sound synch - aaaaarrrrrrrggggghhhhhhh!!!!!!!!!!!!!!!!!!!

[buachille]

god almighty did i do something wrong in an earlier life??????? what is going on?

i've done tons of reading on this forum and others. I have the right tools (agk, virtual dub, adobe premiere). I've sat down with instructions i've printed up from this forum. i've tried lots of different things.

I CANNOT REDUCE THE SIZE OF MY UNCOMPRESSED FAMILY AVI VIDEOS WITHOUT THE SOUND BEING MASSIVELY OUT OF SYNCH.

this is driving me mental.

a quick run down of what i've tried (although i won't supply all the detail or i'll be here all night).

these family vids i have vary between 800 meg to 4 gig. none of them are longer than fifteen minutes. they were all produced in adobe premiere and rendered as uncompressed dv avi because i found every time i used compression the results were terrible.

now i've done a lot of reading about xvid and divx and i'm trying to use this knowledge to reduce the size of these masssive video files.

i've used agk and told it to reduce say one of the 3.5 gig files to 100 meg. the pic is beautiful and the sound is great but the synch is terrible. i've tried using audio interleaving in virtual dub but for some reason it is not working. whether i set it to -2000 ms, -10,000 ms, or 2000 ms or 10,000 ms it doesn't seem to be moving the audio. ive tried this in full processing mode and direct stream copy but no joy. i've used audio interleaving on other video files and it worked, but it won't work on my own home videos.

when this failed i imported the file into adobe premiere and have tried manually dragging the sound or video up and down the timeline (this works for me with lots of other out of synch video files) but no matter what i do i can't get the sound and video in synch.

i also tried the divx converter tonight (although i'd rather use xvid) and it did a great job of reducing the file size without ruining quality, but once again the synch was way off.

i am defeated. over the last year or so i've tried this again and again and always the synch defeats me. i am learning all the time, but ive still not learned enough.

please tell me

a - am i just stupid

b - does everybody have this much difficulty

c - should i just buy a bigger hard drive since i cannot reduce my video

[redwudz]

Assuming these are all DV files. What format is the audio? PCM? How are you encoding the audio for the Xvid?

Have you checked for missing frames with VirtualDub on one of the problematic videos? I'm thinking bad joining in the video may be causing all this.

Also, what kind of sync problem is it? Gradually changing sync during the playback or is the sync error the same throughout the playback? Check the length of the video and audio to see if they are the same.

If there is nothing wrong with the DV file, you should not be having sync problems with the Xvid conversion. So it's either a problem with the DV file or a problem with your encoding. AutoGK and others shouldn't mess up the sync.

If you do have PCM audio, try converting it to MP3 in VirtualDub. I would use the LAME MP3 codec. Then mux it back in and see if it's in sync. Make a copy and 'save as', don't mess up your original file. Don't encode the video with this test, just use 'Direct stream copy' for it and full processing for the audio.

I use VD Mod most of the time, as I prefer the way it handles the audio compared to VD. It also accepts more formats. I assume you have a DV codec installed already that VDM can use?

[buachille]

Assuming these are all DV files. What format is the audio? PCM? How are you encoding the audio for the Xvid?

i'm not sure what format the audio is being encoded in. agk and divx take care of this for me. i know that in agk i was using auto for the audio.

Have you checked for missing frames with VirtualDub on one of the problematic videos? I'm thinking bad joining in the video may be causing all this.

i just did this on my most problematic file by clicking video - scan video stream for errors and it reported 0 errors

Also, what kind of sync problem is it? Gradually changing sync during the playback or is the sync error the same throughout the playback? Check the length of the video and audio to see if they are the same.

i don't know how to check this in virtual dub. however, when i bring the file into premiere they are exactly the same length (15 minutes, 13 seconds.06)

If there is nothing wrong with the DV file, you should not be having sync problems with the Xvid conversion. So it's either a problem with the DV file or a problem with your encoding. AutoGK and others shouldn't mess up the sync.

i don't know how to diagnose a problem with the dv file. here is the info on this file from avicodec



If you do have PCM audio, try converting it to MP3 in VirtualDub. I would use the LAME MP3 codec. Then mux it back in and see if it's in sync. Make a copy and 'save as', don't mess up your original file. Don't encode the video with this test, just use 'Direct stream copy' for it and full processing for the audio.

i am just about to google pcm audio and find out what it is

I use VD Mod most of the time, as I prefer the way it handles the audio compared to VD. It also accepts more formats. I assume you have a DV codec installed already that VDM can use?

i have virtual dub mod but i don't know if i have a dv codec that virtual dub mod can use. vdm can play these dv avi videos so i assume i have the right codec.

and finally, thanks for trying to help.

<<edit>>

i just noticed when i was viewing my post that in the audio bit of the avicodec window it does say pcm. so i am about to try converting it to mp3 with lame (which i've just downloaded).

[yoda313]

i am just about to google pcm audio and find out what it is

Pcm audio is uncompressed wav audio. Really large audio file but usually sounds very crisp and clear.

[redwudz]

PCM:Pulse Code Modulation. Standard for DV, so likely no problem there. It must be Type 2 DV or VD wouldn't accept it.

You do have a DV codec or VD wouldn't open the file.

Try encoding just the audio to MP3 as I described above:

If you do have PCM audio, try converting it to MP3 in VirtualDub. I would use the LAME MP3 codec. Then mux it back in and see if it's in sync. Make a copy and 'save as', don't mess up your original file. Don't encode the video with this test, just use 'Direct stream copy' for it and full processing for the audio.

If your sync is messed up then and the sync was OK in the original DV version with PCM, I'm not sure where the problem is.

[buachille]

ok. i have installed lame and i am currently using virtual dub to change the audio to lame mp3.

i have video set to direct stream copy and audio on full processing mode.

once its done i am going to open the new file in agk and attempt the xvid conversion again.

i will post back with the results.

if the procedure i've outlined above is wrong at alll, please let me know.

thankyou for your help. i appreciate it.

[buachille]

just a quick update. the encode to lame mp3 is finished and the sound is in perfect synch (as it was in the original dv avi).

now for agk............

[buachille]

right the job is done.

changed the audio to lame mp3 in virtual dub and then i used agk to shrink the file, and the synch is a disaster again.

the settings i used in agk can be seen here

maybe its time for me to back my bags and go home

unless anyone has any ideas.

cheers

[redwudz]

One last try. Encode the video with VirtualDub to Xvid, along with your MP3 audio. Maybe there's something in AutoGK or a setting that is causing the problem. I don't really use the program, but it's popular and seems to work well.

VirtualDub would use the same Xvid codec, so that's one way to test if the codec is the problem.

Sync problems normally aren't complicated. Finding their cause and cure can be, though, at times.

It looks like you may have narrowed it down to the Xvid encoding in AutoGK. The audio 'shouldn't' have been modified by AutoGK.

One thought. You haven't changed the format from PAL to NTSC anywhere in AutoGK have you? That could mess up the sync. Everthing should be in PAL settings, 25fps.

[buachille]

that is a very good point about ntsc.

but how do you change the format from pal to ntsc in agk. i can't find that option and thefore i dunno if i changed the format.

<<edit>> one thing i just thought of though. remember i got exactly the same synch problem when i used the divx converter............

One last try. smile.gif Encode the video with VirtualDub to Xvid, along with your MP3 audio. Maybe there's something in AutoGK or a setting that is causing the problem. I don't really use the program, but it's popular and seems to work well.

although i've tried this before (using detailed instructions) i will try it again. cos last time i did not have the audio as lame mp3.

i totally appreciate your advice. thanks

[drewzor]

IN agk, load file then ctl+F9

[buachille]

right ok. thanks for the advice about the hidden options.

i think i've maybe found the thing that needed sorted. frame rate was not set properly. encoding now, but i'm not sure what the result will be.

i'll post back.

[PTsniper]

Hope it works now.

[buachille]

hello.

got up this morning and got right back into this struggle.

and guess what. it is still not working. i used the hidden settings in auto gk to change the frame rate to 25 (for pal) and i'd already changed the audio to lame mp3 in virtual dub. i was hopeful but the sound is still miles off.

there must be something wrong with the original file i think. i found the file info setting in virtual dub. could someone please take a look and see if there is something there that is causing the problem.

this is the original uncompressed file info.



i thought i'd also post the file info from the file after i'd processed it in agk. here it is.



many thanks

<<edit>>

another thing. i've tried bringing the processed file into virtual dub and using audio interleaving to move the audio and try to get it in synch, but it is making absolutely no difference.

how can that be??

[drewzor]

Theory..
Sometimes somesoftware where 0bits are found delete that portion of the file (for example nero and vbr mp3, it collapses the file and sounds like its skipping ahead)

Maybe AutoGk is cutting away at your audio file hence *layout and *Length a different after conversion?

In virtualDubMod you can stretch audio length to fit video duration..

Just a thought.

[buachille]

right i'm trying to do that in virtual dub mod but it doesn't have the sound codec to open the file. the file opens fine in virtual dub but not in vd mod.

[buachille]

i don't know why i didn't try this earlier. there was, as people have said earlier in this thread, something wrong with the source file.

i opened the source file in virtual dub and created an uncompressed copy with audio and video set to full processing mode. i did this because i thought it would give me a flawless avi.

then i opened the new file (all 16 gig of it) in agk and ran it with the same settings i'd been using before.

this time i got a flawless copy. sound in synch.

so it seems now i can begin shrinking my home vids..............at last.

thanks for your help with this.

one other thing i'd like to ask is this.

how small do you think i can shrink a 3 gig file and still get good quality in agk. 100 meg? 50 meg? or would i be better doing the shrinking in virtual dub where i can access all the xvid settings.

cheers

[buachille]

still processing my vids.

running every single one through full processing mode (for audio and video) in virtual dub before i process them with agk........

and getting flawless results with every video.

waaaahhhhaayyyyy.

i hope someone else who finds themself in the same postition as me finds this thread and gets some help from it.

god knows its taken me a long time to get to this stage!!!!!!!!!!!!!

[redwudz]

Actually if you are running them through VirtualDub, why not just encode them to Xvid while you are at it? Unless there is something you specifically need from AutoGK? Both programs are using the same Xvid codec.

The best way to judge compression and how much you can get away with is to do some sample encodes with different settings. Run a 2 pass VBR video encode with VirtualDub with the Xvid codec at about 700 and see how it looks.

Or if you don't have to hit a specific output size, use the Quantizer mode in Xvid and set it to 2 to start with. That should give you about the same quality as the original, but much smaller. Lower the quality to 3 and see how that looks. A 10 minute representative clip should be plenty to work with.

At least you got the problem figured out. Sometimes the simplest explanation is the right one.

[buachille]

well i would love to do them in virtual dub, but i tried before using the instructions i found here but i got terrible quality and since then i've used agk.

i thiink i'll give it another try using the tips you've posted.

i expect i'll be posting back with more questions though.

[buachille]

the job is done.

my videos folder used to be 15.1 gig.

it is now 1.3 gig.

that is a result.

thanks for the help