fixing audio sync in an avi????

aardvark · 30 Jul 2006 at 10:41

i've got an avi where the audio is out of sync and i'm wondering how to fix.

its too slow at the beginning, gradually gets into sync and then at the end its too fast.

i've looked around and i can't find a guide that really tells me how to fix this.

any ideas?

cheers

Van Hellseek · 30 Jul 2006 at 11:40

www.videohelp.com

aardvark · 30 Jul 2006 at 11:45

tried that - i can't find a guide to help my problem and the type of varying sync i have.

Lonewolf · 30 Jul 2006 at 12:49

You could try by using Vdub. Rip and convert the audio or you could try a program such as Decompress.exe.

Is the audio Mp3, AC3, or another format? Is this a file you made or one you came across?

aardvark · 30 Jul 2006 at 13:25

Lonewolf said:
You could try by using Vdub. Rip and convert the audio or you could try a program such as Decompress.exe.

Is the audio Mp3, AC3, or another format? Is this a file you made or one you came across?

i've tried saving in vdub using full prosessing on the audio and its no different.

this is a file i came across

Lonewolf · 30 Jul 2006 at 13:55

I expect the audio will be 48000Hz? have you tried converting it to 44100 and saving it as an Avi?

if you can put up a screenshot of the file info which is shown in Vdub.

aardvark · 30 Jul 2006 at 14:06

it is 4800hz

Lonewolf · 30 Jul 2006 at 14:08

Convert to 44100Hz and see if that works.

aardvark · 30 Jul 2006 at 14:12

Lonewolf said:
Convert to 44100Hz and see if that works.

i've just tried that - its the same

i've currently got tmpgenc converting it to mpg to see if that changing anything

pmbuzz · 30 Jul 2006 at 14:16

Try the Interleaving option in VirtualDub, set audio to Full Processing to enable changes to interleaving.

aardvark · 30 Jul 2006 at 14:40

pmbuzz said:
Try the Interleaving option in VirtualDub, set audio to Full Processing to enable changes to interleaving.

checked my audio settings and interleaving was already selected and i also used full processing, so it didn't work.

i don't really understand why it would be behind the video at first and then end up in front of the video by the end of the avi - odd

Mattus · 30 Jul 2006 at 15:02

aardvark said:
i don't really understand why it would be behind the video at first and then end up in front of the video by the end of the avi - odd

It sounds like the audio and video are offset (they're not in sync from the beginning) and the frame rates are also out (which is why the sync changes.) This kind of thing can be tricky to fix but you're best off using VirtualDub and trying to adjust the frame rates.

Energize · 30 Jul 2006 at 15:04

Yeah probably the framerate, perhaps it is using a variable framerate and hasn't been setup properly.

aardvark · 30 Jul 2006 at 15:14

Mattus said:
This kind of thing can be tricky to fix but you're best off using VirtualDub and trying to adjust the frame rates.

i'm not sure what you mean - could you give me a bit more detail?
thanks

i do get a variable bitrate audio error when i load it into vdub, but i've had these before and they are fixed by full processing the audio - although in the other cases there was no sync problem

Energize · 30 Jul 2006 at 15:36

You need to save the audio in virtual dub as as wav file and then load it up and convert it into another format with a constant bitrate.

Lonewolf · 30 Jul 2006 at 15:38

If Vdub is not helping you then try this alternative. Decompress.exe, it is bundled along with Avi2vcd which you wont need.
Decompress.exe will allow you to throw in your Avi whether it be MP3 or AC3 audio and convert the audio and video to PCM, I think thats what it is called. Decompress.exe will also fix out of sync Avi's. It's easy and fast too.

Avi2vcd

aardvark · 30 Jul 2006 at 16:06

Lonewolf said:
If Vdub is not helping you then try this alternative. Decompress.exe, it is bundled along with Avi2vcd which you wont need.
Decompress.exe will allow you to throw in your Avi whether it be MP3 or AC3 audio and convert the audio and video to PCM, I think thats what it is called. Decompress.exe will also fix out of sync Avi's. It's easy and fast too.

Avi2vcd

thanks, i've just tried that but the audio is still out of sync - i guess that means it was encoded already out of sync?

is there a program that will let me manually match the sound to the video at various points along the file and strech the audio accordingly?

Lonewolf · 30 Jul 2006 at 17:09

Is the Avi in sync when you play it on your PC? It could just be a bad file, one which you should deposit in the nearest bin

aardvark · 30 Jul 2006 at 17:17

no, it plays out of sync in all the media players i've tried.

does this mean its unsalvageable?

pmbuzz · 30 Jul 2006 at 17:36

aardvark said:
checked my audio settings and interleaving was already selected and i also used full processing, so it didn't work.

i don't really understand why it would be behind the video at first and then end up in front of the video by the end of the avi - odd

What i meant was that you can adjust the skew of the audio in the interleave section to delay it or make it start earlier.