format. FFV1 is designed to efficiently compress video data in a		format. FFV1 is designed to efficiently compress video data in a
	variety of pixel formats. Compared to uncompressed video, FFV1		variety of pixel formats. Compared to uncompressed video, FFV1
	offers storage compression, frame fixity, and self-description, which		offers storage compression, frame fixity, and self-description, which
	makes FFV1 useful as a preservation or intermediate video format.		makes FFV1 useful as a preservation or intermediate video format.
	Status of This Memo		Status of This Memo
	skipping to change at page 1, line 36 ¶		skipping to change at page 1, line 36 ¶
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at https://datatracker.ietf.org/drafts/current/.		Drafts is at https://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	This Internet-Draft will expire on March 29, 2019.		This Internet-Draft will expire on April 21, 2019.
	Copyright Notice		Copyright Notice
	Copyright (c) 2018 IETF Trust and the persons identified as the		Copyright (c) 2018 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(https://trustee.ietf.org/license-info) in effect on the date of		(https://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	skipping to change at page 2, line 22 ¶		skipping to change at page 2, line 22 ¶
	2.2. Conventions . . . . . . . . . . . . . . . . . . . . . . . 5		2.2. Conventions . . . . . . . . . . . . . . . . . . . . . . . 5
	2.2.1. Pseudo-code . . . . . . . . . . . . . . . . . . . . . 6		2.2.1. Pseudo-code . . . . . . . . . . . . . . . . . . . . . 6
	2.2.2. Arithmetic Operators . . . . . . . . . . . . . . . . 6		2.2.2. Arithmetic Operators . . . . . . . . . . . . . . . . 6
	2.2.3. Assignment Operators . . . . . . . . . . . . . . . . 6		2.2.3. Assignment Operators . . . . . . . . . . . . . . . . 6
	2.2.4. Comparison Operators . . . . . . . . . . . . . . . . 7		2.2.4. Comparison Operators . . . . . . . . . . . . . . . . 7
	2.2.5. Mathematical Functions . . . . . . . . . . . . . . . 7		2.2.5. Mathematical Functions . . . . . . . . . . . . . . . 7
	2.2.6. Order of Operation Precedence . . . . . . . . . . . . 8		2.2.6. Order of Operation Precedence . . . . . . . . . . . . 8
	2.2.7. Range . . . . . . . . . . . . . . . . . . . . . . . . 8		2.2.7. Range . . . . . . . . . . . . . . . . . . . . . . . . 8
	2.2.8. NumBytes . . . . . . . . . . . . . . . . . . . . . . 8		2.2.8. NumBytes . . . . . . . . . . . . . . . . . . . . . . 8
	2.2.9. Bitstream Functions . . . . . . . . . . . . . . . . . 8		2.2.9. Bitstream Functions . . . . . . . . . . . . . . . . . 8
	3. General Description . . . . . . . . . . . . . . . . . . . . . 9		3. Sample Coding . . . . . . . . . . . . . . . . . . . . . . . . 9
	3.1. Border . . . . . . . . . . . . . . . . . . . . . . . . . 9		3.1. Border . . . . . . . . . . . . . . . . . . . . . . . . . 9
	3.2. Samples . . . . . . . . . . . . . . . . . . . . . . . . . 10		3.2. Samples . . . . . . . . . . . . . . . . . . . . . . . . . 10
	3.3. Median Predictor . . . . . . . . . . . . . . . . . . . . 10		3.3. Median Predictor . . . . . . . . . . . . . . . . . . . . 10
	3.4. Context . . . . . . . . . . . . . . . . . . . . . . . . . 11		3.4. Context . . . . . . . . . . . . . . . . . . . . . . . . . 11
	3.5. Quantization Table Sets . . . . . . . . . . . . . . . . . 11		3.5. Quantization Table Sets . . . . . . . . . . . . . . . . . 11
	3.6. Quantization Table Set Indexes . . . . . . . . . . . . . 11		3.6. Quantization Table Set Indexes . . . . . . . . . . . . . 12
	3.7. Color spaces . . . . . . . . . . . . . . . . . . . . . . 12		3.7. Color spaces . . . . . . . . . . . . . . . . . . . . . . 12
	3.7.1. YCbCr . . . . . . . . . . . . . . . . . . . . . . . . 12		3.7.1. YCbCr . . . . . . . . . . . . . . . . . . . . . . . . 12
	3.7.2. RGB . . . . . . . . . . . . . . . . . . . . . . . . . 12		3.7.2. RGB . . . . . . . . . . . . . . . . . . . . . . . . . 13
	3.8. Coding of the Sample Difference . . . . . . . . . . . . . 14		3.8. Coding of the Sample Difference . . . . . . . . . . . . . 14
	3.8.1. Range Coding Mode . . . . . . . . . . . . . . . . . . 14		3.8.1. Range Coding Mode . . . . . . . . . . . . . . . . . . 14
	3.8.2. Golomb Rice Mode . . . . . . . . . . . . . . . . . . 17		3.8.2. Golomb Rice Mode . . . . . . . . . . . . . . . . . . 18
	4. Bitstream . . . . . . . . . . . . . . . . . . . . . . . . . . 20		4. Bitstream . . . . . . . . . . . . . . . . . . . . . . . . . . 20
	4.1. Parameters . . . . . . . . . . . . . . . . . . . . . . . 20		4.1. Parameters . . . . . . . . . . . . . . . . . . . . . . . 21
	4.1.1. version . . . . . . . . . . . . . . . . . . . . . . . 21		4.1.1. version . . . . . . . . . . . . . . . . . . . . . . . 22
	4.1.2. micro_version . . . . . . . . . . . . . . . . . . . . 22		4.1.2. micro_version . . . . . . . . . . . . . . . . . . . . 23
	4.1.3. coder_type . . . . . . . . . . . . . . . . . . . . . 22		4.1.3. coder_type . . . . . . . . . . . . . . . . . . . . . 23
	4.1.4. state_transition_delta . . . . . . . . . . . . . . . 23		4.1.4. state_transition_delta . . . . . . . . . . . . . . . 24
	4.1.5. colorspace_type . . . . . . . . . . . . . . . . . . . 23		4.1.5. colorspace_type . . . . . . . . . . . . . . . . . . . 24
	4.1.6. chroma_planes . . . . . . . . . . . . . . . . . . . . 23		4.1.6. chroma_planes . . . . . . . . . . . . . . . . . . . . 24
	4.1.7. bits_per_raw_sample . . . . . . . . . . . . . . . . . 23		4.1.7. bits_per_raw_sample . . . . . . . . . . . . . . . . . 24
	4.1.8. log2_h_chroma_subsample . . . . . . . . . . . . . . . 24		4.1.8. log2_h_chroma_subsample . . . . . . . . . . . . . . . 25
	4.1.9. log2_v_chroma_subsample . . . . . . . . . . . . . . . 24		4.1.9. log2_v_chroma_subsample . . . . . . . . . . . . . . . 25
	4.1.10. alpha_plane . . . . . . . . . . . . . . . . . . . . . 24		4.1.10. alpha_plane . . . . . . . . . . . . . . . . . . . . . 25
	4.1.11. num_h_slices . . . . . . . . . . . . . . . . . . . . 24		4.1.11. num_h_slices . . . . . . . . . . . . . . . . . . . . 25
	4.1.12. num_v_slices . . . . . . . . . . . . . . . . . . . . 24		4.1.12. num_v_slices . . . . . . . . . . . . . . . . . . . . 25
	4.1.13. quant_table_set_count . . . . . . . . . . . . . . . . 25		4.1.13. quant_table_set_count . . . . . . . . . . . . . . . . 26
	4.1.14. states_coded . . . . . . . . . . . . . . . . . . . . 25		4.1.14. states_coded . . . . . . . . . . . . . . . . . . . . 26
	4.1.15. initial_state_delta . . . . . . . . . . . . . . . . . 25		4.1.15. initial_state_delta . . . . . . . . . . . . . . . . . 26
	4.1.16. ec . . . . . . . . . . . . . . . . . . . . . . . . . 25		4.1.16. ec . . . . . . . . . . . . . . . . . . . . . . . . . 26
	4.1.17. intra . . . . . . . . . . . . . . . . . . . . . . . . 25		4.1.17. intra . . . . . . . . . . . . . . . . . . . . . . . . 26
	4.2. Configuration Record . . . . . . . . . . . . . . . . . . 26		4.2. Configuration Record . . . . . . . . . . . . . . . . . . 27
	4.2.1. reserved_for_future_use . . . . . . . . . . . . . . . 26		4.2.1. reserved_for_future_use . . . . . . . . . . . . . . . 27
	4.2.2. configuration_record_crc_parity . . . . . . . . . . . 26		4.2.2. configuration_record_crc_parity . . . . . . . . . . . 27
	4.2.3. Mapping FFV1 into Containers . . . . . . . . . . . . 27		4.2.3. Mapping FFV1 into Containers . . . . . . . . . . . . 28
	4.3. Frame . . . . . . . . . . . . . . . . . . . . . . . . . . 28		4.3. Frame . . . . . . . . . . . . . . . . . . . . . . . . . . 29
	4.4. Slice . . . . . . . . . . . . . . . . . . . . . . . . . . 28		4.4. Slice . . . . . . . . . . . . . . . . . . . . . . . . . . 29
	4.5. Slice Header . . . . . . . . . . . . . . . . . . . . . . 29		4.5. Slice Header . . . . . . . . . . . . . . . . . . . . . . 30
	4.5.1. slice_x . . . . . . . . . . . . . . . . . . . . . . . 30		4.5.1. slice_x . . . . . . . . . . . . . . . . . . . . . . . 31
	4.5.2. slice_y . . . . . . . . . . . . . . . . . . . . . . . 30		4.5.2. slice_y . . . . . . . . . . . . . . . . . . . . . . . 31
	4.5.3. slice_width . . . . . . . . . . . . . . . . . . . . . 30		4.5.3. slice_width . . . . . . . . . . . . . . . . . . . . . 31
	4.5.4. slice_height . . . . . . . . . . . . . . . . . . . . 30		4.5.4. slice_height . . . . . . . . . . . . . . . . . . . . 31
	4.5.5. quant_table_set_index_count . . . . . . . . . . . . . 30		4.5.5. quant_table_set_index_count . . . . . . . . . . . . . 31
	4.5.6. quant_table_set_index . . . . . . . . . . . . . . . . 30		4.5.6. quant_table_set_index . . . . . . . . . . . . . . . . 31
	4.5.7. picture_structure . . . . . . . . . . . . . . . . . . 31		4.5.7. picture_structure . . . . . . . . . . . . . . . . . . 32
	4.5.8. sar_num . . . . . . . . . . . . . . . . . . . . . . . 31		4.5.8. sar_num . . . . . . . . . . . . . . . . . . . . . . . 32
	4.5.9. sar_den . . . . . . . . . . . . . . . . . . . . . . . 31		4.5.9. sar_den . . . . . . . . . . . . . . . . . . . . . . . 32
	4.6. Slice Content . . . . . . . . . . . . . . . . . . . . . . 31		4.6. Slice Content . . . . . . . . . . . . . . . . . . . . . . 32
	4.6.1. primary_color_count . . . . . . . . . . . . . . . . . 32		4.6.1. primary_color_count . . . . . . . . . . . . . . . . . 33
	4.6.2. plane_pixel_height . . . . . . . . . . . . . . . . . 32		4.6.2. plane_pixel_height . . . . . . . . . . . . . . . . . 33
	4.6.3. slice_pixel_height . . . . . . . . . . . . . . . . . 32		4.6.3. slice_pixel_height . . . . . . . . . . . . . . . . . 33
	4.6.4. slice_pixel_y . . . . . . . . . . . . . . . . . . . . 32		4.6.4. slice_pixel_y . . . . . . . . . . . . . . . . . . . . 33
	4.7. Line . . . . . . . . . . . . . . . . . . . . . . . . . . 32		4.7. Line . . . . . . . . . . . . . . . . . . . . . . . . . . 33
	4.7.1. plane_pixel_width . . . . . . . . . . . . . . . . . . 32		4.7.1. plane_pixel_width . . . . . . . . . . . . . . . . . . 34
	4.7.2. slice_pixel_width . . . . . . . . . . . . . . . . . . 33		4.7.2. slice_pixel_width . . . . . . . . . . . . . . . . . . 34
	4.7.3. slice_pixel_x . . . . . . . . . . . . . . . . . . . . 33		4.7.3. slice_pixel_x . . . . . . . . . . . . . . . . . . . . 34
	4.7.4. sample_difference . . . . . . . . . . . . . . . . . . 33		4.7.4. sample_difference . . . . . . . . . . . . . . . . . . 34
	4.8. Slice Footer . . . . . . . . . . . . . . . . . . . . . . 33		4.8. Slice Footer . . . . . . . . . . . . . . . . . . . . . . 34
	4.8.1. slice_size . . . . . . . . . . . . . . . . . . . . . 33		4.8.1. slice_size . . . . . . . . . . . . . . . . . . . . . 35
	4.8.2. error_status . . . . . . . . . . . . . . . . . . . . 33		4.8.2. error_status . . . . . . . . . . . . . . . . . . . . 35
	4.8.3. slice_crc_parity . . . . . . . . . . . . . . . . . . 34		4.8.3. slice_crc_parity . . . . . . . . . . . . . . . . . . 35
	4.9. Quantization Table Set . . . . . . . . . . . . . . . . . 34		4.9. Quantization Table Set . . . . . . . . . . . . . . . . . 35
	4.9.1. quant_tables . . . . . . . . . . . . . . . . . . . . 35		4.9.1. quant_tables . . . . . . . . . . . . . . . . . . . . 36
	4.9.2. context_count . . . . . . . . . . . . . . . . . . . . 35		4.9.2. context_count . . . . . . . . . . . . . . . . . . . . 37
	5. Restrictions . . . . . . . . . . . . . . . . . . . . . . . . 35		5. Restrictions . . . . . . . . . . . . . . . . . . . . . . . . 37
	6. Security Considerations . . . . . . . . . . . . . . . . . . . 36		6. Security Considerations . . . . . . . . . . . . . . . . . . . 37
	7. Media Type Definition . . . . . . . . . . . . . . . . . . . . 36		7. Media Type Definition . . . . . . . . . . . . . . . . . . . . 38
	8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 38		8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 40
	9. Appendixes . . . . . . . . . . . . . . . . . . . . . . . . . 38		9. Appendixes . . . . . . . . . . . . . . . . . . . . . . . . . 40
	9.1. Decoder implementation suggestions . . . . . . . . . . . 38		9.1. Decoder implementation suggestions . . . . . . . . . . . 40
	9.1.1. Multi-threading Support and Independence of Slices . 38		9.1.1. Multi-threading Support and Independence of Slices . 40
	10. Changelog . . . . . . . . . . . . . . . . . . . . . . . . . . 39		10. Changelog . . . . . . . . . . . . . . . . . . . . . . . . . . 40
	11. References . . . . . . . . . . . . . . . . . . . . . . . . . 39		11. References . . . . . . . . . . . . . . . . . . . . . . . . . 40
	11.1. Normative References . . . . . . . . . . . . . . . . . . 39		11.1. Normative References . . . . . . . . . . . . . . . . . . 40
	11.2. Informative References . . . . . . . . . . . . . . . . . 40		11.2. Informative References . . . . . . . . . . . . . . . . . 41
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 41		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 43
	1. Introduction		1. Introduction
	This document describes FFV1, a lossless video encoding format. The		This document describes FFV1, a lossless video encoding format. The
	design of FFV1 considers the storage of image characteristics, data		design of FFV1 considers the storage of image characteristics, data
	fixity, and the optimized use of encoding time and storage		fixity, and the optimized use of encoding time and storage
	requirements. FFV1 is designed to support a wide range of lossless		requirements. FFV1 is designed to support a wide range of lossless
	video applications such as long-term audiovisual preservation,		video applications such as long-term audiovisual preservation,
	scientific imaging, screen recording, and other video encoding		scientific imaging, screen recording, and other video encoding
	scenarios that seek to avoid the generational loss of lossy video		scenarios that seek to avoid the generational loss of lossy video
	skipping to change at page 5, line 7 ¶		skipping to change at page 5, line 7 ¶
	[YCbCr].		[YCbCr].
	2. Notation and Conventions		2. Notation and Conventions
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this		"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
	document are to be interpreted as described in [RFC2119].		document are to be interpreted as described in [RFC2119].
	2.1. Definitions		2.1. Definitions
	"Frame": An encoded representation of a complete static image.		"Container": Format that encapsulates "Frames" (see Section 4.3) and
			(when required) a "Configuration Record" into a bitstream.
	"Slice": A spatial sub-section of a "Frame" that is encoded
	separately from an other region of the same frame.
	"Container": Format that encapsulates "Frames" and (when required) a
	"Configuration Record" into a bitstream.
	"Sample": The smallest addressable representation of a color		"Sample": The smallest addressable representation of a color
	component or a luma component in a "Frame". Examples of sample are		component or a luma component in a "Frame". Examples of "Sample" are
	Luma, Blue Chrominance, Red Chrominance, Alpha, Red, Green, and Blue.		Luma, Blue Chrominance, Red Chrominance, Alpha, Red, Green, and Blue.
			"Plane": A discrete component of a static image comprised of
			"Samples" that represent a specific quantification of "Samples" of
			that image.
	"Pixel": The smallest addressable representation of a color in a		"Pixel": The smallest addressable representation of a color in a
	"Frame". It is composed of 1 or more samples.		"Frame". It is composed of 1 or more "Samples".
	"ESC": An ESCape symbol to indicate that the symbol to be stored is		"ESC": An ESCape symbol to indicate that the symbol to be stored is
	too large for normal storage and that an alternate storage method.		too large for normal storage and that an alternate storage method.
	"MSB": Most Significant Bit, the bit that can cause the largest		"MSB": Most Significant Bit, the bit that can cause the largest
	change in magnitude of the symbol.		change in magnitude of the symbol.
	"RCT": Reversible Color Transform, a near linear, exactly reversible		"RCT": Reversible Color Transform, a near linear, exactly reversible
	integer transform that converts between RGB and YCbCr representations		integer transform that converts between RGB and YCbCr representations
	of a Pixel.		of a "Pixel".
	"VLC": Variable Length Code, a code that maps source symbols to a		"VLC": Variable Length Code, a code that maps source symbols to a
	variable number of bits.		variable number of bits.
	"RGB": A reference to the method of storing the value of a Pixel by		"RGB": A reference to the method of storing the value of a "Pixel" by
	using three numeric values that represent Red, Green, and Blue.		using three numeric values that represent Red, Green, and Blue.
	"YCbCr": A reference to the method of storing the value of a Pixel by		"YCbCr": A reference to the method of storing the value of a "Pixel"
	using three numeric values that represent the luma of the Pixel (Y)		by using three numeric values that represent the luma of the "Pixel"
	and the chrominance of the Pixel (Cb and Cr). YCbCr word is used for		(Y) and the chrominance of the "Pixel" (Cb and Cr). YCbCr word is
	historical reasons and currently references any color space relying		used for historical reasons and currently references any color space
	on 1 luma sample and 2 chrominance samples e.g. YCbCr, YCgCo or		relying on 1 luma "Sample" and 2 chrominance "Samples" e.g. YCbCr,
	ICtCp. Exact meaning of the three numeric values is unspecified.		YCgCo or ICtCp. Exact meaning of the three numeric values is
			unspecified.
	"TBA": To Be Announced. Used in reference to the development of		"TBA": To Be Announced. Used in reference to the development of
	future iterations of the FFV1 specification.		future iterations of the FFV1 specification.
	2.2. Conventions		2.2. Conventions
	2.2.1. Pseudo-code		2.2.1. Pseudo-code
	The FFV1 bitstream is described in this document using pseudo-code.		The FFV1 bitstream is described in this document using pseudo-code.
	Note that the pseudo-code is used for clarity in order to illustrate		Note that the pseudo-code is used for clarity in order to illustrate
	the structure of FFV1 and not intended to specify any particular		the structure of FFV1 and not intended to specify any particular
	skipping to change at page 9, line 11 ¶		skipping to change at page 9, line 11 ¶
	"byte_aligned( )" is true if "remaining_bits_in_bitstream( NumBytes		"byte_aligned( )" is true if "remaining_bits_in_bitstream( NumBytes
	)" is a multiple of 8, otherwise false.		)" is a multiple of 8, otherwise false.
	2.2.9.3. get_bits		2.2.9.3. get_bits
	"get_bits( i )" is the action to read the next "i" bits in the		"get_bits( i )" is the action to read the next "i" bits in the
	bitstream, from most significant bit to least significant bit, and to		bitstream, from most significant bit to least significant bit, and to
	return the corresponding value. The pointer is increased by "i".		return the corresponding value. The pointer is increased by "i".
	3. General Description		3. Sample Coding
	Samples within a plane are coded in raster scan order (left->right,		For each "Slice" (as described in Section 4.4) of a "Frame", the
	top->bottom). Each sample is predicted by the median predictor from		"Planes", "Lines", and "Samples" are coded in an order determined by
	samples in the same plane and the difference is stored see		the "Color Space" (see Section 3.7). Each "Sample" is predicted by
	Section 3.8.		the median predictor as described in Section 3.3 from other "Samples"
			within the same "Plane" and the difference is stored using the method
			described in Section 3.8.
	3.1. Border		3.1. Border
	A border is assumed for each coded slice for the purpose of the		A border is assumed for each coded "Slice" for the purpose of the
	predictor and context according to the following rules:		median predictor and context according to the following rules:
	o one column of samples to the left of the coded slice is assumed as		o one column of "Samples" to the left of the coded slice is assumed
	identical to the samples of the leftmost column of the coded slice		as identical to the "Samples" of the leftmost column of the coded
	shifted down by one row. The value of the topmost sample of the		slice shifted down by one row. The value of the topmost "Sample"
	column of samples to the left of the coded slice is assumed to be		of the column of "Samples" to the left of the coded slice is
	"0"		assumed to be "0"
	o one column of samples to the right of the coded slice is assumed		o one column of "Samples" to the right of the coded slice is assumed
	as identical to the samples of the rightmost column of the coded		as identical to the "Samples" of the rightmost column of the coded
	slice		slice
	o an additional column of samples to the left of the coded slice and		o an additional column of "Samples" to the left of the coded slice
	two rows of samples above the coded slice are assumed to be "0"		and two rows of "Samples" above the coded slice are assumed to be
			"0"
	The following table depicts a slice of samples "a,b,c,d,e,f,g,h,i"		The following table depicts a slice of 9 "Samples"
	along with its assumed border.		"a,b,c,d,e,f,g,h,i" in a 3x3 arrangement along with its assumed
			border.
	+---+---+---+---+---+---+---+---+		+---+---+---+---+---+---+---+---+
	| 0 | 0 | | 0 | 0 | 0 | | 0 |		| 0 | 0 | | 0 | 0 | 0 | | 0 |
	+---+---+---+---+---+---+---+---+		+---+---+---+---+---+---+---+---+
	| 0 | 0 | | 0 | 0 | 0 | | 0 |		| 0 | 0 | | 0 | 0 | 0 | | 0 |
	+---+---+---+---+---+---+---+---+		+---+---+---+---+---+---+---+---+
	| | | | | | | | |		| | | | | | | | |
	+---+---+---+---+---+---+---+---+		+---+---+---+---+---+---+---+---+
	| 0 | 0 | | a | b | c | | c |		| 0 | 0 | | a | b | c | | c |
	+---+---+---+---+---+---+---+---+		+---+---+---+---+---+---+---+---+
	| 0 | a | | d | e | f | | f |		| 0 | a | | d | e | f | | f |
	+---+---+---+---+---+---+---+---+		+---+---+---+---+---+---+---+---+
	| 0 | d | | g | h | i | | i |		| 0 | d | | g | h | i | | i |
	+---+---+---+---+---+---+---+---+		+---+---+---+---+---+---+---+---+
	3.2. Samples		3.2. Samples
	Positions used for context and median predictor are:		Relative to any "Sample" "X", six other relatively positioned
			"Samples" from the coded "Samples" and presumed border are identified
			according to the labels used in the following diagram. The labels
			for these relatively positioned "Samples" are used within the median
			predictor and context.
	+---+---+---+---+		+---+---+---+---+
	| | | T | |		| | | T | |
	+---+---+---+---+		+---+---+---+---+
	| |tl | t |tr |		| |tl | t |tr |
	+---+---+---+---+		+---+---+---+---+
	| L | l | X | |		| L | l | X | |
	+---+---+---+---+		+---+---+---+---+
	"X" is the current processed Sample. The identifiers are made of the		The labels for these relative "Samples" are made of the first letters
	first letters of the words Top, Left and Right.		of the words Top, Left and Right.
	3.3. Median Predictor		3.3. Median Predictor
	The prediction for any sample value at position "X" may be computed		The prediction for any "Sample" value at position "X" may be computed
	based upon the relative neighboring values of "l", "t", and "tl" via		based upon the relative neighboring values of "l", "t", and "tl" via
	this equation:		this equation:
	"median(l, t, l + t - tl)".		"median(l, t, l + t - tl)".
	Note, this prediction template is also used in [ISO.14495-1.1999] and		Note, this prediction template is also used in [ISO.14495-1.1999] and
	[HuffYUV].		[HuffYUV].
	Exception for the media predictor: if "colorspace_type == 0 &&		Exception for the median predictor: if "colorspace_type == 0 &&
	bits_per_raw_sample == 16 && ( coder_type == 1 || coder_type == 2 )",		bits_per_raw_sample == 16 && ( coder_type == 1 || coder_type == 2 )",
	the following media predictor MUST be used:		the following median predictor MUST be used:
	"median(left16s, top16s, left16s + top16s - diag16s)"		"median(left16s, top16s, left16s + top16s - diag16s)"
	where:		where:
	left16s = l >= 32768 ? ( l - 65536 ) : l		left16s = l >= 32768 ? ( l - 65536 ) : l
	top16s = t >= 32768 ? ( t - 65536 ) : t		top16s = t >= 32768 ? ( t - 65536 ) : t
	diag16s = tl >= 32768 ? ( tl - 65536 ) : tl		diag16s = tl >= 32768 ? ( tl - 65536 ) : tl
	Background: a two's complement signed 16-bit signed integer was used		Background: a two's complement signed 16-bit signed integer was used
	for storing sample values in all known implementations of FFV1		for storing "Sample" values in all known implementations of FFV1
	bitstream. So in some circumstances, the most significant bit was		bitstream. So in some circumstances, the most significant bit was
	wrongly interpreted (used as a sign bit instead of the 16th bit of an		wrongly interpreted (used as a sign bit instead of the 16th bit of an
	unsigned integer). Note that when the issue is discovered, the only		unsigned integer). Note that when the issue is discovered, the only
	configuration of all known implementations being impacted is 16-bit		configuration of all known implementations being impacted is 16-bit
	YCbCr with no Pixel transformation with Range Coder coder, as other		YCbCr with no Pixel transformation with Range Coder coder, as other
	potentially impacted configurations (e.g. 15/16-bit JPEG2000-RCT with		potentially impacted configurations (e.g. 15/16-bit JPEG2000-RCT with
	Range Coder coder, or 16-bit content with Golomb Rice coder) were		Range Coder coder, or 16-bit content with Golomb Rice coder) were
	implemented nowhere [ISO.15444-1.2016]. In the meanwhile, 16-bit		implemented nowhere [ISO.15444-1.2016]. In the meanwhile, 16-bit
	JPEG2000-RCT with Range Coder coder was implemented without this		JPEG2000-RCT with Range Coder coder was implemented without this
	issue in one implementation and validated by one conformance checker.		issue in one implementation and validated by one conformance checker.
	It is expected (to be confirmed) to remove this exception for the		It is expected (to be confirmed) to remove this exception for the
	media predictor in the next version of the FFV1 bitstream.		median predictor in the next version of the FFV1 bitstream.
	3.4. Context		3.4. Context
	Relative to any sample "X", the Quantized Sample Differences "L-l",		Relative to any "Sample" "X", the Quantized Sample Differences "L-l",
	"l-tl", "tl-t", "T-t", and "t-tr" are used as context:		"l-tl", "tl-t", "T-t", and "t-tr" are used as context:
	context = Q_{0}[l - tl] +		context = Q_{0}[l - tl] +
	Q_{1}[tl - t] +		Q_{1}[tl - t] +
	Q_{2}[t - tr] +		Q_{2}[t - tr] +
	Q_{3}[L - l] +		Q_{3}[L - l] +
	Q_{4}[T - t]		Q_{4}[T - t]
	If "context >= 0" then "context" is used and the difference between		If "context >= 0" then "context" is used and the difference between
	the sample and its predicted value is encoded as is, else "-context"		the "Sample" and its predicted value is encoded as is, else
	is used and the difference between the sample and its predicted value		"-context" is used and the difference between the "Sample" and its
	is encoded with a flipped sign.		predicted value is encoded with a flipped sign.
	3.5. Quantization Table Sets		3.5. Quantization Table Sets
	The FFV1 bitstream contains 1 or more Quantization Table Sets. Each		The FFV1 bitstream contains 1 or more Quantization Table Sets. Each
	Quantization Table Set contains exactly 5 Quantization Tables, each		Quantization Table Set contains exactly 5 Quantization Tables with
	Quantization Table corresponding to 1 of the 5 Quantized Sample		each Quantization Table corresponding to 1 of the 5 Quantized Sample
	Differences. For each Quantization Table, both the number of		Differences. For each Quantization Table, both the number of
	quantization steps and their distribution are stored in the FFV1		quantization steps and their distribution are stored in the FFV1
	bitstream; each Quantization Table has exactly 256 entries, and the 8		bitstream; each Quantization Table has exactly 256 entries, and the 8
	least significant bits of the Quantized Sample Difference are used as		least significant bits of the Quantized Sample Difference are used as
	index:		index:
	Q_{j}[k] = quant_tables[i][j][k&255]		Q_{j}[k] = quant_tables[i][j][k&255]
	In this formula, "i" is the Quantization Table Set index, "j" is the		In this formula, "i" is the Quantization Table Set index, "j" is the
	Quantized Table index, "k" the Quantized Sample Difference.		Quantized Table index, "k" the Quantized Sample Difference.
	3.6. Quantization Table Set Indexes		3.6. Quantization Table Set Indexes
	For each plane of each slice, a Quantization Table Set is selected		For each "Plane" of each slice, a Quantization Table Set is selected
	from an index:		from an index:
	o For Y plane, "quant_table_set_index [ 0 ]" index is used		o For Y "Plane", "quant_table_set_index [ 0 ]" index is used
	o For Cb and Cr planes, "quant_table_set_index [ 1 ]" index is used		o For Cb and Cr "Planes", "quant_table_set_index [ 1 ]" index is
			used
	o For Alpha plane, "quant_table_set_index [ (version <= 3 ||		o For Alpha "Plane", "quant_table_set_index [ (version <= 3 ||
	chroma_planes) ? 2 : 1 ]" index is used		chroma_planes) ? 2 : 1 ]" index is used
	Background: in first implementations of FFV1 bitstream, the index for		Background: in first implementations of FFV1 bitstream, the index for
	Cb and Cr planes was stored even if it is not used (chroma_planes set		Cb and Cr "Planes" was stored even if it is not used (chroma_planes
	to 0), this index is kept for version <= 3 in order to keep		set to 0), this index is kept for version <= 3 in order to keep
	compatibility with FFV1 bitstreams in the wild.		compatibility with FFV1 bitstreams in the wild.
	3.7. Color spaces		3.7. Color spaces
	FFV1 supports two color spaces: YCbCr and RGB. Both color spaces		FFV1 supports two color spaces: YCbCr and RGB. Both color spaces
	allow an optional Alpha plane that can be used to code transparency		allow an optional Alpha "Plane" that can be used to code transparency
	data.		data.
			The FFV1 bitstream interleaves data in an order determined by the
			color space. In YCbCr for each "Plane", each "Line" is coded from
			top to bottom and for each "Line", each "Sample" is coded from left
			to right. In JPEG2000-RCT for each "Line" from top to bottom, each
			"Plane" is coded and for each "Plane", each "Sample" is encoded from
			left to right.
	3.7.1. YCbCr		3.7.1. YCbCr
	In YCbCr color space, the Cb and Cr planes are optional, but if used		In YCbCr color space, the Cb and Cr "Planes" are optional, but if
	then MUST be used together. Omitting the Cb and Cr planes codes the		used then MUST be used together. Omitting the Cb and Cr "Planes"
	frames in grayscale without color data. An FFV1 "Frame" using YCbCr		codes the frames in grayscale without color data. An FFV1 "Frame"
	MUST use one of the following arrangements:		using YCbCr MUST use one of the following arrangements:
	o Y		o Y
	o Y, Alpha		o Y, Alpha
	o Y, Cb, Cr		o Y, Cb, Cr
	o Y, Cb, Cr, Alpha		o Y, Cb, Cr, Alpha
	The Y plane MUST be coded first. If the Cb and Cr planes are used		The Y "Plane" MUST be coded first. If the Cb and Cr "Planes" are
	then they MUST be coded after the Y plane. If an Alpha		used then they MUST be coded after the Y "Plane". If an Alpha
	(transparency) plane is used, then it MUST be coded last.		(transparency) "Plane" is used, then it MUST be coded last.
	3.7.2. RGB		3.7.2. RGB
	JPEG2000-RCT is a Reversible Color Transform that codes RGB (red,		JPEG2000-RCT is a Reversible Color Transform that codes RGB (red,
	green, blue) planes losslessly in a modified YCbCr color space		green, blue) "Planes" losslessly in a modified YCbCr color space
	[ISO.15444-1.2016]. Reversible Pixel transformations between YCbCr		[ISO.15444-1.2016]. Reversible Pixel transformations between YCbCr
	and RGB use the following formulae.		and RGB use the following formulae.
	Cb=b-g		Cb=b-g
	Cr=r-g		Cr=r-g
	Y=g+(Cb+Cr)>>2		Y=g+(Cb+Cr)>>2
	g=Y-(Cb+Cr)>>2		g=Y-(Cb+Cr)>>2
	skipping to change at page 13, line 24 ¶		skipping to change at page 14, line 4 ¶
	Y=b+(Cb+Cr)>>2		Y=b+(Cb+Cr)>>2
	b=Y-(Cb+Cr)>>2		b=Y-(Cb+Cr)>>2
	r=Cr+b		r=Cr+b
	g=Cb+b		g=Cb+b
	Background: At the time of this writing, in all known implementations		Background: At the time of this writing, in all known implementations
	of FFV1 bitstream, when bits_per_raw_sample was between 9 and 15		of FFV1 bitstream, when bits_per_raw_sample was between 9 and 15
	inclusive and alpha_plane is 0, GBR planes were used as BGR planes		inclusive and alpha_plane is 0, GBR "Planes" were used as BGR
	during both encoding and decoding. In the meanwhile, 16-bit		"Planes" during both encoding and decoding. In the meanwhile, 16-bit
	JPEG2000-RCT was implemented without this issue in one implementation		JPEG2000-RCT was implemented without this issue in one implementation
	and validated by one conformance checker. Methods to address this		and validated by one conformance checker. Methods to address this
	exception for the transform are under consideration for the next		exception for the transform are under consideration for the next
	version of the FFV1 bitstream.		version of the FFV1 bitstream.
	When FFV1 uses the JPEG2000-RCT, the horizontal lines are interleaved		When FFV1 uses the JPEG2000-RCT, the horizontal "Lines" are
	to improve caching efficiency since it is most likely that the RCT		interleaved to improve caching efficiency since it is most likely
	will immediately be converted to RGB during decoding. The		that the JPEG2000-RCT will immediately be converted to RGB during
	interleaved coding order is also Y, then Cb, then Cr, and then if		decoding. The interleaved coding order is also Y, then Cb, then Cr,
	used Alpha.		and then if used Alpha.
	As an example, a "Frame" that is two pixels wide and two pixels high,		As an example, a "Frame" that is two "Pixels" wide and two "Pixels"
	could be comprised of the following structure:		high, could be comprised of the following structure:
	+------------------------+------------------------+		+------------------------+------------------------+
	| Pixel[1,1] | Pixel[2,1] |		| Pixel[1,1] | Pixel[2,1] |
	| Y[1,1] Cb[1,1] Cr[1,1] | Y[2,1] Cb[2,1] Cr[2,1] |		| Y[1,1] Cb[1,1] Cr[1,1] | Y[2,1] Cb[2,1] Cr[2,1] |
	+------------------------+------------------------+		+------------------------+------------------------+
	| Pixel[1,2] | Pixel[2,2] |		| Pixel[1,2] | Pixel[2,2] |
	| Y[1,2] Cb[1,2] Cr[1,2] | Y[2,2] Cb[2,2] Cr[2,2] |		| Y[1,2] Cb[1,2] Cr[1,2] | Y[2,2] Cb[2,2] Cr[2,2] |
	+------------------------+------------------------+		+------------------------+------------------------+
	In JPEG2000-RCT, the coding order would be left to right and then top		In JPEG2000-RCT, the coding order would be left to right and then top
	to bottom, with values interleaved by lines and stored in this order:		to bottom, with values interleaved by "Lines" and stored in this
			order:
	Y[1,1] Y[2,1] Cb[1,1] Cb[2,1] Cr[1,1] Cr[2,1] Y[1,2] Y[2,2] Cb[1,2]		Y[1,1] Y[2,1] Cb[1,1] Cb[2,1] Cr[1,1] Cr[2,1] Y[1,2] Y[2,2] Cb[1,2]
	Cb[2,2] Cr[1,2] Cr[2,2]		Cb[2,2] Cr[1,2] Cr[2,2]
	3.8. Coding of the Sample Difference		3.8. Coding of the Sample Difference
	Instead of coding the n+1 bits of the Sample Difference with Huffman		Instead of coding the n+1 bits of the Sample Difference with Huffman
	or Range coding (or n+2 bits, in the case of RCT), only the n (or		or Range coding (or n+2 bits, in the case of JPEG2000-RCT), only the
	n+1) least significant bits are used, since this is sufficient to		n (or n+1, in the case of JPEG2000-RCT) least significant bits are
	recover the original sample. In the equation below, the term "bits"		used, since this is sufficient to recover the original "Sample". In
	represents bits_per_raw_sample+1 for RCT or bits_per_raw_sample		the equation below, the term "bits" represents bits_per_raw_sample+1
	otherwise:		for JPEG2000-RCT or bits_per_raw_sample otherwise:
	coder_input =		coder_input =
	[(sample_difference + 2^(bits-1)) & (2^bits - 1)] - 2^(bits-1)		[(sample_difference + 2^(bits-1)) & (2^bits - 1)] - 2^(bits-1)
	3.8.1. Range Coding Mode		3.8.1. Range Coding Mode
	Early experimental versions of FFV1 used the CABAC Arithmetic coder		Early experimental versions of FFV1 used the CABAC Arithmetic coder
	from H.264 as defined in [ISO.14496-10.2014] but due to the uncertain		from H.264 as defined in [ISO.14496-10.2014] but due to the uncertain
	patent/royalty situation, as well as its slightly worse performance,		patent/royalty situation, as well as its slightly worse performance,
	CABAC was replaced by a Range coder based on an algorithm defined by		CABAC was replaced by a Range coder based on an algorithm defined by
	skipping to change at page 17, line 9 ¶		skipping to change at page 17, line 40 ¶
	210,211,212,213,215,215,216,217,218,219,220,220,222,223,224,225,		210,211,212,213,215,215,216,217,218,219,220,220,222,223,224,225,
	226,227,227,229,229,230,231,232,234,234,235,236,237,238,239,240,		226,227,227,229,229,230,231,232,234,234,235,236,237,238,239,240,
	241,242,243,244,245,246,247,248,248, 0, 0, 0, 0, 0, 0, 0,		241,242,243,244,245,246,247,248,248, 0, 0, 0, 0, 0, 0, 0,
	3.8.1.6. Alternative State Transition Table		3.8.1.6. Alternative State Transition Table
	The alternative state transition table has been built using iterative		The alternative state transition table has been built using iterative
	minimization of frame sizes and generally performs better than the		minimization of frame sizes and generally performs better than the
	default. To use it, the coder_type MUST be set to 2 and the		default. To use it, the coder_type (see Section 4.1.3) MUST be set
	difference to the default MUST be stored in the "Parameters", see		to 2 and the difference to the default MUST be stored in the
	Section 4.1. The reference implementation of FFV1 in FFmpeg uses		"Parameters", see Section 4.1. The reference implementation of FFV1
	this table by default at the time of this writing when Range coding		in FFmpeg uses this table by default at the time of this writing when
	is used.		Range coding is used.
	0, 10, 10, 10, 10, 16, 16, 16, 28, 16, 16, 29, 42, 49, 20, 49,		0, 10, 10, 10, 10, 16, 16, 16, 28, 16, 16, 29, 42, 49, 20, 49,
	59, 25, 26, 26, 27, 31, 33, 33, 33, 34, 34, 37, 67, 38, 39, 39,		59, 25, 26, 26, 27, 31, 33, 33, 33, 34, 34, 37, 67, 38, 39, 39,
	40, 40, 41, 79, 43, 44, 45, 45, 48, 48, 64, 50, 51, 52, 88, 52,		40, 40, 41, 79, 43, 44, 45, 45, 48, 48, 64, 50, 51, 52, 88, 52,
	53, 74, 55, 57, 58, 58, 74, 60,101, 61, 62, 84, 66, 66, 68, 69,		53, 74, 55, 57, 58, 58, 74, 60,101, 61, 62, 84, 66, 66, 68, 69,
	87, 82, 71, 97, 73, 73, 82, 75,111, 77, 94, 78, 87, 81, 83, 97,		87, 82, 71, 97, 73, 73, 82, 75,111, 77, 94, 78, 87, 81, 83, 97,
	skipping to change at page 19, line 5 ¶		skipping to change at page 19, line 48 ¶
	Run mode is entered when the context is 0 and left as soon as a non-0		Run mode is entered when the context is 0 and left as soon as a non-0
	difference is found. The level is identical to the predicted one.		difference is found. The level is identical to the predicted one.
	The run and the first different level are coded.		The run and the first different level are coded.
	3.8.2.5. Run Length Coding		3.8.2.5. Run Length Coding
	The run value is encoded in 2 parts, the prefix part stores the more		The run value is encoded in 2 parts, the prefix part stores the more
	significant part of the run as well as adjusting the run_index that		significant part of the run as well as adjusting the run_index that
	determines the number of bits in the less significant part of the		determines the number of bits in the less significant part of the
	run. The 2nd part of the value stores the less significant part of		run. The 2nd part of the value stores the less significant part of
	the run as it is. The run_index is reset for each plane and slice to		the run as it is. The run_index is reset for each "Plane" and slice
	0.		to 0.
	pseudo-code | type		pseudo-code | type
	--------------------------------------------------------------|-----		--------------------------------------------------------------|-----
	log2_run[41]={ |		log2_run[41]={ |
	0, 0, 0, 0, 1, 1, 1, 1, |		0, 0, 0, 0, 1, 1, 1, 1, |
	2, 2, 2, 2, 3, 3, 3, 3, |		2, 2, 2, 2, 3, 3, 3, 3, |
	4, 4, 5, 5, 6, 6, 7, 7, |		4, 4, 5, 5, 6, 6, 7, 7, |
	8, 9,10,11,12,13,14,15, |		8, 9,10,11,12,13,14,15, |
	16,17,18,19,20,21,22,23, |		16,17,18,19,20,21,22,23, |
	24, |		24, |
	skipping to change at page 19, line 47 ¶		skipping to change at page 20, line 44 ¶
	3.8.2.6. Level Coding		3.8.2.6. Level Coding
	Level coding is identical to the normal difference coding with the		Level coding is identical to the normal difference coding with the
	exception that the 0 value is removed as it cannot occur:		exception that the 0 value is removed as it cannot occur:
	if (diff>0) diff--;		if (diff>0) diff--;
	encode(diff);		encode(diff);
	Note, this is different from JPEG-LS, which doesn't use prediction in		Note, this is different from JPEG-LS, which doesn't use prediction in
	run mode and uses a different encoding and context model for the last		run mode and uses a different encoding and context model for the last
	difference On a small set of test samples the use of prediction		difference On a small set of test "Samples" the use of prediction
	slightly improved the compression rate.		slightly improved the compression rate.
	4. Bitstream		4. Bitstream
			An FFV1 bitstream is composed of a series of 1 or more "Frames" and
			(when required) a "Configuration Record".
			Within the following sub-sections, pseudo-code is used to explain the
			structure of each FFV1 bitstream component, as described in
			Section 2.2.1. The following table lists symbols used to annotate
			that pseudo-code in order to define the storage of the data
			referenced in that line of pseudo-code.
	+--------+----------------------------------------------------------+		+--------+----------------------------------------------------------+
	| Symbol | Definition |		| Symbol | Definition |
	+--------+----------------------------------------------------------+		+--------+----------------------------------------------------------+
	| u(n) | unsigned big endian integer using n bits |		| u(n) | unsigned big endian integer using n bits |
	| sg | Golomb Rice coded signed scalar symbol coded with the |		| sg | Golomb Rice coded signed scalar symbol coded with the |
	| | method described in Section 3.8.2 |		| | method described in Section 3.8.2 |
	| br | Range coded Boolean (1-bit) symbol with the method |		| br | Range coded Boolean (1-bit) symbol with the method |
	| | described in Section 3.8.1.1 |		| | described in Section 3.8.1.1 |
	| ur | Range coded unsigned scalar symbol coded with the method |		| ur | Range coded unsigned scalar symbol coded with the method |
	| | described in Section 3.8.1.2 |		| | described in Section 3.8.1.2 |
	| sr | Range coded signed scalar symbol coded with the method |		| sr | Range coded signed scalar symbol coded with the method |
	| | described in Section 3.8.1.2 |		| | described in Section 3.8.1.2 |
	+--------+----------------------------------------------------------+		+--------+----------------------------------------------------------+
	The same context that is initialized to 128 is used for all fields in		The same context that is initialized to 128 is used for all fields in
	the header.		the header.
	The following MUST be provided by external means during		The following MUST be provided by external means during
	initialization of the decoder:		initialization of the decoder:
	"frame_pixel_width" is defined as "Frame" width in pixels.		"frame_pixel_width" is defined as "Frame" width in "Pixels".
	"frame_pixel_height" is defined as "Frame" height in pixels.		"frame_pixel_height" is defined as "Frame" height in "Pixels".
	Default values at the decoder initialization phase:		Default values at the decoder initialization phase:
	"ConfigurationRecordIsPresent" is set to 0.		"ConfigurationRecordIsPresent" is set to 0.
	4.1. Parameters		4.1. Parameters
	The "Parameters" section contains significant characteristics used		The "Parameters" section contains significant characteristics about
	for all instances of "Frame". The pseudo-code below describes the		the decoding configuration used for all instances of "Frame" (in FFV1
	contents of the bitstream.		version 0 and 1) or the whole FFV1 bitstream (other versions),
			including the stream version, color configuration, and quantization
			tables. The pseudo-code below describes the contents of the
			bitstream.
	pseudo-code | type		pseudo-code | type
	--------------------------------------------------------------|-----		--------------------------------------------------------------|-----
	Parameters( ) { |		Parameters( ) { |
	version | ur		version | ur
	if (version >= 3) |		if (version >= 3) |
	micro_version | ur		micro_version | ur
	coder_type | ur		coder_type | ur
	if (coder_type > 1) |		if (coder_type > 1) |
	for (i = 1; i < 256; i++) |		for (i = 1; i < 256; i++) |
	skipping to change at page 23, line 15 ¶		skipping to change at page 24, line 15 ¶
	4.1.4. state_transition_delta		4.1.4. state_transition_delta
	"state_transition_delta" specifies the Range coder custom state		"state_transition_delta" specifies the Range coder custom state
	transition table.		transition table.
	If state_transition_delta is not present in the FFV1 bitstream, all		If state_transition_delta is not present in the FFV1 bitstream, all
	Range coder custom state transition table elements are assumed to be		Range coder custom state transition table elements are assumed to be
	0.		0.
	4.1.5. colorspace_type		4.1.5. colorspace_type
	"colorspace_type" specifies color space losslessly encoded, Pixel		"colorspace_type" specifies the color space losslessly encoded, the
	transformation used by the encoder, as well as interleave method.		Pixel transformation used by the encoder, as well as interleave
			method.
	+-------+---------------------+------------------+------------------+		+-------+---------------------+------------------+------------------+
	| value | color space | transformation | interleave |		| value | color space | transformation | interleave |
	| | losslessly encoded | | method |		| | losslessly encoded | | method |
	+-------+---------------------+------------------+------------------+		+-------+---------------------+------------------+------------------+
	| 0 | YCbCr | No Pixel | plane then line |		| 0 | YCbCr | No Pixel | "Plane" then |
	| | | transformation | |		| | | transformation | "Line" |
	| 1 | RGB | JPEG2000-RCT | line then plane |		| 1 | RGB | JPEG2000-RCT | "Line" then |
			| | | | "Plane" |
	| Other | reserved for future | reserved for | reserved for |		| Other | reserved for future | reserved for | reserved for |
	| | use | future use | future use |		| | use | future use | future use |
	+-------+---------------------+------------------+------------------+		+-------+---------------------+------------------+------------------+
	Restrictions:		Restrictions:
	If "colorspace_type" is 1, then "chroma_planes" MUST be 1,		If "colorspace_type" is 1, then "chroma_planes" MUST be 1,
	"log2_h_chroma_subsample" MUST be 0, and "log2_v_chroma_subsample"		"log2_h_chroma_subsample" MUST be 0, and "log2_v_chroma_subsample"
	MUST be 0.		MUST be 0.
	4.1.6. chroma_planes		4.1.6. chroma_planes
	"chroma_planes" indicates if chroma (color) planes are present.		"chroma_planes" indicates if chroma (color) "Planes" are present.
	+-------+-------------------------------+		+-------+---------------------------------+
	| value | presence |		| value | presence |
	+-------+-------------------------------+		+-------+---------------------------------+
	| 0 | chroma planes are not present |		| 0 | chroma "Planes" are not present |
	| 1 | chroma planes are present |		| 1 | chroma "Planes" are present |
	+-------+-------------------------------+		+-------+---------------------------------+
	4.1.7. bits_per_raw_sample		4.1.7. bits_per_raw_sample
	"bits_per_raw_sample" indicates the number of bits for each sample.		"bits_per_raw_sample" indicates the number of bits for each "Sample".
	Inferred to be 8 if not present.		Inferred to be 8 if not present.
	+-------+---------------------------------+		+-------+-----------------------------------+
	| value | bits for each sample |		| value | bits for each sample |
	+-------+---------------------------------+		+-------+-----------------------------------+
	| 0 | reserved* |		| 0 | reserved* |
	| Other | the actual bits for each sample |		| Other | the actual bits for each "Sample" |
	+-------+---------------------------------+		+-------+-----------------------------------+
	* Encoders MUST NOT store bits_per_raw_sample = 0 Decoders SHOULD		* Encoders MUST NOT store bits_per_raw_sample = 0 Decoders SHOULD
	accept and interpret bits_per_raw_sample = 0 as 8.		accept and interpret bits_per_raw_sample = 0 as 8.
	4.1.8. log2_h_chroma_subsample		4.1.8. log2_h_chroma_subsample
	"log2_h_chroma_subsample" indicates the subsample factor, stored in		"log2_h_chroma_subsample" indicates the subsample factor, stored in
	powers to which the number 2 must be raised, between luma and chroma		powers to which the number 2 must be raised, between luma and chroma
	width ("chroma_width = 2^(-log2_h_chroma_subsample) * luma_width").		width ("chroma_width = 2^(-log2_h_chroma_subsample) * luma_width").
	4.1.9. log2_v_chroma_subsample		4.1.9. log2_v_chroma_subsample
	"log2_v_chroma_subsample" indicates the subsample factor, stored in		"log2_v_chroma_subsample" indicates the subsample factor, stored in
	powers to which the number 2 must be raised, between luma and chroma		powers to which the number 2 must be raised, between luma and chroma
	height ("chroma_height=2^(-log2_v_chroma_subsample) * luma_height").		height ("chroma_height=2^(-log2_v_chroma_subsample) * luma_height").
	4.1.10. alpha_plane		4.1.10. alpha_plane
	"alpha_plane" indicates if a transparency plane is present.		"alpha_plane" indicates if a transparency "Plane" is present.
	+-------+-----------------------------------+		+-------+-------------------------------------+
	| value | presence |		| value | presence |
	+-------+-----------------------------------+		+-------+-------------------------------------+
	| 0 | transparency plane is not present |		| 0 | transparency "Plane" is not present |
	| 1 | transparency plane is present |		| 1 | transparency "Plane" is present |
	+-------+-----------------------------------+		+-------+-------------------------------------+
	4.1.11. num_h_slices		4.1.11. num_h_slices
	"num_h_slices" indicates the number of horizontal elements of the		"num_h_slices" indicates the number of horizontal elements of the
	slice raster.		slice raster.
	Inferred to be 1 if not present.		Inferred to be 1 if not present.
	4.1.12. num_v_slices		4.1.12. num_v_slices
	"num_v_slices" indicates the number of vertical elements of the slice		"num_v_slices" indicates the number of vertical elements of the slice
	skipping to change at page 28, line 10 ¶		skipping to change at page 29, line 10 ¶
	versions 2 or less, the Matroska "CodecPrivate" Element SHOULD NOT be		versions 2 or less, the Matroska "CodecPrivate" Element SHOULD NOT be
	used. For FFV1 versions 3 or greater, the Matroska "CodecPrivate"		used. For FFV1 versions 3 or greater, the Matroska "CodecPrivate"
	Element MUST contain the FFV1 "Configuration Record" structure and no		Element MUST contain the FFV1 "Configuration Record" structure and no
	other data. See [Matroska] for more information about elements.		other data. See [Matroska] for more information about elements.
	"NumBytes" is defined as the "Element Data Size" of the		"NumBytes" is defined as the "Element Data Size" of the
	"CodecPrivate" Element.		"CodecPrivate" Element.
	4.3. Frame		4.3. Frame
			A "Frame" is an encoded representation of a complete static image.
			The whole "Frame" is provided by the underlaying container.
	A "Frame" consists of the keyframe field, "Parameters" (if version		A "Frame" consists of the keyframe field, "Parameters" (if version
	<=1), and a sequence of independent slices.		<=1), and a sequence of independent slices. The pseudo-code below
			describes the contents of a "Frame".
	pseudo-code | type		pseudo-code | type
	--------------------------------------------------------------|-----		--------------------------------------------------------------|-----
	Frame( NumBytes ) { |		Frame( NumBytes ) { |
	keyframe | br		keyframe | br
	if (keyframe && !ConfigurationRecordIsPresent |		if (keyframe && !ConfigurationRecordIsPresent |
	Parameters( ) |		Parameters( ) |
	while ( remaining_bits_in_bitstream( NumBytes ) ) |		while ( remaining_bits_in_bitstream( NumBytes ) ) |
	Slice( ) |		Slice( ) |
	} |		} |
	skipping to change at page 29, line 4 ¶		skipping to change at page 29, line 46 ¶
	| second slice footer |		| second slice footer |
	| --------------------------------------------------------------- |		| --------------------------------------------------------------- |
	| ... |		| ... |
	| --------------------------------------------------------------- |		| --------------------------------------------------------------- |
	| last slice header |		| last slice header |
	| last slice content |		| last slice content |
	| last slice footer |		| last slice footer |
	+-----------------------------------------------------------------+		+-----------------------------------------------------------------+
	4.4. Slice		4.4. Slice
			A "Slice" is an independent spatial sub-section of a "Frame" that is
			encoded separately from an other region of the same "Frame". The use
			of more than one "Slice" per "Frame" can be useful for taking
			advantage of the opportunities of multithreaded encoding and
			decoding.
			A "Slice" consists of a "Slice Header" (when relevant), a "Slice
			Content", and a "Slice Footer" (when relevant). The pseudo-code
			below describes the contents of a "Slice".
	pseudo-code | type		pseudo-code | type
	--------------------------------------------------------------|-----		--------------------------------------------------------------|-----
	Slice( ) { |		Slice( ) { |
	if (version >= 3) |		if (version >= 3) |
	SliceHeader( ) |		SliceHeader( ) |
	SliceContent( ) |		SliceContent( ) |
	if (coder_type == 0) |		if (coder_type == 0) |
	while (!byte_aligned()) |		while (!byte_aligned()) |
	padding | u(1)		padding | u(1)
	if (version <= 1) { |		if (version <= 1) { |
	skipping to change at page 30, line 4 ¶		skipping to change at page 30, line 44 ¶
	Note in case these bits are used in a later revision of this		Note in case these bits are used in a later revision of this
	specification: any revision of this specification SHOULD care about		specification: any revision of this specification SHOULD care about
	avoiding to add 40 bits of content after "SliceContent" for version 0		avoiding to add 40 bits of content after "SliceContent" for version 0
	and 1 of the bitstream. Background: due to some non conforming		and 1 of the bitstream. Background: due to some non conforming
	encoders, some bitstreams where found with 40 extra bits		encoders, some bitstreams where found with 40 extra bits
	corresponding to "error_status" and "slice_crc_parity", a decoder		corresponding to "error_status" and "slice_crc_parity", a decoder
	conforming to the revised specification could not do the difference		conforming to the revised specification could not do the difference
	between a revised bitstream and a buggy bitstream.		between a revised bitstream and a buggy bitstream.
	4.5. Slice Header		4.5. Slice Header
			A "Slice Header" provides information about the decoding
			configuration of the "Slice", such as its spatial position, size, and
			aspect ratio. The pseudo-code below describes the contents of the
			"Slice Header".
	pseudo-code | type		pseudo-code | type
	--------------------------------------------------------------|-----		--------------------------------------------------------------|-----
	SliceHeader( ) { |		SliceHeader( ) { |
	slice_x | ur		slice_x | ur
	slice_y | ur		slice_y | ur
	slice_width - 1 | ur		slice_width - 1 | ur
	slice_height - 1 | ur		slice_height - 1 | ur
	for( i = 0; i < quant_table_set_index_count; i++ ) |		for( i = 0; i < quant_table_set_index_count; i++ ) |
	quant_table_set_index [ i ] | ur		quant_table_set_index [ i ] | ur
	picture_structure | ur		picture_structure | ur
	skipping to change at page 31, line 10 ¶		skipping to change at page 32, line 10 ¶
	"quant_table_set_index" indicates the Quantization Table Set index to		"quant_table_set_index" indicates the Quantization Table Set index to
	select the Quantization Table Set and the initial states for the		select the Quantization Table Set and the initial states for the
	slice.		slice.
	Inferred to be 0 if not present.		Inferred to be 0 if not present.
	4.5.7. picture_structure		4.5.7. picture_structure
	"picture_structure" specifies the temporal and spatial relationship		"picture_structure" specifies the temporal and spatial relationship
	of each line of the "Frame".		of each "Line" of the "Frame".
	Inferred to be 0 if not present.		Inferred to be 0 if not present.
	+-------+-------------------------+		+-------+-------------------------+
	| value | picture structure used |		| value | picture structure used |
	+-------+-------------------------+		+-------+-------------------------+
	| 0 | unknown |		| 0 | unknown |
	| 1 | top field first |		| 1 | top field first |
	| 2 | bottom field first |		| 2 | bottom field first |
	| 3 | progressive |		| 3 | progressive |
	| Other | reserved for future use |		| Other | reserved for future use |
	+-------+-------------------------+		+-------+-------------------------+
	4.5.8. sar_num		4.5.8. sar_num
	"sar_num" specifies the sample aspect ratio numerator.		"sar_num" specifies the "Sample" aspect ratio numerator.
	Inferred to be 0 if not present.		Inferred to be 0 if not present.
	MUST be 0 if sample aspect ratio is unknown.		A value of 0 means that aspect ratio is unknown.
			Encoders MUST write 0 if "Sample" aspect ratio is unknown.
			If "sar_den" is 0, decoders SHOULD ignore the encoded value and
			consider that "sar_num" is 0.
	4.5.9. sar_den		4.5.9. sar_den
	"sar_den" specifies the sample aspect ratio denominator.		"sar_den" specifies the "Sample" aspect ratio denominator.
	Inferred to be 0 if not present.		Inferred to be 0 if not present.
	MUST be 0 if sample aspect ratio is unknown.		A value of 0 means that aspect ratio is unknown.
			Encoders MUST write 0 if "Sample" aspect ratio is unknown.
			If "sar_num" is 0, decoders SHOULD ignore the encoded value and
			consider that "sar_den" is 0.
	4.6. Slice Content		4.6. Slice Content
			A "Slice Content" contains all "Line" elements part of the "Slice".
			Depending on the configuration, "Line" elements are ordered by
			"Plane" then by row (YCbCr) or by row then by "Plane" (RGB).
	pseudo-code | type		pseudo-code | type
	--------------------------------------------------------------|-----		--------------------------------------------------------------|-----
	SliceContent( ) { |		SliceContent( ) { |
	if (colorspace_type == 0) { |		if (colorspace_type == 0) { |
	for( p = 0; p < primary_color_count; p++ ) |		for( p = 0; p < primary_color_count; p++ ) |
	for( y = 0; y < plane_pixel_height[ p ]; y++ ) |		for( y = 0; y < plane_pixel_height[ p ]; y++ ) |
	Line( p, y ) |		Line( p, y ) |
	} else if (colorspace_type == 1) { |		} else if (colorspace_type == 1) { |
	for( y = 0; y < slice_pixel_height; y++ ) |		for( y = 0; y < slice_pixel_height; y++ ) |
	for( p = 0; p < primary_color_count; p++ ) |		for( p = 0; p < primary_color_count; p++ ) |
	skipping to change at page 32, line 33 ¶		skipping to change at page 33, line 47 ¶
	Its value is "floor(( slice_y + slice_height ) * slice_pixel_height /		Its value is "floor(( slice_y + slice_height ) * slice_pixel_height /
	num_v_slices) - slice_pixel_y".		num_v_slices) - slice_pixel_y".
	4.6.4. slice_pixel_y		4.6.4. slice_pixel_y
	"slice_pixel_y" is the slice vertical position in pixels.		"slice_pixel_y" is the slice vertical position in pixels.
	Its value is "floor(slice_y * frame_pixel_height / num_v_slices)".		Its value is "floor(slice_y * frame_pixel_height / num_v_slices)".
	4.7. Line		4.7. Line
			A "Line" is a list of the sample differences (relative to the
			predictor) of primary color components. The pseudo-code below
			describes the contents of the "Line".
	pseudo-code | type		pseudo-code | type
	--------------------------------------------------------------|-----		--------------------------------------------------------------|-----
	Line( p, y ) { |		Line( p, y ) { |
	if (colorspace_type == 0) { |		if (colorspace_type == 0) { |
	for( x = 0; x < plane_pixel_width[ p ]; x++ ) |		for( x = 0; x < plane_pixel_width[ p ]; x++ ) |
	sample_difference[ p ][ y ][ x ] |		sample_difference[ p ][ y ][ x ] |
	} else if (colorspace_type == 1) { |		} else if (colorspace_type == 1) { |
	for( x = 0; x < slice_pixel_width; x++ ) |		for( x = 0; x < slice_pixel_width; x++ ) |
	sample_difference[ p ][ y ][ x ] |		sample_difference[ p ][ y ][ x ] |
	} |		} |
	} |		} |
	4.7.1. plane_pixel_width		4.7.1. plane_pixel_width
	"plane_pixel_width[ p ]" is the width in pixels of plane p of the		"plane_pixel_width[ p ]" is the width in "Pixels" of "Plane" p of the
	slice.		slice.
	"plane_pixel_width[ 0 ]" and "plane_pixel_width[ 1 + ( chroma_planes		"plane_pixel_width[ 0 ]" and "plane_pixel_width[ 1 + ( chroma_planes
	? 2 : 0 ) ]" value is "slice_pixel_width".		? 2 : 0 ) ]" value is "slice_pixel_width".
	If "chroma_planes" is set to 1, "plane_pixel_width[ 1 ]" and		If "chroma_planes" is set to 1, "plane_pixel_width[ 1 ]" and
	"plane_pixel_width[ 2 ]" value is "ceil(slice_pixel_width / (1 <<		"plane_pixel_width[ 2 ]" value is "ceil(slice_pixel_width / (1 <<
	log2_h_chroma_subsample))".		log2_h_chroma_subsample))".
	4.7.2. slice_pixel_width		4.7.2. slice_pixel_width
	"slice_pixel_width" is the width in pixels of the slice.		"slice_pixel_width" is the width in "Pixels" of the slice.
	Its value is "floor(( slice_x + slice_width ) * slice_pixel_width /		Its value is "floor(( slice_x + slice_width ) * slice_pixel_width /
	num_h_slices) - slice_pixel_x".		num_h_slices) - slice_pixel_x".
	4.7.3. slice_pixel_x		4.7.3. slice_pixel_x
	"slice_pixel_x" is the slice horizontal position in pixels.		"slice_pixel_x" is the slice horizontal position in "Pixels".
	Its value is "floor(slice_x * frame_pixel_width / num_h_slices)".		Its value is "floor(slice_x * frame_pixel_width / num_h_slices)".
	4.7.4. sample_difference		4.7.4. sample_difference
	"sample_difference[ p ][ y ][ x ]" is the sample difference for		"sample_difference[ p ][ y ][ x ]" is the sample difference for
	sample at plane "p", y position "y", and x position "x". The sample		"Sample" at "Plane" "p", y position "y", and x position "x". The
	value is computed based on prediction and context described in		"Sample" value is computed based on median predictor and context
	Section 3.2.		described in Section 3.2.
	4.8. Slice Footer		4.8. Slice Footer
	Note: slice footer is always byte aligned.		A "Slice Footer" provides information about slice size and
			(optionally) parity. The pseudo-code below describes the contents of
			the "Slice Header".
			Note: "Slice Footer" is always byte aligned.
	pseudo-code | type		pseudo-code | type
	--------------------------------------------------------------|-----		--------------------------------------------------------------|-----
	SliceFooter( ) { |		SliceFooter( ) { |
	slice_size | u(24)		slice_size | u(24)
	if (ec) { |		if (ec) { |
	error_status | u(8)		error_status | u(8)
	slice_crc_parity | u(32)		slice_crc_parity | u(32)
	} |		} |
	} |		} |
	skipping to change at page 35, line 43 ¶		skipping to change at page 37, line 16 ¶
	"context_count[ i ]" indicates the count of contexts for Quantization		"context_count[ i ]" indicates the count of contexts for Quantization
	Table Set "i".		Table Set "i".
	5. Restrictions		5. Restrictions
	To ensure that fast multithreaded decoding is possible, starting		To ensure that fast multithreaded decoding is possible, starting
	version 3 and if frame_pixel_width * frame_pixel_height is more than		version 3 and if frame_pixel_width * frame_pixel_height is more than
	101376, slice_width * slice_height MUST be less or equal to		101376, slice_width * slice_height MUST be less or equal to
	num_h_slices * num_v_slices / 4. Note: 101376 is the frame size in		num_h_slices * num_v_slices / 4. Note: 101376 is the frame size in
	pixels of a 352x288 frame also known as CIF ("Common Intermediate		"Pixels" of a 352x288 frame also known as CIF ("Common Intermediate
	Format") frame size format.		Format") frame size format.
	For each "Frame", each position in the slice raster MUST be filled by		For each "Frame", each position in the slice raster MUST be filled by
	one and only one slice of the "Frame" (no missing slice position, no		one and only one slice of the "Frame" (no missing slice position, no
	slice overlapping).		slice overlapping).
	For each "Frame" with keyframe value of 0, each slice MUST have the		For each "Frame" with keyframe value of 0, each slice MUST have the
	same value of slice_x, slice_y, slice_width, slice_height as a slice		same value of slice_x, slice_y, slice_width, slice_height as a slice
	in the previous "Frame".		in the previous "Frame".
	skipping to change at page 36, line 21 ¶		skipping to change at page 37, line 43 ¶
	Implementations of the FFV1 codec need to take appropriate security		Implementations of the FFV1 codec need to take appropriate security
	considerations into account, as outlined in [RFC4732]. It is		considerations into account, as outlined in [RFC4732]. It is
	extremely important for the decoder to be robust against malicious		extremely important for the decoder to be robust against malicious
	payloads. Malicious payloads must not cause the decoder to overrun		payloads. Malicious payloads must not cause the decoder to overrun
	its allocated memory or to take an excessive amount of resources to		its allocated memory or to take an excessive amount of resources to
	decode. Although problems in encoders are typically rarer, the same		decode. Although problems in encoders are typically rarer, the same
	applies to the encoder. Malicious video streams must not cause the		applies to the encoder. Malicious video streams must not cause the
	encoder to misbehave because this would allow an attacker to attack		encoder to misbehave because this would allow an attacker to attack
	transcoding gateways. A frequent security problem in image and video		transcoding gateways. A frequent security problem in image and video
	codecs is also to not check for integer overflows in Pixel count		codecs is also to not check for integer overflows in "Pixel" count
	computations, that is to allocate width * height without considering		computations, that is to allocate width * height without considering
	that the multiplication result may have overflowed the arithmetic		that the multiplication result may have overflowed the arithmetic
	types range.		types range.
	The reference implementation [REFIMPL] contains no known buffer		The reference implementation [REFIMPL] contains no known buffer
	overflow or cases where a specially crafted packet or video segment		overflow or cases where a specially crafted packet or video segment
	could cause a significant increase in CPU load.		could cause a significant increase in CPU load.
	The reference implementation [REFIMPL] was validated in the following		The reference implementation [REFIMPL] was validated in the following
	conditions:		conditions:
	skipping to change at page 39, line 16 ¶		skipping to change at page 40, line 44 ¶
	See <https://github.com/FFmpeg/FFV1/commits/master>		See <https://github.com/FFmpeg/FFV1/commits/master>
	11. References		11. References
	11.1. Normative References		11.1. Normative References
	[I-D.ietf-cellar-ffv1]		[I-D.ietf-cellar-ffv1]
	Niedermayer, M., Rice, D., and J. Martinez, "FFV1 Video		Niedermayer, M., Rice, D., and J. Martinez, "FFV1 Video
	Coding Format Version 0, 1, and 3", draft-ietf-cellar-		Coding Format Version 0, 1, and 3", draft-ietf-cellar-
	ffv1-04 (work in progress), July 2018.		ffv1-05 (work in progress), September 2018.
	[ISO.15444-1.2016]		[ISO.15444-1.2016]
	International Organization for Standardization,		International Organization for Standardization,
	"Information technology -- JPEG 2000 image coding system:		"Information technology -- JPEG 2000 image coding system:
	Core coding system", October 2016.		Core coding system", October 2016.
	[ISO.9899.1990]		[ISO.9899.1990]
	International Organization for Standardization,		International Organization for Standardization,
	"Programming languages - C", ISO Standard 9899, 1990.		"Programming languages - C", ISO Standard 9899, 1990.
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