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• Can not add images after add background to audio

  16 mars 2017, par Thanh Dao

  I use below command to concat background to an audio file :

  "ffmpeg" -i /path/to/image.png -i /path/to/audio.mp3 -vsync vfr -pix_fmt yuv420p /path/to/video-1.mp4 2>&1

  Next, I use that command to add other images to created video :

  "ffmpeg" -f concat -safe 0 -i /path/to/text.txt -i /path/to/video-1.mp4 /path/to/video-2.mp4 2>&1

  Content of my text.txt file :

  /path/to/img1.jpg
  
  duration 6
  
  /path/to/img2.jpg
  
  duration 6
  
  /path/to/img3.jpg
  
  duration 6
  
  /path/to/img4.jpg
  
  duration 6

  Obtained video display only background image. Other images have not been shown.

  What are my wrong in these commands ? And how to set the display position of other images in video ? To display images by position, I use below command, but after it ran, my machine was crashed :

  "ffmpeg" -f concat -safe 0 -i /path/to/text.txt -i /path/to/video-1.mp4 -filter_complex "overlay=0:0, scale=640:640" /path/to/video-2.mp4 2>&1

  Update :

  I do follow order by below steps and got video with text and images, but the position is incorrect. I can’t find any solution for custom :

  "ffmpeg" -f concat -safe 0 -i /path/to/text.txt -i /path/to/audio.mp3 -vsync vfr -pix_fmt yuv420p /path/to/tmp-video-1.mp4 2>&1
  
  
  
  "ffmpeg" -i /path/to/background.png -i /path/to/tmp-video-1.mp4 -filter_complex "overlay=0:0" /path/to/tmp-video-2.mp4 2>&1
  
  
  
  "ffmpeg" -i /path/to/tmp-video-2.mp4 -vf "[in]<define texts="texts" and="and" duration="duration">[out]" -codec:a copy /path/to/endvideo.mp4 2>&amp;1
  
  </define>

  Please take a look my video : http://184.171.170.45/cron/tmp/funny-1489648654.mp4
  I tried to set overlay property in second command : -640:0, let images in horizontal center of background, but its not working

• streaming H.264 over RTP with libavformat

  16 avril 2012, par Jacob Peddicord

  I've been trying over the past week to implement H.264 streaming over RTP, using x264 as an encoder and libavformat to pack and send the stream. Problem is, as far as I can tell it's not working correctly.

  Right now I'm just encoding random data (x264_picture_alloc) and extracting NAL frames from libx264. This is fairly simple :

  x264_picture_t pic_out;
  
  x264_nal_t* nals;
  
  int num_nals;
  
  int frame_size = x264_encoder_encode(this->encoder, &nals, &num_nals, this->pic_in, &pic_out);
  
  
  
  if (frame_size <= 0)
  
  {
  
      return frame_size;
  
  }
  
  
  
  // push NALs into the queue
  
  for (int i = 0; i < num_nals; i++)
  
  {
  
      // create a NAL storage unit
  
      NAL nal;
  
      nal.size = nals[i].i_payload;
  
      nal.payload = new uint8_t[nal.size];
  
      memcpy(nal.payload, nals[i].p_payload, nal.size);
  
  
  
      // push the storage into the NAL queue
  
      {
  
          // lock and push the NAL to the queue
  
          boost::mutex::scoped_lock lock(this->nal_lock);
  
          this->nal_queue.push(nal);
  
      }
  
  }

  nal_queue is used for safely passing frames over to a Streamer class which will then send the frames out. Right now it's not threaded, as I'm just testing to try to get this to work. Before encoding individual frames, I've made sure to initialize the encoder.

  But I don't believe x264 is the issue, as I can see frame data in the NALs it returns back.
  Streaming the data is accomplished with libavformat, which is first initialized in a Streamer class :

  Streamer::Streamer(Encoder* encoder, string rtp_address, int rtp_port, int width, int height, int fps, int bitrate)
  
  {
  
      this->encoder = encoder;
  
  
  
      // initalize the AV context
  
      this->ctx = avformat_alloc_context();
  
      if (!this->ctx)
  
      {
  
          throw runtime_error("Couldn't initalize AVFormat output context");
  
      }
  
  
  
      // get the output format
  
      this->fmt = av_guess_format("rtp", NULL, NULL);
  
      if (!this->fmt)
  
      {
  
          throw runtime_error("Unsuitable output format");
  
      }
  
      this->ctx->oformat = this->fmt;
  
  
  
      // try to open the RTP stream
  
      snprintf(this->ctx->filename, sizeof(this->ctx->filename), "rtp://%s:%d", rtp_address.c_str(), rtp_port);
  
      if (url_fopen(&(this->ctx->pb), this->ctx->filename, URL_WRONLY) < 0)
  
      {
  
          throw runtime_error("Couldn't open RTP output stream");
  
      }
  
  
  
      // add an H.264 stream
  
      this->stream = av_new_stream(this->ctx, 1);
  
      if (!this->stream)
  
      {
  
          throw runtime_error("Couldn't allocate H.264 stream");
  
      }
  
  
  
      // initalize codec
  
      AVCodecContext* c = this->stream->codec;
  
      c->codec_id = CODEC_ID_H264;
  
      c->codec_type = AVMEDIA_TYPE_VIDEO;
  
      c->bit_rate = bitrate;
  
      c->width = width;
  
      c->height = height;
  
      c->time_base.den = fps;
  
      c->time_base.num = 1;
  
  
  
      // write the header
  
      av_write_header(this->ctx);
  
  }

  This is where things seem to go wrong. av_write_header above seems to do absolutely nothing ; I've used wireshark to verify this. For reference, I use Streamer streamer(&enc, "10.89.6.3", 49990, 800, 600, 30, 40000); to initialize the Streamer instance, with enc being a reference to an Encoder object used to handle x264 previously.

  Now when I want to stream out a NAL, I use this :

  // grab a NAL
  
  NAL nal = this->encoder->nal_pop();
  
  cout << "NAL popped with size " << nal.size << endl;
  
  
  
  // initalize a packet
  
  AVPacket p;
  
  av_init_packet(&p);
  
  p.data = nal.payload;
  
  p.size = nal.size;
  
  p.stream_index = this->stream->index;
  
  
  
  // send it out
  
  av_write_frame(this->ctx, &p);

  At this point, I can see RTP data appearing over the network, and it looks like the frames I've been sending, even including a little copyright blob from x264. But, no player I've used has been able to make any sense of the data. VLC quits wanting an SDP description, which apparently isn't required.

  I then tried to play it through gst-launch :

  gst-launch udpsrc port=49990 ! rtph264depay ! decodebin ! xvimagesink

  This will sit waiting for UDP data, but when it is received, I get :

  ERROR : element /GstPipeline:pipeline0/GstRtpH264Depay:rtph264depay0 : No RTP
  format was negotiated. Additional debug info :
  gstbasertpdepayload.c(372) : gst_base_rtp_depayload_chain () :
  /GstPipeline:pipeline0/GstRtpH264Depay:rtph264depay0 : Input buffers
  need to have RTP caps set on them. This is usually achieved by setting
  the 'caps' property of the upstream source element (often udpsrc or
  appsrc), or by putting a capsfilter element before the depayloader and
  setting the 'caps' property on that. Also see
  http://cgit.freedesktop.org/gstreamer/gst-plugins-good/tree/gst/rtp/README

  As I'm not using GStreamer to stream itself, I'm not quite sure what it means with RTP caps. But, it makes me wonder if I'm not sending enough information over RTP to describe the stream. I'm pretty new to video and I feel like there's some key thing I'm missing here. Any hints ?

• lavf : replace FFFormatContext.prefer_codec_framerate with FF_INFMT_FLAG

  13 octobre 2024, par Anton Khirnov

  lavf : replace FFFormatContext.prefer_codec_framerate with FF_INFMT_FLAG
  There is no reason for this to be a dynamic property, as the only
  
  demuxer using this sets it unconditionally.
  

  • [DH] libavformat/demux.c
  • [DH] libavformat/demux.h
  • [DH] libavformat/internal.h
  • [DH] libavformat/mpegts.c