How to Synchronize?

[Jo The Veteran]

I have an mkv with aac dual sound and divx video, i convert the aac into mp3 using NCH Swift Sound WavePad 2.10 and the sound becomes desynched when linked with the video again.
I encoded it into cbr 128 mp3 lame (prety standard format). Anyone knows a program that will synch it again with the divx avi?
Furthermore, anyone knows a way to convert aac into ac3 that would be also synched with the video?
Thanks.

[ShadowrazoR]

hey! i have the exact same problems as you! bunch of anime i can't convert.

sorry though, can't help you.

[mikiem]

If it helps...

Generally 3 ways audio can lose sync: start late or early, length too short or long, & changing video fps. 1st is easy to cure muxing in V/Dub/Mod by setting delay. Some audio editers like Goldwave let you time stretch or shrink, which takes care of length prob. If you change fps, do it with muxed-in audio for 3.

Haven't used Wavepad, don't know what other software you're using, or if there are common issues with your audio conversion, but imagine it would be worth it to try other tools.

[Jo The Veteran]

I used goldwave's Time Warp and the best algorithm i saw there, to avoid pitch changes, and i got a metalized kinda sound as return, what bugged me thought was another thing. I inputed the desired time in time warp (21:25:899 witch matches the avi - the org mp3 was 25omething) and aplied, after its completion i saved it (in mp3 48khz 128 stereo) and it created a file with 23omething lenght!?!?
I any case, i don't think that the way to do it, i mean thanks mikiem but it took me 6 minutes to edit + 6 to save and it takes about 8 to convert from aac and about 3-5 some furthermore processing WOOW, i'm getting dizzy here.
What i need is to access the root of the problem when the encoding is being done so the time difference WONT actually happen, anyone knows any other progs for acc to mp3 encoding? I have a bunch of them but noone actually works except wavepad.
One other thing, what do you mean with this mikiem? "If you change fps, do it with muxed-in audio for 3" How would i know in what fps to change? In what would i change fps? Audio or video? Is this a program (muxed-in audio for 3)?
Some things to help you out, i used Mkvextractgui to extract the tracks from the mkv, then wavepad to convert aac into mp3 and then...desychronization... i stuck. HELP!!!
ShadowrazoR, in past times i used those above and (where i'm stuck now) virtual dub then to mux them and it worked... in another anime. Try it.
Man, I hate those mkvs!

[ShadowrazoR]

yeah. i'm not saying that all won't work. just this particular batch i have sitting around on my computer.

i use mkvextractgui to demux, then dbpoweramp to convert, and mux with virtualdubmod. same results as you. every step of the way. after demux, i find that the AAC audio and the video are of slightly different lengths. it gets worse after conversion to lame MP3.

reading your original question, i think you don't really need the audio to be in any specific format right? just something that virtualdub can handle. right?

same goes for me.

[Jo The Veteran]

I will try something today but it will take time.
I thought that, what if the audio is right and there is something fishy with the video? I'll try to re-encode the video, now i don't recomend this option, it takes allot of time and a considerable amount of quallity will be lost. I'll do it just to see if anything changes nevertheless.
I won't give up until this is over!

[mikiem]

FWIW, don't have Goldwave installed at the moment so I have to rely on memory, but it never did any audible changes when altering length. Cool wave had the feature too, so imagine it's there in Audition, & Sound Forge does it well. However you do it, it is a bit of extra work, & as you've posted, better to not lose sync in the first place.

If the audio is a different length then the video, looking at the length after each step should tell you when it happens, which prog. is causing it. If the problem happens after converting to mp3, might try converting to wav first, or check out doom9.org audio forum paying attention to besweet & dimzon plugins.

[ShadowrazoR]

hey jo, use alltoavi. yeah you'll have to reencode the video but it works. pulls you outta the mkv.

[bambam]

Some audio editers like Goldwave let you time stretch or shrink, which takes care of length prob.

Can you tell me how to do this operation using goldwave
I search in the software but did not found this operation
thanx a lot

[mikiem]

Check the last post here:

https://forum.videohelp.com/viewtopic.php?t=246347&start=0&postdays=0&postorder=asc&hig...time%20stretch

[Delta2]

Try this :

download NanDub or VirtualDubMod

try loading your AVI in NanDub

set video to DirectStream copy

load your MP3 audio and set to DirectStream copy

set Interleaving to :

0 ms (zero) preloading
Iterleave every 1 frame

Save your new AVI

[Jo The Veteran]

Thanks allot you guys,
for the record, i haven't had internet connection for about 1 month now that's why i didn't reply until now, i'll try everything and i'll let each and evyone know of the results.

[Jo The Veteran]

(First of all and try no to hate me, but i just gotta intensively point out what worked and what didn't. This post is striktly reffered to the ones with the same problem as me).

WHAT DIDN'T WORK...
Goldwave doesn't work in this case, or at least in the maner it was shown to me in mikiem's posts.
It is irrelavant in the speciffic problem, so forget all about it.
The suggestion of Delta2 doesn't actually do anything, and that is obvious to anyone who deals with video, however it would in my opinion be the best option (if it worked), no recompression and no loss of time doing so, but it doesn't so also forget about it.

WHAT DID WORK...
The all2avi program suggested by ShadowrazoR is the only thing that seems to be fixing the sync problems while converting an mkv into avi, however as he also toned, it DOES need recompression of the entire file, video and audio alike.
-
Other drawbacks :
Severe loss of quality in video (in audio only if you have surround audio system).
Extremely unstable (still beta after all).
-
Note that this program also aplies into mkvs whose video streams can't be recognized by normal encoders (their format seems unknown for some reason -something to do with the commands inside the mkv-, though it is divx or xvid or relavant codec), well all2avi pulls the video stream out nice.

One other thing, the only program i found to be able to correcty convert aac into mp3 (and other formats) is wavepad wich is actually the expansion of a program called switch, however a conversion from aac into ac3 in this time is not yet possible.
That is all,
Regards everyone.

[Jo The Veteran]

This just came into mind so pay attention.

I used all2avi to encode the mkv into avi includind the 2nd video stream (english), i then checked its total frames and time difference which was this much:
Originall (mkv) - frames 43420, time minutes-24ecs-08:millisecs:782 (24:08:782)
all2avi Converted - frames 54273, time --------------------------------------- (30:10:911)

I figured, if i input my audio stream (the one i converted with wavepad from aac into mp3 from the originall mkv) it won't be sychronized at all for it has the same time difference (24:08:782)vs(30:10:911). I was wrong there, there was NOT time different, audio played just fine. Confussed yet?
However there was something wrong and that was that the audio was abrubtly cut into to that point (24:08:782), the mkv contains more audio, it just does not give it when ripped.

I don't know what to get from all of this, but i see it like an equation. In mathematics all equations HAVE solutions (at least that what they told us in school).
I don't know about you but i'm beginning to see a pattern here.
In any case i'll keep looking into it.

[Jo The Veteran]

HA!!!!! Eyrika!!! I found it, the answer to the equation, and so simple also (well, not so now that is think of). In anycase ENJOY my friends!
1. You run your mkv though all2avi and you recompress it (in the best qty, although i don't really know if it matters for we only need the audio from it and the compression settings suggest video only).
2. You rip the audio from the new recompressed file using vdubmod.
3. You rip the video from the originall mkv using MKVExtractGui.
Using vdubmod,
4a. You merge those 2 (steps 3+2), also when asked from vdubmod about header of vbr format say NO!
4b. You change the frame rate of the avi so that it matches the audio track.
4c. You save the avi (direct stream copy ofcourse).
That's it! No recompression to the video, image qty = crystal clear.

That was the basics:
You can also rip the subtitles an mkv can contain using MKVExtractGui and save them into any format you would like using Subtitle Workshop, you can also synchronize them, IF they go out of sync (haven't seen if they do yet but with this prog it's very easy to synch them)
Yoy may also repeat step 1 and choose another stream if the mkv contains any, and then interpolate it also just like in steps 4abc. Avis support 2 audio stream, though i don't know what happens if you input them more (never tried it/need to).

That's it, hope it helped, especially you ShadowrazoR who seemed to have the same wonderings as me.

Y.G. The programs that i used are up to date till this reply is posted, i don't know how will their future versions respond when implementating my guide again.