HeadAC3he - Bad Sync Frame

[areohbee]

Every now and then, I get this error when transcoding an AC3 file. Neither Re-ripping, re-DVD2AVI-ing, re-booting, nor trying a different DVD-disk helps. I can't help but conclude that the problem stems from the manner in which the DVD author creates the AC3 file, or incorporates it into the VOB file. Note: these AC3 files play fine. Only solution I know is: play and record from system bus, then do manual synchronization. Can anyone shed any light on this subject?

[Matthew]

Don't use this program except for cutting AC3s ocassionally, but an appropriate test is to run the AC3 through BeSplit (or BeSpliced if you want GUI). It will report any corruption in the source AC3. That error message indicates this, even if it is a headAC3he bug.

In any event, I'd use BeSweet :)

[areohbee]

Thanks Matthew, for the hot tip.

I used BeSplit to fix it, then BeSweet to transcode it and all is well.

I've been using HeadAC3he for a long time, but after further consideration I may switch.

Any particular reason(s) you prefer BeSweet? - Don't answer if you're too busy...

Cheers,
Rob.

[Matthew]

Because I like it more :D

Bear in mind that when you use BeSplit to fix bad frames, a frame is lost at every fix point, so to maintain sync it may be best to split the stream and insert a 1 frame dummy at these points.

[RB]

Originally posted by areohbee
Every now and then, I get this error when transcoding an AC3 file. Neither Re-ripping, re-DVD2AVI-ing, re-booting, nor trying a different DVD-disk helps.
How are you ripping the DVD? When you use DVDDecrypter in IFO mode and rip by PGC, this really shouldn't ever happen. However when you rip in file mode for instance and then demux the AC3, you have to expect problems. That's because in the VOB file, there may be "playback discontinuities", for instance where it goes from PGC X to PGC Y or there's a still frame with no audio etc.

[Matthew]

Originally posted by RB
How are you ripping the DVD? When you use DVDDecrypter in IFO mode and rip by PGC, this really shouldn't ever happen.

Actually I've had it happen a couple of times - combination of crappy DVDROM drive and damaged disc. In fact, I always parse the AC3s straight after ripping as a way of verifying that the ripped vobs are not corrupt. I always use DVD2AVI to save the AC3s, and it doesn't necessarily crash with corrupt vobs.

Anyway, from the info given that isn't what is happening here (and I should slap myself for failing to mention that the AC3s should definately not be corrupt to begin with), but thought I'd add this regardless =)

[areohbee]

Originally posted by Matthew
Bear in mind that when you use BeSplit to fix bad frames, a frame is lost at every fix point, so to maintain sync it may be best to split the stream and insert a 1 frame dummy at these points.

You're write about the sync thing. I'm still chewing on your proposed solution...

[areohbee]

Originally posted by RB
How are you ripping the DVD? When you use DVDDecrypter in IFO mode and rip by PGC, this really shouldn't ever happen.

I used DVDDecrypter and I thought it was IFO mode by PGC, however I'm now starting to question my sanity. Shouldn't I expect to see some anomaly in the video as well if the problem were due to a file mode mishap?