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• ffmpeg slideshow piping input and output for image stream [migrated]

  21 avril 2013, par charly

  I am trying to make from a list of images a video and then I will directly upload it.
  I have managed so far to create a video for the images with :

  cat *.jpg | ffmpeg -r 1 -f image2pipe -vcodec mjpeg -i - foo.mp4

  It works well and I'm happy with it. However, now I would like to pipe the output and I can't really manage to do this. I've tried a couple of like :

  cat *.jpg | ffmpeg -f image2pipe -r 1/5 -vcodec mjpeg -i - pipe:1 | cat > p.mpeg

  (for the moment I would just like to pipe back in a file just to test and then I'll had the direct upload).

  I've read in another thread that I should specify the output format which makes sense as the error returned by ffmpeg is "Unable to find a suitable output format for 'pipe:1'". However, all I can find in the doc is :

  -f fmt (input/output)
  
  Force input or output file format. The format is normally auto detected 
  
  for input files and guessed from the file extension for output files, 
  
  so this option is not needed in most cases.

  How can I specify the output format and the input format ?

• How to reencode flash stream to MP4 or/and WebM inside server implementation ?

  18 avril 2013, par user2294505

  Hi guys, lets start with this that I'm totally new in video streaming.

  Currently I have to support one server implemented in C that work as mediator between stream producers and stream consumers. In my case I have one remote machine that generate flash stream and one or more clients that can watch it. The server work as proxy for all of them. We are using our server side implementation for rtmp protocol and for asynchronous work over HTTP we are using libevent library. All this construction work fine in common case.

  Now we need to transfer this stream to HTML5 clients and we need to support new formats. Our decision was that MP4 and WebM are enough for us. Base of the HTTP request our internal implementation recognized what type of stream client need. For example when the client need MP4 URI is something like this :

  http://192.168.0.5/video.mp4?blah-blah-blah

  where "blah-blah-blah" are few parameters to impersonate client. We have already implemented mechanism that convert input frames to raw pictures and this implementation work fine when we stream JPEGs as again we are using libavformat library to encode raw picture to JPEG. In case with JPEGs the contents of the stream data must contain HTTP meta data with description of every picture. The client stream request is same as this for MP4 stream but instead video.mp4 we are uising jpegstream.htm

  Now I need to convert this input stream to MP4 and/or WebM and here start my problems. For generating Mp4 and WebM videos I'm using ffmpeg libraries and base of one of ffmpeg examples (muxing) I'm trying to convert already generated pictures to currently selected new format. More or less this conversion is OK but after than I don't know why I can't send video to consumer. I'm using next code to prepare avio context :

  int iSize = 4 * 1024;
  
  unsigned char *ptrBuf = ( unsigned char * )av_malloc( iSize );
  
  ptrOFC->pb = avio_alloc_context( ptrBuf, iSize, 1, ptrTCDObj, NULL, write_pkg, NULL );
  
  if ( !ptrTCDObj->ptrOFC->pb ) {
  
      goto ERROR;
  
  }
  
  avformat_write_header( ptrOFC, NULL );

  When the server receive frame from flash we are converting it to corresponding output format with code like this :

  iResult = avcodec_encode_video2( ptrTCDataObj->m_ptrOCC, &packet, pictureFrame, &iGotPacket ) ;

  and write it to stream when succeed and packet exist with :

  av_interleaved_write_frame( ptrOFC, &packet );

  Here our code expect to receive in one moment call to write_pkg function. But nothing happen here :-(. Situation is 100% same if I'm using direct write with av_write_frame. The write_pkg function has very simple body :

  int write_pkg( void *ptrOpaque, uint8_t *ptrBuffer, int iBufferSize ) 
  
  {
  
      STransCoderData_t *ptrTCDObj = ( STransCoderData_t * ) ptrOpaque;
  
      struct evbuffer *ptrFrameOut;
  
      ptrFrameOut = evbuffer_new();
  
      evbuffer_add( ptrFrameOut, ptrBuffer,( size_t ) iBufferSize );
  
      http_client_write_video( ptrFrameOut, ptrTCDObj->m_ptrHTTPClient, NULL );
  
      evbuffer_free( ptrFrameOut );
  
      return iBufferSize;
  
  }

  Structure STransCoderData_t and function http_client_write_video is not interesting in this moment because we don't reach them for now :-(

  For test consumer I'm using VLC player as open network stream :

  http://192.168.0.5/video.mp4?blah-blah-blah

  VLC don't show anything even errors.

  Any ideas, comments and help are welcome.

• how to get width/ height of video file using S3FS, FFMPEG in ec2

  16 juillet 2013, par Khalid

  at the moment I succeed to install S3FS & FFMPEG in ec2, but i don't know why I can't get information about height and width of a video file, but another properties such as duration, audio stream, etc are shown,

  I already try in local within same a video file, and all properties are shown (within width and height).

  does anyone know, what's wrong with this ?