Sur d’autres sites (11148)

• How to save stream with ffmpeg to chunks, But in temporary name and change the name after to const

  10 janvier, par Eliya

  I use ffmpeg to record IP camera and I save every 10 minutes to mp4 file.
This is my code :

  


  ffmpeg -rtsp_transport tcp -i "rtsp://$user_name:$password@$IP:$port/cam/realmonitor?channel=1&subtype=1" -c copy -map 0 -reset_timestamps 1  -f segment -segment_time 600 -strftime 1   "%Y-%m-%d__%H:%M:%S.mp4"


  


  Is there a way to save the file in temporary name until 10 minutes is done ?
I mean when the recording of 10 minutes didn't end the suffix will be bla.temp and when the recording of the 10 minutes is over, ffmpeg will change the suffix to .mp4 ?
is that possible ?

  


• Save frame as image during video stream using ffmpeg, in C

  30 avril 2017, par George T.

  I’m using the Parrot SDK3 to retrieve the video stream from a Bebop2 drone. From it I need to "extract" a frame and save it as an image.

  The whole code can be found here, but I shall try to include the (what I understand as) important parts here.

  Where the video is sent to mplayer. I assume from this that the video format is h624.

  if (videoOut != NULL)
  
  {
  
      if (codec.type == ARCONTROLLER_STREAM_CODEC_TYPE_H264)
  
      {
  
          if (DISPLAY_WITH_MPLAYER)
  
          {
  
              fwrite(codec.parameters.h264parameters.spsBuffer, codec.parameters.h264parameters.spsSize, 1, videoOut);
  
              fwrite(codec.parameters.h264parameters.ppsBuffer, codec.parameters.h264parameters.ppsSize, 1, videoOut);
  
  
  
              fflush (videoOut);
  
          }
  
      }
  
  }

  Where the frame is received and written to videoOut, to be displayed

  eARCONTROLLER_ERROR didReceiveFrameCallback (ARCONTROLLER_Frame_t *frame, void *customData)
  
  {
  
      if (videoOut != NULL)
  
      {
  
          if (frame != NULL)
  
          {
  
              if (DISPLAY_WITH_MPLAYER)
  
              {
  
                  fwrite(frame->data, frame->used, 1, videoOut);
  
  
  
                  fflush (videoOut);
  
              }
  
          }
  
      }
  
      return ARCONTROLLER_OK;
  
  }

  The idea I had in mind is to fwrite(frame->data, frame->used, 1, videoOut); to a different file but that just creates a corrupted file, probably because of encoding. In what way can I get this frame and store it to a separate image ? The preferable image filetype .png, .jpg or .gif

  Any help will be greatly appreciated ! Thanks in advance !

• Why my code that based on ffmpeg can't sync video' time and audio's time ?

  6 juillet 2021, par ZSpirytus

  Background

  


  Recently, I use ffmpeg to write my first Android video player. But video channel's time is faster than audio channel's time about 2 3 times.

  


  Code

  


  In short, I use PacketDispatcher to read AVPacket from http hlv source :

  


  void PacketDispatcher::RealDispatch() {
    while (GetStatus() != DISPATCHER_STOP) {
        while (GetStatus() == DISPATCHER_PAUSE) {
            LOGD(TAG, "wait signal");
            pthread_mutex_lock(&mutex);
            pthread_cond_wait(&cond, &mutex);
            pthread_mutex_unlock(&mutex);
        }

        AVPacket *av_packet = av_packet_alloc();
        int ret = av_read_frame(av_format_context, av_packet);
        if (ret) {
            LOGE(TAG, "av_read_frame ret=%d", ret);
            break;
        }

        // PacketDispatcher is who read the AVPacket from http hlv source 
        // and dispatch to decoder by its stream index.
        decoder_map[av_packet->stream_index]->Push(av_packet);
    }
}


  


  And then, Decoder written by Producer-Consumer Pattern, Decoder maintain a queue that store all the AVPacket received from PacketDispatcher. The code like this :

  


  // write to the queue
void BaseDecoder::Push(AVPacket *av_packet) {
    pthread_mutex_lock(&av_packet_queue_mutex);
    av_packet_queue.push(av_packet);
    pthread_cond_signal(&av_packet_queue_cond);
    pthread_mutex_unlock(&av_packet_queue_mutex);
}

// real decode logic
void BaseDecoder::RealDecode() {
    SetDecoderState(START);
    LOGI(LogSpec(), "start decode");

    while (true) {
        // 1. check decoder status and queue size to decide if call thread.wait

        // 2. send packet to codec
        AVPacket* av_packet = av_packet_queue.front();
        int ret = avcodec_send_packet(av_codec_ctx, av_packet);

        // 3. read frame from codec
        AVFrame *av_frame = av_frame_alloc();
        ret = avcodec_receive_frame(av_codec_ctx, av_frame);

        if (m_render) {
            // 3. custom decode logic overrided by child class
            void *decode_result = DecodeFrame(av_frame);
            if (decode_result) {
                // 4. dispatch to render
                m_render->Render(decode_result);
            } else {
                LOGD("BaseDecoder", "decode_result=nullptr");
            }
        }
    }
}


  


  Finally, I do rendering logic in Render. Render also written by Producer-Consumer Pattern, it maintain a queue that store AVFrame received from Decoder, the code like this :

  


  // write AVFrame
void BaseRender::Render(void *frame_data) {
    Lock();
    frame_queue.push(frame_data);
    Signal();
    UnLock();
}

// render to surface or Open SL
void BaseRender::RealRender() {
    // frame data that contain frame pts and other metadata
    frame_data->pts = av_frame->pts = av_frame->best_effort_timestamp * av_q2d(GetTimeBase());
    // video only
    frame_data->video_extra_delay = av_frame->repeat_pict * 1.0 / fps * 2.0;
    if (m_render_synchronizer && m_render_synchronizer->Sync(frame_data)) {
        continue;
    }
}


  


  And then, the synchronizer will decide to sleep time or drop video frame according to the frame pts, frame pts is :

  


  frame_data->pts = av_frame->best_effort_timestamp * av_q2d(GetTimeBase());


  


  Also, video extra delay is :

  


  frame_data->video_extra_delay = av_frame->repeat_pict * 1.0 / fps * 2.0;


  


  RenderSynchronizer code like this :

  


  bool RenderSynchronizer::Sync(void *frame_data) {&#xA;    auto base_frame_data = static_cast<baseframedata>(frame_data);&#xA;    if (base_frame_data->media_type == AVMEDIA_TYPE_AUDIO) {&#xA;        return ReceiveAudioFrame(static_cast<pcmdata>(frame_data));&#xA;    } else if (base_frame_data->media_type == AVMEDIA_TYPE_VIDEO) {&#xA;        return ReceiveVideoFrame(static_cast<rgbadata>(frame_data));&#xA;    }&#xA;    return false;&#xA;}&#xA;&#xA;bool RenderSynchronizer::ReceiveAudioFrame(PCMData *pcm_data) {&#xA;    audio_pts = pcm_data->pts;&#xA;    return false;&#xA;}&#xA;&#xA;bool RenderSynchronizer::ReceiveVideoFrame(RGBAData *rgba_data) {&#xA;    video_pts = rgba_data->pts;&#xA;&#xA;    if (audio_pts &lt;= 0 || video_pts &lt;= 0) {&#xA;        return false;&#xA;    }&#xA;&#xA;    double diff = video_pts - audio_pts;&#xA;    if (diff > 0) {&#xA;        if (diff > 1) {&#xA;            av_usleep((unsigned int) (rgba_data->extra_delay * 1000000.0));&#xA;        } else {&#xA;            av_usleep((unsigned int) ((diff &#x2B; rgba_data->extra_delay) * 1000000.0));&#xA;        }&#xA;        return false;&#xA;    } else if (diff &lt; 0) {&#xA;        LOGD(TAG, "drop video frame");&#xA;        return true;&#xA;    } else {&#xA;        return false;&#xA;    }&#xA;}&#xA;</rgbadata></pcmdata></baseframedata>

  


  Why my code can not sync video time and audio time ? Thanks for your reading and answers.