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• How can I store a live stream when internet connection is interrupted ?

  5 juin 2019, par Marcello Moreira

  I’m building a solution using drone and 3g/4g connection.
  I have an IP camera encoded in H.264 by a hardware encoder connected to a raspberry pi and a 3g/4g moldem. The hardware encoder livestream de video via RTMP to a remote server I have. All these devices are in a moving platform, and sometimes the moldem loses connection with internet for a few seconds/minutes. When this happens, I want to store the live footage in the raspberry with ffmpeg, and when the connection restores I can send it back to the server. I have access to the encoded livestream from the raspberry pi over LAN even when internet is down.

  I do not know how and where should I start.
  I see two approaches for this.

  First approach

  One is to do all the streaming via ffmpeg, and disable the automatic hardware stream, when ffmpeg detects that it can’t send stream to the remote server, it starts to store the video (like a buffer) until the connection is restore. The issue with this, is that I don’t know if ffmpeg can detect if internet connection is down, and how can I buffer the video. Also by doing this, when connection is restored, live video would have a huge delay, and I can’t have lot’s of delay in my solution.

  Second approach

  The second is simultaneously store with ffmpeg the live video, when internet goes down, a process records the timestamp, and keeps watching until internet connection is restored. Then it sends to my server only the missing piece. At my server I would need to figure out a way to join those streams back up.. (I would gladly accept tips on that too). Issue with this is that there’s limited space in my raspberry, so I can only store a limited amount. Also, my device may be turned off when it lands so I need to send the video recording ASAP after connection is restored.

  So, which approach seems to be the better one ?

• Clipping audio problem on ffmpeg live stream

  20 mars 2019, par Ivan Bombash Stokic

  in 30-40% of the live stream i get some king of distortion or clipping in the streamed audio and i have no idea why, is is only because low hardware performance maybe ? I am running the stream on a Raspberry pi 3b+ CPU usage while streaming from 25 to 30% Ram usage 28% , storage device is a USB pen drive.

  Here is the code :

  ffmpeg -re -f alsa -i default -re -stream_loop -1 -i "/home/pi/Documents/Youtube/video720p.mp4" -c:v copy -c:a aac -f flv -max_muxing_queue_size 400 rtmp://a.rtmp.youtube.com/live2/pfjd-jhjs-k3td-xxxx

  Or i should buffer it before streaming or re-encode the audio before streaming ?

  Thanks in advance !

• 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.