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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

• Xuggler encoding images to video FPS issue

  1er novembre 2011, par Chris Robinson

  I've been experimenting with encoding a video from a series of images using CaptureScreenToFile.java as a basis. My output is to be an MP4 file. From 26 images, using the code as is (taking the images from a directory instead of from a screen capture obviously), the encoding video is 11s. However, if I change the framerate variable to :

  frameRate = IRational.make(1, 24);

  which I believe should result in a video of 24FPS. It does not however, (no change from the original video in fact). I experimented with changing the timeStamp variable in encodeImage() method to :

  long timeStamp = (firstTimeStamp*1000)+(i*40);

  where 0 < i < 25 to see if that would help but it doesn't. Can anyone explain to me how to encode a directory of images to a video with a framerate that I can set ?

• FFmpeg with PHP causes Internal Server Error

  19 novembre 2015, par Scott Heath

  I have a PHP script that calls exec() to convert video files using ffmpeg. The script works fine with smaller files, but larger files, usually around 20MB, produce a 500 Internal Server Error after the conversion has run for about 45 seconds.

  The max_execution_time is set to 600 seconds (10 minutes) and the max post and upload sizes are set to 1000 MB. The server is Unix based and is not running in safe mode.

  Although the issue only happens with larger sizes, I’m not even sure it’s a file size issue. The script will pass with a 12.6MB MOV file but will fail with an 11MB MP4 file.

  Below is the exec() line from my script :

  exec('ffmpeg -y -i '.escapeshellarg($uploadFile).' -vcodec libx264 -ab 128k -ac 2 -b 640k -g 300 -keyint_min 25 -sc_threshold 40 -i_qfactor 0.71 -maxrate 10M -bufsize 10M -qcomp 0.6 -qmin 10 -qmax 51 -qdiff 4 -level 30 '.$convertFile);

  Thanks !