[FFmpeg-trac] #8624(avcodec:new): Codec Copy Reencodes AAC VBR Audio

FFmpeg trac at avcodec.org
Sun Apr 19 21:16:27 EEST 2020


#8624: Codec Copy Reencodes AAC VBR Audio
------------------------------------+--------------------------------------
             Reporter:  aminhusni   |                     Type:  defect
               Status:  new         |                 Priority:  normal
            Component:  avcodec     |                  Version:  git-master
             Keywords:  AAC MP4 TS  |               Blocked By:
             Blocking:              |  Reproduced by developer:  0
Analyzed by developer:  0           |
------------------------------------+--------------------------------------
 Summary of the bug:
 Codec Copy or Audio Codec Copy Reencodes AAC VBR Audio

 Flow: .ts -> .mp4

 Tried with -c:a copy and -codec copy and both does not give expected
 result.

 The original .ts file has a VBR audio.
 When copying into .mp4, it reencodes the audio into CBR and byte
 comparison for the audio track does not match with original AAC that comes
 from the .ts file.

 How to reproduce:
 {{{
 %  ffmpeg -i .\sample_media.ts -c:v copy -c:a copy .\vacopy.mp4
 ffmpeg git-2020-04-17-889ad93
 built on gcc 9.3.1 (GCC) 20200328
 }}}

 Additional console log:

 {{{
 ffmpeg version git-2020-04-17-889ad93 Copyright (c) 2000-2020 the FFmpeg
 developers
   built with gcc 9.3.1 (GCC) 20200328
   configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-
 fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-
 libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame
 --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg
 --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr
 --enable-libsrt --enable-libtheora --enable-libtwolame --enable-libvpx
 --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265
 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp
 --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvo-
 amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-
 libaom --disable-w32threads --enable-libmfx --enable-ffnvcodec --enable-
 cuda-llvm --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec
 --enable-dxva2 --enable-avisynth --enable-libopenmpt --enable-amf
   libavutil      56. 42.102 / 56. 42.102
   libavcodec     58. 80.100 / 58. 80.100
   libavformat    58. 42.100 / 58. 42.100
   libavdevice    58.  9.103 / 58.  9.103
   libavfilter     7. 77.101 /  7. 77.101
   libswscale      5.  6.101 /  5.  6.101
   libswresample   3.  6.100 /  3.  6.100
   libpostproc    55.  6.100 / 55.  6.100
 [h264 @ 0000022e104ecfc0] missing picture in access unit with size 8
 Input #0, mpegts, from '.\sample_media.ts':
   Duration: 00:00:04.05, start: 12.027933, bitrate: 6135 kb/s
     Stream #0:0[0x100]: Video: h264 (Main), yuv420p(tv,
 bt709/unknown/unknown, progressive), 1920x1080 [SAR 1:1 DAR 16:9], 29.97
 fps, 29.97 tbr, 90k tbn, 59.94 tbc
     Stream #0:1[0x101]: Audio: aac (LC), 44100 Hz, stereo, fltp, 229 kb/s
 Output #0, mp4, to '.\vacopy.mp4':
   Metadata:
     encoder         : Lavf58.42.100
     Stream #0:0: Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv,
 bt709/unknown/unknown, progressive), 1920x1080 [SAR 1:1 DAR 16:9], q=2-31,
 29.97 fps, 29.97 tbr, 90k tbn, 90k tbc
     Stream #0:1: Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo,
 fltp, 229 kb/s
 Stream mapping:
   Stream #0:0 -> #0:0 (copy)
   Stream #0:1 -> #0:1 (copy)
 Press [q] to stop, [?] for help
 [NULL @ 0000022e104ecfc0] missing picture in access unit with size 8
 [mp4 @ 0000022e10bd8040] Timestamps are unset in a packet for stream 0.
 This is deprecated and will stop working in the future. Fix your code to
 set the timestamps properly
 [mp4 @ 0000022e10bd8040] pts has no value
 frame=  121 fps=0.0 q=-1.0 Lsize=    2955kB time=00:00:03.98
 bitrate=6070.3kbits/s speed= 499x
 video:2825kB audio:126kB subtitle:0kB other streams:0kB global headers:0kB
 muxing overhead: 0.148198%
 }}}

 The issue might be similar to ticket #4546

--
Ticket URL: <https://trac.ffmpeg.org/ticket/8624>
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