Audio out of sync after converting AC3 to MP3 in AVI with VD

[huykin]

I used the latest VirtualDub + AC3 ACM + Lame ACM to convert audio in an XVID AVI from 6 channel 48 kHz 448 kbps AC3 to stereo 128 kbps CBR MP3. (VD: open AVI, video direct stream copy, audio full processing, audio conversion no change for kHz sampling rate and bit precision but down mix from 6 channels to stereo, audio compression Lame MP3 48 kHz 128 kbps CBR stereo, save AVI.) While audio and video is in sync in the original file with AC3, it isn't in the new one with MP3, at least when I jump to different places in the video in MPC-HC.

Is there an easy way to convert audio in XVID AVI from 6 channel AC3 to MP3 and keep it in sync with video? Thanks

[jagabo]

I suspect your original AVI has a audio delay. Use the Audio -> Interleaving to set the delay for your MP3 audio. You don't need to reencode. Open the AVI with MP3 in VirtualDub and put both Audio and Video in Direct Stream Copy mode. Set the delay and save.

[huykin]

Thanks. Is there a way to figure out the required delay (perhaps from the original file with AC3) other than by trial and error?

[jagabo]

When you preview the video in VirtualDub the delay will take effect. You can eyeball it that way.

If the audio has a delay MediaInfo shows it in the Audio section although it's called Video Delay for some reason.

[huykin]

jagabo: Thank you!!! You definitely know this stuff. Grabbed the delay from the original file using MediaInfo, and ran VD using that delay in Audio Interleaving. The sync is back! MediaInfo is very comrehensive, so going forward will use it instead, or at least in addition to GSpot and AVIcodec.

[pierssy]

This really works great, so simple when you know how. So just wanted to say Thanks

[jagabo]

Glad it's working out for you guys.