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• Stream video from bitmap frames with x264 and ffmpegs swscale

  25 mars 2016, par Jones

  The goal is to create a video stream from bitmap frames.

  Current solution : I am streaming raw 24bpp bitmap data over tcp from my machine to a "remote" server, to distribute the frames to the clients. This works well when everything runs on my local machine.

  Problem : The size of a frame is 1440000 (800*600*3) bytes, I only have a 2Mbps upstream and I need the video to be 25 frames per second with a resolution of 800x600.

  Approach : So after a bit of research my approach would be to encode the bitmap frames into h264 and stream the resulting video.

  Current situation : I compiled x264 and ffmpeg (for swscale, to convert RGB to YUV) and I am able to encode 24bpp bitmap Frames with x264. The last action in my test program is a call to x264_encoder_encode. The bitmap data in the test program is randomly generated for every frame.

  Now to my question(s) :

  Where do I go from here ? TCP, UDP, RTMP ? Which data would be transfered ? Do i just transmit the resulting frame from x264_encoder_encode ?
  Which still has a size of 140000 bytes, according to the return value of the function. That would result in
  (25*140000 = 3500000) 3,5 Mbps which is still greater than the 2Mpbs I have available.

  While I dont really know how (yet !), I am confidend that this task is feasable. For example, here is a spreadsheet displaying needed bandwith for different resolutions for streaming platforms like twitch.tv (using RTMP).

  My current x264_param (from this post) looks like this (just fyi) :

  x264_param_default_preset(&param, "veryfast", "zerolatency");
  
  param.i_threads = 1;
  
  param.i_width = width;
  
  param.i_height = height;
  
  param.i_fps_num = fps;
  
  param.i_fps_den = 1;
  
  // Intra refres:
  
  param.i_keyint_max = fps;
  
  param.b_intra_refresh = 1;
  
  //Rate control:
  
  param.rc.i_rc_method = X264_RC_CRF;
  
  param.rc.f_rf_constant = 25;
  
  param.rc.f_rf_constant_max = 35;
  
  //For streaming:
  
  param.b_repeat_headers = 1;
  
  param.b_annexb = 1;
  
  x264_param_apply_profile(&param, "baseline");

  thank you in advance.

• Playing and recording a live stream from another computer webcam using VLC/FFmpeg [closed]

  22 octobre 2012, par user573014

  I was trying lately to set a video server on one machine and play it in a differen machine, it works with me.. but the problem is that it always stuck and become jammed in the middle .. and it is very slow comparing to the original stream.. something like 5 seconds delay which is not acceptable at all !
  The warning messages I get usually includes something like that :
  in the client side, which is the one which is jammed

  [0x24d1ab0] ts demux warning: discontinuity received 0x5 instead of 0xe (pid=68)
  
  [0x7f4340015e50] rtp demux warning: 2 packet(s) lost
  
  reference picture missing during reorder
  
  Missing reference picture
  
  mmco: unref short failure
  
  Reference 4 >= 4 (H264 - MPEG-4 AVC (part 10)) stopped
  
  error while decoding MB 34 14, bytestream (575)

  and that is the picture of the streaming when it is jammed

  

  and that is what it looks like when it is running smoothly

  

  This is the error message I got on the server

  [0x2513820] main generic debug: auto hidding mouse
  
  [0x2296230] main mux warning: late buffer for mux input (1840085)

  and Finally here is my command line that I am using >
  on the server :

  vlc -vvv v4l2:///dev/video1:v4l2-width=640:v4l2-height=480 --sout 
  
  '#duplicate{dst=display,dst="transcode{vcodec=h264,vb=800,ab=128}
  
  :duplicate{dst=rtp{mux=ts,dst=172.22.2.87,port=50004}'

  on the client :

  vlc -vvv rtp://@:50004 

  I thought that it might be from VLC or from my command .. I tried different protocol for transmission, with no luck I also tried FFmpeg and I got similar results + warning messages .. I thought then that both of them are using the same libraries in Linux

  here is the command using FFMpeg :

  ffmpeg -f video4linux2 -i /dev/video1 -vcodec libx264 -s 320x240 -pix_fmt 
  
  yuv420p -vb 200000 -minrate 200000 -maxrate 200000 -bufsize 2000000 -acodec 
  
  libmp3lame -ab 128k -ar 44100 -ac 2 -f mpegts udp://172.22.2.87:5544 

  In conclusion, I would like to find a solution for the latency of the streaming (which is very high) and the jamming problem
  I appreciate anyone's input, thank you

• Find the library calls from FFMPEG command line

  6 octobre 2013, par Budius

  I'm trying to create an Android app that will use video edition, thou, using FFMPEG for the task. I already successfully compiled FFMPEG as a library (libavcodec, libavformat, etc) and included them in the Android project.

  Note that it does not contain the ffmpeg.c that can be called as a command line and the problem is that I only know the command lines to be used for all different things I want to accomplish.

  So the question is :

  from my Linux machine, how would I call ffmpeg main() in a "debug mode" to follow line-by-line what is being calling on those libraries, so I can write methods to mimic what I need to get done ? (currently I only have Android Studio installed, but I'm open to install whatever IDE ppl might suggest)