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• Video Concatenation or Merging

  19 juin 2013, par 2vision2

  I need to join/merge/concatenate more than two different video files (Eg :3gp, mp4 ) in android platform and need to store them as mp4 file.

  So far from my analysis, I’ve seen people referring FFMPEG for these purposes.

  Is FFMPEG available for android ? Or any other alternative packages available for video concatenation ?

  Can FFMPEG concatenate two different kinds of Video files ?(Eg : Combination of mp4 and 3gp)

  Update : Can OpenGL be helpful for merging more than two videos along with audio ?

• How to publish selfmade stream with ffmpeg and c++ to rtmp server ?

  25 octobre 2013, par Alexandr R

  Have a nice day to you, people !

  I am writing an application for Windows that will capture the screen and send the stream to Wowza server by rtmp (for broadcasting). My application use ffmpeg and Qt.
  I capture the screen with WinApi, convert a buffer to YUV444(because it's simplest) and encode frame as described at the file decoding_encoding.c (from FFmpeg examples) :

  ///////////////////////////
  
  //Encoder initialization
  
  ///////////////////////////
  
  avcodec_register_all();
  
  codec=avcodec_find_encoder(AV_CODEC_ID_H264);
  
  c = avcodec_alloc_context3(codec);
  
  c->width=scr_width;
  
  c->height=scr_height;
  
  c->bit_rate = 400000;
  
  int base_num=1;
  
  int base_den=1;//for one frame per second
  
  c->time_base= (AVRational){base_num,base_den};
  
  c->gop_size = 10;
  
  c->max_b_frames=1;
  
  c->pix_fmt = AV_PIX_FMT_YUV444P;
  
  av_opt_set(c->priv_data, "preset", "slow", 0);
  
  
  
  frame = avcodec_alloc_frame();
  
  frame->format = c->pix_fmt;
  
  frame->width  = c->width;
  
  frame->height = c->height;
  
  
  
  for(int counter=0;counter<10;counter++)
  
  {
  
  ///////////////////////////
  
  //Capturing Screen
  
  ///////////////////////////
  
      GetCapScr(shotbuf,scr_width,scr_height);//result: shotbuf is filled by screendata from HBITMAP
  
  ///////////////////////////
  
  //Convert buffer to YUV444 (standard formula)
  
  //It's handmade function because of problems with prepare buffer to swscale from HBITMAP
  
  ///////////////////////////
  
      RGBtoYUV(shotbuf,frame->linesize,frame->data,scr_width,scr_height);//result in frame->data
  
  ///////////////////////////
  
  //Encode Screenshot
  
  ///////////////////////////
  
      av_init_packet(&pkt);
  
      pkt.data = NULL;    // packet data will be allocated by the encoder
  
      pkt.size = 0;
  
      frame->pts = counter;
  
      avcodec_encode_video2(c, &pkt, frame, &got_output);
  
      if (got_output) 
  
      {
  
          //I think that  sending packet by rtmp  must be here!
  
          av_free_packet(&pkt);             
  
  
  
      }
  
  
  
  }
  
  // Get the delayed frames
  
  for (int got_output = 1,i=0; got_output; i++)
  
  {
  
      ret = avcodec_encode_video2(c, &pkt, NULL, &got_output);
  
      if (ret < 0)
  
          {
  
              fprintf(stderr, "Error encoding frame\n");
  
              exit(1);
  
          }
  
          if (got_output)
  
          {
  
          //I think that  sending packet by rtmp  must be here!
  
          av_free_packet(&pkt);      
  
          }
  
  }
  
  
  
  ///////////////////////////
  
  //Deinitialize encoder
  
  ///////////////////////////
  
  avcodec_close(c);
  
  av_free(c);
  
  av_freep(&frame->data[0]);
  
  avcodec_free_frame(&frame);

  I need to send video stream generated by this code to RTMP server.
  In other words, I need c++/c analog for this command :

  ffmpeg -re -i "sample.h264" -f flv rtmp://sample.url.com/screen/test_stream

  It's useful, but I don't want to save stream to file, I want to use ffmpeg libraries for realtime encoding screen capture and sending encoded frames to RTMP server inside my own application.
  Please give me a little example how to initialize AVFormatContext properly and to send my encoded video AVPackets to server.

  Thanks.

• flv reencode to mp4 for iphone/ipod via ffmpeg and x264 (quality issue)

  3 octobre 2011, par zeroasterisk

  There are a lot of questions on this topic, and I've read most of them and most of the google search results I could come up with.

  When I use FFMPEG to convert a FLV to a iphone3 compatble MP4 file, it just doesn't preserver enough of the quality. Yes, I've worked the hell out of -sameq and -b and -bt settings, text just isn't readable.

  Next I tried to split the video out and process it directly, using these instructions :
  https://sites.google.com/site/linuxencoding/x264-encoding-guide

  The problem is myplayer (via ffmpeg) was not able to determine the duration of the FLV (even though the metadata was set).

  (I assume) Because of that unknown duration, when I create the MP4 file, the resulting x264 file plays through super-fast while the audio plays at the normal rate.

  user@server:/tmp# mplayer -nosound -benchmark -sws 9 -vf dsize=640:480:0,scale=0:0,expand=640:480 -vo yuv4mpeg:file=>(x264 --demuxer y4m --crf 0 --preset slow --threads auto --output output.264 - 2>x264.log) 'input.flv'
  
  MPlayer 1.0rc4-4.4.5 (C) 2000-2010 MPlayer Team
  
  mplayer: could not connect to socket
  
  mplayer: No such file or directory
  
  Failed to open LIRC support. You will not be able to use your remote control.
  
  
  
  Playing input.flv.
  
  libavformat file format detected.
  
  [flv @ 0x1202460]Estimating duration from bitrate, this may be inaccurate
  
  [lavf] stream 0: video (vp6f), -vid 0
  
  [lavf] stream 1: audio (nellymoser), -aid 0
  
  VIDEO:  [VP6F]  1680x992  0bpp  1000.000 fps   33.4 kbps ( 4.1 kbyte/s)
  
  Clip info:
  
   audiocodecid: 6
  
   audiodatarate: 86
  
   audiosamplerate: 44100
  
   audiosamplesize: 16
  
   audiosize: 6097005
  
   canSeekToEnd: true
  
   datasize: 8609138
  
   duration: 567
  
   framerate: 2
  
   hasAudio: true
  
   hasCuePoints: false
  
   hasKeyframes: true
  
   hasMetadata: true
  
   hasVideo: true
  
   height: 992
  
   lasttimestamp: 567
  
   metadatacreator: flvtool++ (Facebook, Motion project, dweatherford)
  
   stereo: false
  
   totalframes: 1043
  
   videocodecid: 4
  
   videodatarate: 33
  
   videosize: 2316256
  
   width: 1680
  
  Using (default) progressive frame mode.Opening video filter: [expand w=640 h=480]
  
  Expand: 640 x 480, -1 ; -1, osd: 0, aspect: 0.000000, round: 1
  
  Opening video filter: [scale w=0 h=0]
  
  Opening video filter: [dsize=640:480:0]
  
  ==========================================================================
  
  Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family
  
  Selected video codec: [ffvp6f] vfm: ffmpeg (FFmpeg VP6 Flash)
  
  ==========================================================================
  
  Audio: no sound
  
  Starting playback...
  
  Movie-Aspect is undefined - no prescaling applied.
  
  [swscaler @ 0x7f0c738b9620]Lanczos scaler, from yuv420p to yuv420p using MMX2
  
  VO: [yuv4mpeg] 640x480 => 641x480 Planar YV12

  I have also tried specifying FPS, but no change in results

  user@server:/tmp# mplayer -nosound -fps 25-benchmark -sws 9 -vf dsize=640:480:0,scale=0:0,expand=640:480 -vo yuv4mpeg:file=>(x264 --demuxer y4m --fps 25 --crf 0 --preset slow --threads auto --output output.264 - 2>x264.log) 'input.flv'

  Can someone tell me how to either :

  1. fix my split A/V processing/timing/duration issues ?
  2. improve the
     quality of the FFMPEG conversion of FLV to iphone3 compatible
     format ?