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• FFmpeg concat demuxer and keyframes

  12 janvier 2023, par Rems

  I am trying to use to the concat protocol but I have troubles with keyframes

  


  I use this ffprobe command to visualize the keyframes pts of my videos :

  


  ffprobe -loglevel error -select_streams v:0 -show_entries packet=pts_time,flags -of csv=print_section=0 inout.mp4  | awk -F',' '/K/ {print $1}'

  


  Here is my process : I have the original video, with these keyframes :

  


  0.000000 5.000000 9.760000 14.240000  18.440000 ...

  


  I trim the first 5 seconds, so the output has these keyframes :

  


  0.000000 4.760000 9.240000 13.440000 ...

  


  I create a 5 seconds video by looping an image, with the same parameters/codec... that were used to produce the original video. This video just has one keyframe at 0.000000

  


  Then I concat this video with the trimmed video like this :

  


  ffmpeg -f concat -safe 0 -i list.txt -c copy -shortest  output.mp4 -y

  


  But when I look for the keyframes of the output video, I get this :

  


  0.021016 5.035000 9.795000 14.275000 ...

  


  Is this behavior normal ? Should I add a parameter to handle keyframes during concatenation ? Thanks

  


• avcodec/aacdec : default to non-wide 7.1 in non-strict mode

  17 décembre 2013, par Anssi Hannula

  avcodec/aacdec : default to non-wide 7.1 in non-strict mode
  AAC specification has 7.1(wide) as a default layout for 8-channel
  
  streams (channel config 7). However, at least Nero AAC encoder encodes
  
  non-wide 7.1 streams using the default channel config 7, mapping the
  
  side channels of the original audio stream to the second
  
  AAC_CHANNEL_FRONT pair in the AAC stream. Similarly, e.g. FAAD decodes
  
  the second AAC_CHANNEL_FRONT pair as side channels, therefore decoding
  
  the incorrect streams as if they were correct (and as the encoder
  
  intended).
  FFmpeg currently decodes such files by-the-spec, i.e. after decoding the
  
  original front pair will be in AV_CH_FRONT_x_OF_CENTER and the original
  
  side pair will be in AV_CH_FRONT_x.
  As actual intended 7.1(wide) streams are very rare while misencoded 7.1
  
  files actually exist in the wild, default to assuming a 7.1 layout was
  
  intended unless in strict mode.
  Fixes playback of e.g. 8_Channel_ID.m4a in samples.
  Signed-off-by : Anssi Hannula <anssi.hannula@iki.fi>
  
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavcodec/aacdec.c

• what is the exact path to specify in php for ffmpeg for windows

  17 janvier 2014, par user3196597

  i'm new to ffmpeg..and i've been trying to figure out the exact path to specify while running it in a php exec() function the code below runs fine in terminal but not in php :

     1)c:/ffmpeg/bin/ffmpeg -y -i c:/xampp/htdocs/video/media/original.mp4 -f avi c:/xampp/htdocs/video/media/new.avi 2<&1
  
  
  
  
  
     2)c:/xampp/htdocs/video/ffmpeg/bin/ffmpeg.exe -y -i c:/xampp/htdocs/video/media/original.mp4 -f avi c:/xampp/htdocs/video/media/new.avi 2<&1

  that works fine in terminal but not in php, i think the problem is with the path specification..can anyone tell the exact path to use while working in windows,please ??

  thanks in advance friends :D