--- 1/draft-ietf-cellar-ffv1-14.txt 2020-06-23 13:14:44.355286128 -0700 +++ 2/draft-ietf-cellar-ffv1-15.txt 2020-06-23 13:14:44.451288672 -0700 @@ -1,20 +1,20 @@ cellar M. Niedermayer Internet-Draft Intended status: Informational D. Rice -Expires: 27 November 2020 +Expires: 25 December 2020 J. Martinez - 26 May 2020 + 23 June 2020 FFV1 Video Coding Format Version 0, 1, and 3 - draft-ietf-cellar-ffv1-14 + draft-ietf-cellar-ffv1-15 Abstract This document defines FFV1, a lossless intra-frame video encoding format. FFV1 is designed to efficiently compress video data in a variety of pixel formats. Compared to uncompressed video, FFV1 offers storage compression, frame fixity, and self-description, which makes FFV1 useful as a preservation or intermediate video format. Status of This Memo @@ -25,21 +25,21 @@ Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - This Internet-Draft will expire on 27 November 2020. + This Internet-Draft will expire on 25 December 2020. Copyright Notice Copyright (c) 2020 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights @@ -70,82 +70,82 @@ 3.4. Context . . . . . . . . . . . . . . . . . . . . . . . . . 11 3.5. Quantization Table Sets . . . . . . . . . . . . . . . . . 12 3.6. Quantization Table Set Indexes . . . . . . . . . . . . . 12 3.7. Color spaces . . . . . . . . . . . . . . . . . . . . . . 12 3.7.1. YCbCr . . . . . . . . . . . . . . . . . . . . . . . . 13 3.7.2. RGB . . . . . . . . . . . . . . . . . . . . . . . . . 13 3.8. Coding of the Sample Difference . . . . . . . . . . . . . 15 3.8.1. Range Coding Mode . . . . . . . . . . . . . . . . . . 15 3.8.2. Golomb Rice Mode . . . . . . . . . . . . . . . . . . 20 4. Bitstream . . . . . . . . . . . . . . . . . . . . . . . . . . 25 - 4.1. Parameters . . . . . . . . . . . . . . . . . . . . . . . 26 - 4.1.1. version . . . . . . . . . . . . . . . . . . . . . . . 28 - 4.1.2. micro_version . . . . . . . . . . . . . . . . . . . . 28 - 4.1.3. coder_type . . . . . . . . . . . . . . . . . . . . . 29 - 4.1.4. state_transition_delta . . . . . . . . . . . . . . . 29 - 4.1.5. colorspace_type . . . . . . . . . . . . . . . . . . . 30 - 4.1.6. chroma_planes . . . . . . . . . . . . . . . . . . . . 30 - 4.1.7. bits_per_raw_sample . . . . . . . . . . . . . . . . . 31 - 4.1.8. log2_h_chroma_subsample . . . . . . . . . . . . . . . 31 - 4.1.9. log2_v_chroma_subsample . . . . . . . . . . . . . . . 31 - 4.1.10. extra_plane . . . . . . . . . . . . . . . . . . . . . 31 - 4.1.11. num_h_slices . . . . . . . . . . . . . . . . . . . . 32 - 4.1.12. num_v_slices . . . . . . . . . . . . . . . . . . . . 32 - 4.1.13. quant_table_set_count . . . . . . . . . . . . . . . . 32 - 4.1.14. states_coded . . . . . . . . . . . . . . . . . . . . 32 - 4.1.15. initial_state_delta . . . . . . . . . . . . . . . . . 32 - 4.1.16. ec . . . . . . . . . . . . . . . . . . . . . . . . . 33 - 4.1.17. intra . . . . . . . . . . . . . . . . . . . . . . . . 33 - 4.2. Configuration Record . . . . . . . . . . . . . . . . . . 34 - 4.2.1. reserved_for_future_use . . . . . . . . . . . . . . . 34 - 4.2.2. configuration_record_crc_parity . . . . . . . . . . . 34 - 4.2.3. Mapping FFV1 into Containers . . . . . . . . . . . . 34 - 4.3. Frame . . . . . . . . . . . . . . . . . . . . . . . . . . 35 - 4.4. Slice . . . . . . . . . . . . . . . . . . . . . . . . . . 37 - 4.5. Slice Header . . . . . . . . . . . . . . . . . . . . . . 38 - 4.5.1. slice_x . . . . . . . . . . . . . . . . . . . . . . . 38 - 4.5.2. slice_y . . . . . . . . . . . . . . . . . . . . . . . 38 - 4.5.3. slice_width . . . . . . . . . . . . . . . . . . . . . 38 - 4.5.4. slice_height . . . . . . . . . . . . . . . . . . . . 38 - 4.5.5. quant_table_set_index_count . . . . . . . . . . . . . 39 - 4.5.6. quant_table_set_index . . . . . . . . . . . . . . . . 39 - 4.5.7. picture_structure . . . . . . . . . . . . . . . . . . 39 - 4.5.8. sar_num . . . . . . . . . . . . . . . . . . . . . . . 39 - 4.5.9. sar_den . . . . . . . . . . . . . . . . . . . . . . . 40 - 4.6. Slice Content . . . . . . . . . . . . . . . . . . . . . . 40 - 4.6.1. primary_color_count . . . . . . . . . . . . . . . . . 40 - 4.6.2. plane_pixel_height . . . . . . . . . . . . . . . . . 41 - 4.6.3. slice_pixel_height . . . . . . . . . . . . . . . . . 41 - 4.6.4. slice_pixel_y . . . . . . . . . . . . . . . . . . . . 41 - 4.7. Line . . . . . . . . . . . . . . . . . . . . . . . . . . 41 - 4.7.1. plane_pixel_width . . . . . . . . . . . . . . . . . . 41 - 4.7.2. slice_pixel_width . . . . . . . . . . . . . . . . . . 42 - 4.7.3. slice_pixel_x . . . . . . . . . . . . . . . . . . . . 42 - 4.7.4. sample_difference . . . . . . . . . . . . . . . . . . 42 - 4.8. Slice Footer . . . . . . . . . . . . . . . . . . . . . . 42 - 4.8.1. slice_size . . . . . . . . . . . . . . . . . . . . . 42 - 4.8.2. error_status . . . . . . . . . . . . . . . . . . . . 43 - 4.8.3. slice_crc_parity . . . . . . . . . . . . . . . . . . 43 - 4.9. Quantization Table Set . . . . . . . . . . . . . . . . . 43 - 4.9.1. quant_tables . . . . . . . . . . . . . . . . . . . . 44 - 4.9.2. context_count . . . . . . . . . . . . . . . . . . . . 44 - 5. Restrictions . . . . . . . . . . . . . . . . . . . . . . . . 45 - 6. Security Considerations . . . . . . . . . . . . . . . . . . . 45 - 7. Media Type Definition . . . . . . . . . . . . . . . . . . . . 46 - 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 47 - 9. Changelog . . . . . . . . . . . . . . . . . . . . . . . . . . 48 - 10. Normative References . . . . . . . . . . . . . . . . . . . . 48 - 11. Informative References . . . . . . . . . . . . . . . . . . . 49 - Appendix A. Multi-theaded decoder implementation suggestions . . 50 + 4.1. Quantization Table Set . . . . . . . . . . . . . . . . . 26 + 4.1.1. quant_tables . . . . . . . . . . . . . . . . . . . . 27 + 4.1.2. context_count . . . . . . . . . . . . . . . . . . . . 28 + 4.2. Parameters . . . . . . . . . . . . . . . . . . . . . . . 28 + 4.2.1. version . . . . . . . . . . . . . . . . . . . . . . . 30 + 4.2.2. micro_version . . . . . . . . . . . . . . . . . . . . 30 + 4.2.3. coder_type . . . . . . . . . . . . . . . . . . . . . 31 + 4.2.4. state_transition_delta . . . . . . . . . . . . . . . 31 + 4.2.5. colorspace_type . . . . . . . . . . . . . . . . . . . 32 + 4.2.6. chroma_planes . . . . . . . . . . . . . . . . . . . . 32 + 4.2.7. bits_per_raw_sample . . . . . . . . . . . . . . . . . 33 + 4.2.8. log2_h_chroma_subsample . . . . . . . . . . . . . . . 33 + 4.2.9. log2_v_chroma_subsample . . . . . . . . . . . . . . . 33 + 4.2.10. extra_plane . . . . . . . . . . . . . . . . . . . . . 33 + 4.2.11. num_h_slices . . . . . . . . . . . . . . . . . . . . 34 + 4.2.12. num_v_slices . . . . . . . . . . . . . . . . . . . . 34 + 4.2.13. quant_table_set_count . . . . . . . . . . . . . . . . 34 + 4.2.14. states_coded . . . . . . . . . . . . . . . . . . . . 34 + 4.2.15. initial_state_delta . . . . . . . . . . . . . . . . . 34 + 4.2.16. ec . . . . . . . . . . . . . . . . . . . . . . . . . 35 + 4.2.17. intra . . . . . . . . . . . . . . . . . . . . . . . . 35 + 4.3. Configuration Record . . . . . . . . . . . . . . . . . . 36 + 4.3.1. reserved_for_future_use . . . . . . . . . . . . . . . 36 + 4.3.2. configuration_record_crc_parity . . . . . . . . . . . 36 + 4.3.3. Mapping FFV1 into Containers . . . . . . . . . . . . 36 + 4.4. Frame . . . . . . . . . . . . . . . . . . . . . . . . . . 37 + 4.5. Slice . . . . . . . . . . . . . . . . . . . . . . . . . . 39 + 4.6. Slice Header . . . . . . . . . . . . . . . . . . . . . . 40 + 4.6.1. slice_x . . . . . . . . . . . . . . . . . . . . . . . 41 + 4.6.2. slice_y . . . . . . . . . . . . . . . . . . . . . . . 41 + 4.6.3. slice_width . . . . . . . . . . . . . . . . . . . . . 41 + 4.6.4. slice_height . . . . . . . . . . . . . . . . . . . . 41 + 4.6.5. quant_table_set_index_count . . . . . . . . . . . . . 41 + 4.6.6. quant_table_set_index . . . . . . . . . . . . . . . . 42 + 4.6.7. picture_structure . . . . . . . . . . . . . . . . . . 42 + 4.6.8. sar_num . . . . . . . . . . . . . . . . . . . . . . . 42 + 4.6.9. sar_den . . . . . . . . . . . . . . . . . . . . . . . 43 + 4.7. Slice Content . . . . . . . . . . . . . . . . . . . . . . 43 + 4.7.1. primary_color_count . . . . . . . . . . . . . . . . . 43 + 4.7.2. plane_pixel_height . . . . . . . . . . . . . . . . . 43 + 4.7.3. slice_pixel_height . . . . . . . . . . . . . . . . . 44 + 4.7.4. slice_pixel_y . . . . . . . . . . . . . . . . . . . . 44 + 4.8. Line . . . . . . . . . . . . . . . . . . . . . . . . . . 44 + 4.8.1. plane_pixel_width . . . . . . . . . . . . . . . . . . 44 + 4.8.2. slice_pixel_width . . . . . . . . . . . . . . . . . . 45 + 4.8.3. slice_pixel_x . . . . . . . . . . . . . . . . . . . . 45 + 4.8.4. sample_difference . . . . . . . . . . . . . . . . . . 45 + 4.9. Slice Footer . . . . . . . . . . . . . . . . . . . . . . 45 + 4.9.1. slice_size . . . . . . . . . . . . . . . . . . . . . 45 + 4.9.2. error_status . . . . . . . . . . . . . . . . . . . . 46 + 4.9.3. slice_crc_parity . . . . . . . . . . . . . . . . . . 46 + 5. Restrictions . . . . . . . . . . . . . . . . . . . . . . . . 46 + 6. Security Considerations . . . . . . . . . . . . . . . . . . . 47 + 7. Media Type Definition . . . . . . . . . . . . . . . . . . . . 48 + 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 49 + 9. Changelog . . . . . . . . . . . . . . . . . . . . . . . . . . 49 + 10. Normative References . . . . . . . . . . . . . . . . . . . . 49 + 11. Informative References . . . . . . . . . . . . . . . . . . . 50 + Appendix A. Multi-theaded decoder implementation suggestions . . 52 Appendix B. Future handling of some streams created by non - conforming encoders . . . . . . . . . . . . . . . . . . . 50 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 51 + conforming encoders . . . . . . . . . . . . . . . . . . . 52 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 52 1. Introduction This document describes FFV1, a lossless video encoding format. The design of FFV1 considers the storage of image characteristics, data fixity, and the optimized use of encoding time and storage requirements. FFV1 is designed to support a wide range of lossless video applications such as long-term audiovisual preservation, scientific imaging, screen recording, and other video encoding scenarios that seek to avoid the generational loss of lossy video @@ -187,21 +187,21 @@ 2. Notation and Conventions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. 2.1. Definitions - "Container": Format that encapsulates "Frames" (see Section 4.3) and + "Container": Format that encapsulates "Frames" (see Section 4.4) and (when required) a "Configuration Record" into a bitstream. "Sample": The smallest addressable representation of a color component or a luma component in a "Frame". Examples of "Sample" are Luma, Blue Chrominance, Red Chrominance, Transparency, 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. @@ -356,21 +356,21 @@ 2.2.7. Range "a...b" means any value starting from a to b, inclusive. 2.2.8. NumBytes "NumBytes" is a non-negative integer that expresses the size in 8-bit octets of a particular FFV1 "Configuration Record" or "Frame". FFV1 relies on its "Container" to store the "NumBytes" values; see - Section 4.2.3. + Section 4.3.3. 2.2.9. Bitstream Functions 2.2.9.1. remaining_bits_in_bitstream "remaining_bits_in_bitstream( )" means the count of remaining bits after the pointer in that "Configuration Record" or "Frame". It is computed from the "NumBytes" value multiplied by 8 minus the count of bits of that "Configuration Record" or "Frame" already read by the bitstream parser. @@ -386,21 +386,21 @@ )" is a multiple of 8, otherwise false. 2.2.9.4. get_bits "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 return the corresponding value. The pointer is increased by "i". 3. Sample Coding - For each "Slice" (as described in Section 4.4) of a "Frame", the + For each "Slice" (as described in Section 4.5) of a "Frame", the "Planes", "Lines", and "Samples" are coded in an order determined by the "Color Space" (see Section 3.7). Each "Sample" is predicted by 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 A border is assumed for each coded "Slice" for the purpose of the median predictor and context according to the following rules: @@ -664,24 +664,25 @@ 3.8. Coding of the Sample Difference Instead of coding the n+1 bits of the Sample Difference with Huffman or Range coding (or n+2 bits, in the case of JPEG2000-RCT), only the n (or n+1, in the case of JPEG2000-RCT) least significant bits are used, since this is sufficient to recover the original "Sample". In the equation below, the term "bits" represents "bits_per_raw_sample + 1" for JPEG2000-RCT or "bits_per_raw_sample" otherwise: - coder_input = - [(sample_difference + 2 ^ (bits-1)) & (2 ^ bits - 1)] - 2 ^ (bits - 1) + coder_input = [(sample_difference + 2 ^ (bits - 1)) & + (2 ^ bits - 1)] - 2 ^ (bits - 1) - Figure 7 + Figure 7: Description of the coding of the Sample Difference in + the bitstream. 3.8.1. Range Coding Mode 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 patent/royalty situation, as well as its slightly worse performance, CABAC was replaced by a Range coder based on an algorithm defined by G. Nigel and N. Martin in 1979 [range-coding]. 3.8.1.1. Range Binary Values @@ -781,50 +782,56 @@ To encode scalar integers, it would be possible to encode each bit separately and use the past bits as context. However that would mean 255 contexts per 8-bit symbol that is not only a waste of memory but also requires more past data to reach a reasonably good estimate of the probabilities. Alternatively assuming a Laplacian distribution and only dealing with its variance and mean (as in Huffman coding) would also be possible, however, for maximum flexibility and simplicity, the chosen method uses a single symbol to encode if a number is 0, and if not, encodes the number using its exponent, mantissa and sign. The exact contexts used are best described by - Figure 15, followed by some comments. + Figure 15. - pseudo-code | type - --------------------------------------------------------------|----- - void put_symbol(RangeCoder *c, uint8_t *state, int v, int \ | - is_signed) { | - int i; | - put_rac(c, state+0, !v); | - if (v) { | - int a= abs(v); | - int e= log2(a); | - | - for (i = 0; i < e; i++) { | - put_rac(c, state+1+min(i,9), 1); //1..10 | - } | - | - put_rac(c, state+1+min(i,9), 0); | - for (i = e-1; i >= 0; i--) { | - put_rac(c, state+22+min(i,9), (a>>i)&1); //22..31 | - } | - | - if (is_signed) { | - put_rac(c, state+11 + min(e, 10), v < 0); //11..21| - } | - } | - } | + int get_symbol(RangeCoder *c, uint8_t *state, int is_signed) { + if (get_rac(c, state + 0) { + return 0; + } + + int e = 0; + while (get_rac(c, state + 1 + min(e, 9)) { //1..10 + e++; + } + + int a = 1; + for (int i = e - 1; i >= 0; i--) { + a = a * 2 + get_rac(c, state + 22 + min(i, 9)); // 22..31 + } + + if (!is_signed) { + return a; + } + + if (get_rac(c, state + 11 + min(e, 10))) { //11..21 + return -a; + } else { + return a; + } + } Figure 15: A pseudo-code description of the contexts of Range Non Binary Values. + "get_symbol" is used for the read out of "sample_difference" + indicated in Figure 7. + + "get_rac" is the process described in Section 3.8.1.1. + 3.8.1.3. Initial Values for the Context Model At keyframes all Range coder state variables are set to their initial state. 3.8.1.4. State Transition Table one_state_{i} = default_state_transition_{i} + state_transition_delta_{i} @@ -864,23 +871,23 @@ 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, 241,242,243,244,245,246,247,248,248, 0, 0, 0, 0, 0, 0, 0, 3.8.1.6. Alternative State Transition Table The alternative state transition table has been built using iterative minimization of frame sizes and generally performs better than the - default. To use it, the "coder_type" (see Section 4.1.3) MUST be set + default. To use it, the "coder_type" (see Section 4.2.3) MUST be set to 2 and the difference to the default MUST be stored in the - "Parameters", see Section 4.1. The reference implementation of FFV1 + "Parameters", see Section 4.2. The reference implementation of FFV1 in FFmpeg uses Figure 18 by default at the time of this writing when Range coding is used. 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, 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, @@ -916,37 +923,41 @@ The end of the bitstream of the "Frame" is filled with 0-bits until that the bitstream contains a multiple of 8 bits. 3.8.2.1. Signed Golomb Rice Codes This coding mode uses Golomb Rice codes. The VLC is split into two parts. The prefix stores the most significant bits and the suffix stores the k least significant bits or stores the whole number in the ESC case. - pseudo-code | type - --------------------------------------------------------------|----- - int get_ur_golomb(k) { | - for (prefix = 0; prefix < 12; prefix++) { | - if (get_bits(1)) { | - return get_bits(k) + (prefix << k) | - } | - } | - return get_bits(bits) + 11 | - } | - | - int get_sr_golomb(k) { | - v = get_ur_golomb(k); | - if (v & 1) return - (v >> 1) - 1; | - else return (v >> 1); | + int get_ur_golomb(k) { + for (prefix = 0; prefix < 12; prefix++) { + if (get_bits(1)) { + return get_bits(k) + (prefix << k); + } + } + return get_bits(bits) + 11; } + Figure 19: A pseudo-code description of the read of an unsigned + integer in Golomb Rice mode. + + int get_sr_golomb(k) { + v = get_ur_golomb(k); + if (v & 1) return - (v >> 1) - 1; + else return (v >> 1); + } + + Figure 20: A pseudo-code description of the read of a signed + integer in Golomb Rice mode. + 3.8.2.1.1. Prefix +----------------+-------+ | bits | value | +================+=======+ | 1 | 0 | +----------------+-------+ | 01 | 1 | +----------------+-------+ | ... | ... | @@ -1000,56 +1011,72 @@ 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. The run and the first different level are coded. 3.8.2.2.1. Run Length Coding The run value is encoded in two parts. The prefix part stores the more 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 run. The second part of the value stores the less significant - part of the run as it is. The run_index is reset for each "Plane" + part of the run as it is. The "run_index" is reset for each "Plane" and slice to 0. - pseudo-code | type - --------------------------------------------------------------|----- - log2_run[41]={ | - 0, 0, 0, 0, 1, 1, 1, 1, | - 2, 2, 2, 2, 3, 3, 3, 3, | - 4, 4, 5, 5, 6, 6, 7, 7, | - 8, 9,10,11,12,13,14,15, | - 16,17,18,19,20,21,22,23, | - 24, | - }; | - | - if (run_count == 0 && run_mode == 1) { | - if (get_bits(1)) { | - run_count = 1 << log2_run[run_index]; | - if (x + run_count <= w) { | - run_index++; | - } | - } else { | - if (log2_run[run_index]) { | - run_count = get_bits(log2_run[run_index]); | - } else { | - run_count = 0; | - } | - if (run_index) { | - run_index--; | - } | - run_mode = 2; | - } | - } | + log2_run[41] = { + 0, 0, 0, 0, 1, 1, 1, 1, + 2, 2, 2, 2, 3, 3, 3, 3, + 4, 4, 5, 5, 6, 6, 7, 7, + 8, 9,10,11,12,13,14,15, + 16,17,18,19,20,21,22,23, + 24, + }; + + if (run_count == 0 && run_mode == 1) { + if (get_bits(1)) { + run_count = 1 << log2_run[run_index]; + if (x + run_count <= w) { + run_index++; + } + } else { + if (log2_run[run_index]) { + run_count = get_bits(log2_run[run_index]); + } else { + run_count = 0; + } + if (run_index) { + run_index--; + } + run_mode = 2; + } + } The "log2_run" array is also used within [ISO.14495-1.1999]. -3.8.2.3. Scalar Mode +3.8.2.3. Sign extension + + "sign_extend" is the function of increasing the number of bits of an + input binary number in twos complement signed number representation + while preserving the input number's sign (positive/negative) and + value, in order to fit in the output bit width. It MAY be computed + with: + + sign_extend(input_number, input_bits) { + negative_bias = 1 << (input_bits - 1); + bits_mask = negative_bias - 1; + output_number = input_number & bits_mask; // Remove negative bit + is_negative = input_number & negative_bias; // Test negative bit + if (is_negative) + output_number -= negative_bias; + return output_number + } + +3.8.2.4. Scalar Mode Each difference is coded with the per context mean prediction removed and a per context value for k. get_vlc_symbol(state) { i = state->count; k = 0; while (i < state->error_sum) { k++; i += i; @@ -1079,36 +1106,36 @@ -state->count + 1); } else if (state->drift > 0) { state->bias = min(state->bias + 1, 127); state->drift = min(state->drift - state->count, 0); } return ret; } -3.8.2.3.1. Level Coding +3.8.2.4.1. Level Coding Level coding is identical to the normal difference coding with the exception that the 0 value is removed as it cannot occur: diff = get_vlc_symbol(context_state); if (diff >= 0) { diff++; } 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 difference. On a small set of test "Samples" the use of prediction slightly improved the compression rate. -3.8.2.4. Initial Values for the VLC context state +3.8.2.5. Initial Values for the VLC context state At keyframes all coder state variables are set to their initial state. drift = 0; error_sum = 4; bias = 0; count = 1; 4. Bitstream @@ -1139,41 +1166,105 @@ | sr | Range coded signed scalar symbol coded with | | | the method described in Section 3.8.1.2 | +--------+----------------------------------------------+ | sd | Sample difference coded with the method | | | described in Section 3.8 | +--------+----------------------------------------------+ Table 4: Definition of pseudo-code symbols for this document. - The same context that is initialized to 128 is used for all fields in - the header. - The following MUST be provided by external means during initialization of the decoder: "frame_pixel_width" is defined as "Frame" width in "Pixels". "frame_pixel_height" is defined as "Frame" height in "Pixels". Default values at the decoder initialization phase: "ConfigurationRecordIsPresent" is set to 0. -4.1. Parameters +4.1. Quantization Table Set + + The Quantization Table Sets are stored by storing the number of equal + entries -1 of the first half of the table (represented as "len - 1" + in the pseudo-code below) using the method described in + Section 3.8.1.2. The second half doesn't need to be stored as it is + identical to the first with flipped sign. "scale" and "len_count[ i + ][ j ]" are temporary values used for the computing of + "context_count[ i ]" and are not used outside Quantization Table Set + pseudo-code. + + Example: + + Table: 0 0 1 1 1 1 2 2 -2 -2 -2 -1 -1 -1 -1 0 + + Stored values: 1, 3, 1 + + "QuantizationTableSet" has its own initial states, all set to 128. + + pseudo-code | type + --------------------------------------------------------------|----- + QuantizationTableSet( i ) { | + scale = 1 | + for (j = 0; j < MAX_CONTEXT_INPUTS; j++) { | + QuantizationTable( i, j, scale ) | + scale *= 2 * len_count[ i ][ j ] - 1 | + } | + context_count[ i ] = ceil( scale / 2 ) | + } | + + "MAX_CONTEXT_INPUTS" is 5. + + pseudo-code | type + --------------------------------------------------------------|----- + QuantizationTable(i, j, scale) { | + v = 0 | + for (k = 0; k < 128;) { | + len - 1 | ur + for (n = 0; n < len; n++) { | + quant_tables[ i ][ j ][ k ] = scale * v | + k++ | + } | + v++ | + } | + for (k = 1; k < 128; k++) { | + quant_tables[ i ][ j ][ 256 - k ] = \ | + -quant_tables[ i ][ j ][ k ] | + } | + quant_tables[ i ][ j ][ 128 ] = \ | + -quant_tables[ i ][ j ][ 127 ] | + len_count[ i ][ j ] = v | + } | + +4.1.1. quant_tables + + "quant_tables[ i ][ j ][ k ]" indicates the quantification table + value of the Quantized Sample Difference "k" of the Quantization + Table "j" of the Set Quantization Table Set "i". + +4.1.2. context_count + + "context_count[ i ]" indicates the count of contexts for Quantization + Table Set "i". "context_count[ i ]" MUST be less than or equal to + 32768. + +4.2. Parameters The "Parameters" section contains significant characteristics about the decoding configuration used for all instances of "Frame" (in FFV1 version 0 and 1) or the whole FFV1 bitstream (other versions), including the stream version, color configuration, and quantization - tables. Figure 19 describes the contents of the bitstream. + tables. Figure 21 describes the contents of the bitstream. + + "Parameters" has its own initial states, all set to 128. pseudo-code | type --------------------------------------------------------------|----- Parameters( ) { | version | ur if (version >= 3) { | micro_version | ur } | coder_type | ur if (coder_type > 1) { | @@ -1206,25 +1297,25 @@ initial_state_delta[ i ][ j ][ k ] | sr } | } | } | } | ec | ur intra | ur } | } | - Figure 19: A pseudo-code description of the bitstream contents. + Figure 21: A pseudo-code description of the bitstream contents. CONTEXT_SIZE is 32. -4.1.1. version +4.2.1. version "version" specifies the version of the FFV1 bitstream. Each version is incompatible with other versions: decoders SHOULD reject FFV1 bitstreams due to an unknown version. Decoders SHOULD reject FFV1 bitstreams with version <= 1 && ConfigurationRecordIsPresent == 1. Decoders SHOULD reject FFV1 bitstreams with version >= 3 && @@ -1241,21 +1332,21 @@ +-------+-------------------------+ | 3 | FFV1 version 3 | +-------+-------------------------+ | Other | reserved for future use | +-------+-------------------------+ Table 5 * Version 2 was experimental and this document does not describe it. -4.1.2. micro_version +4.2.2. micro_version "micro_version" specifies the micro-version of the FFV1 bitstream. After a version is considered stable (a micro-version value is assigned to be the first stable variant of a specific version), each new micro-version after this first stable variant is compatible with the previous micro-version: decoders SHOULD NOT reject FFV1 bitstreams due to an unknown micro-version equal or above the micro- version considered as stable. @@ -1270,21 +1361,21 @@ +-------+-------------------------+ | Other | reserved for future use | +-------+-------------------------+ Table 6: The definitions for "micro_version" values for FFV1 version 3. * development versions may be incompatible with the stable variants. -4.1.3. coder_type +4.2.3. coder_type "coder_type" specifies the coder used. +-------+-------------------------------------------------+ | value | coder used | +=======+=================================================+ | 0 | Golomb Rice | +-------+-------------------------------------------------+ | 1 | Range Coder with default state transition table | +-------+-------------------------------------------------+ @@ -1297,30 +1388,30 @@ Restrictions: If "coder_type" is 0, then "bits_per_raw_sample" SHOULD NOT be > 8. Background: At the time of this writing, there is no known implementation of FFV1 bitstream supporting Golomb Rice algorithm with "bits_per_raw_sample" greater than 8, and Range Coder is prefered. -4.1.4. state_transition_delta +4.2.4. state_transition_delta "state_transition_delta" specifies the Range coder custom state transition table. If "state_transition_delta" is not present in the FFV1 bitstream, all Range coder custom state transition table elements are assumed to be 0. -4.1.5. colorspace_type +4.2.5. colorspace_type "colorspace_type" specifies the color space encoded, the pixel transformation used by the encoder, the extra plane content, as well as interleave method. +-------+-------------+----------------+--------------+-------------+ | value | color space | pixel | extra plane | interleave | | | encoded | transformation | content | method | +=======+=============+================+==============+=============+ | 0 | YCbCr | None | Transparency | "Plane" | @@ -1335,267 +1426,269 @@ | | for future | future use | future use | for future | | | use | | | use | +-------+-------------+----------------+--------------+-------------+ Table 8 FFV1 bitstreams with "colorspace_type" == 1 && ("chroma_planes" != 1 || "log2_h_chroma_subsample" != 0 || "log2_v_chroma_subsample" != 0) are not part of this specification. -4.1.6. chroma_planes +4.2.6. chroma_planes "chroma_planes" indicates if chroma (color) "Planes" are present. +-------+---------------------------------+ | value | presence | +=======+=================================+ | 0 | chroma "Planes" are not present | +-------+---------------------------------+ | 1 | chroma "Planes" are present | +-------+---------------------------------+ Table 9 -4.1.7. bits_per_raw_sample +4.2.7. bits_per_raw_sample "bits_per_raw_sample" indicates the number of bits for each "Sample". Inferred to be 8 if not present. +-------+-----------------------------------+ | value | bits for each sample | +=======+===================================+ | 0 | reserved* | +-------+-----------------------------------+ | Other | the actual bits for each "Sample" | +-------+-----------------------------------+ Table 10 * Encoders MUST NOT store "bits_per_raw_sample" = 0. Decoders SHOULD accept and interpret "bits_per_raw_sample" = 0 as 8. -4.1.8. log2_h_chroma_subsample +4.2.8. log2_h_chroma_subsample "log2_h_chroma_subsample" indicates the subsample factor, stored in powers to which the number 2 must be raised, between luma and chroma width ("chroma_width = 2 ^ -log2_h_chroma_subsample * luma_width"). -4.1.9. log2_v_chroma_subsample +4.2.9. log2_v_chroma_subsample "log2_v_chroma_subsample" indicates the subsample factor, stored in powers to which the number 2 must be raised, between luma and chroma height ("chroma_height = 2 ^ -log2_v_chroma_subsample * luma_height"). -4.1.10. extra_plane +4.2.10. extra_plane "extra_plane" indicates if an extra "Plane" is present. +-------+------------------------------+ | value | presence | +=======+==============================+ | 0 | extra "Plane" is not present | +-------+------------------------------+ | 1 | extra "Plane" is present | +-------+------------------------------+ Table 11 -4.1.11. num_h_slices +4.2.11. num_h_slices "num_h_slices" indicates the number of horizontal elements of the slice raster. Inferred to be 1 if not present. -4.1.12. num_v_slices +4.2.12. num_v_slices "num_v_slices" indicates the number of vertical elements of the slice raster. Inferred to be 1 if not present. -4.1.13. quant_table_set_count +4.2.13. quant_table_set_count "quant_table_set_count" indicates the number of Quantization Table Sets. "quant_table_set_count" MUST be less than or equal to 8. Inferred to be 1 if not present. MUST NOT be 0. -4.1.14. states_coded +4.2.14. states_coded "states_coded" indicates if the respective Quantization Table Set has the initial states coded. Inferred to be 0 if not present. +-------+--------------------------------+ | value | initial states | +=======+================================+ | 0 | initial states are not present | | | and are assumed to be all 128 | +-------+--------------------------------+ | 1 | initial states are present | +-------+--------------------------------+ Table 12 -4.1.15. initial_state_delta +4.2.15. initial_state_delta "initial_state_delta[ i ][ j ][ k ]" indicates the initial Range coder state, it is encoded using "k" as context index and pred = j ? initial_states[ i ][j - 1][ k ] : 128 - Figure 20 + Figure 22 initial_state[ i ][ j ][ k ] = ( pred + initial_state_delta[ i ][ j ][ k ] ) & 255 - Figure 21 + Figure 23 -4.1.16. ec +4.2.16. ec "ec" indicates the error detection/correction type. - +-------+--------------------------------------------+ + +-------+-------------------------------------------------+ | value | error detection/correction type | - +=======+============================================+ - | 0 | 32-bit CRC on the global header | - +-------+--------------------------------------------+ - | 1 | 32-bit CRC per slice and the global header | - +-------+--------------------------------------------+ + +=======+=================================================+ + | 0 | 32-bit CRC in "ConfigurationRecord" | + +-------+-------------------------------------------------+ + | 1 | 32-bit CRC in "Slice" and "ConfigurationRecord" | + +-------+-------------------------------------------------+ | Other | reserved for future use | - +-------+--------------------------------------------+ + +-------+-------------------------------------------------+ Table 13 -4.1.17. intra +4.2.17. intra "intra" indicates the constraint on "keyframe" in each instance of "Frame". Inferred to be 0 if not present. +-------+-------------------------------------------------------+ | value | relationship | +=======+=======================================================+ | 0 | "keyframe" can be 0 or 1 (non keyframes or keyframes) | +-------+-------------------------------------------------------+ | 1 | "keyframe" MUST be 1 (keyframes only) | +-------+-------------------------------------------------------+ | Other | reserved for future use | +-------+-------------------------------------------------------+ Table 14 -4.2. Configuration Record +4.3. Configuration Record In the case of a FFV1 bitstream with "version >= 3", a "Configuration - Record" is stored in the underlying "Container", at the track header - level. It contains the "Parameters" used for all instances of - "Frame". The size of the "Configuration Record", "NumBytes", is + Record" is stored in the underlying "Container" as described in + Section 4.3.3. It contains the "Parameters" used for all instances + of "Frame". The size of the "Configuration Record", "NumBytes", is supplied by the underlying "Container". pseudo-code | type -----------------------------------------------------------|----- ConfigurationRecord( NumBytes ) { | ConfigurationRecordIsPresent = 1 | Parameters( ) | while (remaining_symbols_in_syntax(NumBytes - 4)) { | reserved_for_future_use | br/ur/sr } | configuration_record_crc_parity | u(32) } | -4.2.1. reserved_for_future_use +4.3.1. reserved_for_future_use "reserved_for_future_use" has semantics that are reserved for future use. Encoders conforming to this version of this specification SHALL NOT write this value. Decoders conforming to this version of this specification SHALL ignore its value. -4.2.2. configuration_record_crc_parity +4.3.2. configuration_record_crc_parity "configuration_record_crc_parity" 32 bits that are chosen so that the "Configuration Record" as a whole has a CRC remainder of 0. This is equivalent to storing the CRC remainder in the 32-bit parity. - The CRC generator polynomial used is described in Section 4.8.3. + The CRC generator polynomial used is described in Section 4.9.3. -4.2.3. Mapping FFV1 into Containers +4.3.3. Mapping FFV1 into Containers This "Configuration Record" can be placed in any file format supporting "Configuration Records", fitting as much as possible with how the file format uses to store "Configuration Records". The "Configuration Record" storage place and "NumBytes" are currently defined and supported by this version of this specification for the following formats: -4.2.3.1. AVI File Format +4.3.3.1. AVI File Format The "Configuration Record" extends the stream format chunk ("AVI ", "hdlr", "strl", "strf") with the ConfigurationRecord bitstream. See [AVI] for more information about chunks. "NumBytes" is defined as the size, in bytes, of the strf chunk indicated in the chunk header minus the size of the stream format structure. -4.2.3.2. ISO Base Media File Format +4.3.3.2. ISO Base Media File Format The "Configuration Record" extends the sample description box ("moov", "trak", "mdia", "minf", "stbl", "stsd") with a "glbl" box that contains the ConfigurationRecord bitstream. See [ISO.14496-12.2015] for more information about boxes. "NumBytes" is defined as the size, in bytes, of the "glbl" box indicated in the box header minus the size of the box header. -4.2.3.3. NUT File Format +4.3.3.3. NUT File Format The "codec_specific_data" element (in "stream_header" packet) contains the ConfigurationRecord bitstream. See [NUT] for more information about elements. "NumBytes" is defined as the size, in bytes, of the "codec_specific_data" element as indicated in the "length" field of "codec_specific_data". -4.2.3.4. Matroska File Format +4.3.3.4. Matroska File Format FFV1 SHOULD use "V_FFV1" as the Matroska "Codec ID". For FFV1 versions 2 or less, the Matroska "CodecPrivate" Element SHOULD NOT be used. For FFV1 versions 3 or greater, the Matroska "CodecPrivate" Element MUST contain the FFV1 "Configuration Record" structure and no other data. See [Matroska] for more information about elements. "NumBytes" is defined as the "Element Data Size" of the "CodecPrivate" Element. -4.3. Frame +4.4. 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" <= 1), and a sequence of independent slices. The pseudo- code below describes the contents of a "Frame". + "keyframe" field has its own initial state, set to 128. + pseudo-code | type --------------------------------------------------------------|----- Frame( NumBytes ) { | keyframe | br if (keyframe && !ConfigurationRecordIsPresent { | Parameters( ) | } | while (remaining_bits_in_bitstream( NumBytes )) { | Slice( ) | } | @@ -1627,21 +1720,21 @@ +-----------------------------------------------------------------+ | last slice header | +-----------------------------------------------------------------+ | last slice content | +-----------------------------------------------------------------+ | last slice footer | +-----------------------------------------------------------------+ Table 15 -4.4. Slice +4.5. Slice A "Slice" is an independent spatial sub-section of a "Frame" that is encoded separately from another 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". @@ -1672,86 +1765,88 @@ byte alignment. MUST be 0. "reserved" specifies a bit without any significance in this revision of the specification and may have a significance in a later revision of this specification. Encoders SHOULD NOT fill these bits. Decoders SHOULD ignore these bits. -4.5. Slice Header +4.6. 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". + "Slice Header" has its own initial states, all set to 128. + pseudo-code | type --------------------------------------------------------------|----- SliceHeader( ) { | slice_x | ur slice_y | ur slice_width - 1 | ur slice_height - 1 | ur for (i = 0; i < quant_table_set_index_count; i++) { | quant_table_set_index[ i ] | ur } | picture_structure | ur sar_num | ur sar_den | ur } | -4.5.1. slice_x +4.6.1. slice_x "slice_x" indicates the x position on the slice raster formed by num_h_slices. Inferred to be 0 if not present. -4.5.2. slice_y +4.6.2. slice_y "slice_y" indicates the y position on the slice raster formed by num_v_slices. Inferred to be 0 if not present. -4.5.3. slice_width +4.6.3. slice_width "slice_width" indicates the width on the slice raster formed by num_h_slices. Inferred to be 1 if not present. -4.5.4. slice_height +4.6.4. slice_height "slice_height" indicates the height on the slice raster formed by num_v_slices. Inferred to be 1 if not present. -4.5.5. quant_table_set_index_count +4.6.5. quant_table_set_index_count "quant_table_set_index_count" is defined as: 1 + ( ( chroma_planes || version <= 3 ) ? 1 : 0 ) + ( extra_plane ? 1 : 0 ) -4.5.6. quant_table_set_index +4.6.6. quant_table_set_index "quant_table_set_index" indicates the Quantization Table Set index to select the Quantization Table Set and the initial states for the - slice. + "Slice Content". Inferred to be 0 if not present. -4.5.7. picture_structure +4.6.7. picture_structure "picture_structure" specifies the temporal and spatial relationship of each "Line" of the "Frame". Inferred to be 0 if not present. +-------+-------------------------+ | value | picture structure used | +=======+=========================+ | 0 | unknown | @@ -1760,47 +1855,47 @@ +-------+-------------------------+ | 2 | bottom field first | +-------+-------------------------+ | 3 | progressive | +-------+-------------------------+ | Other | reserved for future use | +-------+-------------------------+ Table 16 -4.5.8. sar_num +4.6.8. sar_num "sar_num" specifies the "Sample" aspect ratio numerator. Inferred to be 0 if not present. 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 +4.6.9. sar_den "sar_den" specifies the "Sample" aspect ratio denominator. Inferred to be 0 if not present. 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 +4.7. 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 --------------------------------------------------------------|----- SliceContent( ) { | if (colorspace_type == 0) { | @@ -1811,216 +1906,154 @@ } | } else if (colorspace_type == 1) { | for (y = 0; y < slice_pixel_height; y++) { | for (p = 0; p < primary_color_count; p++) { | Line( p, y ) | } | } | } | } | -4.6.1. primary_color_count +4.7.1. primary_color_count "primary_color_count" is defined as: 1 + ( chroma_planes ? 2 : 0 ) + ( extra_plane ? 1 : 0 ) -4.6.2. plane_pixel_height +4.7.2. plane_pixel_height "plane_pixel_height[ p ]" is the height in "Pixels" of "Plane" p of the "Slice". It is defined as: (chroma_planes == 1 && (p == 1 || p == 2)) ? ceil(slice_pixel_height / (1 << log2_v_chroma_subsample)) : slice_pixel_height -4.6.3. slice_pixel_height +4.7.3. slice_pixel_height "slice_pixel_height" is the height in pixels of the slice. It is defined as: floor( ( slice_y + slice_height ) * slice_pixel_height / num_v_slices ) - slice_pixel_y. -4.6.4. slice_pixel_y +4.7.4. slice_pixel_y "slice_pixel_y" is the slice vertical position in pixels. It is defined as: floor( slice_y * frame_pixel_height / num_v_slices ) -4.7. Line +4.8. 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 --------------------------------------------------------------|----- Line( p, y ) { | if (colorspace_type == 0) { | for (x = 0; x < plane_pixel_width[ p ]; x++) { | sample_difference[ p ][ y ][ x ] | sd } | } else if (colorspace_type == 1) { | for (x = 0; x < slice_pixel_width; x++) { | sample_difference[ p ][ y ][ x ] | sd } | } | } | -4.7.1. plane_pixel_width +4.8.1. plane_pixel_width "plane_pixel_width[ p ]" is the width in "Pixels" of "Plane" p of the "Slice". It is defined as: (chroma_planes == 1 && (p == 1 || p == 2)) ? ceil( slice_pixel_width / (1 << log2_h_chroma_subsample) ) : slice_pixel_width. -4.7.2. slice_pixel_width +4.8.2. slice_pixel_width "slice_pixel_width" is the width in "Pixels" of the slice. It is defined as: floor( ( slice_x + slice_width ) * slice_pixel_width / num_h_slices ) - slice_pixel_x -4.7.3. slice_pixel_x +4.8.3. slice_pixel_x "slice_pixel_x" is the slice horizontal position in "Pixels". It is defined as: floor( slice_x * frame_pixel_width / num_h_slices ) -4.7.4. sample_difference +4.8.4. sample_difference "sample_difference[ p ][ y ][ x ]" is the sample difference for "Sample" at "Plane" "p", y position "y", and x position "x". The "Sample" value is computed based on median predictor and context described in Section 3.2. -4.8. Slice Footer +4.9. Slice Footer A "Slice Footer" provides information about slice size and (optionally) parity. The pseudo-code below describes the contents of the "Slice Footer". Note: "Slice Footer" is always byte aligned. pseudo-code | type --------------------------------------------------------------|----- SliceFooter( ) { | slice_size | u(24) if (ec) { | error_status | u(8) slice_crc_parity | u(32) } | } | -4.8.1. slice_size +4.9.1. slice_size "slice_size" indicates the size of the slice in bytes. Note: this allows finding the start of slices before previous slices have been fully decoded, and allows parallel decoding as well as error resilience. -4.8.2. error_status +4.9.2. error_status "error_status" specifies the error status. +-------+--------------------------------------+ | value | error status | +=======+======================================+ | 0 | no error | +-------+--------------------------------------+ | 1 | slice contains a correctable error | +-------+--------------------------------------+ | 2 | slice contains a uncorrectable error | +-------+--------------------------------------+ | Other | reserved for future use | +-------+--------------------------------------+ Table 17 -4.8.3. slice_crc_parity +4.9.3. slice_crc_parity "slice_crc_parity" 32 bits that are chosen so that the slice as a whole has a crc remainder of 0. This is equivalent to storing the crc remainder in the 32-bit parity. The CRC generator polynomial used is the standard IEEE CRC polynomial (0x104C11DB7), with initial value 0, without pre-inversion and without post-inversion. -4.9. Quantization Table Set - - The Quantization Table Sets are stored by storing the number of equal - entries -1 of the first half of the table (represented as "len - 1" - in the pseudo-code below) using the method described in - Section 3.8.1.2. The second half doesn't need to be stored as it is - identical to the first with flipped sign. "scale" and "len_count[ i - ][ j ]" are temporary values used for the computing of - "context_count[ i ]" and are not used outside Quantization Table Set - pseudo-code. - - Example: - - Table: 0 0 1 1 1 1 2 2 -2 -2 -2 -1 -1 -1 -1 0 - Stored values: 1, 3, 1 - - pseudo-code | type - --------------------------------------------------------------|----- - QuantizationTableSet( i ) { | - scale = 1 | - for (j = 0; j < MAX_CONTEXT_INPUTS; j++) { | - QuantizationTable( i, j, scale ) | - scale *= 2 * len_count[ i ][ j ] - 1 | - } | - context_count[ i ] = ceil( scale / 2 ) | - } | - - "MAX_CONTEXT_INPUTS" is 5. - - pseudo-code | type - --------------------------------------------------------------|----- - QuantizationTable(i, j, scale) { | - v = 0 | - for (k = 0; k < 128;) { | - len - 1 | ur - for (a = 0; a < len; a++) { | - quant_tables[ i ][ j ][ k ] = scale * v | - k++ | - } | - v++ | - } | - for (k = 1; k < 128; k++) { | - quant_tables[ i ][ j ][ 256 - k ] = \ | - -quant_tables[ i ][ j ][ k ] | - } | - quant_tables[ i ][ j ][ 128 ] = \ | - -quant_tables[ i ][ j ][ 127 ] | - len_count[ i ][ j ] = v | - } | - -4.9.1. quant_tables - - "quant_tables[ i ][ j ][ k ]" indicates the quantification table - value of the Quantized Sample Difference "k" of the Quantization - Table "j" of the Set Quantization Table Set "i". - -4.9.2. context_count - - "context_count[ i ]" indicates the count of contexts for Quantization - Table Set "i". "context_count[ i ]" MUST be less than or equal to - 32768. - 5. Restrictions To ensure that fast multithreaded decoding is possible, starting with version 3 and if "frame_pixel_width * frame_pixel_height" is more than 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 "Pixels" of a 352x288 frame also known as CIF ("Common Intermediate Format") frame size format. For each "Frame", each position in the slice raster MUST be filled by @@ -2072,77 +2105,68 @@ * Sending the decoder random packets that are not FFV1. In all of the conditions above, the decoder and encoder was run inside the [VALGRIND] memory debugger as well as clangs address sanitizer [Address-Sanitizer], which track reads and writes to invalid memory regions as well as the use of uninitialized memory. There were no errors reported on any of the tested conditions. 7. Media Type Definition - This section completes the media type registration template defined - in [RFC6838] and following [RFC4855]. + This registration is done using the template defined in [RFC6838] and + following [RFC4855]. Type name: video Subtype name: FFV1 Required parameters: None. - Optional parameters: - - This parameter is used to signal the capabilities of a receiver - implementation. This parameter MUST NOT be used for any other - purpose. - - "version": The "version" of the FFV1 encoding as defined by - Section 4.1.1. - - "micro_version": The "micro_version" of the FFV1 encoding as defined - by Section 4.1.2. + Optional parameters: These parameters are used to signal the + capabilities of a receiver implementation. These parameters MUST NOT + be used for any other purpose. - "coder_type": The "coder_type" of the FFV1 encoding as defined by - Section 4.1.3. + * "version": The "version" of the FFV1 encoding as defined by + Section 4.2.1. - "colorspace_type": The "colorspace_type" of the FFV1 encoding as - defined by Section 4.1.5. + * "micro_version": The "micro_version" of the FFV1 encoding as + defined by Section 4.2.2. - "bits_per_raw_sample": The "bits_per_raw_sample" of the FFV1 encoding - as defined by Section 4.1.7. + * "coder_type": The "coder_type" of the FFV1 encoding as defined by + Section 4.2.3. - "max_slices": The value of "max_slices" is an integer indicating the - maximum count of slices with a frames of the FFV1 encoding. + * "colorspace_type": The "colorspace_type" of the FFV1 encoding as + defined by Section 4.2.5. - Encoding considerations: + * "bits_per_raw_sample": The "bits_per_raw_sample" of the FFV1 + encoding as defined by Section 4.2.7. - This media type is defined for encapsulation in several audiovisual - container formats and contains binary data; see Section 4.2.3. This - media type is framed binary data; see Section 4.8 of [RFC6838]. + * "max_slices": The value of "max_slices" is an integer indicating + the maximum count of slices with a frames of the FFV1 encoding. - Security considerations: + Encoding considerations: This media type is defined for encapsulation + in several audiovisual container formats and contains binary data; + see Section 4.3.3. This media type is framed binary data; see + Section 4.8 of [RFC6838]. - See Section 6 of this document. + Security considerations: See Section 6 of this document. Interoperability considerations: None. - Published specification: - - RFC XXXX. + Published specification: RFC XXXX. [RFC Editor: Upon publication as an RFC, please replace "XXXX" with the number assigned to this document and remove this note.] - - Applications which use this media type: - - Any application that requires the transport of lossless video can use - this media type. Some examples are, but not limited to screen - recording, scientific imaging, and digital video preservation. + Applications which use this media type: Any application that requires + the transport of lossless video can use this media type. Some + examples are, but not limited to screen recording, scientific + imaging, and digital video preservation. Fragment identifier considerations: N/A. Additional information: None. Person & email address to contact for further information: Michael Niedermayer michael@niedermayer.cc (mailto:michael@niedermayer.cc) Intended usage: COMMON @@ -2161,123 +2185,123 @@ 9. Changelog See https://github.com/FFmpeg/FFV1/commits/master (https://github.com/FFmpeg/FFV1/commits/master) [RFC Editor: Please remove this Changelog section prior to publication.] 10. Normative References - [ISO.15444-1.2016] - International Organization for Standardization, - "Information technology -- JPEG 2000 image coding system: - Core coding system", October 2016. - - [Matroska] IETF, "Matroska", 2019, . - [RFC4732] Handley, M., Ed., Rescorla, E., Ed., and IAB, "Internet Denial-of-Service Considerations", RFC 4732, DOI 10.17487/RFC4732, December 2006, . + [RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type + Specifications and Registration Procedures", BCP 13, + RFC 6838, DOI 10.17487/RFC6838, January 2013, + . + [RFC4855] Casner, S., "Media Type Registration of RTP Payload Formats", RFC 4855, DOI 10.17487/RFC4855, February 2007, . - [ISO.9899.2018] - International Organization for Standardization, - "Programming languages - C", 2018. - - [RFC6716] Valin, JM., Vos, K., and T. Terriberry, "Definition of the - Opus Audio Codec", RFC 6716, DOI 10.17487/RFC6716, - September 2012, . - [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [ISO.9899.1990] International Organization for Standardization, "Programming languages - C", 1990. - [RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type - Specifications and Registration Procedures", BCP 13, - RFC 6838, DOI 10.17487/RFC6838, January 2013, - . + [ISO.9899.2018] + International Organization for Standardization, + "Programming languages - C", 2018. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . -11. Informative References + [Matroska] IETF, "Matroska", 2019, . - [YCbCr] Wikipedia, "YCbCr", undated, - . + [ISO.15444-1.2016] + International Organization for Standardization, + "Information technology -- JPEG 2000 image coding system: + Core coding system", October 2016. + + [RFC6716] Valin, JM., Vos, K., and T. Terriberry, "Definition of the + Opus Audio Codec", RFC 6716, DOI 10.17487/RFC6716, + September 2012, . + +11. Informative References [REFIMPL] Niedermayer, M., "The reference FFV1 implementation / the FFV1 codec in FFmpeg", undated, . - [Address-Sanitizer] - The Clang Team, "ASAN AddressSanitizer website", undated, - . + [range-coding] + Nigel, G. and N. Martin, "Range encoding: an algorithm for + removing redundancy from a digitised message.", July 1979. + + [NUT] Niedermayer, M., "NUT Open Container Format", December + 2013, . [VALGRIND] Valgrind Developers, "Valgrind website", undated, . - [ISO.14495-1.1999] - International Organization for Standardization, - "Information technology -- Lossless and near-lossless - compression of continuous-tone still images: Baseline", - December 1999. - - [ISO.14496-10.2014] - International Organization for Standardization, - "Information technology -- Coding of audio-visual objects - -- Part 10: Advanced Video Coding", September 2014. - [ISO.14496-12.2015] International Organization for Standardization, "Information technology -- Coding of audio-visual objects -- Part 12: ISO base media file format", December 2015. - [HuffYUV] Rudiak-Gould, B., "HuffYUV", December 2003, - . - [AVI] Microsoft, "AVI RIFF File Reference", undated, . - [NUT] Niedermayer, M., "NUT Open Container Format", December - 2013, . - - [FFV1_V3] Niedermayer, M., "Commit to mark FFV1 version 3 as non- - experimental", August 2013, . - - [range-coding] - Nigel, G. and N. Martin, "Range encoding: an algorithm for - removing redundancy from a digitised message.", July 1979. + [HuffYUV] Rudiak-Gould, B., "HuffYUV", December 2003, + . [FFV1_V0] Niedermayer, M., "Commit to mark FFV1 version 0 as non- experimental", April 2006, . + [ISO.14496-10.2014] + International Organization for Standardization, + "Information technology -- Coding of audio-visual objects + -- Part 10: Advanced Video Coding", September 2014. + [FFV1_V1] Niedermayer, M., "Commit to release FFV1 version 1", April 2009, . + [YCbCr] Wikipedia, "YCbCr", undated, + . + + [ISO.14495-1.1999] + International Organization for Standardization, + "Information technology -- Lossless and near-lossless + compression of continuous-tone still images: Baseline", + December 1999. + + [Address-Sanitizer] + The Clang Team, "ASAN AddressSanitizer website", undated, + . + + [FFV1_V3] Niedermayer, M., "Commit to mark FFV1 version 3 as non- + experimental", August 2013, . + Appendix A. Multi-theaded decoder implementation suggestions This appendix is informative. The FFV1 bitstream is parsable in two ways: in sequential order as described in this document or with the pre-analysis of the footer of each slice. Each slice footer contains a "slice_size" field so the boundary of each slice is computable without having to parse the slice content. That allows multi-threading as well as independence of slice content (a bitstream error in a slice header or slice