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• Feeding a series of images to ffmpeg as each image is created [closed]

  5 février 2013, par Mark Schneider

  I'm trying to use ffmpeg to build a 1280x720 slide-show from a sequence of pictures and videos, but I have concerns about potential disk I/O bottleneck.

  I expect a typical slide-show to have about 50 pictures and 2-3 videos (10-15 seconds each at 30 fps). I would like to show each picture for 3-4 seconds (possibly with a
  Ken Burns effect) with a smooth 2 second crossfade between each set of pictures (or for pictures adjacent to videos - between the picture and the first/last frame of the video).

  Given about 50 pictures, the crossfades alone would amount to about 3,000 images (50 transitions x 2 secs/transition x 30 fps). And I suppose if I implement a Ken Burns effect during each picture's 3-4 second showing, I'd have to provide ffmpeg with individual images for each of those frames. (I'm writing a script in Ruby that will pull a list of images from a database and in turn call ImageMagick to create the individual images for each frame. As I understand it, the RMagick library interfaces with ImageMagick such that the output images come back as in-memory objects without needing to write to disk. FWIW, I'm developing in Windows 8 and will deploy to Heroku.)

  All of the slideshow examples I've found online feed ffmpeg a set of images which have already been created. However, in an effort to avoid waiting on considerable disk I/O, I'd like to feed each image to ffmpeg as the image is created rather than create them all in advance.

  Is there a way to send each image file to ffmpeg on the fly as the file is created in memory ?

• MPEG-TS, Android and FFMPEG

  31 janvier 2013, par STeN

  I am receiving the MPEG-TS (MPEG transport stream) packets with the multiplexed H.264 video and AAC audio streams. I need to be able to show the audio and video on the Android phone. My assumption is that I need :

  • MPEG-TS de-multiplexer
  • AAC decoder
  • H.264 decoder
  • Synchronize the audio and video playback

  Assuming that I am right then (in Android 2.x) MPEG-TS de-multiplexer is not part of the OS and must be ported, both AAC and H.264 decoder are part of the Android OS, but I am not sure if they have interface, which allows passing the data in buffers and if they allow mutual timing synchronization. In the worst case those components must be ported here as well.

  Can you give me some advices where to start ? I was thinking about the FFMPEG porting. Are there any other ways ?

  Regards,
  STeN

• FFmpeg How to write video to a file

  9 décembre 2014, par NoviceAndNovice

  What i want is

   1. Get video packet from stream source
  
   2. Decode it
  
   3. And write  that decoded data as video file(avi, mpeg etc)

  I can able to get video Packets from a file (as AVPacket) and also can decode and save as an image.(raw)( FFmpeg tutorials show how to do it).
  But i can not ( do not know ) write that video data to a file(other) which can be played by media players(such as VLC).

  Best Wishes

  Ps : Real code samples will be great if possible...

  Now i make test with av_interleaved_write but i got strange error "non monotone timestamps" ( i have no control over pts values of media source )

  Some Extra Info

  In FFmpeg I have to

  1. Read media packets from media source ( it may be real file(.avi,mov) or even rtsp server).
  2. Then write those media packets to a real file (physical .avi, .mov etc file)

  I need reader and writer. I can read the media source file ( even encode packets according to given format). But i can not write to file...(which any player can play)

  And some pseudoCode

  File myFile("MyTestFile.avi");
  
  
  
  while ( source ->hasVideoPackets)
  
  {
  
       packet = source->GetNextVideoPacket();
  
       Frame decodedFrame = Decode(packet);
  
       VideoPacket encodedPacket = Encode( decodedFrame);
  
       myFile.WriteFile(encodedPacket);
  
   }

  Or Just write the original file without encode decode

       File myFile("MyTestFile.avi");
  
  
  
       while ( source ->hasVideoPackets)
  
       {
  
           packet = source->GetNextVideoPacket();
  
           myFile.WriteFile(packet);
  
       }

  Then

  I can able to open MyTest.avi file with a player.