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• FFMPEG Stream series of pictures over network

  11 septembre 2015, par Commodore63

  I would like to generate video frames on one computer and stream them to another computer to be manipulated and displayed. I want to do this programatically, because the source images are generated from a 3rd party c++ library and on the receiving end I want to manipulate the images before displaying them. I have been pulling my hair out trying FFMPEG. I got the encoding example to work, but am not sure what to do after that. I have just about googled everything i could think of but cannot figure out which FFMPEG library/function to call once I have a stuffed AVPacket. It seems that I need to use either the AVIO or AVFormat or the muxer but it is not clear how to initialize and get them working. I would appreciate any help you could offer.

  To provide some context I have the example ’decoding_encoding.c’ which is provided with ffmpeg working. Here is the spot that I am struggling with :

          /* encode the image */
  
          ret = avcodec_encode_video2(c, &pkt, frame, &got_output);
  
          if (ret < 0) {
  
              fprintf(stderr, "Error encoding frame\n");
  
              exit(1);
  
          }
  
  
  
          if (got_output) {
  
              printf("Write frame %3d (size=%5d)\n", i, pkt.size);
  
              fwrite(pkt.data, 1, pkt.size, f);
  
  
  
              //
  
              // instead of writing to a file, i want to stream to a network
  
              // What do I need to do with pkt to do that?
  
              //
  
              av_free_packet(&pkt);
  
          }

  Most documentation (and the Dranger tutorial) focus on reading and writing files. I do not need to use a file. I want to stream video over a network. It seems like I need AVFormat and AVio but I jsut can’t figure out how they fit together.

• libavfilter/scale : Populate ow/oh when using 0 as w/h

  14 juin 2017, par Kevin Mark

  libavfilter/scale : Populate ow/oh when using 0 as w/h
  The input width and height is known at parse time so there's no
  
  reason ow/oh should not be usable when using 0 as the width or
  
  height expression.
  Previously in "scale=0:ow" ow would be set to "0" which works,
  
  conveniently, as "scale=0:0" is perfectly valid input but this breaks
  
  down when you do something like "scale=0:ow/4" which one could
  
  reasonably expect to work as well, but does not as ow is 0 not the
  
  real value.
  This change handles the 0 case for w/h immediately so the ow/oh
  
  variables work as expected. Consequently, the rest of the code does
  
  not need to handle 0 input. w/h will always be > 0 or < 0.
  The second explicit (int) cast ensures that ow/oh appear as integers
  
  as a user might expect when dealing with pixel dimensions.
  Signed-off-by : Kevin Mark <kmark937@gmail.com>
  
  Signed-off-by : Ronald S. Bultje <rsbultje@gmail.com>
  

  • [DH] libavfilter/scale.c

• Convert .mp3/.wav file into g729/amr/g711 codec file and vice versa using PJSIP

  19 septembre 2017, par NandhaKumar

  PJSIP is used for SIP Registering, audio/video Calling and supporting some other VoIP Call features. If you want to create an VoIP Application, you will create an application using their libraries.

  In this library, there are available lot of codecs and some of codecs are available as third party codecs and you can integrate into PJSIP library. Then you can able to support those codecs while calling another SIP user/client.

  Generally In mobile phones, the voice is record as audio file through
  mic and it has passed to PJSIP library. Then those codec/pjmedia library take care
  of other operations like converting into anyother codec format which
  they want to send.

  Instead of that, can we able to pass .mp3/.wav file into PJSIP library and convert it into codec files like .g729/.amr/.g711-u and vice versa

  I don’t about how codec conversion/codec engine internally works around.
  If you know about the codec conversion from .mp3 format is possible using PJSIP library, please suggest me how to solve this problem.

  Thanks in Advance !