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• Horizontally show two videos side by side and export to one video

  15 juin 2015, par Michael Liberman

  What I am trying to achieve :
  Programmatically (using some kind of script) combine two different videos to one video where the videos are shown side by side and sound from both videos is played simultaneously.

  I found at least two ways I could display two videos side by side but in each one I have a different problem that makes it difficult to complete the process :

  1. Avisyth and Avs2Avi :
     Avisyth really makes the process easy. With a simple Avisyth script like this you should be able to play two videos side by side :

     video1=AVISource("d:\file1.avi")<br />
video2=AVISource("d:\file2.avi")<br />
StackHorizontal(video1,video2)

     The creation of a new output file can be done with avs2avi.
     The problem here is that i am not able to play even one avi file with avisyth because I get "AviSource couldn’t locate a decompressor for fourcc xvid" message. I googled for the solutions to that problem but nothing helped. GSpot says that i have all the codecs needed and it seems I can not do anything. Because I can not get to running real videos, I dont know if the final video plays sounds from both videos. Avisyth installed correctly and I am able to run the following script StackHorizontal(version ,version).

  2. ffmpeg
     Works like a charm with two videos and the final file BUT i do not get the sounds from both videos but only the first one. I found out that the solution to add sound from the second video will be by using the libfaac in the command line, like that :
     

     ffmpeg.exe -i video1.mp4 -vf "[in] scale=iw/2:ih/2, pad=2*iw:ih [left]; movie=video2.mp4, scale=iw/3:ih/3 [right]; [left][right] overlay=main_w/2:0 [out]" -c:a libfaac -b:v 768k Output.mp4

  but i always get an error that the encoder libfaac can not be found. I downloaded the libfaac.dll but still no result.

  Is there a solution to any of these problems ? Is there another way to programmatically make one video from two videos that are played side by side ? Thanks in advance.

• How can I stream very long H.264 videos over HTTP without long startup times ? (or : MOOV atom too large)

  5 octobre 2012, par michael

  I want to stream videos of public meetings that are often 10 hours long. Users will generally be starting at some point in the middle of the video and jumping around frequently.

  H.264 in an MP4 container seems like the current best option for encoding streaming video (right ?). But these are large files — about 1.3GB for one file — and the metadata (MOOV atom) at the beginning of the file is itself about 40MB. If I understand correctly, clients need to download the full metadata before they're able to seek within the remainder of the file. Obviously, having to download 40MB before you can start streaming is unacceptable.

  (My tests of streaming have been with VLC and the HTML5 tag in Chrome.)

  I'm encoding the file using avconv, and am currently providing no additional settings beyond telling it which encoders to use (x264 and libfaac). I then move the metadata to the beginning of the file using qt-faststart.

  Is there a way to make the MOOV atom smaller ?

  If not, are there other strategies to use (e.g. is splitting long videos into several files something that's frequently done ? it seems like a real pain in terms of users seeking around the whole day's video) ?

  Or should I be using a different codec or container ?

  thanks !

  Here's a breakdown of the file header structure, from AtomicParsley :

  Atom ftyp @ 0 of size: 32, ends @ 32
  
  Atom moov @ 32 of size: 40157673, ends @ 40157705
  
       Atom mvhd @ 40 of size: 108, ends @ 148
  
       Atom iods @ 148 of size: 24, ends @ 172
  
       Atom trak @ 172 of size: 20156304, ends @ 20156476
  
           Atom tkhd @ 180 of size: 92, ends @ 272
  
           Atom edts @ 272 of size: 36, ends @ 308
  
               Atom elst @ 280 of size: 28, ends @ 308
  
           Atom mdia @ 308 of size: 20156168, ends @ 20156476
  
               Atom mdhd @ 316 of size: 32, ends @ 348
  
               Atom hdlr @ 348 of size: 45, ends @ 393
  
               Atom minf @ 393 of size: 20156083, ends @ 20156476
  
                   Atom vmhd @ 401 of size: 20, ends @ 421
  
                   Atom dinf @ 421 of size: 36, ends @ 457
  
                       Atom dref @ 429 of size: 28, ends @ 457
  
                   Atom stbl @ 457 of size: 20156019, ends @ 20156476
  
                       Atom stsd @ 465 of size: 147, ends @ 612
  
                           Atom avc1 @ 481 of size: 131, ends @ 612
  
                               Atom avcC @ 567 of size: 45, ends @ 612
  
                       Atom stts @ 612 of size: 6115608, ends @ 6116220
  
                       Atom stss @ 6116220 of size: 16960, ends @ 6133180
  
                       Atom ctts @ 6133180 of size: 5683824, ends @ 11817004
  
                       Atom stsc @ 11817004 of size: 28, ends @ 11817032
  
                       Atom stsz @ 11817032 of size: 4169724, ends @ 15986756
  
                       Atom stco @ 15986756 of size: 4169720, ends @ 20156476
  
       Atom trak @ 20156476 of size: 20001133, ends @ 40157609
  
           Atom tkhd @ 20156484 of size: 92, ends @ 20156576
  
           Atom mdia @ 20156576 of size: 20001033, ends @ 40157609
  
               Atom mdhd @ 20156584 of size: 32, ends @ 20156616
  
               Atom hdlr @ 20156616 of size: 45, ends @ 20156661
  
               Atom minf @ 20156661 of size: 20000948, ends @ 40157609
  
                   Atom smhd @ 20156669 of size: 16, ends @ 20156685
  
                   Atom dinf @ 20156685 of size: 36, ends @ 20156721
  
                       Atom dref @ 20156693 of size: 28, ends @ 20156721
  
                   Atom stbl @ 20156721 of size: 20000888, ends @ 40157609
  
                       Atom stsd @ 20156729 of size: 96, ends @ 20156825
  
                           Atom mp4a @ 20156745 of size: 80, ends @ 20156825
  
                               Atom esds @ 20156781 of size: 44, ends @ 20156825
  
                       Atom stts @ 20156825 of size: 9348168, ends @ 29504993
  
                       Atom stsc @ 29504993 of size: 28, ends @ 29505021
  
                       Atom stsz @ 29505021 of size: 5326296, ends @ 34831317
  
                       Atom stco @ 34831317 of size: 5326292, ends @ 40157609
  
       Atom udta @ 40157609 of size: 96, ends @ 40157705
  
           Atom meta @ 40157617 of size: 88, ends @ 40157705
  
               Atom hdlr @ 40157629 of size: 33, ends @ 40157662
  
               Atom ilst @ 40157662 of size: 43, ends @ 40157705
  
                   Atom ©too @ 40157670 of size: 35, ends @ 40157705
  
                       Atom data @ 40157678 of size: 27, ends @ 40157705
  
  Atom free @ 40157705 of size: 8, ends @ 40157713
  
  Atom mdat @ 40157713 of size: 1320096566, ends @ 1360254279

• Evolution #2454 (Nouveau) : distinguer auteurs et visiteurs en attente de confirmation

  11 décembre 2011, par Jacques Bouthier

  Un rédacteur passe de statut nouveau à 1comite lorsqu’il renvoie le mail de confirmation. Mais il peut arriver que ce mail n’arrive pas, qu’il soit détruit par erreur dans les spams... Aujourd’hui on ne les voit que dans la table des auteurs. Serait-il possible de rajouter une option qui (...)