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• Do avcodec_receive_frame and avcodec_send_packet block / how to design ffmpeg decoding loop ?

  12 octobre 2020, par Paprika

  I'm thinking about how to design a loop that reads frames from internet, feed to ffmpeg decoder and then receive from ffmpeg to send to a render.

  


  Take this pseudocode loop in consideration :

  


  while true {
    auto packet = receive_packet_from_network();
    avcodec_send_packet(packet);
    auto frame = alloc_empty_frame();
    int r = avcodec_receive_frame(&frame);
    if (r==0) {
        send_to_render(frame);
    }
}


  


  do avcodec_send_packet or avcodec_receive_frame block or ffmpeg has an internal thread ? I'm concerned about this loop because it waits for packets from network, so it has some delay. I'd like to do something like this instead :

  


  //thread 1
while true {
    auto packet = receive_packet_from_network();
    avcodec_send_packet(packet);
}
//thread 2
while true {
    auto frame = alloc_empty_frame();
    int r = avcodec_receive_frame(&frame);
    if (r==0) {
        send_to_render(frame);
    }
}


  


  however, now, if avcodec_receive_frame does not block, then this loop would run too fast, millions of times per second.

  


  So, how should I design the send/receive of packets in ffmpeg in the most efficient way ? I don't want to spend cpu cycles like in the thread2 loop.

  


• Live Video Chat for iPhone and HTTP Live Streaming

  2 novembre 2014, par mayuur

  So generally, I want to make an app which has video chat functionality for iPhone. But after many searches, I am still not able to find any successful results. Is there any public or even for that matter, private API available for doing this on iPhone ??? If you have an YES answer, please help me.

  Basically, what I want is to read the streams of the video on both the devices connected for chatting. Thanks a lot in advance and please help me if you can.

  p.s - I have already checked iDoubs but it failed and always shows some unknown problem and for that reason, doesn’t allow me to connect to anyone.

  ALSO : The suggested method I have found is via HTTP Live Streaming. But, in that too, I have multiple doubts.

  1.) I need to find how do I upload my video from iPhone to the HTTP server from where I would be broadcasting ?

  2.) Can you please post something related to setting up the server ? How do I feed the video to the FFMPEG Server ?

  Mainly, I need to find the upload method. I am right now simply sending hex-code in the form of NSDATA to the server and I am stuck there. The main problem is, It is live. How do I handle that ?

  It would be best, if you could help me make the iDoubs work properly.

  Thank you so much for any kind of support !

• Use ffmpeg to move moov atom to front of mp4 file on Google Cloud Platform and Google Cloud Storage

  19 avril 2021, par BlueBoy

  I would like to use ffmpeg to move the moov atom of a .mp4 file to the front of the file so that it can then be streamed.

  


  The .mp4 file is in Google Cloud Storage. I want to take that file and apply the conversion on it (or copy it if needed).

  


  I have successfully run the following command in the terminal and it works. I want to essentially run this command server side on the Google Cloud in a Java environment :

  


  ffmpeg -i input_video_file.mp4 -vcodec copy -acodec copy -movflags faststart output_video_file.mp4

  


  I can get my file from Google Cloud Storage like this :

  


  GcsService gcsService = GcsServiceFactory.createGcsService();
GcsFilename file = new GcsFilename("bucket", "folder/filename;


  


  I was able to find a Java library wrapper for ffmpeg (https://github.com/bramp/ffmpeg-cli-wrapper) but it doesn't seem to allow to move the moov atom. Could anyone help me figure this out further ? Is there a