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• Learning Shell - creating a script with parameters that runs two separate cli apps

  16 mai 2013, par GuilhermeNagatomo

  I want to learn shell script, so I'm trying to download a youtube video using youtube-dl then convert it to mp3 using ffmpeg.

  I do it manually running youtube-dl http://youtube.com/watch?v=...
  then
  ffmpeg -i downloadedFile -ab 256000 -ar 44100 audioFile.mp3.

  I know that I need to pass two arguments to my script, one for the video url and another for the audio file to keep things as simple as possible, but I don't know how to start. Maybe grep the video id in the url and using it to know which file to use to convert into mp3 ? (since youtube-dl saves the video named by it's id)

  Can someone recommend me an article or documentation that can help me ?

• 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.

• fluent-ffmpeg child_process and fs not found

  1er mai 2017, par Angus Simons

  I getting this error when running npm run hot or npm run watch or npm run dev or whatever on webpack :

  These dependencies were not found:
  
  
  
  * child_process in ./~/fluent-ffmpeg/lib-cov/utils.js, ./~/fluent-ffmpeg/lib-cov/processor.js and 4 others
  
  * fs in ./~/fluent-ffmpeg/lib-cov/processor.js, ./~/fluent-ffmpeg/lib-cov/capabilities.js and 8 others

  I’m a bit confused because if I run npm list I can see both child_process and fs installed.

  Error is generated when using import ffmpeg from 'fluent-ffmpeg'; on app.js

  I’ve setup also the FFMPEG_PATH and FFPROBE_PATH but it is not working.