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Synch correction in ps mpg transformed with PVAstrumento?

Discussion in 'DVD±R for advanced users' started by pede, Oct 16, 2003.

  1. pede

    pede Regular member

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    I have a ps mpg which has been transformed from the original DVB-C ts mpg by PVAstrumento. I did this by unchecking the choices on the Expert page of the settings, which means that whole GOP:s are not dropped. There were a number of video frames missing in the ts file, according to the PVAstrumento log, hoever ususally only one or two, and unevenly over the ts file.

    At the end of the ps file the audio lags begind quite a bit if the file is viewed with PowerDVD. To my understanding this is because the missing videorframes. To my understanding the audio, which is complete, starts to lag behind and the video, which lacks some frames runs "faster".

    However, if I view the ps file with WinDVD the audio is in synch!!

    A layman conclusion is, that the file contains (correct)timecodes that WinDVD is able to read and process, but PowerDVD doesn't.

    If I only would need to watch the file on a pc, everything would be ok since WinDVD works, but since I'm trying to get this movie on DVD to be played on a "normal" player, I have a problem.


    I've tried to author the file with TMPGenc Author and Ulead DVD Workshop, but both programs produce a dvd which is out of synch.

    I also tried to reencode with TMPGencillä, but the program gives the error message "Illegal MPG:stream". TMPGenc Author by the same company accepts the file, but produces the out of synch result.

    Has any one a clue about an authoring software which, as WinDVD evidently does, would find these timecodes and respect them instead of just gobbling the elementary stream frames as they are thrown at the authoring software?

    Should i try to demux and remux? The original ts file or the ps file? Using which program?

    If remuxing and demuxing, would the timecode survive this, or would I just get two files with different lenght, which would not match since the drops are unevenly spread?

    Shold I process the ps file with some patching program?

    Any suggestions or clues?
     
  2. Minion

    Minion Senior member

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    Because there are so many Frame dropped the audio and Video files are different Lengths and this is why the file is out of Sync...This can be fixed though...What you should do is First De-Mux your Mpeg file and Find out the exact length of the Video file and then write it down then you are going to need a Good Audio editor like GoldWave or Sound Forge or Cool edit, I actually use the audio editor in Vegas Video 4, and what you have to do is Shrink the audio file to the same length as the video file, each of these Audio editors have setting were then can change the length of a Video file without changeing the Pitch...After changeing the length of the Audio file Just export it and Mux it back with the Video and it should be in Sync...I have used this Method for Syncing Movies Lots of Times and It usually works great as long as the Video frames were dropped in a Fairly consistant pattern.....Cheers
     
  3. pede

    pede Regular member

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    Thank you for the answer.

    I understand what the reason is. Your suggestion woiould work, but since the first 1/4 of the file (2h 9 min) doesn't have any drops, the sound would here be a bit "early". after that it would eventually be better placed.

    I might do this as a "last resort"

    However, since the timecode is in the file, witnessed bu that WindDVD, and also Nero's Media player does play the file correctly, in synch. Also Zoomplayer does. Zoomplayer does not, however have own filters, so it uses another programs filters.

    Now, since posting I haveunderstood, that the difference of the behaviour of the ssoftwareplayers depend on the filters they use.

    First a softwareplayer will use filters to do the work. First a video splitter splitting audio and video, then a decoder separately for both and finally again separately a renderer to output the audio and video.

    Evidently the filters used by WinDVD, Nero's mediaplayer and zoomplayer are able to do the job correctly, also takin into account the timeastamps in the stream.

    Now I would need a program that either fills the empty spaces, padding I belive it is called or a DVD-authoring program that is able to take into account the timecode in the file. Does anyone know of either possibilities?

    As said, TMPPGenc does not accept the file. Ther might be a possibility to alter the information on the file, in order to make TMPGenc accept the file. Does anyone know?


     
  4. dirinfo

    dirinfo Guest

    Did someone try NeroVision Express?
    In the affirmative, did it produce an "in synch" mpeg file?
     
  5. pede

    pede Regular member

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    Nero vision express crashes if I try to edit he few extra seconds at the end.

    It also crashed when doing the autochapter function. I might still try to leave the few seconds at the end and do the chapers manually. I'll see if I have the patience..
     
  6. alainc

    alainc Member

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    Hi,
    I was faced to the same problem when I started to burn DVDs from DVB streams. I just discovered that looking at the DVD from begin to end I was finishing with about 1 or seconds of audio lagging the video, but if I was going directly to chapters (which I had inserted with TMPGenc dvd authoring,) then the audio was resync'ed by the player (same thing with PowerDVD).For example going directly to the last chapter no longer showed the 1-2 seconds delay.
    I still don't know why and how.
    The trick I am using now (which gives an acceptable result) is to split the stream in several small files (there is an option in PVAstrumento for that) of about 4 minutes. Then I rebuild the complete stream with TMPGenc, adding all the files generated by PVAstrumento. this tricks automatically resync the audio every 4 minutes, and unless you have a big hole in your video the result is viewable. still not perfect, and still looking at trick to resync the audio in case some frames are cut by PVA strumento.

    Any idea

    Alainc

     

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