Audio sync. Please educate me!

[jaggerdss]

I am curious if anyone can explain to me some specifics on audio sync problems particularly in authoring. First let me state that I know what causes sync problems when capturing.(dropped frames,,etc..) What I do not understand is how a file can play perfect on the PC but goes out of sync when authoring? If the PC can interpret the file fine why is there not any authoring software that can do the same? I have converted a recent avi (downloaded) that is in sync when played. I converted it to a DVD compliant vob.(and tried mpeg) That file plays fine (on the PC) as soon as I author it the audio is off, and I tried authoring with all available authoring programs(everything on this site). It just seems as if this is a common problem with no simple cure.(or any at all) Some will say that "your original file is bad" If it is bad then why can windows play it? I guess what i'm looking for is a technical description of why this happens.(technical as you want to get, I can handle it!) And maybe why no one has made any software to cure this "simple" problem (I haven't found any yet)

[Baldrick]

Just authoring shouldn't cause any sync problems....not if you use a good authoring tool. What converter and authoring tool are you using?

[jman98]

By any chance is the audio VBR MP3? This will play perfectly well on PCs and be problematic elsewhere. If so, the fix is to extract the audio to WAV format using something like VirtualDubMod and then convert the WAV file when authoring to DVD.

[FulciLives]

Load the AVI into GSpot to determine if it is MP3 audio (and if it is then it is probably VBR MP3 audio).

If that is the case then load the AVI into GOLDWAVE and save the audio to a PCM WAV audio file.

Now when you do the conversion you use the PCM WAV audio file as the sound source (and not the sound in the AVI) and all should be A-OK.

GOLDWAVE seems to excel at this when the source is VBR MP3 audio (I even do it when I have CBR MP3 audio).

Please note that if you want MP2 or AC3 audio on the DVD you can convert the PCM WAV that GOLDWAVE spits out to that format. For instance ffmpeggui is a good program for converting from PCM WAV to AC-3 audio format.

- John "FulciLives" Coleman

[jaggerdss]

Well the original avi is vbr mp3 but I re-encode this to AC3 (also tried mp2) and it is still in sync. Only when I author does it go out of sync? I will try the goldwave trick though as that is one that I have not tried.
Still though what is technically happening as far as PC can play fine but authoring software can't?
As far as what I have used here is a list:
Authoring tools:
TMPGEnc DVD Author (all versions),Ulead VideoStudio 7 SE DVD & Ulead DVD MovieFactory 2.5 SE,dvdSanta,DVD Flick,InterVideo WinDVR 3,SpruceUp DVD Authoring, etc..(can't remember any others)
Convert tools:
Mpeg Video Wizard DVD,AVI to VCD SVCD DVD Converter,EasyX Video Converter,TMPGEnc.exe,TMPGEnc DVD Source Creator,WinMPG Video Convert,ConvertXtoDvd,SUPER,VirtualDub_sync.,mpeg-vcr.
I have had this problem with mpeg's that were captured fine (no sync problems on pc) also. Sometimes I get lucky ,sometimes not. I don't count the captures that had dropped frames or sync problems before authored.
Capturing tools used:amcap.exe,CaptureFlux,iuVCR,PowerVCR II,iZE TV - Lite Edition,MiBaoTV,WinFast PVR, along with the author/capture stuff above.
I got so tired of sync problems with no rhyme or reason(one day work, next won't. Same settings & nothing running in background) with my capture card (Leadtek Winfast 2000XP Pro) that I bought a standalone dvdr.
Now I download video's and I'm back to playing the game again!

[jaggerdss]

Well here is a weird thing to add. I play the VOB file in the authored folder on my PC and it is in sync. When I burn it to a DVD it is out of sync? I assumed it was out in the authored folder before as when it was done authoring I just automatically burned it.

[Barnabas]

jaggerdss,

Dropped video frames are the usual reason for loss of sync in a captured file. This happens much of the time when capping from video tape. The original file is in sync because of padding, but the padding is lost when you author. If your file was an MPEG file, there is a program called VideoReDo that can usually save it, but it doesn't handle avi files.

Audio sync loss is a MAJOR problem at times. Once it's out of sync, it's usually NOT fixable, UNLESS it's out the same amount from start to finish. Usually, it starts in sync and gradually goes out. That's not possible to fix with any decent results.

[snafubaby]

There is a file you can try. It's mainly for video players like Ipod's and the like, but it also has some parameters for a pc monitor. It may work if you can resize it. Anyway, it's called Pocket DivX Encoder. Just do a google search for it. After you download it, run it, and then choose which type of device you are using by choosing a screen size. It's got one for a PC, too. It will show the monitor, and you can input a size for the monitor. Anyway, you load the video, and convert it to DivX, XviD, and a few other formats. Here's the best part.. It has a syncronizing feature. You encode the video to the format you want, and then you can run it through the syncronizer, to get it in sync. I've fixed MANY videos with it for my Archos video player. Try it out and see if it will work for you.

You may be having the same issue i am having. I have an mpeg that is in great A/V sync, until i do the DVD multiplexing. THEN, it's out of sync. Try the above mentioned program and see what happens, though. It may fix things, if it's a problem with variable or constant bitrate.