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• FFmpeg progress track visual C++

  15 août 2019, par jAckOdE

  In my main process, i create a ffmpeg child process using CreateProcess(...).
  I need to track the status of converting progress to update a progress bar. To do it, I read text from ffmpeg output and extract progress status from it.

  I make a sample programm like this :

  HANDLE rPipe, wPipe;
  
  CreatePipe(&rPipe,&wPipe,&secattr,0);
  
  
  
  STARTUPINFO sInfo; 
  
  ZeroMemory(&sInfo,sizeof(sInfo));
  
  PROCESS_INFORMATION pInfo; 
  
  ZeroMemory(&pInfo,sizeof(pInfo));
  
  sInfo.cb=sizeof(sInfo);
  
  sInfo.dwFlags=STARTF_USESTDHANDLES;
  
  sInfo.hStdInput=NULL; 
  
  sInfo.hStdOutput=wPipe; 
  
  sInfo.hStdError=wPipe;
  
  
  
  // pStr contain ffmpeg command
  
  CreateProcess(0,(LPTSTR)pStr,0,0,TRUE,NORMAL_PRIORITY_CLASS|CREATE_NO_WINDOW,0,0,&sInfo,&pInfo);
  
  CloseHandle(wPipe);
  
  
  
  BOOL ok;
  
  do
  
  {
  
      memset(buf,0,bufsize);
  
      ok=::ReadFile(rPipe,buf,100,&reDword,0);
  
      result += buf;            
  
  }while(ok);

  But I couldnt get "result" interactively updated. My app is held during conversion, and "result" string update only after ffmpeg’s process finish.

  How can I have my main process and ffmpeg’s run simultaneously, and interactively read from/write to ffmpeg process’s output/input ?

  Thanks for your time !

  LRs

• ffmpeg replacing audio track with track from another video but different length (sync audio)

  27 août 2019, par Matt

  Background

  I have digitized some old Canon Video8 tapes. I used a SONY Digital8 camera (which is backwards compatible with Video8) to output DV (using it’s inbuilt ADC). The conversion process worked well for the video but the audio came through jumpy/distorted in places. This left me with a problem, was it the Camera or the tape ? So I bought another Samsung Video8 camera (just analog) and using the SONY’s passthrough feature output from the Samsung (Composite & mono audio) into the SONY which output the DV. Much to my delight it worked ! The audio was clear.

  Result

  DV01.avi - Good Video / Crap Audio
  
  DV02.avi - Crap Video / Good Audio

  Ok so obviously what I would like to do is take the video track from DV01 and the audio track from DV02 and join/mux ? them WITHOUT re-encoding.

  Problem 1 : They have different start times so just copying over the audio track will result it not being in sync.

  After some googling I found you can use ffmpeg to take care of this :

  Firstly here is the Video info using : ffmpeg -i DV01.avi

  Input #0, avi, from 'DV01.avi':
  
    Duration: 02:53:06.68, start: 0.000000, bitrate: 28878 kb/s
  
      Stream #0:0: Video: dvvideo, yuv420p, 720x576 [SAR 16:15 DAR 4:3], 25000 kb/s, 25 fps, 25 tbr, 25 tbn, 25 tbc
  
      Stream #0:1: Audio: pcm_s16le, 32000 Hz, stereo, s16, 1024 kb/s
  
      Stream #0:2: Audio: pcm_s16le, 32000 Hz, stereo, s16, 1024 kb/s

  Muxing :

  ffmpeg -itsoffset 4 -i DV01.avi -i DV02.avi -map 0:v -map 1:a -c copy output.avi

  In the example above I am delaying the start of the video 4 seconds (I think ?) This is just an example I haven’t actually tried it as the file sizes are 40Gb !

  So my QUESTION is :

  Given the background above what would be the best way to join/mux the two streams together (without re-encoding) with the audio being in sync. Given that syncing the audio to the video may need millisecond tweaking I don’t believe trial and error is a good idea (I don’t want to tweak it by 10ms then rinse and repeat for a 40Gb file) ?

  I just had a thought, could I say create a 10 second clip (from the start) of each video and use them to find the reference/sync start point then use that when muxing the 40Gb versions ?

  Anyway, you get the idea. Looking for ways to solve this problem. Thanks !

• how to extract a metadata track from MP4 file

  30 août 2019, par ravi

  I need to extract metadata track from a MP4 file and save as separate file. I see that, using ffmpeg I can extract standard tracks like Audio or Video or Subtitle track and save it as a new file. For ex : to save audio track I use the command below :

  ffmpeg -i input-video.avi -vn -acodec copy output-audio.aac

  But my need is to save a proprietary metadata track. Any pointers will be helpful.

  Here is output of ffmpeg to know different traks that are present in the file. Particuarly, I am interested in extracting track corresponding to Stream #0:3(eng)...

  C:\Users\rkumar\Documents\work\tools\ffmpeg\bin>ffmpeg.exe -i input.MP4
  
  ffmpeg version N-57176-g64b3aaf Copyright (c) 2000-2013 the FFmpeg developers
  
  built on Oct 15 2013 21:32:52 with gcc 4.8.1 (GCC)
  
  
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'input.MP4':
  
  Metadata:
  
  major_brand     : mp41
  
  minor_version   : 538120216
  
  compatible_brands: mp41
  
  creation_time   : 1970-01-01 00:00:09
  
  Duration: 00:00:10.52, start: 0.000000, bitrate: 834 kb/s
  
  
  
  Stream #0:0(eng): Video: h264 (Main) (avc1 / 0x31637661), yuvj420p(pc, bt709), 
  
  854x480 [SAR 1:1 DAR 427:240], 679 kb/s, 29.97 fps, 29.97 tbr, 90k tbn, 59.94 tbc (default)
  
  Metadata:
  
  creation_time   : 1970-01-01 00:00:09
  
  handler_name    : AVC
  
  timecode        : 00:00:13:22
  
  
  
  Stream #0:1(eng): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 128 kb/s (default)
  
  Metadata:
  
  creation_time   : 1970-01-01 00:00:09
  
  handler_name    : AAC
  
  timecode        : 00:00:13:22
  
  
  
  Stream #0:2(eng): Data: none (tmcd / 0x64636D74), 0 kb/s (default)
  
  Metadata:
  
  creation_time   : 1970-01-01 00:00:09
  
  handler_name    : TCD
  
  timecode        : 00:00:13:22
  
  
  
  Stream #0:3(eng): Data: none (ssmd / 0x646D7067), 5 kb/s (default)
  
  Metadata:
  
  creation_time   : 1970-01-01 00:00:09
  
  handler_name    : MET
  
  
  
  Stream #0:4(eng): Data: none (fdsc / 0x63736466), 10 kb/s (default)
  
  Metadata:
  
  creation_time   : 1970-01-01 00:00:09
  
  handler_name    : SOS