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• Fail to set profile to high when using ffmpeg with libx264

  10 mars 2012, par user1258095

  Here is my command :

  ffmpeg -i input.avi -vcodec libx264 -vpre fast -vpre high -acodec copy output.avi

  The output :

  Input #0, avi, from 'short.avi':
  
    Metadata:
  
      encoder         : Lavf53.3.0
  
    Duration: 00:00:25.04, start: 0.000000, bitrate: 12705 kb/s
  
      Stream #0.0: Video: msmpeg4v2, yuv420p, 1920x1080, 24 tbr, 24 tbn, 24 tbc
  
      Stream #0.1: Audio: aac, 48000 Hz, 5.1, s16, 316 kb/s
  
      Metadata:
  
        title           : ED-CM-5.1-DVD-Final2
  
  File for preset 'high' not found

  However, I am able to successfully transcode files when setting the profile to baseline or main, from the man page of x264 it is clear that "high" should also be a valid argument. I also want to know where these preset files are located in the file system(I am running ubuntu 11.10) so that I can make sure what arguments I can actually use for presets and profiles at the moment. I am very frustrated by this issue and would really appreciate any input from you guys. Thanks in advance.

• ffmpeg : record/capture stream and do scene detection at the same time

  2 août 2022, par AnodeCathode

  Is it possible to both capture (record) an RTSP stream and capture scene change events using a single ffmpeg command ? I can almost do what I want with :

  



  ffmpeg -i 'rtsp://mystream' \
-map 0:v -map 0:a -c:v copy -c:a copy -f segment \
-segment_time 300 -segment_format matroska -strftime 1 "%Y%m%d%H%M%S_video.mkv" \
-map 0:v -an -filter:v "select='gt(scene,0.1)'" -frames:v 1 "%Y%m%d%H%M%S_scenechange.png"


  



  This gives me nice 300s stream segments saved to disk, and a scene.png when a scene change is detected. However, scene.png only appears when I terminate the process, and when I do, I only get the last scene event. Ideally I'd like to get a new PNG (or even better, a short video clip) anytime a scene change is detected, without interrupting the recording of video.mkv. I'm sure it can be done with pipes and multiple ffmpeg commands, but for simplicity's sake (and mostly my own curiosity at this point), I'd like to see what can be done with just a single process.

  


• avcodec/ac3dec : Check expacc

  3 novembre 2016, par Michael Niedermayer

  avcodec/ac3dec : Check expacc
  this is somewhat a magic number, which can be understood from reading section
  
  "7.1.2 Exponent Strategy" of the ac3 specification, in short :
  
  Three exponents each represented as number 0-4 are grouped together and
  
  base-5 encoded, so the maximal correct value is 25*4 + 5*4 + 4 = 124.
  Reviewed-by : Andreas Cadhalpun <andreas.cadhalpun@googlemail.com>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/ac3dec.c