XSVCD (PAL) out-of-sync

[havema-1]

In some of my longish PAL XSVCD's audio tend to be out-of-sync.

The ordinary ~2500 kb/s SVCDs and corresponding 37-45 minute 352x576 XSVCDs have been OK. But the in the few ~60 minute XSVCDs I have made the audio has been ad 1 second out-of-sync with the video and the error seems to somewhat fluctuate in time so some parts the audio is almost in sync.

I have used 224 kb/s 48 kHz audio with the XSVCD with either 48 kHz AIF or WAF as input but both are somewhat out-of-sync so the input seems to be not the problem.

The video and audio lengths are identical (with at least 1 second precision on a 60 minute video -- how can I check them more precisely?) before multiplexing.

For example, I have encoded 59 minute video with:
ppmtoy4m -v 0 -S 420_mpeg2 -L -I b -F 25:1
mpeg2enc -v 0 -f 5 -F 3 -n p -a 2 -b 1484 -I 1 -r 16 -q 7 -V 224 -g 9 -G 15

I have noticed that extremely large video buffers tend to get audio out-of-sync but I guess -V 224 should be OK.

Should I just encode video in smaller chunks or is there something else I could try?

[galactica]

reencoding at smaller intervals and putting them together in the end is perhaps the best optiion

Sometimes, the frame rate will change thought the video. I had this problem once, and found that I had to do about a 1-2 chapter segment inorder to keep the sync correct.

If i just did the entire video, it would slowly get more of out sync as it played back. The solution of ripping per chapter and encoding then attaching to form a single .mpeg worked well.

hope that helps ya

[havema-1]

> attaching to form a single .mpeg

What do you mean by attaching to form a single .mpeg? Encoding a few smaller mpegs and authoring them as (X)SVCD? Or joining them as a single mpeg? How?

thanks,

[galactica]

When you run ffmpegx, set it such that you only get the finalized mpeg2 file thats muxed.

Just turn off the author as SVCD and stuff that gives you the image files.

Then grab the 1st one thats done, move it and name it part1
repeat for all parts, until you have all of the mpeg files sitting in a folder, and these will be the portions you have encoded, the sections that have correct sync.

you can then "rejoin" these together to make an entire mpeg file. Or if you want, just join half together since you are going to have to split the movie file anyways right!

You can use ffmpegx join tool if you like, but i prefer mpgtx split/join program (http://www.versiontracker.com/dyn/moreinfo/macosx/15987) to just join the mpeg files.

then use vcdtoolsX to make your image files and you have your movie.

[havema-1]

Thanks, I'll try it! (I wasn't aware that DVD players accept joined mpegs).

Previously I did encode in smaller chunks but authored them individually so at least with my DVD player there was a slight pause between chapters which is disturbing in live concerts.

So recently I decided to try long mpegs which I broke into chapters with VCD Builder (you need to replace VCD Builder 1.1.1's mpgtx engine with a newer version in order to add chapters to longer mpegs, BTW).

Breaking a long mpeg into chapters worked great in VCD Builder and the transitions between chapters were smooth because it was one big mpeg. ...but the sync problem spoiled it.

I'll see how my Pioneer 444 likes these joined mpegs. Is there any noticeable stutter or hiccups between joined mpeg segments?

I noticed that also MoreMissingTools has mpg join among many other tools:

http://homepage.mac.com/rnc/

[galactica]

True, there are more apps that can join. I have just had no problem with the mpgtx program.

Some mpeg splitters/joniers will work, but playback is stalled or halted right when you get to the 2nd mpeg in the list to be split/joined.

mpgtx has never presented the problem for me.

Im just offering you a way to encode each section individually to ensure sync, where you get a lot of mpeg files, and joinging to make one large one or how ever many are required to fulfill your XSVCD requirements.

If memory serves, 794 megs is the MAX size of any mpeg portion to give you a 805 meg .bin for your 80 min CD-r.

so i suggest running the endoding in chunks, and combining the chuncks to form a 794 meg mpeg. then author as .bin/.cue with VCDTOOLSX and you have your XSVCD image ready to burn.

there should be no suttering with the joined files. (I dont think you get chapter selections with this method, rather just ff/rw and GO TO certian time progression mark (like go to 10.45 and it jumps to 10min 45 seconds of the movie.)