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• Tailing last frame of a growing video file

  9 janvier 2012, par ebayindir

  On windows, I have a dynamically created uncompressed avi video file which grows overtime. The application which generates the video file can only write to a physical file. I can start/stop generation of video file and delete the old video file easily.

  I would like to analyze the changing last frame of the growing video file to make some decision depending on the content of the current/latest image in real time. If I can achieve more than 10fps it should be enough.
  I would like to get uncompressed images whenever a new frame available in the video file.

  As a file format I think png could be the best options in that case but I am open to alternatives.
  I wonder if such a thing is possible with ffmpeg or with a similar tool.

  I prefer to analyze the image and make decisions by using a perl+Imager module.
  Tha analyisis requirements are not complicated. Basically I just need to find existence of a few small images in certain locations inside the last frame.
  I would also appreciate if you can suggest an efficient way to get this information in to my application from ffmpeg.
  For example piping directly to my code or reading from saved png files.

  I know perl already has an ffmpeg interface module but as far as I understand that module can't provide the functionality I need.

• rtsp stream capturing

  12 avril 2016, par ДМИТРИЙ МАЛИКОВ

  I’m looking for some universal way to dump rtsp stream. I want to figure out, that some rtsp stream is working well and server is sending some watchable video.

  openRTSP

  At first, google recommends me openRTSP tool.

   openRTSP -4 ${stream_link} > ${output_file}

  But output video file dumped by that tool is not really correct. Video decoder (ffdec) returns many errors like "Failed to decode video packet" and "[h264] no frame !", which don’t suit me.

  ffmpeg

  Then I’ve tried to dump rtsp stream with ffmpeg tool.

  ffmpeg -loglevel debug -i "${stream_link}" -s 640x480 -vcodec copy -acodec copy -y ${output_file}

  But streaming process was interrupted often by error :

  Application provided invalid, non monotonically increasing dts to muxer in stream 0: 730672 >= 730672
  
  av_interleaved_write_frame(): Invalid argument

  I’m trying to use --fflags igndts but ffmpeg doesn’t ignore these errors. It doesn’t make any sense, because that error actually means that audio and video streams are sending asynchronously. The worst thing is that dumped file, resulted by that interrupted dump, is not correct too. Ffdec return some error :

  ERROR [mov,mp4,m4a,3gp,3g2,mj2] moov atom not found
  
  ERROR [ffdec] av_open_input_file: Operation not permitted

  After a nice cup of googling I’ve found, that it’s really old ffmpeg’s muxer bug.

  mplayer

  Than I’ve tried to use mplayer with LIVE_555 lib.

  mplayer -noframedrop -dumpfile ${output_file} -dumpstream ${stream_link}

  But I’ve got some errors too.

  Stream not seekable!
  
  Core dumped ;)

  Question

  I think I’m doing something wrong. It’s sounds really ridiculous, that there is no way to save rtsp stream in correct and playable video-file.

  Maybe there are some another tools which can help with that task ? Actually, I will be grateful for any advice for all kind of libs and languages. But that process should be automatic and have cli.

  Refinements

  Something about 50% experiments I’ve done on the localhost with vlc-streamer that emulates rtsp-broadcaster. Here is a manual which I try to follow.

  I have really fresh and latest ffmpeg with x264 support, that I’ve installed by that useful thread.

• Transmux video to .mp4 using FFmpeg (dref) ?

  30 octobre 2012, par vale4674

  There is a cool tool called MP4Box which uses FFmpeg.
  It has a nice feature to transmux .avi file to .mp4 drefed.

  .avi file size is 500MB
  
  
  
  .mp4 file size is 200kb

  In that .mp4 file are only indexes/timestamps which reference that .avi file.

  So the question is :

  Is this possible with only FFmpeg or this is a MP4Box specific feature ?