Divx encoding - audio sync problem

[TheJudge]

Hi all!!!
I'm new in the Divx-encoding-world. I have a Leadtek XP 2000 Expert tuner card. With this card I can capture programs in mpeg2 format (768*576 PAL) audio: MPEG1 Audio layer II 224 kbps. The result is very good quality but it is a large mpeg2 file (4-5GB/90min). I've try to encode that in divx movie. But at the end. I've got an audio sync problem (the audio part is faster then the video). I've use Virtualdub-Mpeg2 (1.5.10-build 18189) for encode. I've try the following settings: video: full processing, frame rate change so video and audio duration match(24.904)(but I've try also with 25), compression - Divx 5.05(variable bitrate mode, 1 pass, 950 kbps, resize to 480*352 - bilinear, very soft)
audio: full processing mode, compression: MPEG Layer3, 128 kBit/s, 44100 stereo (I've also try to convert to 48000 but I've got still the same result). At the begining I've try to encode to a bigger resolution (640*480) and I've try more divx bitrate settings (from 900 to 1400). I've done all that on Athlon XP 2400+, 256 MB, Seagate 80GB, 7200. Where is the problem? Is this system is too slow for encoding or in these settings I've made some mistake? Sorry for my bad english. Thanks for help. Bye.

[UncasMS]

i woud NOT change the framerate in any way

unless you have so called dropped frames while capturing (i.e. same frames might be skipped when the system can not keep up) your oridnal file should be fine and in sync

is that the case or do you already have problems at that stage??
check your file at the beginning, in the middle and at the end

if the source-file is fine, i would give it a try with DVX, because this tool was first written for dvb => divx conversion and your captured mpeg-2 with an mp2 audio is similar in terms of what has to be done in the whole process

[TheJudge]

The mpeg2 file does not have sync problems. Thanx for your hepl, I've downloaded the DVX but that gives me a lots of error at the beginning. I've found two other solutions. FlaskMpeg and Xmpeg. If I made the conversion with these progz, I've got a perfect video-audio sync. But in both case I've got an another problem. The original mpeg2 file's video quality is perfect, but after I've converted, I've got a picture with some thin bands (I don't know how this effect calls, maybe interlace? ), that is only in case of fast motion. I've try to deinterlace it, but the result is a very blury background in fast motion. I've try it with differnet codecs (xvid, divx3.11, 5.05) but with the same result . Help me please. Thanx.

[megamachine]

Welcome to the forum, Judge. I think the problem you are having is dropped frames during the capture stage, resulting in a corrupted audio or video stream. Media players, like PowerDVD, can play these without a problem, probably by skipping the bad frames, but it seems when rendering into MPEG-4 the bad frames get removed and that results in the sync problem. This has plagued my VHS to XviD/DivX conversions, and I have not yet found a solution. It sounds like we need something that will fix the corrupted streams by replacing, not deleting, the bad frames in the original MPEG-2. I had a hunch, though haven't tried it yet, that re-rendering the captured file might help, and it sounds like you've done something like that with FlaskMpeg and Xmpeg. Can you outline that procedure a bit more here, for our information? As for the lines, that sounds like an interlacing issue. What did you use to de-interlace? Sorry for not giving you a solution, but I am struggling with this problem, too, so maybe by keeping this thread alive for a while, some one can recommend a solution.

[TheJudge]

Yesterday I've found the soulution after 4 weeks of unsuccesfull experiment...The captured mpeg2 it has a perfect quality, I don't think the dropped frames caused that audio sync problem. At the end, I've tried the flaskmpeg...with that, I've got a perfect audio-video sync, but also I've got an interlaced video. I've try to deinterlace it with flask but the result it was a very blury image. I've try the xmpeg. With that, I'v got a perfect audio-video sync and a deinterlaced picture. I've used the these settings. Xmpeg - load the mpeg2 file - video compression: Divx 5.05 pro, deinterlace with motion detection option (motion treshold=5), audio: uncompressed pcm. After that, with virtualdub, I've compress the audio part (mpeglayer3, 128 kbps). I've checked the result, the begining, the middle and the end, it has a perfect video-audio sync and a deinterlaced picture. I must test the whole movie, from the begining to the end.

[megamachine]

Thanks Judge, please keep us posted. I've had some success with short clips using various methods, but the problem persists with full length movies, the audio seeming to gradually slip out of sync, so by the end there is several seconds delay. I'll try XMpeg.

P.S. The drifting sync is usually attributed to frame rate problems, but I wonder if it is also caused by dropped frames in one stream but not in the other, or by dropped frames in different locations.