DV burnt to disc with AC-3 lose audio sync (Nero and Roxio)

[bigrig]

So I've got a couple DV clips about 40 minutes in length that I want to put on a DVD. I captured them with Cyberlink PowerDirector, using a mpeg2 format. Playing them with WinDVD, they are fine.

When I put them on disc, I have to change from LPCM to AC-3 in order for them to fit. Both Nero 6 and Roxio 7 have given me the same problem. The audio seems good at the beginning, but the sync just keeps getting more off, until it's laughable.

Any suggestions would be appreciated.

Thanks!

Matt

[Dimmer]

Check the LPCM audio sampling rate. If it's 44.1kHz or anything else but 48kHz, resample it to 48kHz (DVD standard) before encoding to AC-3.

[yoda313]

Hello,
You may not have to convert the audio. Is it a dvd compliant mpg 2 file? If so than just load it into your authoring software and it should work as is. I do that with my wintv pvr250 all the time. It records to a dvd compliant mpg file and all of my dvd authoring software recognizes it without conversion (as long as the audio is in 48000 hz, dvd standard).
Kevin

[bigrig]

Check the LPCM audio sampling rate. If it's 44.1kHz or anything else but 48kHz, resample it to 48kHz (DVD standard) before encoding to AC-3.

Okay, thanks for that tip. How can I check?

Kevin, I switched it to AC-3 because it's a compressed format which allowed me to fit both videos on disc. Using LPCM, it was too large.

Thanks,

Matt

[DVD_Ripper]

Roxio is notorious for lousy conversions... try to use another program outside your burning app to convert the streams. I've used Womple's MPEG Editor to convert from LPCM to MPEG1L2 Audio with very good success.

[yoda313]

Hello,

bigrig-switched it to AC-3 because it's a compressed format which allowed me to fit both videos on disc. Using LPCM, it was too large.

I understand about the space saving issues. How do you estimate your video bitrate to take advantage of the savings?

I've got a hauppauge mpeg card and I can set the bitrate I want. I did one audio conversion of a wav to mp2 (I think it shrunk it from 1gig to 200-300mb). If I could accurately predict the savings I might do that more often. If you could share your procedures that would be appreciated.
Kevin

[yoda313]

Hello,
I forgot to tell you how to check the audio sampling rate, sorry. Use tmpgenc and open mpeg tools. Click the demultiplex tab. Open the mpg. It will tell you what the bitrates are for the audio and video portions of the file. It should say 44100 or 48000 for the audio. It needs to be 48000 for dvd. Hope that helps.
Kevin
P.S. You can use tmpgenc to upcode the audio.
[/quote]

[bigrig]

Thanks for the instructions, Kevin. TMPGEnc says:

MPEG-2 Video 720x480 29.97fps 6000kbps
MPEG-1 Audio Layer-2 48000Hz 224kbps

So I guess the sample rate is correct...now what? Maybe if I put chapters in the file I would have better results?

DVD_Ripper, I used both Nero and Roxio, with identical results. Thanks for the info about Womple.

Matt

[yoda313]

Hello,
It looks like this is your original mpg. All I can suggest is to remix the files again. If you lost synch it may be your multiplex step. It seems from the tmpgenc read out to be the correct format (no ac3 info).

Sorry I can't be much more help. Digital video can be tricky. I've done several projects mutiple times before I've gotten the desired results.
Good luck.
Kevin

[bigrig]

Whoops, I forgot to give an update of my results.

I tried it again, this time adding chapter breaks about 5 minutes apart. This fixed it! I dunno why.

Thanks for your advice.

Matt