Recherche avancée

Sur d’autres sites (4364)

• avformat/cafdec : Check that bytes_per_packet and frames_per_packet are non negative

  22 octobre 2020, par Michael Niedermayer

  avformat/cafdec : Check that bytes_per_packet and frames_per_packet are non negative
  These fields are not signed in the spec (1.0) so they cannot be negative
  
  Changing bytes_per_packet to unsigned would not solve this as it is exported
  
  as block_align which is signed
  Fixes : Infinite loop
  
  Fixes : 26492/clusterfuzz-testcase-minimized-ffmpeg_dem_CAF_fuzzer-5632087614554112
  Found-by : continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavformat/cafdec.c

• FFmpeg concat demuxer negative start time

  6 février 2021, par modfun

  Problem

  


  When using FFmpeg concat demuxer with the -c:v copy option, the initial start time is negative, introducing a black frame for around 0.02 seconds. The video then plays with no other problems. Another question was asked here without any answers.

  


  The black frame appears in Quicktime but not VLC.

  


  Input

  


  The command below shows the start time is at -0.023220, not 0.0

  


  ffmpeg -f concat -safe 0 -i moments.txt -c:v copy combined.mp4
ffmpeg version 4.3.1 Copyright (c) 2000-2020 the FFmpeg developers
  built with Apple clang version 12.0.0 (clang-1200.0.32.28)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/4.3.1_9 --enable-shared --enable-pthreads --enable-version3 --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libbluray --enable-libdav1d --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librtmp --enable-libspeex --enable-libsoxr --enable-videotoolbox --enable-libzmq --enable-libzimg --disable-libjack --disable-indev=jack
  libavutil      56. 51.100 / 56. 51.100
  libavcodec     58. 91.100 / 58. 91.100
  libavformat    58. 45.100 / 58. 45.100
  libavdevice    58. 10.100 / 58. 10.100
  libavfilter     7. 85.100 /  7. 85.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  7.100 /  5.  7.100
  libswresample   3.  7.100 /  3.  7.100
  libpostproc    55.  7.100 / 55.  7.100
Input #0, concat, from 'moments.txt':
  Duration: N/A, start: -0.023220, bitrate: 1067 kb/s
    Stream #0:0(und): Video: hevc (Main) (hvc1 / 0x31637668), yuv420p(tv, progressive), 720x1280, 836 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 29.97 tbc
    Metadata:
      handler_name    : Core Media Video
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 230 kb/s
    Metadata:
      handler_name    : Core Media Audio
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (aac (native) -> aac (native))
Press [q] to stop, [?] for help
Output #0, mp4, to 'combined.mp4':
  Metadata:
    encoder         : Lavf58.45.100
    Stream #0:0(und): Video: hevc (Main) (hvc1 / 0x31637668), yuv420p(tv, progressive), 720x1280, q=2-31, 836 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 30k tbc
    Metadata:
      handler_name    : Core Media Video
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 128 kb/s
    Metadata:
      handler_name    : Core Media Audio
      encoder         : Lavc58.91.100 aac
frame=  318 fps=0.0 q=-1.0 Lsize=    2208kB time=00:00:10.70 bitrate=1689.9kbits/s speed=72.1x
video:2026kB audio:168kB subtitle:0kB other streams:0kB global headers:2kB muxing overhead: 0.673558%
[aac @ 0x7fd530866a00] Qavg: 472.463



  


  Observations

  


  The negative start time does not occur if I encode the video rather than copy it but encoding takes significantly more time.

  


  Thanks for the help !

  


• avcodec/fits : Check gcount and pcount being non negative

  2 février 2021, par Michael Niedermayer

  avcodec/fits : Check gcount and pcount being non negative
  Fixes : signed integer overflow : 9223372036854775807 - -30069403896 cannot be represented in type 'long'
  
  Fixes : 30046/clusterfuzz-testcase-minimized-ffmpeg_dem_FITS_fuzzer-5807144773484544
  Found-by : continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/fits.c