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• Encoding H.264 CBR videos with FFmpeg

  3 février 2018, par Cornstalks

  I’m trying to encode a video with ffmpeg into H.264 (via the libx264 library) with a constant bit rate. I know, I know, VBR is often preferred, but for this specific job I’m required to use CBR (just as long as it’s so many kilobytes per second ; it doesn’t have to be an exact kilobytes per frame, afaik). My sample video I’m using to test is from here : http://a1408.g.akamai.net/5/1408/1388/2005110403/1a1a1ad948be278cff2d96046ad90768d848b41947aa1986/sample_iTunes.mov.zip (it comes from http://support.apple.com/kb/HT1425)

  I can get a constant bit rate when encoding the video with MPEG-4 Video (using the commands ffmpeg -i sample_iTunes.mov -b 819968 -minrate 819968 -maxrate 819968 out.mov), and the bit rate is as expected. Reading the video’s specs via the QuickTime Inspector, it’s got a data rate of 844.94 kbit/s. Cool.

  However, when I change the codec to libx264, it seems to completely ignore my bitrate requests ! The command I’m trying is "ffmpeg -i sample_iTunes.mov -vcodec libx264 -vpre medium -b 819968 -vb 819968 -minrate 819968 -maxrate 819968 -bufsize 400000 test.mov". But when I check the video’s specs via the QuickTime Inspector, it’s got a data rate of 254.74 kbit/s. WTF ? That’s not even close !

  I’ve tried changing so many parameters and adding tons of different things, and I’ve spent 2 days googling this, but I can’t seem to get it to work. If I encode the video with the MainConcept H.264 encoder, I can get a constant bitrate, but I need this to work with ffmpeg.

  If someone can help me figure out how to do CBR H.264 encoding with FFmpeg, I will love you forever !

• Encoding H.264 CBR videos with FFmpeg

  3 février 2018, par Cornstalks

  I’m trying to encode a video with ffmpeg into H.264 (via the libx264 library) with a constant bit rate. I know, I know, VBR is often preferred, but for this specific job I’m required to use CBR (just as long as it’s so many kilobytes per second ; it doesn’t have to be an exact kilobytes per frame, afaik). My sample video I’m using to test is from here : http://a1408.g.akamai.net/5/1408/1388/2005110403/1a1a1ad948be278cff2d96046ad90768d848b41947aa1986/sample_iTunes.mov.zip (it comes from http://support.apple.com/kb/HT1425)

  I can get a constant bit rate when encoding the video with MPEG-4 Video (using the commands ffmpeg -i sample_iTunes.mov -b 819968 -minrate 819968 -maxrate 819968 out.mov), and the bit rate is as expected. Reading the video’s specs via the QuickTime Inspector, it’s got a data rate of 844.94 kbit/s. Cool.

  However, when I change the codec to libx264, it seems to completely ignore my bitrate requests ! The command I’m trying is "ffmpeg -i sample_iTunes.mov -vcodec libx264 -vpre medium -b 819968 -vb 819968 -minrate 819968 -maxrate 819968 -bufsize 400000 test.mov". But when I check the video’s specs via the QuickTime Inspector, it’s got a data rate of 254.74 kbit/s. WTF ? That’s not even close !

  I’ve tried changing so many parameters and adding tons of different things, and I’ve spent 2 days googling this, but I can’t seem to get it to work. If I encode the video with the MainConcept H.264 encoder, I can get a constant bitrate, but I need this to work with ffmpeg.

  If someone can help me figure out how to do CBR H.264 encoding with FFmpeg, I will love you forever !

• ffmpeg streamaudio video webcam raspberry pi

  5 novembre 2015, par user3291059

  I’m using a webcam on my Rpi to record audio video. I’m using ffmpeg
  and here is my command :

  ffmpeg -y -ac 1 -f alsa -i hw:1,0 -i /dev/video1 -r 10 -s 120*120 -async 1 -strict -2 -c:a aac -pix_fmt yuv420p -threads 0 -ar 44100 -f mpegts out.avi

  This generates a .avi file with video and audio however when I try to stream using ffserver using :

  ffmpeg -y -ac 1 -f alsa -i hw:1,0 -i /dev/video1 -r 10 -s 120*120 -async 1 -strict -2 -c:a aac -pix_fmt yuv420p -threads 0 -ar 44100 -f mpegts http\\some_ip:someport\webcam.ffm

  I get av_interleaved_write_frame(): Broken pip

  How I can fix this ? Any other suggestion to stream audio video (not with Motion please).

  UPDATE

  here is my ffserver config file

      Port 8090
  
  BindAddress 0.0.0.0
  
  MaxHTTPConnections 2000
  
  MaxClients 1000
  
  MaxBandwidth 1000
  
  CustomLog -
  
  #NoDaemon
  
  
  
  <feed>
  
      File /tmp/feed1.ffm
  
      FileMaxSize 200K
  
      ACL allow 127.0.0.1
  
  </feed>
  
  
  
  # if you want to use mpegts format instead of flv
  
  # then change "live.flv" to "live.ts"
  
  # and also change "Format flv" to "Format mpegts"
  
  <stream>
  
      Format mpegts
  
      Feed feed1.ffm
  
  
  
      VideoCodec mjpeg
  
      VideoFrameRate 30
  
      VideoBitRate 512
  
      VideoSize 320x240
  
      AVOptionVideo crf 23
  
      AVOptionVideo preset medium
  
      # for more info on crf/preset options, type: x264 --help
  
      AVOptionVideo flags +global_header
  
  
  
      AudioCodec aac
  
      Strict -2
  
      AudioBitRate 128
  
      AudioChannels 2
  
      AudioSampleRate 44100
  
      AVOptionAudio flags +global_header
  
  </stream>

  when I save the stream to a local file out.avi I can see video and audio but when I use ffserver vlc on my windows machine is not even able to display video (black screen with some sound glitches from time to time)
  Thanks.