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• Linux use a filename to derive parameters from

  5 avril 2017, par JoAnywhere

  I am using raspbian for a project.

  Here is my situation. I’m creating three files :

  1. a wav file with a filename format of [date_and_timestamp].wav.
  2. an avi file with a filename format of [date_and_timestamp].avi.
  3. a file with the name marker_[date_and_timestamp]

  The value of [date_and_timestamp] is consistent across all three files.

  What I want to do is look for all files starting with marker_, get the [date_and_timestamp] portion and use it to pass as a parameter to ffmpeg to combine the two files (i.e. ending up with a command that looks like

  ffmpeg -i /home/motion/[date_and_timestamp].avi -i /home/motion/[date_and_timestamp].wav /home/motion/[date_and_timestamp].mp4

  Given how powerful sh is, I know there will be a way, but I am far to n00bish to know what it is.

  The square brackets are there for clarity. They do not appear in the filenames.

• Repeat RTMP with FFMPEG when stream already started

  1er avril 2017, par John Doee

  I have an NGINX RTMP Server setup, unfortunately the playback of the rtmp source is only possible for a few seconds after the specific stream has been published.

  Though connections that have already been opened e.g. Transcoding through FFMPEG works fine without any problems even for a few hours but they have to be started within a few seconds after the video signal is being published.

  So while the stream is transcoded and hence definitely available, FFProbe can’t find the specific stream ending with the following output (Debug mode) :

  [rtmp @ 0x7fadbdc0b5e0] Proto = rtmp, path = /live/4_9_lLV7GhFmTG0w, app = live, fname = 4_9_lLV7GhFmTG0w

  [rtmp @ 0x7fadbdc0b5e0] Server bandwidth = 5000000

  [rtmp @ 0x7fadbdc0b5e0] Client bandwidth = 5000000

  [rtmp @ 0x7fadbdc0b5e0] New incoming chunk size = 4096

  [rtmp @ 0x7fadbdc0b5e0] Creating stream...

  [rtmp @ 0x7fadbdc0b5e0] Sending play command for ’4_9_lLV7GhFmTG0w’

  [rtmp @ 0x7fadbdc0b5e0] Deleting stream...

  rtmp ://***:80/live/4_9_lLV7GhFmTG0w : Input/output error

  (Executing exactly the same command within two or three seconds after / before initial publishing of the video signal succeeds. Transcoding processes last for the whole duration of the stream) It seems that there is missing some header data that is used to identify the current stream after a few seconds.

  Any suggestions on this ? Thank you very much for your help in advance.

• File encoded as FFV1 with libavcodec is unplayable

  19 novembre 2016, par Ali Alidoust

  I’m using the following code to encode a series of frames into an mkv or avi file with FFV1 encoding :

  HRESULT Session::createContext(LPCSTR filepath, UINT width, UINT height, UINT fps_num, UINT fps_den) {
  
      LOG(filepath);
  
  
  
      this->codec = avcodec_find_encoder(AV_CODEC_ID_FFV1);
  
      RET_IF_NULL(this->codec, "Could not create codec", E_FAIL);
  
  
  
      this->oformat = av_guess_format(NULL, filepath, NULL);
  
      RET_IF_NULL(this->oformat, "Could not create format", E_FAIL);
  
      this->oformat->video_codec = AV_CODEC_ID_FFV1;
  
      this->width = width;
  
      this->height = height;
  
      this->context = avcodec_alloc_context3(this->codec);
  
      RET_IF_NULL(this->context, "Could not allocate context for the codec", E_FAIL);
  
  
  
      this->context->codec = this->codec;
  
      this->context->codec_id = AV_CODEC_ID_FFV1;
  
      this->context->codec_type = AVMEDIA_TYPE_VIDEO;
  
  
  
      this->context->pix_fmt = AV_PIX_FMT_YUV420P;
  
      this->context->width = this->width;
  
      this->context->height = this->height;
  
      this->context->time_base.num = fps_den;
  
      this->context->time_base.den = fps_num;
  
  
  
      this->context->gop_size = 1;
  
  
  
      av_opt_set_int(this->context->priv_data, "coder", 0, 0);
  
      av_opt_set_int(this->context->priv_data, "context", 1, 0);
  
      av_opt_set_int(this->context->priv_data, "slicecrc", 1, 0);
  
  
  
      avformat_alloc_output_context2(&fmtContext, NULL, NULL, filepath);
  
  
  
      this->fmtContext->oformat = this->oformat;
  
      this->fmtContext->video_codec_id = AV_CODEC_ID_FFV1;
  
  
  
      this->stream = avformat_new_stream(this->fmtContext, this->codec);
  
      RET_IF_NULL(this->fmtContext, "Could not create new stream", E_FAIL);
  
      avcodec_parameters_from_context(this->stream->codecpar, this->context);
  
      this->stream->codecpar->level = 3;
  
  
  
      /*if (this->fmtContext->oformat->flags & AVFMT_GLOBALHEADER)
  
      {*/
  
          this->context->flags |= CODEC_FLAG_GLOBAL_HEADER;
  
      /*}*/
  
  
  
      RET_IF_FAILED_AV(avcodec_open2(this->context, this->codec, NULL), "Could not open codec", E_FAIL);
  
      RET_IF_FAILED_AV(avio_open(&this->fmtContext->pb, filepath, AVIO_FLAG_READ_WRITE), "Could not open output file", E_FAIL);
  
      RET_IF_NULL(this->fmtContext->pb, "Could not open output file", E_FAIL);
  
      RET_IF_FAILED_AV(avformat_write_header(this->fmtContext, NULL), "Could not write header", E_FAIL);
  
  
  
      frame = av_frame_alloc();
  
      RET_IF_NULL(frame, "Could not allocate frame", E_FAIL);
  
      frame->format = this->context->pix_fmt;
  
      frame->width = width;
  
      frame->height = height;
  
      // RET_IF_FAILED(av_image_alloc(frame->data, frame->linesize, context->width, context->height, context->pix_fmt, 32), "Could not allocate image", E_FAIL);
  
      return S_OK;
  
  }
  
  
  
  HRESULT Session::writeFrame(IMFSample * pSample) {
  
      IMFMediaBuffer *mediaBuffer = NULL;
  
      BYTE *pData = NULL;
  
      DWORD length;
  
  
  
      RET_IF_FAILED(pSample->ConvertToContiguousBuffer(&mediaBuffer), "Could not convert IMFSample to contagiuous buffer", E_FAIL);
  
      RET_IF_FAILED(mediaBuffer->GetCurrentLength(&length), "Could not get buffer length", E_FAIL);
  
      RET_IF_FAILED(mediaBuffer->Lock(&pData, NULL, NULL), "Could not lock the buffer", E_FAIL);
  
      RET_IF_FAILED(av_image_fill_arrays(frame->data, frame->linesize, pData, AV_PIX_FMT_YUV420P, this->width, this->height, 1), "Could not fill the frame with data from the buffer", E_FAIL);
  
      LOG_IF_FAILED(mediaBuffer->Unlock(), "Could not unlock the buffer");
  
  
  
      frame->pts = this->pts++;
  
  
  
      AVPacket pkt;
  
  
  
      av_init_packet(&pkt);
  
      pkt.data = NULL;
  
      pkt.size = 0;
  
  
  
      RET_IF_FAILED_AV(avcodec_send_frame(this->context, frame), "Could not send the frame to the encoder", E_FAIL);
  
      if (SUCCEEDED(avcodec_receive_packet(this->context, &pkt))) {
  
          RET_IF_FAILED_AV(av_interleaved_write_frame(this->fmtContext, &pkt), "Could not write the received packet.", E_FAIL);
  
      }
  
  
  
      av_packet_unref(&pkt);
  
  
  
      return S_OK;
  
  }
  
  
  
  HRESULT Session::endSession() {
  
      LOG("Ending session...");
  
      LOG("Closing files...");
  
      av_write_trailer(this->fmtContext);
  
      avio_close(this->fmtContext->pb);
  
      avcodec_close(this->context);
  
      av_free(this->context);
  
      //fclose(this->file);
  
      LOG("Done.");
  
      return S_OK;
  
  }

  The problem is that the generated file is not playable in either VLC or MPC-HC. However, MPC-HC reports following info in file properties :

  General
  
  Unique ID                      : 202978442142665779317960161865934977227 (0x98B439D9BE859109BD5EC00A62A238CB)
  
  Complete name                  : T:\Test.mkv
  
  Format                         : Matroska
  
  Format version                 : Version 4 / Version 2
  
  File size                      : 24.6 MiB
  
  Duration                       : 147ms
  
  Overall bit rate               : 1 401 Mbps
  
  Writing application            : Lavf57.57.100
  
  Writing library                : Lavf57.57.100
  
  
  
  Video
  
  ID                             : 1
  
  Format                         : FFV1
  
  Format version                 : Version 0
  
  Codec ID                       : V_MS/VFW/FOURCC / FFV1
  
  Duration                       : 147ms
  
  Width                          : 1 280 pixels
  
  Height                         : 720 pixels
  
  Display aspect ratio           : 16:9
  
  Frame rate mode                : Constant
  
  Frame rate                     : 1 000.000 fps
  
  Color space                    : YUV
  
  Chroma subsampling             : 4:2:0
  
  Bit depth                      : 8 bits
  
  Compression mode               : Lossless
  
  Default                        : Yes
  
  Forced                         : No
  
  DURATION                       : 00:00:00.147000000
  
  coder_type                     : Golomb Rice

  Something to note is that it reports 1000 FPS which is weird since I’ve set AVCodecContext::time_base in the code.

  UPDATE :

  I managed to set the correct fps by setting time_base property of the stream :

  this->stream->time_base.den = fps_num;
  
  this->stream->time_base.num = fps_den;

  VLC plays the output file but it shows VLC logo instead of the video, as if there is no video stream in the file.