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• Given 2 input videos of different lengths at 60 FPS with multiple common sections in between, what is the best way to sync them at the common section ?

  27 janvier 2024, par PirateApp

  
input vs output

  


  

  • In my actual case, there are 4 videos (basically gaming videos recorded from 4 different machines)

  


  • Each video may start or end at different duration (manually controlled by people starting and stopping recording and therefore their lengths vary slightly)

  


  • Each video has one or more common sections (basically a cutscene playing at the same time)

  


  • The distance between the common sections is the same in every video

  


  • How do I sync the videos at the common section ?

  


  • Basically I want to create a split screen video such that the common part plays at the same time on all the sub parts of the video

  


  • Keep in mind that the common sections wont be EXACTLY equal (because of graphics differences between machines but highly similar like dx9 vs dx11 or gamma)
What have I tried ?

  


  • Naive approach

  


  • Start video 1 at 0, start video 2 at 0.017, render the whole thing and check if it is in sync

  


  • Start video 1 at 0, start video 2 at 0.033, render the whole thing and check if it is in sync

  


  • Basically loop through the length of the video at each frame interval, render the full video and check if we get a synced version

  


  


  This sounds like a terrible idea honestly

  


    for (t1 in length of video a) {
    for (t2 in length of video b) {
       render a video with a and b starting at t1, t2 respectively
       increment t2 by 0.017 for b
    }
    increment t1 by 0.017 for a
  }


  


  Final output with 4 videos should look like this all synced at common sections


  


  Any better ideas ?

  


• c++ mp3 library

  31 mai 2012, par user1288043

  I am exhausted searching for a c++ mp3 decoding library, preferably free (like lgpl) and cross-platform or for windows and mac. Can anyone suggest such library and post some tutorial for using it ?
  ffmpeg and sdl (sdl_sound, sdl_mixer) aren't compiling. I am unable to get mpg123 working - is it for linux world only or what ? Is there some tutorial on using mpg123 on windows ? mpg123 is unable to find some symbols that is I am not putting some dll's at right path - but which ?

  Overall, I want be able to read and write all major audio file formats on windows and mac - starting with windows.

• Unable to convert .mp3 to .m4a using ffmpeg [closed]

  4 mai 2013, par rahulg

  I am fully aware the legal constraints in using libfaac but this is just for my testing purpose.

  I have compiled ffmpeg with faac enabled. So when I tried to convert an .mp3 to a .m4a here is the error that I am getting. Please provide a resolution to this problem. I tried it on two different sources of .mp3, still I am getting the same error.

  [user@ip-10-161-13-26 ~]$ ffmpeg  -i Kalimba.mp3 -c:a libfaac Kalimba.m4a
  
  ffmpeg version 0.11.1 Copyright (c) 2000-2012 the FFmpeg developers
  
    built on May  4 2013 09:33:27 with gcc 4.4.6 20120305 (Red Hat 4.4.6-4)
  
    configuration: --enable-libfaac --enable-nonfree --disable-yasm
  
    libavutil      51. 54.100 / 51. 54.100
  
    libavcodec     54. 23.100 / 54. 23.100
  
    libavformat    54.  6.100 / 54.  6.100
  
    libavdevice    54.  0.100 / 54.  0.100
  
    libavfilter     2. 77.100 /  2. 77.100
  
    libswscale      2.  1.100 /  2.  1.100
  
    libswresample   0. 15.100 /  0. 15.100
  
  [mp3 @ 0x2464680] Header missing
  
  [mp3 @ 0x2463100] max_analyze_duration 5000000 reached at 5015510
  
  [mp3 @ 0x2463100] Estimating duration from bitrate, this may be inaccurate
  
  Input #0, mp3, from 'Kalimba.mp3':
  
    Metadata:
  
      publisher       : Ninja Tune
  
      track           : 1
  
      album           : Ninja Tuna
  
      artist          : Mr. Scruff
  
      album_artist    : Mr. Scruff
  
      title           : Kalimba
  
      genre           : Electronic
  
      composer        : A. Carthy and A. Kingslow
  
      date            : 2008
  
    Duration: 00:05:50.60, start: 0.000000, bitrate: 191 kb/s
  
      Stream #0:0: Audio: mp3, 44100 Hz, stereo, s16, 192 kb/s
  
      Stream #0:1: Video: mjpeg, yuvj420p, 512x512, 90k tbr, 90k tbn, 90k tbc
  
      Metadata:
  
        title           : thumbnail
  
        comment         : Cover (front)
  
  Output #0, ipod, to 'Kalimba.m4a':
  
    Metadata:
  
      publisher       : Ninja Tune
  
      track           : 1
  
      album           : Ninja Tuna
  
      artist          : Mr. Scruff
  
      album_artist    : Mr. Scruff
  
      title           : Kalimba
  
      genre           : Electronic
  
      composer        : A. Carthy and A. Kingslow
  
      date            : 2008
  
      Stream #0:0: Video: none, q=2-31, 128 kb/s, 90k tbn
  
      Metadata:
  
        title           : thumbnail
  
        comment         : Cover (front)
  
      Stream #0:1: Audio: none, 0 channels, 128 kb/s
  
  Stream mapping:
  
    Stream #0:1 -> #0:0 (mjpeg -> ?)
  
    Stream #0:0 -> #0:1 (mp3 -> libfaac)
  
  Encoder (codec none) not found for output stream #0:0

  MP3 file is at http://db.tt/HtpEBpFU

  Also while using Faac independently I get this weird error for any file.

  Freeware Advanced Audio Coder
  
  FAAC 1.28
  
  
  
  Couldn't open input file sample.mp3