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• Programming in C : Opening, Reading and Transcoding of Live TV with libavcodec. libavformat etc

  19 décembre 2011, par mmoment

  I'm currently developing a live streaming Software for my University Project.

  I am supposed to open a Live Video Stream from a USB Stick( I am using the Hauppauge WinTV-HVR 950Q under Linux) and read the Stream.
  Then I'm supposed to transcode it to h246. and send it to some devices in the Network.

  My Problem

  ---

  I can use the v4l API to access the USB Stick, but transcoding does currently not work as far as I know, therefore I want to use the libav to do so. I know that using the command line tools transcoding of live streams with ffmpeg is not a big deal, but doing so in C seems to be more of a problem.

  1. Here's how I open some static Video File :

     static char* path = "./video.mpeg" ;
     AVFormatContext *pFormatCtx ;

     av_register_all() ;

     if(av_open_input_file(&pFormatCtx, path, NULL, 0, NULL) !=0)
     
     printf("Opening file \"%s\" failed", path) ;
     return -1 ;
     else printf("Opening the file \"%s\" succeeded", path) ;

  2. Here's how I understand to how open a Live Feed

     static char* path = "/dev/dvb/adapter0/dvr0" ;
     AVFormatContext *pFormatCtx ;

     av_register_all() ;
     avdevice_register_all() ;

     if(avformat_open_input(&pFormatCtx, path, NULL, NULL) != 0)
     
     perror("avformat_open_input") ;
     return -1 ;
     else printf("Yay") ;

  3. Here's how I understand to how open a Live Feed

     if(av_find_stream_info(pFormatCtx)<0)
     
     printf("Could not find any Stream Information the file \"%s\"", path) ;
     return -1 ;
     
     // Dump information about file onto standard error
     dump_format(pFormatCtx, 0, path, 0) ;
     AVCodecContext *pCodecCtx ;

     // Find the first video stream
     int videoStream=-1 ;
     for(i=0 ; inb_streams ; i++)
     

     if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO)
     
     {
     
         videoStream=i;
     
         break;
     
     }

     if(videoStream==-1) return -1 ; // Didn't find a video stream

     // Get a pointer to the codec context for the video stream
     pCodecCtx=pFormatCtx->streams[videoStream]->codec ;

     AVCodec *pCodec ;

     // Find the decoder for the video stream
     pCodec=avcodec_find_decoder(pCodecCtx->codec_id) ;
     if(pCodec==NULL)
     
     fprintf(stderr, "Unsupported codec !\n") ;
     return -1 ; // Codec not found
     
     //Open codec
     if(avcodec_open(pCodecCtx, pCodec)<0)
     
     printf("Could not open the Codec") ;
     return -1 ; // Could not open codec
     

  So now how can you help me ?

  I would really appreciate it if anyone knew how to open a live stream and could give me a good example.

• Streaming jpegs live to iphone app

  14 février 2012, par Raven

  Im progressing through taking the depth camera feed from my kinect and streaming it to my iphone app. I have got to stage of being able save jpegs for every frame created from the kinect depth image (30 fps) and save them to the local disk. I have than been able to convert this to mpeg with ffmpeg.

  My question is now how can I view this live on my iphone ? Basically I want to view it live on the iphone as you are seeing it coming from the kinect.

  Should I use http live streaming and use the segmenter to use apples HttpLiveStreaming functionality ? Or can I stream the raw jpeg image files up in some way as they are saved to disk and than just cycle the images on the phone as they go ?

  Im wondering how video conferencing is achieved on the iphone (facetime/skype etc) ? because I'd prefer that it wasnt played inside the video player, just want to display live content on the screen as it happens.

  Any ideas ? Thanks in advance

• how to restream rtsp h264 as "live dvr" for iOs using ffserver ?

  18 mai 2017, par mojovski

  I would like to grab an existing stream from an IP-Camera delivering h264 encoded rtsp stream and restream it for iPhone/Ipad, where the user would have the opportunity to jump back in time for aprox. 1 minute. And later jump back to the "live" feed.

  Actually I would like to do the same as in wowza (http://www.wowza.com/addons/wowza-ndvr-addon) but with ff** software.

  Thank you for all your hints !