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• FFMpeg used in a C# MVC 3 app

  2 février 2012, par Chris

  I'm slowly going mad here and I'll apologise now as this question is going to be vague but I'm really struggling with getting video converting working reliably with FFMpeg. I've tried a few different wrappers but they all seem to go the same way.

  What I mean by that is unreliable converting (told you it would be vague), one time it will convert a video fine with no problems then the next it will just create a empty file. One solution I have tried is http://jasonjano.wordpress.com/2010/02/09/a-simple-c-wrapper-for-ffmpeg/ with unreliable results. I've currently even tried to get a trial version of a paid solution working (Media Handler by http://www.mediasoftpro.com/) with no joy either. I've worked on this for nearly the whole week and I've still go no closer to a reliable solution. Anyone with any help about anything really would be appreciated as I'm slowly going insane.

• Copy 3gp moov atom from one file to another

  1er août 2016, par message

  I was in Norway and I had an awesome time ; I recorded my ride on the sledges, and my HTC Sensation turned off when I finished my ride because my battery ran out.

  When I reached my laptop I found a 630 Mb video file my the phone, but I was not able to play it with VLC. Since I’m using Ubuntu, I tried to ffprobe my file and I received the following :

  [22:22 @ ~/Desktop] $ ffprobe VIDEO0002.3gp 
  
  FFprobe version 0.6-4:0.6-2ubuntu6.3, Copyright (c) 2007-2010 the FFmpeg developers
  
    built on Dec 21 2011 18:43:14 with gcc 4.4.5
  
    configuration: --extra-version=4:0.6-2ubuntu6.3 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-vaapi --enable-pthreads --enable-zlib --enable-libvpx --disable-stripping --enable-runtime-cpudetect --enable-gpl --enable-postproc --enable-x11grab --enable-libdc1394 --shlibdir=/usr/lib/i686/cmov --cpu=i686 --enable-shared --disable-static --disable-ffmpeg --disable-ffplay
  
    libavutil     50.15. 1 / 50.15. 1
  
    libavcodec    52.72. 2 / 52.72. 2
  
    libavformat   52.64. 2 / 52.64. 2
  
    libavdevice   52. 2. 0 / 52. 2. 0
  
    libavfilter    1.19. 0 /  1.19. 0
  
    libswscale     0.11. 0 /  0.11. 0
  
    libpostproc   51. 2. 0 / 51. 2. 0
  
  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x8c3c010]moov atom not found
  
  VIDEO0002.3gp: Operation not permitted

  I had an idea that I might be able to use an older recorded video from my phone and simply copy the moov atom from that working file to the broken one. Any ideas about that ? How can I fix this problem ?

• YouTube's HD Video Streaming Server Technology ?

  30 septembre 2013, par bgentry

  Lately I've been researching different methods for streaming MP4s to the browser. Flash Media Server is an obvious choice here (using Cloudfront), and most solutions I've seen use the RTMP protocol.

  However, I spent some time on YouTube with Firebug and Chrome debugger figuring out how their streaming worked and I discovered some interesting differences between some of their videos and quality rates.

  My two sample videos are A and B. A is available up to 480p and B is available up to 1080p. For both videos, all rates up to 480p are served in an FLV container with H.264 video and AAC audio, over HTTP. What's interesting here is that if you have not yet downloaded (cached) the entire video, and you try to skip forward to an uncached part of the video, a new request will be made with a 'begin' parameter equal to the target offset in milliseconds. Example from Video A at 480p :

  http://v11.lscache8.c.youtube.com/videoplayback?ip=0.0.0.0&sparams=id%2Cexpire%2Cip%2Cipbits%2Citag%2Calgorithm%2Cburst%2Cfactor%2Coc%3AU0dWTldQVF9FSkNNNl9PSlhJ&fexp=904806%2C902906%2C903711&algorithm=throttle-factor&itag=35&ipbits=0&burst=40&sver=3&expire=1279756800&key=yt1&signature=D2D704D63C242CF187CAA5B5D5BAFB8DFACAC5FF.39180C01559C976717B651A7EB1D0C6249231EB7&factor=1.25&id=8568eb3135971f6f&begin=111863
  
  
  
  Response Headers:
  
  Cache-Control:public,max-age=23472
  
  Connection:close
  
  Content-Length:14320637
  
  Content-Type:video/x-flv
  
  Date:Wed, 21 Jul 2010 17:23:48 GMT
  
  Expires:Wed, 21 Jul 2010 23:55:00 GMT
  
  Last-Modified:Wed, 19 May 2010 12:31:41 GMT
  
  Server:gvs 1.0
  
  X-Content-Type-Options:nosniff

  The file returned by this URL is a fully valid FLV containing only the portion of the video after the requested offset.

  I did the same kind of test on the higher resolution versions of Video B. At 720p and 1080p, YouTube will return a video in an MP4 container, also with H.264 video and AAC audio. What's impressive to me is that their server takes the same type of offset for an MP4 video (via the 'begin' parameter) and returns a valid, streamable MP4 (moov atom at the front of the file with correct offsets) that also only includes the requested portion of the video.

  So, how does YouTube do this ? How do they generate the FLV or MP4 container on the fly with the correct headers and only the desired segment of the requested video ? I know this can be accomplished using FFMPEG to seek to the desired start point and the qt-faststart script to reposition the moov atom to the front of the stream, but it seems like this would be too slow to handle on-demand for millions of YouTube viewers.

  Ideas ?

  Thanks in advance !

  Footnote : I am not allowed to include more than 1 link at this point, so here is Video A's URL : http:// www.youtube .com/watch ?v=hWjrMTWXH28 "Video available up to 480p"