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
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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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
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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
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[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
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"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
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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( ) |
} | } |
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| 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) { |
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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
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"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)
} | } |
} | } |
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"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".
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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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