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• How to understand the given ffplay C code snippet ?

  20 juillet 2015, par Jerikc XIONG

  The following code snippet is from ffplay :

  static int decoder_decode_frame(Decoder *d, AVFrame *frame, AVSubtitle *sub) {
  
      int got_frame = 0;
  
  
  
      do {
  
          int ret = -1;
  
  
  
          if (d->queue->abort_request)
  
              return -1;
  
  
  
          if (!d->packet_pending || d->queue->serial != d->pkt_serial) {
  
              AVPacket pkt;
  
              do {
  
                  if (d->queue->nb_packets == 0)
  
                      SDL_CondSignal(d->empty_queue_cond);
  
                  if (packet_queue_get(d->queue, &pkt, 1, &d->pkt_serial) < 0)
  
                      return -1;
  
                  if (pkt.data == flush_pkt.data) {
  
                      avcodec_flush_buffers(d->avctx);
  
                      d->finished = 0;
  
                      d->next_pts = d->start_pts;
  
                      d->next_pts_tb = d->start_pts_tb;
  
                  }
  
              } while (pkt.data == flush_pkt.data || d->queue->serial != d->pkt_serial);
  
              av_free_packet(&d->pkt);
  
              d->pkt_temp = d->pkt = pkt;
  
              d->packet_pending = 1;
  
          }
  
  
  
          switch (d->avctx->codec_type) {
  
              case AVMEDIA_TYPE_VIDEO:
  
                  ret = avcodec_decode_video2(d->avctx, frame, &got_frame, &d->pkt_temp);
  
                  if (got_frame) {
  
                      if (decoder_reorder_pts == -1) {
  
                          frame->pts = av_frame_get_best_effort_timestamp(frame);
  
                      } else if (decoder_reorder_pts) {
  
                          frame->pts = frame->pkt_pts;
  
                      } else {
  
                          frame->pts = frame->pkt_dts;
  
                      }
  
                  }
  
                  break;
  
              case AVMEDIA_TYPE_AUDIO:
  
                  ret = avcodec_decode_audio4(d->avctx, frame, &got_frame, &d->pkt_temp);
  
                  if (got_frame) {
  
                      AVRational tb = (AVRational){1, frame->sample_rate};
  
                      if (frame->pts != AV_NOPTS_VALUE)
  
                          frame->pts = av_rescale_q(frame->pts, d->avctx->time_base, tb);
  
                      else if (frame->pkt_pts != AV_NOPTS_VALUE)
  
                          frame->pts = av_rescale_q(frame->pkt_pts, av_codec_get_pkt_timebase(d->avctx), tb);
  
                      else if (d->next_pts != AV_NOPTS_VALUE)
  
                          frame->pts = av_rescale_q(d->next_pts, d->next_pts_tb, tb);
  
                      if (frame->pts != AV_NOPTS_VALUE) {
  
                          d->next_pts = frame->pts + frame->nb_samples;
  
                          d->next_pts_tb = tb;
  
                      }
  
                  }
  
                  break;
  
              case AVMEDIA_TYPE_SUBTITLE:
  
                  ret = avcodec_decode_subtitle2(d->avctx, sub, &got_frame, &d->pkt_temp);
  
                  break;
  
          }
  
  
  
          if (ret < 0) {
  
              d->packet_pending = 0;
  
          } else {
  
              d->pkt_temp.dts =
  
              d->pkt_temp.pts = AV_NOPTS_VALUE;
  
              if (d->pkt_temp.data) {
  
                  if (d->avctx->codec_type != AVMEDIA_TYPE_AUDIO)
  
                      ret = d->pkt_temp.size;
  
                  d->pkt_temp.data += ret;
  
                  d->pkt_temp.size -= ret;
  
                  if (d->pkt_temp.size <= 0)
  
                      d->packet_pending = 0;
  
              } else {
  
                  if (!got_frame) {
  
                      d->packet_pending = 0;
  
                      d->finished = d->pkt_serial; // FLAG
  
                  }
  
              }
  
          }
  
      } while (!got_frame && !d->finished);
  
  
  
      return got_frame;
  
  }

  It’s difficult for me to understand the following code :

  d->finished = d->pkt_serial; // FLAG

  Can anyone help me ?

  Thanks.

• Specify timestamp in ffmpeg video segment command

  25 mars 2019, par Soumya

  I have a continuous RTSP stream coming from a camera over the network.
  I want to dump the stream but in video files of length 1 min each.

  I an using the following command

  ffmpeg -i "rtsp://user:pass@example.com"  -f mp4 -r 12 -s 640x480 -ar 44100 \
  
  -ac 1 -segment_time 60 -segment_format mp4 "out%03d.mp4"

  The name of the files being created are of the form out001.mp4, out002.mp4, etc.

  I want to include the timestamp (hour and minute) in the name of the file segments eg. 09-30.mp4, 09-31.mp4, etc.

  If it is mandatory to provide a serial number for the segment, is it possible to get something like 09-30-001.mp4, 09-31-002.mp4 ?

• rtsp to rtmp using ffmpeg or any tool wrapper

  27 août 2017, par Chakri

  I have a requirement where I need to restream the RTSP stream from camera source to RTMP server. I know this may sound a repeated question but my exact scenario is I cannot do it manually over command line with ffmpeg command. I need a wrapper where I receive the rtsp and rtmp url from external source say through REST invocation. Then the code can trigger the ffmpeg restream.

  Basically flow is like this :

  1. Camera source application sends RTSP read event(could be basic HTTP(REST) request with RTSP url, metadata about camera info, serial no etc) to my streamer app

  Ex : /usr/bin/ffmpeg -i rtsp ://10.144.11.22:554/stream1 -f flv rtmp ://10.13.11.121:1935/stream1

  2. Streamer app computes the RTMP server url for corresponding camera and triggers a ffmpeg command to stream RTSP to RTMP

  3. Streamer app triggers above(2) in separate thread and keeps reading the logs for monitoring purpose. Also identifies the end of RTSP stream and sends an update(Example : RTSP END) event to UI

  Now at point(2) I need a suggestion. Here I need a stable wrapper/api which can help. I tried this through some Java wrappers but the process hangs or fails to read the output from ffmpeg. Also I need to handle streams from many cameras where spawning thread for each one could be exhaustive.

  So I am looking for some similar api/wrapper in C++ or Go Lang which might have more closer interaction in handling ffmpeg command.

  Please point if similar issue is addressed elsewhere