A/V sync issue with chapters on standalone

[avdmb]

Thanks to the great DVD2SVCD program and advises from this forum, all initial problems to have SVCDs playing on my standalone Pioneer DV-444 are now resolved. All but one : while selecting chapters (direct or FF/RW), there is sometimes a few 100 ms sync delta between voice and data (I don't think this issue is specific to Pioneer DV-444). I have tried all suggestions from this forum, without luck. Hereafter the (long) description of everything I tested. Thanks in advance if anybody has a new suggestion to eventually resolve this last annoying problem.

1) Tested movie is encoded with CCE 2.50, with bitrate min 600, max 2500, max avg 2200. It is a 1 hour movie with 21 chapters, and resulting Avg bitrate is around 1600. Quite standard DVD2sVCD settings are used. Always using I-Author muxer (a must to avoid blocky video on Pioneer DV-444). Burned CD always using fullprrof DDogg method with Nero. It is a PAL movie, played on a PAL TV set.

2) After most of the trials, I tried to to view the burned CD on the PC with a software DVD player (PowerDVD XP). The result was always perfect : absolutely no sync issue when selecting chapters.

3) Issue happens with movies authored with chapters (using I-Author or VCDXbuild), and chapter selection is used on the standalone player. After a while (few seconds up to > 10 seconds), the movie usually goes back in sync. When playing the SVCD using continuous play on DVD player, or author the SVCD without chapters, the movie also usually plays in sync.

4) Issue only happens with some chapters, and depends on Authoring program (not on muxer). I first tested with standard DVD2SVCD, using I-Author to finalize CD, with as result a sync issue only at the beginning of chapter 6 (no issue on chapter 14). When manually using same I-author muxed file (with ps option checked) and authoring with VCDXbuild, the sync issue on chapter 6 is solved ... but the problem now happens on chapter 14 ! Complete bypass of bbMPEG (manual muxing with I-Author of CCE_encoded video stream and original audio stream, authoring with VCDXbuild) gives similar results (chapter 6 OK, chapter 14 KO).

5) In most of my trials, I have the perception that on most chapter starts, A/V are slightly desync (maybe 100 ms) while playing on my standalone Pioneer. I have the perception that A/V are always sharp in sync on my software DVD player.

6) In some trials, I had to run VCDXbuild from a DOS window (instruction cut&paste from DVD2SVCD.log file). In this case, VCDXbuild is run in debug mode, and I noticed warning messages saying that chapters could not be set at the exact requested time, and were set at the closest possible time (delta being a multiple of (1/25 frames =) 40 ms : 40, 80 or 120). This is maybe the root cause of the problem, but I don't know how this can be controlled.

7) Following tests were done, with no positive effect on the result :
. Always removing Title Picture (by default DVD2sVCD smiley logo).
. Always removing "Save XML" and "Save Movie Info".
. Tried Movie Offset= 0 and 2 seconds : no effect.
. Tried Startup delays= 180, 180, 180 and 240, 120, 120 : no effect.
. Disable "Add Scan Offsets" and/or "bbMPEG Align Sequence Headers" : no effect.
. Selected MPEGAV : no effect.
. Selected the 3 PBC options in VCDXbuild : no effect (always works when playing continuous on standalone DVD player).
. Use DVD2AVI v.1.76 (standard in DVD2SVCD bundle).
. Audio @ 44.1 kHZ : not tried.
. Use VCDEasy to burn : not tried (in principle, fullproof method OK).

[gerti67]

Hello avdmb,

it's nice to hear someone doing a lot of testing on its own - trying to solve his problems - it seems this is not so common nowadays. :)

So now you have tried a lot of things and it's time to enter the advanced encoder settings for CCE then. Have you already tried to play around with the GOP settings? - Try a 3/4 setting instead of the standard 3/5 and see if this helps? - It's just a guess - might be that the decoding chipset of your player can handle a GOP length of 12 (3/4) better than the one of 15 (3/5).

Another thing to try might be the "Add sequence end code" option of CCE but you have to start CCE manually and load the ECL file created by DVD2SVCD then double-click on the "AviSynth_Script_file.avs", hit the "Video" button and uncheck this setting. Then encode again - some players are reported to work better with this setting unchecked - and this setting is reported to cure the problem of some players to not be able to play the last 2 seconds of a SVCD also.

So again - still some space for testing. ;) (I know it's a pain in the a..)

HTH,
Gerti

[avdmb]

Thanks again Gerti67. I will give it a try and report results ... in a few days (1 hour movie CCE encode on my PII-450 machine takes a looong time). Notice that I am more thinking about an issue (and solution ?) related to muxing/authoring combination, as differents trials with I-Author/bbMPEG solved the problem on some chapters (while introducing the problem in other chapters !). I indeed also feel the pain in the arm :p

[gerti67]

Me again,

I thought you persist on using I-Author - if not there's another option to lay with: bbMPEG. ;) Have you tried to set the forced muxrate to "6972" instead of "0" ? - This is the standard for SVCD streams and DVD2SVCD uses the "0" to enable bbMPEG's (max) automatic adjustement feature. Perhaps this lets your player stumble after skipping chapters because this setting has an effect on the VBV buffer used by your player - who knows? ;)

Gerti

[avdmb]

Herewith the test results based on higly valuable Gerti67 suggestions. Unfortunately, still not yet a 100 % solution.

1) I tried the options to change GOP length from 15 to 12, without positive effect. I have not tried the "Add sequence end code" option (I have not really a problem with last 2 seconds, testing very long, I think more about a solution with muxer/authoring).

2) I tried the option "forced muxrate=6972" in bbMPEG ... and miracle , A/V desync issue when switching from chapter to chapter was gone (thanks Gerti). Well, the only problem is that using bbMPEG instead of I-Author left the DV-444 problem at low bitrate present.

3) I tried several combinations to use first bbMPEG for muxing-cutting-demuxing, then I-Author to remux and either I-Author or VCDXbuild for Authoring. I tried with "forced muxrate=6972", with or without "Add Scan Offsets" and/or "bbMPEG Align Sequence Headers", with "Use Private Stream2", with SVCD or ~DVD option, ... In all cases, use of I-Author muxer would destroy the positive effect of bbMPEG forced muxrate.

In summary, either a solution to A/V sync when switching between chapters (use bbMPEG muxer with with "forced muxrate=6972") or a solution to video blocking at low bitrate (use I-Author muxer), but no solution to both for the Pionerr DV-444. In order to solve the dilemma, I investigated how to mimic I-Author with bbMPEG settings. As this is no longer related to this thread topic, I will start a new thread to report on these trials.