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• Révision 23409 : |affdate{Y-m-d} qui utilise la fonction PHP est un peu plus smart et sait traiter...

  9 février 2017, par cedric@yterium.com

• C++ smart pointers to FFmpeg objects

  15 octobre 2024, par Elija

  Can I create and use C++ smart pointers for different pointer types from FFmpeg ?

  


  

  1. "AVCodecContext *" which is used only as a pointer in all functions except deallocation.

  


  


  Alloc :

  


  AVCodecContext *avcodec_alloc_context3(const AVCodec *codec);


  


  Free :

  


  void avcodec_free_context(AVCodecContext **avctx);


  


  Use :

  


  int avcodec_open2(AVCodecContext *avctx, const AVCodec *codec, AVDictionary **options);


  


  Then the smart pointer :

  


  std::shared_ptr<avcodeccontext> av_codec_context(avcodec_alloc_context3(av_codec),&#xA;[](AVCodecContext* _context)&#xA;{&#xA;  if (_context) avcodec_free_context(&amp;_context);&#xA;});&#xA;avcodec_open2(av_codec_context.get(), av_codec, NULL)&#xA;</avcodeccontext>

  


  Is this correct ?

  


  

  2. "AVDictionary **" which is used in all functions only as a pointer to a pointer.

  


  


  Alloc and use :

  


  int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags);


  


  where pm is a Pointer to a pointer to a dictionary struct. If *pm is NULL a dictionary struct is allocated and put in *pm.

  


  Free :

  


  void av_dict_free(AVDictionary **m);


  


  Then a smart pointer :

  


  std::shared_ptr av_dict(new (AVDictionary*),
[](AVDictionary** _dict)
{
  if (_dict)
  {
    if(*_dict)
      av_dict_free(_dict);
    delete _dict;
  }
});
av_dict_set(av_dict.get(), "key", "value", 0);


  


  Is this correct ?

  


  

  3. "AVFormatContext *" which is used both as a pointer and as a pointer to a pointer.

  


  


  Alloc :

  


  AVFormatContext *avformat_alloc_context(void);


  


  Free :

  


  void avformat_free_context(AVFormatContext *s);


  


  Use :

  


  int avformat_find_stream_info(AVFormatContext *ic, AVDictionary **options);


  


  or

  


  int avformat_open_input(AVFormatContext **ps, const char *url, const AVInputFormat *fmt, AVDictionary **options);


  


  where ps is a Pointer to user-supplied AVFormatContext (allocated by avformat_alloc_context). May be a pointer to NULL, in which case an AVFormatContext is allocated by this function and written into ps.

  


  Then a smart pointer :

  


  std::shared_ptr<avformatcontext> av_format_context(avformat_alloc_context(),&#xA;[](AVFormatContext* _context)&#xA;{&#xA;  if(_context)&#xA;    avformat_free_context(_context);&#xA;});&#xA;avformat_find_stream_info(av_format_context.get(), NULL);&#xA;</avformatcontext>

  


  Is this correct ? But how can I use it with the avformat_open_input() function, which needs a pointer to a pointer and may want to create an object by this pointer ?

  


• ffmpeg audio over network [closed]

  22 août 2023, par mcam77

  I am trying to transmit audio(from mic) over network with ffmpeg. When the audio is silent, ffmpeg seems to reduce the datastream.
I have reduced the problem to an audiofile with Hello World, 2sec pause and Hello World again.

  


  When i play this with

  


  ffmpeg.exe -re -i F:\hw.mp3   -acodec mp3  -f mp3 udp://192.168.10.10:40001
ffplay.exe -i udp://192.168.10.10:40001 -nodisp


  


  I can hear 2 times "Hello World" with a pause.

  


  When i do it with a raspberry

  


  ffmpeg.exe -re -i F:\hw.mp3   -acodec mp3  -f mp3 udp://192.168.10.100:40001
ffplay -i udp://192.168.10.100:40001 -nodisp


  


  I only hear "World pause Hello World"

  


  The first hello is gone.

  


  Anybody could help me ?

  


  adding a black screen video no success

  


  reduced to a hello world audio file.

  


  tried different containers/codecs with/without video