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• How to decode audiostream to play with AudioUnits ?

  4 décembre 2015, par sadhi

  I have a PCM ulaw stream that I receive and I want to play this on iOS. To play audio in my app I made an AudioUnit implementation, but since it requires linear PCM I must decode it first. For this I use ffmpeg with the following code :

          AVCodec *codec = avcodec_find_decoder(AV_CODEC_ID_PCM_MULAW);
  
  
  
          self.audio_codec_context = avcodec_alloc_context3(codec);
  
          self.audio_codec_context->codec_type = AVMEDIA_TYPE_AUDIO;
  
          self.audio_codec_context->sample_fmt = *codec->sample_fmts;
  
          self.audio_codec_context->sample_rate = 48000;
  
          self.audio_codec_context->channels    = 1;
  
          //open codec
  
          int result = avcodec_open2(self.audio_codec_context, codec,NULL);            
  
  
  
          //this should hold the raw data
  
          AVFrame * audioFrm = av_frame_alloc();
  
  
  
          AVPacket pkt;
  
          av_init_packet(&pkt);
  
          pkt.data = (unsigned char*)buf;
  
          pkt.size = ret;
  
          pkt.flags = AV_PKT_FLAG_KEY;
  
  
  
          int got_packet;
  
          result = avcodec_decode_audio4(self.audio_codec_context, audioFrm, &got_packet, &pkt);
  
  
  
          AVPacket encodedPkt;
  
          av_init_packet(&encodedPkt);
  
          encodedPkt.size = 0;
  
          encodedPkt.data = NULL;
  
  
  
          if (audioFrm != NULL) {
  
              self.audio_codec_context = NULL;
  
              AVCodec *codec = avcodec_find_encoder(AV_CODEC_ID_PCM_S16LE);
  
  
  
              self.audio_codec_context = avcodec_alloc_context3(codec);
  
              self.audio_codec_context->codec_type = AVMEDIA_TYPE_AUDIO;
  
              self.audio_codec_context->sample_fmt = *codec->sample_fmts;
  
              self.audio_codec_context->bit_rate = 64000;
  
              self.audio_codec_context->sample_rate = 48000;
  
              self.audio_codec_context->channels    = 1;
  
  
  
  
  
              int result = avcodec_open2(self.audio_codec_context, codec,NULL);
  
              if (result < 0) {
  
                  NSLog(@"avcodec_open2 returned %i", result);
  
              }
  
  
  
  
  
              result = avcodec_encode_audio2(self.audio_codec_context, &encodedPkt, audioFrm, &got_packet);
  
  
  
              if (result < 0) {
  
                  NSLog(@"avcodec_encode_audio2 returned %s", av_err2str (result));
  
                  continue;
  
              }
  
          }

  For some reason no matter what I do the audio that comes out at the end is all noise.
  So my question is : How should I decode my audiostrean to play it with AudioUnits ?

• ffplay does not play hls continuously and it stop after a few first segments

  31 mai 2023, par LeXela-ED

  I am using the following command to read a RTSP stream from an IP camera and record it as HLS :

  


  ffmpeg -i rtsp://<user>:<password>@<ip>:<port> -c:v copy -c:a copy -hls_segment_type mpegts -segment_list_type m3u8 -hls_list_size 5 -hls_wrap 5 -hls_time 5 -hls_flags split_by_time -segment_time_delta 1.00 -start_number 1 -segment_list live -reset_timestamps 1 -movflags faststart live.m3u8</port></ip></password></user>

  


  However, while I am using ffplay as ffplay -i live.m3u8, it only plays a few first segments. Even VLC does play a few first segments too ! What am I missing ? shall I change my ffmpeg command or what ?

  


  Thank you all in advance.

  


• Create a thumbnail with play icon inside with ffmpeg

  14 décembre 2016, par somenxavier

  I want to create a thubnail with ffmpeg with a play inside (like a picture above ; taking from Dan Meyer site) for showing that it’s a video and not an image.