SVCD Audio Sync Problem

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Hi,

My DVD player is a Philips 711, runing latest firmware, I encode a SVCD Mpeg2 file using TMPGEnc12f, to 480x576 (pal) and burn it to cd with nero 5.5...but when I play it back on the philips the video quality is great but the audio is slightly out of sync, I`ve tried using lower bitrates etc..but nothing seems to work, Any one got any tips or ideas to try ? or anyone got a similar problem ? I dont have any problems with choppy video, and can ff/rew no problem..

Thanks

-- Alan (alansam@lineone.net), July 31, 2001

Answers

TMPGenc has options for correcting audio/video sync; try to figure out where with its multitude of buttons. The trick is to encode, say, just a minute's worth of program material with speech (a talking head preferably) and play with the audio skew + or - milliseconds. You may have to do this several times trial and error to get the exact amount of skew, tedious maybe, but when you have found out the correct amount, you can now encode the entire clip. By the way this is assuming you have independent audio and video source files to begin with; not just re-encoding some other MPEG file (in which case you have to de-mux it first).

-- Mehmet Tekdemir (turk690@yahoo.com), August 01, 2001.

What are you using for video capture? There is much debate on this very topic right now in a SVCD forum as to what causes or can fix sync problems. I have an ATI AIW Radeon and I get sync problems if my video is > 30 minutes per CD-R. I can offer a few suggestions. Go to www.tecoltd.com and get the free bit rate viewer. Put your video through it and see what the max. bit rate is. If it's > 2.6 Mbps, your video is not SVCD compliant. Nero will tell you that it is compliant, but Nero doesn't check the entire bit stream. It only reads the avg. bit rate and if it's less than 2.6 Mpbs, Nero says it's OK. According to the spec, the video can't ever exceed 2.6 Mpbs and be in spec. I know that my video is not in spec because it has brief periods where it spikes above 2.6 Mbps. Like I said, if it's under 30 mins. I have no problem. For longer video, I use ReMPEG (check www.labdv.com for it) and re-encode it so that the bit rate stays below 2.6. Bad news for you - ReMPEG doesn't do PAL. If my video is in spec and I mux and make it with I-Author, I have no sync problems. Another solution is to get the Womble MPG2VCR product (www.womble.com) which has a tool under the multiplexer that allows you to shift audio forwards or backwards while muxing. Play with it a little and you can fix just about any audio problem. One of the reasons recording at a lower bit rate won't work is that your video is usually still not in spec. I have a SVCD I recorded at 1.9 Mbps and it still has a brief segment that is at 3.0 Mbps, which is not SVCD compliant. TMPGenc in theory can be used to re-encode your video to a lower bit rate, but I have a lot of trouble getting it to work, so I use ReMPEG since I record in NTSC. If you can keep your entire video under 2.6 Mbps, you might have better luck with it staying in sync, but there is much debate right now over this in another forum. All I can say is it works for me.

-- Jason (Jason.Shumate@equant.com), August 01, 2001.

Just to follow up, if you feel brave and want to check out the SVCD forum for a bunch of conflicting answers on your question, go to network54.com/Hide/Forum/70438 The other post is correct, that TMPGenc can be used to try to correct sync problems. In my opinion TMPGenc does a very poor job of dealing with sync issues and I would be surprised if this works for you, but it's free so you could easily try it and see. Maybe you'll have better luck than I did with it.

-- Jason (Jason.Shumate@equant.com), August 01, 2001.

I got it too work, I canged the Audio from 44.1k to 48,000 and now the audio is in perfect sync..when played on my dvd.....I`m using A studio DC10+ for capture, the Audio is in sync before and after i encode to mpeg..it seemed to be too do with playback..thanks for your tips

Alan.

-- Alan (alansam@lineone.net), August 01, 2001.


Hi Alan, I'm glad it worked, but please be aware that 48 MHz is not supported by the SVCD spec. It only supports 44 MHz, just like audio CD. Should you care, you can read the SVCD spec at: www.licensing.philips.com/partner/data/sl00811.pdf The last part of the address is SL00811.pdf. Make sure you use lower case. I just wanted to make sure you could distinguish between the letter L and the number 1. Many DVD players will accept non-compliant SVCD discs and play them without complaining, but you should be aware that what you did is not officially supported and might be a problem for other DVD players.

-- Jason (Jason.Shumate@equant.com), August 02, 2001.


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