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• How to reconnect using avformat_open_input without having to alloc the decoder again ?

  26 septembre 2012, par Jona

  Currently, I have a code based on ffplay to stream live content.

  One thing I'm looking to do is be able to reconnect upon loosing a connection without having to shutdown the whole decoding process.

  To me the solution is alloc the decoder myself once and keep using it across reconnections. I can't seem to figure out how to setup a decoder without having to depend on the AVFormatContext. Right now my code is failing when trying to use my own allocated AVCodecContext to decode. But it doesn't fail if I use the AVCodecContext given by AVFormatContext.

  This is part of my initial code :

  // attempt to find more information about the codec
  
  // also it will open the codecs needed.
  
  fferror = avformat_find_stream_info(ic, NULL);
  
  if (0 > fferror)
  
  {
  
      // TODO verify type of error to better map it to our errors
  
      error = ERROR_FAIL_TO_CONNECT;
  
      LOGE("download() -> avformat_find_stream_info failed! fferror:%d, error:%d", fferror, error);
  
      goto fail;
  
  }
  
  
  
  AVCodec *dec;
  
  // select the audio stream
  
  int ret = av_find_best_stream(ic, AVMEDIA_TYPE_AUDIO, -1, -1, &dec, 0);
  
  if (0 > ret) {
  
      error = ERROR_UNEXPECTED_ERROR;
  
      LOGE("download() -> av_find_best_stream failed! ret:%d, error:%d", ret, error);
  
      goto fail;
  
  }
  
  
  
  LOGI("download() -> STREAM: nb_streams:%d", ic->nb_streams);
  
  LOGI("download() -> STREAM: audio format:%s", ic->iformat->name);
  
  LOGI("download() -> STREAM: audio bitrate:%d", ic->bit_rate);
  
  
  
  
  
  // save the audio stream index and source
  
  is->audio_stream_index = ret;
  
  is->audio_st = ic->streams[is->audio_stream_index];
  
  is->audio_buf_size = 0;
  
  is->audio_buf_index = 0;
  
  
  
  is->audio_st->discard = AVDISCARD_DEFAULT;
  
  
  
  if(ic->pb) {
  
      ic->pb->eof_reached= 0; //FIXME hack, ffplay maybe should not use url_feof() to test for the end
  
  }
  
  
  
  if (show_status) {
  
          av_dump_format(ic, 0, is->filename, 0);
  
      }
  
  
  
  // open codec
  
      error = open_decoder(is->audio_st->codec, dec);
  
      if (ERROR_NO_ERROR != error) {
  
          LOGE("receive_thread() -> open_decoder failed! error:%d", error);
  
          goto fail;
  
      }

  And this is the funtion that initializes the decoder.

  static int open_decoder (AVCodecContext *avctx, AVCodec *codec)
  
  {
  
      int fferror         = 0;
  
      AVCodecContext *c   = NULL;
  
  
  
      if (smDecoder.open) {
  
          LOGW("open_decoder() -> decoder is already open!");
  
          return ERROR_NO_ERROR;
  
      }
  
  
  
      // find the decoder
  
      if (!codec)
  
      {
  
          codec = avcodec_find_decoder(avctx->codec_id);
  
          if (!codec)
  
          {
  
              LOGE("open_decoder() -> avcodec_find_decoder failed!");
  
              return ERROR_UNEXPECTED_ERROR;
  
          }
  
      }
  
  
  
      // allocate the decoder av context
  
      c = avcodec_alloc_context3(codec);
  
      if (NULL == c) {
  
          LOGE("open_decoder() -> avcodec_alloc_context3 failed! Out of memory?");
  
          return ERROR_UNEXPECTED_ERROR;
  
      }
  
  
  
      // check if the type of codec we support
  
      if (AVMEDIA_TYPE_AUDIO != c->codec_type)
  
      {
  
          LOGE("open_decoder() -> codec_type not supported! codec_type:%d",c->codec_type);
  
          return ERROR_UNEXPECTED_ERROR;
  
      }
  
  
  
      // set the proper channels if not properly set
  
      if (c->channels > 0) {
  
          c->request_channels = FFMIN(2, c->channels);
  
      } else {
  
          c->request_channels = 2;
  
      }
  
  
  
      c->debug_mv = 0;
  
      c->debug = 0;
  
      c->workaround_bugs = workaround_bugs;
  
      c->idct_algo= idct;
  
      if(fast) c->flags2 |= CODEC_FLAG2_FAST;
  
      c->error_concealment= error_concealment;
  
      c->thread_count = thread_count;
  
  
  
      // open the decoder
  
      fferror = avcodec_open2(avctx, codec, NULL);
  
      if (fferror < 0)
  
      {
  
          LOGE("open_decoder() -> avcodec_open2 failed! fferror:%d", fferror);
  
          return ERROR_UNEXPECTED_ERROR;
  
      }
  
  
  
      // clean up our reusable packet
  
      memset(&smDecoder.audio_pkt, 0, sizeof(smDecoder.audio_pkt));
  
  
  
      smDecoder.open = 1;
  
      smDecoder.codec = codec;
  
      smDecoder.avctx = c;
  
  
  
      return ERROR_NO_ERROR;
  
  }

• Anomalie #2792 (Fermé) : 2.1.16 bug possible pipeline_definir_session + ajouter_session( )

  11 mai 2013, par cedric -

  La version 3.0 a introduit le pipeline preparer_visiteur_session appelé au moment de l’initialisation de la session, c’est ce qu’il te faudrait. Pas de solution propre en 2.1, c’est à toi de gérer le cas de ré-entrance pour l’éviter dans ta solution, mais elle n’est pas "propre"

• ffmpeg - very slow conversion

  25 juillet 2015, par karoluch

  I create web app in JavaEE which displays many video formats. I use ffmpeg solution to convert videos to formats which is supported natively by main browsers.

  According to : http://www.jwplayer.com/html5/formats/
  I convert to WEBM container (VP8/VORBIS or VP9/OPUS). But conversion is very slow, bit rate equals to 200kbits/s. To convert I execute following command

  ffmpeg -i file.mov -c:v libvpx -preset ultrafast result.webm

  How to speed up conversion to natively supported formats by main browsers ?