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• avcodec/vc1_block : Fix undefined behavior in ac prediction rescaling

  31 octobre 2019, par Michael Niedermayer

  avcodec/vc1_block : Fix undefined behavior in ac prediction rescaling
  The intermediates are required to fit in 12bit (8.1.3.9 Coefficient Scaling)
  
  See SMPTE 421M-2006 and Amendment 1-2007
  Fixes : signed integer overflow : -20691 * 262144 cannot be represented in type 'int'
  
  Fixes : 18479/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_VC1_fuzzer-5128912371187712
  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/vc1_block.c

• Converting Quicktime (.mov ) from iPhone to mp4

  24 mars 2020, par user3094755

  On iPhones running iOS 11, if a video is pre-recorded and uploaded I get the following errors :- ( ie, the video is recoded on the iPhone and then uploaded as an attachment ).

  $ ./ffmpeg -i .mov -vcodec h264 -acodec mp4 test-output.mp4
  
  FFmpeg version CVS, Copyright (c) 2000-2004 Fabrice Bellard
  
  Mac OSX universal build for ffmpegX
  
    configuration:  --enable-memalign-hack --enable-mp3lame --enable-gpl --disable-vhook --disable-ffplay --disable-ffserver --enable-a52 --enable-xvid --enable-faac --enable-faad --enable-amr_nb --enable-amr_wb --enable-pthreads --enable-x264 
  
    libavutil version: 49.0.0
  
    libavcodec version: 51.9.0
  
    libavformat version: 50.4.0
  
    built on Apr 15 2006 04:58:19, gcc: 4.0.1 (Apple Computer, Inc. build 5250)
  
  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x5597b8]mov: header not found !!! (err:0, moov:0, mdat:0) pos:3189455560
  
  .mov: Error while opening file
  
  $

  If the video is recorded and then transferred to a Desktop uploaded and then converted it works OK.

  If I use a ‘live’ recording then all is OK.

  I found this…

  https://www.howtogeek.com/327689/how-to-make-your-iphone-use-jpg-and-mp4-files-instead-of-heif-and-hevc/

  Which seems to suggest iOS 11 will use different formats, but this appears to make no difference whatever the settings are for ‘High Efficiency / Most Compatible’.

  Any ideas ?

• Concatenating *.mkv files using ffmpeg

  25 mars 2020, par Daniel F

  I’ve just about lost my mind on this, I’m sure I’m missing something simple.

  I have two *.mkv files generated by OBS. Even better, I’ve just copied one file twice, so I am sure I have the same bitrate, fps, tbn, whatever.

  then I do :

  ffmepg -i "concat:file1.mkv|file1_copy.mkv" -c copy test.mkv

  It runs and my screen fills with yellow messages :

      ffmpeg -i "concat:file1.mkv|file1_copy.mkv" -c copy test.mkv
  
  ffmpeg version 4.2 Copyright (c) 2000-2019 the FFmpeg developers
  
    built with gcc 9.1.1 (GCC) 20190807
  
    configuration: --disable-static --enable-shared --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-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-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libmfx --enable-amf --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt
  
    libavutil      56. 31.100 / 56. 31.100
  
    libavcodec     58. 54.100 / 58. 54.100
  
    libavformat    58. 29.100 / 58. 29.100
  
    libavdevice    58.  8.100 / 58.  8.100
  
    libavfilter     7. 57.100 /  7. 57.100
  
    libswscale      5.  5.100 /  5.  5.100
  
    libswresample   3.  5.100 /  3.  5.100
  
    libpostproc    55.  5.100 / 55.  5.100
  
  Input #0, matroska,webm, from 'concat:file1.mkv|file1_copy.mkv':
  
    Metadata:
  
      ENCODER         : Lavf58.20.100
  
    Duration: 00:00:09.15, start: 0.000000, bitrate: 2006 kb/s
  
      Stream #0:0: Video: h264 (High), yuv420p(progressive), 1920x1080 [SAR 1:1 DAR 16:9], 60 fps, 60 tbr, 1k tbn, 120 tbc (default)
  
      Metadata:
  
        DURATION        : 00:00:09.150000000
  
      Stream #0:1: Audio: aac (LC), 44100 Hz, stereo, fltp (default)
  
      Metadata:
  
        title           : simple_aac_recording
  
        DURATION        : 00:00:09.102000000
  
  Output #0, matroska, to 'test.mkv':
  
    Metadata:
  
      encoder         : Lavf58.29.100
  
      Stream #0:0: Video: h264 (High) (H264 / 0x34363248), yuv420p(progressive), 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 60 fps, 60 tbr, 1k tbn, 1k tbc (default)
  
      Metadata:
  
        DURATION        : 00:00:09.150000000
  
      Stream #0:1: Audio: aac (LC) ([255][0][0][0] / 0x00FF), 44100 Hz, stereo, fltp (default)
  
      Metadata:
  
        title           : simple_aac_recording
  
        DURATION        : 00:00:09.102000000
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
    Stream #0:1 -> #0:1 (copy)
  
  Press [q] to stop, [?] for help
  
  [matroska,webm @ 00000156ce7f14c0] File extends beyond end of segment.
  
  [matroska @ 00000156cef62040] Non-monotonous DTS in output stream 0:0; previous: 9100, current: 0; changing to 9100. This may result in incorrect timestamps in the output file.
  
  [matroska @ 00000156cef62040] Non-monotonous DTS in output stream 0:0; previous: 9100, current: 67; changing to 9100. This may result in incorrect timestamps in the output file.
  
  [matroska @ 00000156cef62040] Non-monotonous DTS in output stream 0:0; previous: 9100, current: 33; changing to 9100. This may result in incorrect timestamps in the output file.
  
  [matroska @ 00000156cef62040] Non-monotonous DTS in output stream 0:1; previous: 9102, current: 0; changing to 9102. This may result in incorrect timestamps in the output file.
  
  [matroska @ 00000156cef62040] Non-monotonous DTS in output stream 0:0; previous: 9100, current: 17; changing to 9100. This may result in incorrect timestamps in the output file.
  
  
  
  ############## thousands of the above lines here #####################
  
  
  
  frame= 1098 fps=0.0 q=-1.0 Lsize=    2241kB time=00:00:09.11 bitrate=2013.0kbits/s speed=24.9x
  
  video:2068kB audio:159kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.607770%

  When opened, the timestamps only go to the end of the first segment, even though the video continues afterwards. Normally this would be fine, but I’m recording instructional videos and it would be nice for users to be able to skip around them. This occurs even if I re-encode the videos (which I shouldn’t need, since they are identical) or re-encode the output.

  Everything I have read online says :

  • re-encode*into .mkv to fix this, since .mkv has a fixed tbn - it’s already .mkv

  • the problem is different bitrates/tbs/fps/whatever - for now, they’re the same video twice

  • use -fflags +genpts, -use_wallclock_as_timestamps 1, vsync 0 -enc_time_base -1 - none of these do anything as far as I can tell, either before -i or after -c copy

  I’ve run out of ideas. What am I doing wrong.