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• How can I convince ffserver to save a locally-sourced webcam stream to a file in high resolution AND stream it in lower resolution ?

  2 novembre 2015, par Dominic Jacobssen

  We have a remote Linux machine, accessible over VPN, which has a USB webcam. We want to use this for video conferencing, but we also want to store the stream for archiving.

  Since the streaming bandwidth is limited, it makes sense to capture the stream on the same machine as the webcam and rsync that across after-the-fact, rather than trying to capture the streamed content, which is necessarily going to be poor quality.

  We’re trying to use ffmpeg and ffserver to achieve this, but with little success. Most of the articles on the internet either deal with just streaming a webcam, or rebroadcasting a remote stream. We found we had to recompile ffserver because of a missing "my_addr->sin_family = AF_INET ;" in the version of ffserver.c we had been using, since fixed in git.

  Here’s the ffserver.conf we’re trying to use :

  Port 43688
  
  BindAddress 127.0.0.1
  
  MaxHTTPConnections 2000
  
  MaxClients 1000
  
  MaxBandwidth 1000
  
  CustomLog -
  
  NoDaemon
  
  <feed>
  
  ReadOnlyFile /tmp/feed.ffm
  
  FileMaxSize 20M
  
  ACL allow 127.0.0.1
  
  </feed>
  
  <stream>
  
  Feed feed.ffm
  
  Format mp4
  
  VideoSize qvga
  
  VideoGopSize 12
  
  VideoHighQuality
  
  Video4MotionVector
  
  VideoCodec libx264
  
  VideoBitRate 100
  
  VideoBufferSize 40
  
  VideoFrameRate 5
  
  VideoQMin 3
  
  VideoQMax 31
  
  AudioCodec libfaac
  
  AudioBitRate 32
  
  AudioChannels 2
  
  AudioSampleRate 22050
  
  ACL allow localhost
  
  </stream>

  When we fire this up, we get the error :

  Unable to create feed file '/tmp/feed.ffm' as it is marked readonly

  Fair enough, but this is not what is implied in the docs. Changing the directive to :

  File /tmp/feed.ffm

  allows ffserver to fire up and appear to sit and wait for ffmpeg to connect to it. However, when we fire up ffmpeg with the command :

  ffmpeg -f alsa -i pulse -r 16000 -f video4linux2 -s qvga -i /dev/video0 -r 5 -f mp4 -vcodec libx264 -sameq -acodec libfaac -ab 32k http://127.0.0.1:43688/feed.ffm

  then the webcam lights up and ffserver acknowledges the connection with the messages :

  New connection: POST /feed.ffm
  
  [POST] "/feed.ffm HTTP/1.1" 200 0

  but after a few seconds we get the errors :

  [mp4 @ 0x264b160] muxer does not support non seekable output
  
  Could not write header for output file #0 (incorrect codec parameters ?)

  We’ve tried various other formats (mpeg, mpegts, avi) and codecs (mpeg1video, mpeg2video, mpeg4), all without success.

  Moreover, we were under the impression that ffserver could reencode input format to a lower resolution for streaming, but if the stream resolution doesn’t match the feed resolution, we get an error about the resolutions not matching.

  Has anyone ever managed to get this working correctly ? I’ve read about vlc being able to do something like this, but the vlc command lines are well nigh impenetrable.

  Thanks !

  Dominic

• H264 encoder settings

  30 novembre 2011, par Chris Robinson

  I'm using xuggler to encode a series of images to an MP4 file. I use the following code to setup the IStreamCoder and specify the H264 codec :

  // only set if codec is H264
  
  Configuration.configure("/usr/local/xuggler/share/ffmpeg/libx264-hq.ffpreset",
  
              outStreamCoder);
  
  
  
  outStreamCoder.setNumPicturesInGroupOfPictures(12);
  
  outStreamCoder.setCodec(codec);
  
  outStreamCoder.setBitRate(videoSettings.getBitrate());
  
  outStreamCoder.setBitRateTolerance(videoSettings.getBitrateTolerance());
  
  outStreamCoder.setPixelType(IPixelFormat.Type.YUV420P);
  
  outStreamCoder.setHeight(videoSettings.getResolution().height);
  
  outStreamCoder.setWidth(videoSettings.getResolution().width);
  
  outStreamCoder.setFlag(IStreamCoder.Flags.FLAG_QSCALE, true);
  
  outStreamCoder.setGlobalQuality(0);
  
  fps = IRational.make((int) videoSettings.getFramerate(), 1);
  
  outStreamCoder.setFrameRate(fps);
  
  outStreamCoder.setTimeBase(IRational.make(fps.getDenominator(), fps.getNumerator()));

  which yields the following output :

  Codec: CODEC_ID_H264
  
  Resolution: 1280x720
  
  Bitrate: 25000
  
  Bitrate Tolerance: 1000
  
  Framerate: 25.0

  

  Now when I specify the MPEG4 codec, I get the following output :

  Codec: CODEC_ID_MPEG4
  
  Resolution: 1280x720
  
  Bitrate: 25000
  
  Bitrate Tolerance: 1000
  
  Framerate: 25.0

  

  As you can see, the only difference is the ICodec type (MPEG4 instead of H264) and the use of the preset (which is required by xuggler when using an H264 codec). Can anyone explain to me the huge difference in quality and tell me how to resolve the issue ?

• How to enable different components of FFMPEG ?

  3 décembre 2011, par Richard77

  I've found this C# wrapper code around FFMPEG. I'm using ASP.NET MVC3 and C#. When trying to get it work, I'm getting the following error :

          RawOutput   "ffmpeg version N-34906-g4e7b3ef, Copyright (c) 2000-2011
  
          the FFmpeg developers
  
  
  
          built on Nov 16 2011 12:35:07 with gcc 4.6.2
  
  
  
          configuration: --enable-gpl --enable-version3 --disable-w32threads 
  
          --enable-runtime-cpudetect --enable-avisynth --enable-bzlib --enable-frei0r 
  
          --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libfreetype 
  
          --enable-libgsm --enable-libmp3lame --enable-libopenjpeg --enable-librtmp 
  
          --enable-libschroedinger --enable-libspeex --enable-libtheora 
  
          --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis 
  
          --enable-libvpx --enable-libx264 --enable-libxavs --enable-libxvid 
  
          --enable-zlib
  
  
  
          libavutil    51. 25. 0 / 51. 25. 0
  
          libavcodec   53. 34. 0 / 53. 34. 0 
  
          libavformat  53. 20. 0 / 53. 20. 0 
  
          libavdevice  53.  4. 0 / 53.  4. 0  
  
          libavfilter   2. 48. 1 /  2. 48. 1 
  
          libswscale    2.  1. 0 /  2.  1. 0 
  
          libpostproc  51.  2. 0 / 51.  2. 0
  
          [wmv3 @ 002BFA00] Extra data: 8 bits left, value: 0
  
          [asf @ 002B8A80] parser not found for codec wmav2, packets or times may be invalid.
  
          Seems stream 1 codec frame rate differs from container frame rate: 1000.00 (1000/1) -> 30.00 (30/1)
  
          Input #0, asf, from 'C:\\FfMpeg\\Videos\\Original\\Video1.wmv':
  
          Metadata:
  
          WMFSDKVersion   : 11.0.6002.18049   
  
          WMFSDKNeeded    : 0.0.0.0000
  
          IsVBR           : 0
  
          Duration: 00:00:41.80, start: 0.000000, bitrate: 888 kb/s
  
          Stream #0:0(eng): Audio: wmav2 (a[1][0][0] / 0x0161), 44100 Hz, 2 channels, s16, 64 kb/s
  
          Stream #0:1(eng): Video: wmv3 (Main) (WMV3 / 0x33564D57), yuv420p, 320x240, 786 kb/s, 30 tbr, 1k tbn, 1k tbc
  
          Incompatible pixel format 'yuv420p' for codec 'mjpeg', auto-selecting format 'yuvj420p'
  
          [buffer @ 031D8DA0] w:320 h:240 pixfmt:yuv420p tb:1/1000000 sar:0/1 sws_param:
  
          [buffersink @ 031D8FA0] auto-inserting filter 'auto-inserted scale 0' between the filter 'src' and the filter 'out'
  
          [scale @ 03106C20] w:320 h:240 fmt:yuv420p -> w:320 h:240 fmt:yuvj420p flags:0x4
  
          [wmv3 @ 002BFA00] Extra data: 8 bits left, value: 0
  
          Output #0, image2, to '87334ed0-2bcf-4be5-82ae-9089c14e0323.jpg':
  
          Metadata:
  
          WMFSDKVersion   : 11.0.6002.18049
  
          WMFSDKNeeded    : 0.0.0.0000
  
          IsVBR           : 0
  
          encoder         : Lavf53.20.0
  
          Stream #0:0(eng): Video: mjpeg, yuvj420p, 320x240, q=2-31, 200 kb/s, 90k tbn, 30 tbc
  
          Stream mapping:
  
          Stream #0:1 -> #0:0 (wmv3 -> mjpeg)
  
          Press [q] to stop, [?] for help
  
          [image2 @ 03107920] Could not open file : 87334ed0-2bcf-4be5-82ae-9089c14e0323.jpg
  
          av_interleaved_write_frame(): Input/output error
  
          "   string

  I'm absolutely new to FFMPEG, so I don't know where to start to solve the above probleme.

  EDIT

  public ActionResult Convert()
  
      {
  
          Converter _converter = new Converter(@"C:\FfMpeg\ffmpeg.exe");
  
          OutputPackage oo = _converter.ConvertToFLV(@"C:\FfMpeg\Videos\Original\Video1.wmv");
  
  
  
          FileStream outStream = System.IO.File.OpenWrite(@"C:\FfMpeg\Videos\Converted\Video1.flv");
  
          oo.VideoStream.WriteTo(outStream);
  
          outStream.Flush();
  
          outStream.Close();
  
  
  
          oo.PreviewImage.Save(@"C:\FfMpeg\Videos\Thumbnail\Thumbnail1.jpg");
  
  
  
          return RedirectToAction("WatchMovie");
  
      }

  Thanks for helping