Audio Sync Correction


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Audio Sync Correction

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lajams

Newbie

11. June 2006 @ 13:37

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Hey guys,
I rip my kid's DVD's to our server, and have found that some have the audio sync off by 500-1000ms. This is not a big deal, I've learned to correct it by those amounts, plus-or-minus. But I've been wondering...is there an exact way to measure the EXACT amount of correction needed?
Here is how I'm encoding...DVD -> SVCD (MPEG2). I rip the disc, then re-author with DVD-shrink down to the main movie. I then use DVD2AVI to downmix and strip the audio to WAV format. I then use TMPGEnc to do the re-encoding to MPEG2.
I try to be as exact as possible in all things, and I always have to guess how much audio-gap correction is needed, is there a tool to measure the exact amount without changing my technique too much? Thanks in advance to all who answer.

Regards, LA.

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SOCOMII

Senior Member

11. June 2006 @ 14:58

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whe DVD2AVI spits out the audio file it should give you a delay in the file name.
For example:
TEST FILE T01 3_2ch 384Kbps DELAY -678ms.mp3

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lajams

Newbie

11. June 2006 @ 17:52

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I checked and this is not the case....all but the delay are in the filename. Is this a feature I must turn on somehow, or maybe the version I have is too old? Version I am using is 1.77.4. Also, I am demuxing the audio to WAV, rather than MP3 if that would make a difference. Thanks in advance.

LA.

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This message has been edited since posting. Last time this message was edited on 11. June 2006 @ 17:55

SOCOMII

Senior Member

11. June 2006 @ 18:11

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Just set the option to Demux all streams and then see if it shows a delay, if not then get the latest version and see if it gives you a delay (but i think all versions should give a delay)
anyways hers a direct link to the latest version (now know as DgIndex)
http://www.doom9.org/Soft21/Decoders/dgmpgdec147.zip

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lajams

Newbie

11. June 2006 @ 18:31

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I tried demuxing all tracks with DVD2AVI and no delay in the filename. I tried the latest DVD2AVI that I could find but it would bomb out on me when trying to save the project. I'll try the new version you mentioned above and respond back. Thanks much.

LA.

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lajams

Newbie

11. June 2006 @ 19:01

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Gave the DGIndex proggie a shot and got a wav file with the following filename:

test T01 3_2ch 448Kbps 44.1KHz.wav

I'm pretty sure I must be leaving something out in the config, I'm just not sure what. Any ideas?

LA.

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SOCOMII

Senior Member

11. June 2006 @ 20:08

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im not sure if there is a delay in .wav files.
did you hit "demux all streams" instead of demux to wav or somtehing like that.
Here is a small file for you to demux and then tell me if a delay is written in the audio file it spits out.
*removed*

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This message has been edited since posting. Last time this message was edited on 15. June 2006 @ 14:12

lajams

Newbie

12. June 2006 @ 17:46

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Well, I couldn't figure out how to Demux your file, but I did play around and ended up getting an AC3 stream with the delay notation in it. I'm kinda confused at this, but perhaps there is no way to tell what the delay will be in the audio file if you convert it from AC3 on the fly. I guess I could try stripping the stream out in its AC3 format, and then convert it back to WAV for re-muxing via TMPGEnc. I would just have to note the delay, AND it would take an extra step. What are your thoughts?

LA.

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SOCOMII

Senior Member

12. June 2006 @ 18:36

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Well ya you can convert AC3 to wav in many ways, i would recomend besweet lite
http://www.doom9.org/Soft21/Audio/BeLight-0.22beta9.zip
It does a very good job of encoding sound and can even fix the delay for you as you can see in the image below,