PR #24968 opened by Forgejo_Fairy URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24968 Patch URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24968.patch
Matroska streamcopy can modify H.264/HEVC presentation timestamps when the native decoders are disabled. The demuxer's H.264 B-picture heuristic only establishes a one-frame delay, while Matroska skips HEVC parsing entirely. Without the actual reorder bound, reconstructed DTS can force the CLI to rewrite PTS. Export the SPS reorder bound from each parser when its native decoder is disabled, and enable HEVC parsing in Matroska for that configuration. Preserve any larger delay already established. Native-decoder builds retain their existing behavior. This follows the parser-based approach proposed by tyan0 in #23365; no forced MAX_REORDER_DELAY fallback or demuxer delay-guessing change is needed. H.264 without an explicit reorder limit uses the existing level-derived bound, which can be conservative. Add two FATE tests using existing samples: `fate-matroska-h264-remux-nodec` and `fate-matroska-hevc-remux-nodec`. They remux MP4 to Matroska and streamcopy to framecrc, checking timestamps and payloads. The H.264 sample also covers an absent explicit bitstream restriction. Validation: - Both tests fail without the code fix and pass with it. - Both pass on AArch64 and x86-64 with native decoders disabled, and on AArch64 with OpenH264 2.4.1 enabled. - Generated 120-frame H.264 and HEVC B-frame inputs previously changed 28 and 89 PTS values respectively; the fix preserves all PTS values and packet payload hashes without warnings. - Separate no-B-frame controls for both codecs pass, as do additional interlaced H.264 samples and H.264 samples without explicit reorder limits. - Native-decoder builds preserve all timestamps on the generated controls. For the FATE configuration, use `--disable-everything --disable-autodetect --disable-doc --enable-ffmpeg --enable-ffprobe --enable-protocol=file,pipe --enable-demuxer=matroska,mov --enable-muxer=matroska,framehash,framecrc --enable-parser=h264,hevc`, optionally adding `--enable-libopenh264 --enable-decoder=libopenh264`. Run `make fate-matroska-h264-remux-nodec fate-matroska-hevc-remux-nodec SAMPLES=/opt/fate-suite`. Fixes #23365. >From 91ece23b840d62b1af1162dd3d6df10d3ea1a7b8 Mon Sep 17 00:00:00 2001 From: Michael Niedermayer <[email protected]> Date: Thu, 8 Oct 2026 04:59:41 +0000 Subject: [PATCH 1/2] avcodec: export reorder delay when H.264/HEVC decoders are disabled Matroska supplies presentation timestamps without decoding timestamps. Without the native decoders, the H.264 parser only triggers demux.c's one-frame B-picture heuristic, while HEVC is not parsed at all. Reorder depths larger than those guesses produce invalid DTS and cause streamcopy to modify PTS. Export the SPS reorder bound from the parsers in these configurations, and allow Matroska to use the HEVC parser when its native decoder is absent. Preserve a larger delay already reported by another component. Keep native-decoder builds unchanged so H.264 can still refine its delay from observed picture order where appropriate. This follows the parser-based approach proposed by tyan0 in #23365. There is no need to force MAX_REORDER_DELAY in demux.c for these streams; SPS values also preserve a signalled zero delay for non-reordering input. Fixes #23365. Assisted-by: Fairy --- libavcodec/h264_parser.c | 8 ++++++++ libavcodec/hevc/parser.c | 9 +++++++++ libavformat/matroskadec.c | 3 ++- 3 files changed, 19 insertions(+), 1 deletion(-) diff --git a/libavcodec/h264_parser.c b/libavcodec/h264_parser.c index 1bd0be38a5..8b77757d3b 100644 --- a/libavcodec/h264_parser.c +++ b/libavcodec/h264_parser.c @@ -27,6 +27,8 @@ #define UNCHECKED_BITSTREAM_READER 1 +#include "config_components.h" + #include <stdint.h> #include "libavutil/attributes.h" @@ -385,6 +387,12 @@ static inline int parse_nal_units(AVCodecParserContext *s, p->ps.sps = p->ps.pps->sps; sps = p->ps.sps; +#if !CONFIG_H264_DECODER + // Use the SPS reorder bound when the decoder cannot refine it. + avctx->has_b_frames = FFMAX(avctx->has_b_frames, + sps->num_reorder_frames); +#endif + // heuristic to detect non marked keyframes if (p->ps.sps->ref_frame_count <= 1 && p->ps.pps->ref_count[0] <= 1 && s->pict_type == AV_PICTURE_TYPE_I) s->key_frame = 1; diff --git a/libavcodec/hevc/parser.c b/libavcodec/hevc/parser.c index 47a1ac70d0..0830e7089d 100644 --- a/libavcodec/hevc/parser.c +++ b/libavcodec/hevc/parser.c @@ -20,6 +20,8 @@ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ +#include "config_components.h" + #include "libavutil/common.h" #include "libavutil/mem.h" @@ -95,6 +97,13 @@ static int hevc_parse_slice_header(AVCodecParserContext *s, H2645NAL *nal, avctx->profile = sps->ptl.general_ptl.profile_idc; avctx->level = sps->ptl.general_ptl.level_idc; +#if !CONFIG_HEVC_DECODER + // Without the native decoder, provide the delay needed for DTS generation. + avctx->has_b_frames = + FFMAX(avctx->has_b_frames, + sps->temporal_layer[sps->max_sub_layers - 1].num_reorder_pics); +#endif + if (sps->vps->vps_timing_info_present_flag) { num = sps->vps->vps_num_units_in_tick; den = sps->vps->vps_time_scale; diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c index bceb4f7e17..e05c3fe4f0 100644 --- a/libavformat/matroskadec.c +++ b/libavformat/matroskadec.c @@ -3058,7 +3058,8 @@ static int mkv_parse_video(MatroskaTrack *track, AVStream *st, bytestream_put_le32(&cropping, track->video.pixel_cropl); bytestream_put_le32(&cropping, track->video.pixel_cropr); } - if (par->codec_id != AV_CODEC_ID_HEVC) + // The HEVC parser supplies the reorder delay when the decoder is disabled. + if (!CONFIG_HEVC_DECODER || par->codec_id != AV_CODEC_ID_HEVC) sti->need_parsing = AVSTREAM_PARSE_HEADERS; if (track->default_duration) { -- 2.52.0 >From 4da669ab7eec1dce9789a5129ac5e6bec4fd6ef2 Mon Sep 17 00:00:00 2001 From: Michael Niedermayer <[email protected]> Date: Thu, 8 Oct 2026 04:59:41 +0000 Subject: [PATCH 2/2] fate/matroska: cover streamcopy without native H.264/HEVC decoders Remux existing MP4 samples to Matroska, then streamcopy to framecrc. Verify the reconstructed DTS, preserved PTS and packet payloads when the native decoders are disabled. The H.264 sample also exercises the level-derived reorder bound without explicit bitstream restrictions. Both tests fail before the parser reorder-delay fix and pass with it, with no decoders enabled and with libopenh264 enabled. Assisted-by: Fairy --- tests/fate/matroska.mak | 11 ++++++++ tests/ref/fate/matroska-h264-remux-nodec | 33 ++++++++++++++++++++++++ tests/ref/fate/matroska-hevc-remux-nodec | 28 ++++++++++++++++++++ 3 files changed, 72 insertions(+) create mode 100644 tests/ref/fate/matroska-h264-remux-nodec create mode 100644 tests/ref/fate/matroska-hevc-remux-nodec diff --git a/tests/fate/matroska.mak b/tests/fate/matroska.mak index f165ce1947..2e9fcd6210 100644 --- a/tests/fate/matroska.mak +++ b/tests/fate/matroska.mak @@ -1,3 +1,14 @@ +# Exercise parser-provided reorder delays without the native decoders. +ifndef CONFIG_H264_DECODER +FATE_MATROSKA-$(call REMUX, MATROSKA, MOV_DEMUXER H264_PARSER) += fate-matroska-h264-remux-nodec +fate-matroska-h264-remux-nodec: CMD = transcode mov $(TARGET_SAMPLES)/h264/h264_3bf_pyramid_nobsrestriction.mp4 matroska "-map 0:v:0 -c copy" "-map 0:v:0 -c copy" +endif + +ifndef CONFIG_HEVC_DECODER +FATE_MATROSKA-$(call REMUX, MATROSKA, MOV_DEMUXER HEVC_PARSER) += fate-matroska-hevc-remux-nodec +fate-matroska-hevc-remux-nodec: CMD = transcode mov $(TARGET_SAMPLES)/hevc/dv84.mov matroska "-map 0:v:0 -c copy -frames:v 20" "-map 0:v:0 -c copy" +endif + FATE_MATROSKA-$(call FRAMECRC, MATROSKA,, ZLIB) += fate-matroska-prores-zlib fate-matroska-prores-zlib: CMD = framecrc -i $(TARGET_SAMPLES)/mkv/prores_zlib.mkv -c:v copy diff --git a/tests/ref/fate/matroska-h264-remux-nodec b/tests/ref/fate/matroska-h264-remux-nodec new file mode 100644 index 0000000000..a44b0db872 --- /dev/null +++ b/tests/ref/fate/matroska-h264-remux-nodec @@ -0,0 +1,33 @@ +3ddeff9d725b3f8f25bd3c705ed5df4e *tests/data/fate/matroska-h264-remux-nodec.matroska +55337 tests/data/fate/matroska-h264-remux-nodec.matroska +#extradata 0: 38, 0xbef609bd +#tb 0: 1/1000 +#media_type 0: video +#codec_id 0: h264 +#dimensions 0: 320x240 +#sar 0: 1/1 +0, -280, 0, 40, 5628, 0x5f78e7d8 +0, -240, 160, 40, 3516, 0xd1c8d0c8, F=0x0 +0, -200, 80, 40, 2192, 0x19fa319b, F=0x0 +0, -160, 40, 40, 1561, 0xf97cfce6, F=0x0 +0, -120, 120, 40, 1598, 0xc03005c0, F=0x0 +0, -80, 320, 40, 3217, 0x2b472fec, F=0x0 +0, -40, 240, 40, 1920, 0xe85fbc36, F=0x0 +0, 0, 200, 40, 1572, 0xefc81615, F=0x0 +0, 40, 280, 40, 1467, 0x3724dec5, F=0x0 +0, 80, 480, 40, 2989, 0x5820d06d, F=0x0 +0, 120, 400, 40, 1896, 0x5d0aadba, F=0x0 +0, 160, 360, 40, 1471, 0xe422e476, F=0x0 +0, 200, 440, 40, 1478, 0x39bbe5d8, F=0x0 +0, 240, 640, 40, 2693, 0x9007492a, F=0x0 +0, 280, 560, 40, 2098, 0x19e51843, F=0x0 +0, 320, 520, 40, 1573, 0xbdfc1ca3, F=0x0 +0, 360, 600, 40, 1562, 0x71390e2b, F=0x0 +0, 400, 800, 40, 2879, 0x7761851a, F=0x0 +0, 440, 720, 40, 1860, 0x67c89627, F=0x0 +0, 480, 680, 40, 1529, 0x8ad5ee49, F=0x0 +0, 520, 760, 40, 1485, 0xe3a6dc4e, F=0x0 +0, 560, 960, 40, 2794, 0xbfaf8827, F=0x0 +0, 600, 880, 40, 2175, 0x589626f3, F=0x0 +0, 640, 840, 40, 1713, 0x28884797, F=0x0 +0, 680, 920, 40, 1758, 0x653c625b, F=0x0 diff --git a/tests/ref/fate/matroska-hevc-remux-nodec b/tests/ref/fate/matroska-hevc-remux-nodec new file mode 100644 index 0000000000..12d3bcf559 --- /dev/null +++ b/tests/ref/fate/matroska-hevc-remux-nodec @@ -0,0 +1,28 @@ +aee64ecba0664c6fd1c8b1c212ddefe1 *tests/data/fate/matroska-hevc-remux-nodec.matroska +721746 tests/data/fate/matroska-hevc-remux-nodec.matroska +#extradata 0: 551, 0xb1ddcd66 +#tb 0: 1/1000 +#media_type 0: video +#codec_id 0: hevc +#dimensions 0: 1920x1080 +#sar 0: 0/1 +0, -67, 0, 33, 63375, 0xc76606ab +0, -34, 133, 33, 46706, 0x0e08a7e5, F=0x0 +0, 0, 67, 33, 29766, 0x753c031a, F=0x0 +0, 33, 33, 33, 19409, 0x4b948b6c, F=0x0 +0, 67, 100, 33, 21086, 0x1b9412ce, F=0x0 +0, 100, 267, 33, 62043, 0xc2356b56, F=0x0 +0, 133, 200, 33, 36175, 0x0a7df38c, F=0x0 +0, 167, 167, 33, 16028, 0xa57fcbe9, F=0x0 +0, 200, 233, 33, 15428, 0x9a91f357, F=0x0 +0, 233, 400, 33, 66072, 0xa542b6d7, F=0x0 +0, 267, 333, 33, 34985, 0xbfd8ff45, F=0x0 +0, 300, 300, 33, 16036, 0xfc39c6ea, F=0x0 +0, 333, 367, 33, 19893, 0x7e746f4e, F=0x0 +0, 367, 533, 33, 77576, 0xeba2e5c8, F=0x0 +0, 400, 467, 33, 35400, 0xbe179462, F=0x0 +0, 433, 433, 33, 15962, 0x7703dcd8, F=0x0 +0, 467, 500, 33, 16136, 0x78a74880, F=0x0 +0, 500, 667, 33, 74990, 0xb6fc1da7, F=0x0 +0, 533, 600, 33, 36594, 0xc3c61c3e, F=0x0 +0, 567, 567, 33, 16524, 0xb297a886, F=0x0 -- 2.52.0 _______________________________________________ ffmpeg-devel mailing list -- [email protected] To unsubscribe send an email to [email protected]
