How To Fix Gradual Sync Problems

[Phat J]

How To Fix Gradual Sync Problems

this is how to fix sync problems in mpeg videos where the audio
starts out being in sync and becomes off sync later

u need:
- sound forge www.sonicfoundry.com
- tmpgenc, or any other video software that can demux and mux the
video and audio streams
- virtualdub

1. first watch your video and go to a
part near the end where it is off sync, the nearer the end the
better
watch for a event that will allow u to determine how it is off
sync, like a door slamming or a person clapping

2. open your video in virtualdub and seek
to that part and note the exact time where the event happened
(the door slamming, person clapping, etc) write down this
time



3. use tmpgenc or a similar program to
seperate the audio and video streams into a video file and a mp2
audio file
information on how to do that is at the beginning of the other
audio sync guide, www.vcdhelp.com/sync.htm

4. open the mp2 file in sound forge and
find the sound that was the event that u used to determine the
off-syncness of the video (the sound of the door slamming, etc)
note the time where this event begins and write down this
time



5. subtract the numbers from the video
and audio and find a difference, that number is what u will
stretch or compress the mp2 file by in sound forge

-example (does not apply to the pictures on this guide):
video time: 00:21:04.53
audio time: 00:21:03.27
00:21:04.53 - 00:21:03.27 = 1.26 seconds
therefore the sync is off by approximately 1.26 seconds

- if the video time is larger then the audio time, then u will
stretch (make longer) the audio by the difference
- if the video time is shorter then the audio time, then u will
compress (make shorter) the audio by the difference
here is how to do this in sound forge:







1. choose "A01: Music 1" ive never had any problems
with it
2. take the initial time and:
- add the difference you got in step 5 to the initial time if the
video comes before the audio.
- subtract the difference you got in step 5 from the initial time
if the audio comes before the video.
take this number and enter it as the Final Time.
3. hit OK

6. then save it as a wav file with
these settings:



7. then convert the wav file back to mp2,
using tmpgenc or a similar program, with the settings 224kb/s,
stereo, 44100hz.
remux the video with the new audio stream with tmpgenc and the
video and audio should be in sync.
-Phat J-

[Roginator]

You "might" be able to save a lot of time by just clicking on the frame rate setting in Virtualdub that says to make audio and video durations match.

[Phat J]

that would not work for MPEG movies if u are planning to make a VCD because VCD has to have a specific frame rate
plus u will have to re-encode the video if u use virtualdub because it saves in avi

[Roginator]

TMPGEnc doesn't seem to care if the frame rate is off a little. But yes, you would have to re-encode.

[sean madison]

that is a pretty interesting guide but i wonder is, when would u need to use it???

The only problems anyone should ever have is dvd rips but those are simply manmade mistakes in settings, not the way it was ripped.

Even for capturing-
If its outt sync, tmpgenc fixes that anyway cuz i had to do it before in tmpgenc.

[Phat J]

i use it for downloaded videos since i do not make my own
for example if u get a music video and u want to add cd quality audio to it, but the audio is shorter/longer then the video duration, then the lyrics would be off sync. u can follow my guide to fix that

[sean madison]

hey, thats true, awesome. I might have to use this sometime.

GREAT guide!

[Phat J]

no prob

[rogun]

For some reason I'm unable to get this to work. My videos are still out of synch after doing everything exactly as this guide suggests. I'm sure it's something which I'm doing wrong, but I don't know what?

[Phat J]

hmm are u sure u entered your time values into sound forge correctly?
initial time and final time should be different
and your final audio file should have a different length then the original file
(unless the amount that it was off sync was really small, in which case the original probably would still be watchable being off sync very little)

are there any steps u were having trouble with?

[klumbz]

Great idea, and great guide.
but, like the other person said running it threw vdub with "change so video and audio match" works perfectly for my downloaded south park episodes, even if the sorce framerate is 16fps, the resulting vcd is perfectly in sync.

klumbz

[Phat J]

what format are your southpark episodes?

[klumbz]

Mostly .rm (unfortunately) then convert to .avi with tinra w/stable using huffy compretion. Then use Virtualdub to clean it up some w/noise reduction and smart smoother and sync the framerate while I'm at it.
then just use the defualt vcd template in TPMGEnc.
Its a long process (even w/a fairly fast cpu and lotsa ddr memory) but that's what batch mode is for

just for the record tho, I'm not expecting great video quality but a/v sync is a must and that "match a/v framerate" is doing the job (for my 20 minute clips).

-P.S. your guide rox. I've been muxing great quality mp3s to my music videos all night! thx

klumbz

[Lars_blohm]

I've had some problems editing AVI files as well regarding sync problems. The basic problem is that the framerate is controlled by the playbackdevice (e.g. camera, vcr) and the audio bitrate is controlled by the capturecard/soundcard and there is no chance for that to be in sync - 25 frames for 44100 audiosamples, so here are what I do:

1) Capture the AVIfile with the capturecard. If the properties for the AVI hereafter is checked there is no chance it is excatly e.g. 25,000 fps
2) Open Preimere 4.2 and do a "conform AVI movie" to the desired framerate. Takes only a few seconds for each AVI
3) Open after that the AVI in SoundForge. The audio fps is now a littyle beside the 44100 Hz. Now do a resample to 44100 Hz. Save the AVI.

After that the AVI is excatly 25,000 fps and 44100 Hz and no problems during the following editing or MPEG conversion occurs !!!

[rogun]

The only step I'm unsure about is step 5. What I did was add the difference to the initial time and put that value into the place for the final time. When I did this everything seemed more out of synch than before I began.

I also tried subtracting the difference as well and this resulted in the end of the video being synched, but the beginning didn't seem any better. I also noticed that Soundforge seems to cut some off when my final time is larger than my initial time and I'm wondering if this might be the problem?

I captured the video using my AIW MMC software and am also wondering if there might be some problem with this software? Ironically, I believe I've done this exact procedure in the past without any problem. I don't understand why I'm having problems with it now. Any ideas?

[Embotelhamento]

Dear Friends,

When you convert files directly from a ripped DVD, what can make them get out of sync? Isn't there a way to solve this problem directly from its origin?

Yours,

angelmir

[Phat J]

The only step I'm unsure about is step 5. What I did was add the difference to the initial time and put that value into the place for the final time. When I did this everything seemed more out of synch than before I began.

I also tried subtracting the difference as well and this resulted in the end of the video being synched, but the beginning didn't seem any better. I also noticed that Soundforge seems to cut some off when my final time is larger than my initial time and I'm wondering if this might be the problem?

I captured the video using my AIW MMC software and am also wondering if there might be some problem with this software? Ironically, I believe I've done this exact procedure in the past without any problem. I don't understand why I'm having problems with it now. Any ideas?

probably the best way for u, since u are capturing ur own AVI, u should open the avi with the audio in VirtualDub, and go to Video>Framerate then choose "Change so video and audio durations match" then choose "Direct Stream Copy" under Video and Audio then go to File>Save AVI
then convert the AVI to MPEG and ur sync should be fine

my guide is mainly for MPEG videos that were downloaded and are off sync, not for ones u capture urself.

[rogun]

Thanks for the help Phat J.

FWIW, I captured the video to MPEG and not AVI. Everything is synched until I try to cut the video and then it loses synch. I don't think the methods you described in this article will work for me because of something to do with how the AIW captures MPEG video.

I've used your technique before with other MPEG video and had no trouble. I was finally able to find a way to get my captured MPEG cut and the audio synched, but it's still lacking some.

Anyway, thanks for the help!!

[asxzone]

If you r ripping from a dvd...the best program to use is FairUse. It perfectly syncs audio and video separately then use Tmpg to combine the video and audio.

[jsaint]

Oddly enough, I am having a sync problem when i use TMPGEnc. I have a file that is too long to go on one VCD, so I tried to cut it with this program. It worked fine, except that as the movie goes, the audio gets more and more off. Not sure how to address this, maybe if I get all of the software here I can do it.

J

[Embotelhamento]

I cannot imagine how a problem like this happens with TMPGEncoder, seeing that it's such a well-recommended program. It's so slow at splitting files and it even causes synch problems...
I was wondering, when I cut AVIs I use Virtualdub with the option "Direct Stream Copy" for both audio and video. After the splitting, all resulting files are perfect, and the splitting takes place in just few minutes (usually less that 2). Isn't there a program that does the same with MPEGs with the same speed and preciseness?

[tigervideo]

i just looked at sound forge on the website. it's too expensive to have it. i have a question about this issue, what's the exact reason caused a/v synch problem. i never got such problem before unless i used avi server with premier v6. if any one has any idea what's the problem with it? if i didn't use server, the movie output from primier can't be recognized by tmpgenc.

any help will be great appreciated.

[Joe018]

I've got a sync problem when "capturing" with virtual dub. It goes out of sync and progresses worse and worse. It doesnt seem to be stretching you will be watching at the begining and it is fine then all of a sudden the audio sutters. i mean repeats itself a couple of miliseconds. and then it's off and then it will happen again and it's off worse. The only capture program i've tried that seems to work is avi_io. so mayb eyou could try that program tiger

i'd like to stick with virtual dub though for my captures. does anyone know what my problem could be?

[Jez]

When i make a Vcd from a ripped dvd as mpg on pc it is fine on my stand
alone dvd drive (tv room) it is out of sinc i have tried all diff methods settings and programs results all the same finaly

done a -470 in audio gap settigs of tmpgenc and it is fine

how ever on a svcd it is +57(again audio gap settings) to sinc

if you forward wind or rewind while watching the movie then it goes out of sinc again

ps They are PAL films

Anyone any thoughts?

Jez......

[Daagar]

You know, this method seems as if it would work perfect if Sound Forge actually did the right thing...

I have a movie that is 1:13:06.838 long. Doing all the measurements, etc., I know I need to do a Time Stretch to 1:13:06.459. So I tell Sound Forge to get cracking, and it dutifully gives me a Time Stretched file that is 1:13:06.119!!! A lot of good that does... now I'm almost off my the same amount I was orignally, just in the opposite direction! How do I convince Sound Forge to actually use the numbers I tell it? Can Sound Forge not handle doing something that exact?

[parkan]

I am having this exact problem with converting an MPEG2 file to DivX. I am using the Gordian Knot bundle as well as the FHG-Radium codec and DivX 5.0.2 pro. The source MPEG has perfect sync, however whn I create a project in DVD2AVI the audio file extracted is about 20 seconds shorter than the original 1-hour movie (it's not a dvd rip, just something I captured with my ATI TV-wonder). I follow the procedure described exactly (i.e. I open the sound file in sound forge and streatch it), then encode the video using virtual dub (actually, GKnot does it for me) into Divx, 2-pass and then mux the two together using Nandub (manually). I have heard of problems with raidum codec and I was advised to set interleave to every 500 ms which I did. DVD2AVI also includes the words "delay 156ms" into the filename of the adio file, which I assumed was the delay I should specifiy in nandub. After 2 minutes, I get a file that gradually goes out of sync but then at the very end becomes perfectly synced again (in the middle is off by as much as a couple of minutes). Using the "adjust framerate to match the audio length" yeilds nothing good both with the original sound file and with the one edited according to this method. I am absolutely clueless as on how to fix this and I am already running out of hard drive space, so I need to convert those (I have several more) MPEG2 files to divx. Please help? (sorry for the long post).

[BluVCD]

I have only run into this problem once - I had a downloaded file that started in sync and then ended up with the audio about 2 seconds behind the video - maybe more. I tried to fix it with the usual methods before I figured out that the source was messed up (silly me). I just gave up and decided to live with it (it's not THAT bad).

Then, I saw this guide. Anyway, I looked for this program (Sound Forge) and it is 400 dollars! Is there a cheaper way to do this? Since it seems to happen quite infrequently, I cannot see spending this much money.

But, your guide is quite good.

Thanks!

[parkan]

Well, I've tried it with another MPEG2 file and once again I get the audio completely off sync. Anyone?

[tturner]

I've had this same problem with cutting / splitting MPEG/MPEG2 files for about a year now and I'm about to give up on it.
I capture directly into MPEG1 or 2 with a Creative Labs Moviemaker USB device
Before anyone says it , I can't capture in AVI and reencode.
No matter which cutting program I use, some of my videos sync the audio perfectly with the video and others don't. I used , VCDCutter, TMpgenc (about 6 different versions up to 2.56), and anything else I could get to cut MPEG and they all have the same problem.
I've muxed, remuxed, demultiplexed, multplexed and nothing helps.
It's obvious to me that since so many users love Tmpgenc for cutting/merging that it must have something to do with my source mpg file. Somehow, the source needs cleaned up before cutting. Anyone have any new ideas to try.
Any help is greatly appreciated.

[calimero]

Hi guys,


I have a audio/video synch. I've record TV with my AIW radeon, and it said I've gor <1% dropped frame. It appears that
the video size after DVD2AVI is 1h 07min 43s while the sound file is 1h 08min 14s. so I've got a synch pb when I transform
the mp2 file to divx or any other format. The ATI player file still synch correctly the captured video file.

compress the wav file is not a solution since the dropped frame is not uniform on the video file. I've already try this solution
and the result is not good. Recapture is not also a solution because it's TV capture, so I won't get a chance to do
it again. I'm looking for a software that will accept MPEG file (MP2) and will copy the frame before the dropped frame
in order to give a video file that match the wav file exactly by inserting freeze frame where there is dropped frame.

Do you have any ideo or information about this