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• tools/target_swr_fuzzer : do not use negative numbers of samples

  30 novembre 2024, par Michael Niedermayer

  tools/target_swr_fuzzer : do not use negative numbers of samples
  Fixes : signed integer overflow : -277109688 * 8 cannot be represented in type 'int'
  
  Fixes : 376118159/clusterfuzz-testcase-minimized-ffmpeg_SWR_fuzzer-5884436320681984
  Found-by : continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] tools/target_swr_fuzzer.c

• FFmpeg : MD5 hash of M3U8 playlists generated from same input video with different segment durations (after applying video filter) don't match

  30 juillet 2020, par Saurabh P Bhandari

  Here are a few commands I am using to convert and transize a video in MP4 format to a M3U8 playlist.

  


  For a given input video (MP4 format), generate multiple video segments with segment duration 30 seconds.

  


  ffmpeg -loglevel error -i input.mp4 -dn -sn -an -c:v copy -bsf:v h264_mp4toannexb -copyts -start_at_zero -f segment -segment_time 30 30%03d.mp4 -dn -sn -vn -c:a copy audio.aac


  


  Apply a video filter (in this case scaling) on each segment and convert it to a M3U8 format.

  


  ls 30*.mp4 | parallel 'ffmpeg -loglevel error -i {} -vf scale=-2:144 -hls_list_size 0 {}.m3u8'


  


  Store the list of m3u8 files generated in list.txt in this format file 'segment-name.m3u8'

  


  for f in 30*.m3u8; do echo "file '$f'" >> list.txt; done


  


  Using concat demuxer, combine all segment files (which are in M3U8 format) and the audio to get one final m3u8 playlist pointing to segments with duration of 10 seconds.

  


  ffmpeg -loglevel error -f concat -i list.txt -i audio.aac -c copy -hls_list_size 0 -hls_time 10 output_30.m3u8


  


  ---

  


  I can change the segment duration in the first step from 30 seconds to 60 seconds, and compare the MD5 hash of the final M3U8 playlist generated in both the cases using this command :

  


  ffmpeg -loglevel error -i <input m3u8="m3u8" playlist="playlist" /> -f md5 -&#xA;

  


  The MD5 hash of the output files differ, i.e., video streams of output_30.m3u8 and output_60.m3u8 are not the same.

  


  Can anyone elaborate on this ?

  


  (I expected the MD5 hash to be the same)

  


• Concatenating Video Files using FFMPEG YUV issue

  3 novembre 2015, par SpoiledTechie.com

  I am concatenating three videos with FFMPEG.

  The 1st and 3rd video of the concatenation were pulled from an AVI file using FFMPEG and converted into MP4.

  Their codec information is below.

  

  The 2nd video in the concatenation is compiled using FFMPEG. I am compiling frames with FFMPEG to create this video.

  Its codec information is below.

  
  As you can see, the videos share the same codec, resolution and frame rate.

  The only thing they don’t share is the Decoded format. One being 4:4:4 and one being 4:2:2

  I think I understand what YUV means from this link, https://msdn.microsoft.com/en-us/library/windows/desktop/dd391027%28v=vs.85%29.aspx?f=255&MSPPError=-2147217396

  When I concatenate these three videos together, using concat demuxer, it works, but when I try to watch the final video, the video shows the first file playing just right, then the 2nd video in the final video shows up BLANK and the third video plays just fine as well.

  So my question is, how do I concat 3 MP4 files, but change what seems to be the decoded format for the 2nd video to 4:2:2. When I compile the frames, I imagine I can change the YUV format, but I don’t know how just yet.