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• Wrapping an existing RTP stream with RTSP

  12 janvier 2015, par Neverbirth

  I have a RTP multicast stream from ffmpeg that requires users to use external SDP files, as this sometimes becomes a problem I was thinking of wrapping the stream using RTSP.

  I have an application that already makes some management for the RTP stream, so it would be useful to have the RTSP wrapper inside it as well, although I don’t want the wrapper to do anything beyond delivering the SDP information. Right now I’d say I’m correctly delivering the SDP information (otherwise it’s stuck in that request), however I’m not getting any PLAY command, the player is stuck after the SETUP request, so I guess my reply is wrong, but after testing many different values for the Transport header I haven’t been able to get anything beyond this point.

  This is the SDP :

  v=0
o=- 0 0 IN IP4 127.0.0.1
s=No Name
c=IN IP4 236.0.0.1
t=0 0
a=tool:libavformat 56.7.102
m=video 2000 RTP/AVP 96
b=AS:500
a=rtpmap:96 H264/90000
a=fmtp:96 packetization-mode=1

  This is a sample SETUP request from VLC :

  SETUP rtsp://127.0.0.1:34343/live.sdp/ RTSP/1.0
CSeq: 4
User-Agent: LibVLC/2.1.5 (LIVE555 Streaming Media v2014.05.27)
Transport: RTP/AVP;multicast;client_port=2000-2001

  And one of many replies I’ve tried :

  RTSP/1.0 200 OK
CSeq: 4
Transport: RTP/AVP;multicast;client_port=2000-2001;source=236.0.0.1;port=2000-2001
Session: 0456804596

  I’ve tried using destination instead of source, server_port instead of port, also, although the RTP multicast port is 2000, I’ve seen the streaming is also using other ports like 57927 and 57928, so I’ve tried those ones as well, etc.

• Metadata is not showing ffmpeg C++

  18 août 2015, par Kaidul Islam

  I am muxing h264 encoded video data and PCM g711 encoded audio data into a .mov media container. I am trying to write metadata on header but the metadata is not showing when I go to file->right click->properties->details on windows and likewise in Ubuntu. This is my code -

  // Instead of creating new AVDictionary object, I also tried following way
  
  // stated here: http://stackoverflow.com/questions/17024192/how-to-set-header-metadata-to-encoded-video 
  
  // but no luck
  
  AVDictionary* pMetaData = m_pFormatCtx->metadata;
  
  av_dict_set(&pMetaData, "title", "Cloud Recording", 0);
  
  av_dict_set(&pMetaData, "artist", "Foobar", 0);
  
  av_dict_set(&pMetaData, "copyright", "Foobar", 0);
  
  av_dict_set(&pMetaData, "filename", m_sFilename.c_str(), 0);
  
  time_t now = time(0);
  
  struct tm tStruct = *localtime(&now);
  
  char date[100];
  
  strftime(date, sizeof(date), "%c", &tStruct); // i.e. Thu Aug 23 14:55:02 2001
  
  av_dict_set(&pMetaData, "date", date, 0);
  
  av_dict_set(&pMetaData, "creation_time", date, 0);
  
  av_dict_set(&pMetaData, "comment", "This video has been created using Eyeball MSDK", 0);
  
  
  
  // ....................
  
  // .................
  
  
  
  /* write the stream header, if any */
  
  int ret = avformat_write_header(m_pFormatCtx, &pMetaData);

  I also tried to see if the file contains any metadata using mediainfo and exiftools in linux. Also I tried ffmpeg -i output.mov but no metadata is shown.

  Whats the problem ? Is the flags value 0 in av_dict_set okay ? DO I need to set different flags for different platform (windows/linux) ?

  I saw this link and it stated that for windows, I have to use id3v2_version 3 and -write_id3v1 1 to make metadata working. If so, how can I do this in C++ ?

• vframes option ignored in ffmpeg ?

  25 mars 2016, par cooper

  I have a directory that contains 2001 PNG files. I can convert all of the frames to an mp4 video using ffmpeg and the following command :

  ffmpeg -framerate 60 -start_number 0 \
  
  -i pic.comp2.%07d.png -c:v libx264 -r 30 \
  
  -pix_fmt yuv420p input1ia.mp4

  This works fine. However, I am creating a more complicated application that needs to read only the first 1020 files in the directory (specifically 0 thru 1019). Some googling around led me to the -vframes option. My problem is — it seems to get ignored or at least interpreted differently than I expect.

  My modified command looks like :

  ffmpeg -framerate 60 -start_number 0 \
  
  -i pic.comp2.%07d.png -vframes 1020 -c:v libx264 
  
  -r 30 -pix_fmt yuv420p input1.mp4

  It seems like many other people doing the same thing as me do not encounter this issue. So I did some more digging. I tried changing vframes from 1020 to -vframes 20, and this seemed to work properly. So now I am thinking it might be some kind of mismatch between -framerate and -r ?

  The full resultant video is 33 sec long... which makes sense mathematically.

   1 sec
  
   ---------   x  2001 frames = 33.35 seconds
  
   60 frames

  That’s why I thought that specifying 1/2 of the PNGs as the ’end point’ would result in a video of the first 16-17 seconds. But I always get the full length video from using the -vframes option.

  I assume my input to -vframes must be incorrect mathematically, since a small number of frames seems to work. However, I do not understand why.

  The most educated guess I can seem to make is that it is reading the PNGs as 60fps (-framerate), but the -r makes the output video 30fps or something ? However, then I would assume that the full output video would not be 33 seconds long.