#8690: FFmpeg treats all audio samples as sync samples for fragmented MP4 files ----------------------------------+-------------------------------------- Reporter: berndcz | Type: defect Status: new | Priority: normal Component: avformat | Version: git-master Keywords: | Blocked By: Blocking: | Reproduced by developer: 0 Analyzed by developer: 0 | ----------------------------------+-------------------------------------- Summary of the bug: It seems that currently all audio samples (AVMEDIA_TYPE_AUDIO) belonging to a fragmented MP4 file are treated as sync samples (keyframe = 1, mov.c:4937). Since there are audio formats where samples depend on other samples, e.g. xHE-AAC , the sample metadata should not be overwritten. How to reproduce: Attached hereto, you can find a fragmented MP4 file containing one xHE-AAC audio track. For each fragment, only the first file format sample is signalled as sync sample. However, when seeking into the file, FFmpeg is forwarding non-sync samples to the decoder (please have a look at the libfdk_aac log message).. {{{ % ./ffmpeg -acodec libfdk_aac -ss 10 -i ./fragmented-5s_frag_duration-2ch- xheaac-64kbps.mp4 skip_start.wav ffmpeg version N-97830-gb707abf091 Copyright (c) 2000-2020 the FFmpeg developers built with gcc 9 (Ubuntu 9.3.0-10ubuntu2) configuration: --enable-libfdk-aac --disable-encoder=aac --disable- decoder=aac --disable-decoder=aac_latm libavutil 56. 46.100 / 56. 46.100 libavcodec 58. 84.100 / 58. 84.100 libavformat 58. 43.100 / 58. 43.100 libavdevice 58. 9.103 / 58. 9.103 libavfilter 7. 81.100 / 7. 81.100 libswscale 5. 6.101 / 5. 6.101 libswresample 3. 6.100 / 3. 6.100 Input #0, mov,mp4,m4a,3gp,3g2,mj2, from './fragmented-5s_frag_duration- 2ch-xheaac-64kbps.mp4': Metadata: major_brand : mp42 minor_version : 0 compatible_brands: mp42isomdash creation_time : 2020-04-15T12:36:42.000000Z Duration: 00:04:00.00, start: 0.000000, bitrate: 66 kb/s Stream #0:0(und): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo, s16, 1 kb/s (default) Metadata: creation_time : 2020-04-15T12:36:42.000000Z handler_name : soun Stream mapping: Stream #0:0 -> #0:0 (aac (libfdk_aac) -> pcm_s16le (native)) Press [q] to stop, [?] for help [libfdk_aac @ 0x55e234844c80] aacDecoder_DecodeFrame() failed: 5 Error while decoding stream #0:0: Unknown error occurred [libfdk_aac @ 0x55e234844c80] aacDecoder_DecodeFrame() failed: 5 Error while decoding stream #0:0: Unknown error occurred [libfdk_aac @ 0x55e234844c80] aacDecoder_DecodeFrame() failed: 5 Error while decoding stream #0:0: Unknown error occurred [libfdk_aac @ 0x55e234844c80] aacDecoder_DecodeFrame() failed: 5 Error while decoding stream #0:0: Unknown error occurred Output #0, wav, to 'skip_start.wav': Metadata: major_brand : mp42 minor_version : 0 compatible_brands: mp42isomdash ISFT : Lavf58.43.100 Stream #0:0(und): Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, stereo, s16, 1536 kb/s (default) Metadata: creation_time : 2020-04-15T12:36:42.000000Z handler_name : soun encoder : Lavc58.84.100 pcm_s16le size= 43096kB time=00:03:49.99 bitrate=1535.0kbits/s speed= 108x video:0kB audio:43096kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.000177% }}} -- Ticket URL: <https://trac.ffmpeg.org/ticket/8690> FFmpeg <https://ffmpeg.org> FFmpeg issue tracker