Detailed questions about audio sync issues. I already read the sticky

[organic io]

Hi. I need some help with some audio sync issues. It's driving me crazy... I looked through the sticky thread regarding this topic and couldn't really find an answer to my questions.

I have a movie that I edited using Windows Movie Maker, to take out all the curse words and objectionable parts, so my kids can watch it.

The movie plays fine in VLC on my computer, and the audio stays in sync with the video through the entire movie.

However, when I try to export it to watch it on my TV, the audio is out of sync. My TV has a DVD player, and also supports divx/xvid. So I have tried exporting to xvid, and also a plain DVD. With both methods, the audio is out of sync with the video (Video ahead of audio by about 1 second)

I have several questions:

1) How does VLC "know" to stay in sync, when my TV can't?

2) Whose fault is it, the video file, or my TV?

3) Is there a way to automatically sync the files to play on my TV properly? i.e. using whatever data VLC is using to keep them together, is there a program that can automatically "stitch them together" at the right points for the output file?

4) Are there not some kind of markers that say "yes, frame 153782 of the video corresponds to 01:15:51 in the audio)? If not, why hasn't someone invented this yet? Wouldn't it solve audio sync issues once and for all?

5) If #3 does not exist, how am I supposed to manually fix the audio sync error, when it doesn't show up when playing back on the PC? Other than trial and error (and wasting time and blank DVDs in the process)


Thank you for your help. I have already spent many many hours trying to edit this film (Edited the entire movie several times for nothing, because I had problems with the softwares..) and I'm really wanting to get a streamlined process going from: Editing a film, exporting it, being able to watch it on the TV with the kids.. Because I have a list of classics from my childhood that I would love to be able to watch with the kids. But it's been discouraging having so many hiccups with the first film or two.

Thanks for any help!

[hello_hello]

I don't know anything about Windows Movie Maker but if you specify the format of the source videos and the type of output file (I assume it's AVI?) someone might be able to offer some specific help, and maybe offer a better method of editing/converting that doesn't involve Windows Movie Maker.

If the output is AVI, try remuxing the output files with VirtualDub. Open the AVI and from the Video menu select "direct stream copy" as the video compression method, then use the "File/Save as AVI" menu to save it as a new AVI. It won't take long (no re-encoding). Test the new version.

If it's constantly out by a set amount you can adjust the audio sync under the Audio/Interleaving menu. You can set a positive or negative delay. Generally though, the video/audio sync should remain the same regardless of the playback device.

[organic io]

Hey, thanks for the response. The reason I am using Windows Movie Maker is because I tried 3 other times to edit this movie, and failed each time, whether it was something crashing, or the program locking up during exporting. So in finding Windows Movie Maker, I was actually thrilled to find something that worked.

The file conversions go like this:

1) Original: avi (not sure what codec)
2) After editing with Movie Maker: wmv (sucks I know, but the only output options are wmv or h.264 and for some reason my h.264 files are truncated to 1gb)
3) Either of the below (I have tried both)
a) Converted back to avi/xvid with "format factory"
b) Converted to DVD-Video format

Both a and b result in sync problems on my TV.

I am currently running another export experiment where I changed the audio samplerate to 44100 instead of 48k, and I am going to encode to DVD/burn the DVD with Windows DVD Maker (which pops up anyway after you finish exporting the wmv from Windows Movie Maker), but I doubt that will fix it. I'm just letting it run while I'm here at work anyway.

So I guess after that fails, then I will definitely try encoding the wmv to xvid, run Virtualdub/remux and go from there.

Thanks for your help!
I'll keep the thread updated with my failures/progress.

Any more suggestions or ideas are also welcome

[redwudz]

Drop the original video into MediaInfo and tell us what video and audio codec it's using. It's a waste of all our time just to guess.

Some highly compressed codecs can't just be randomly edited. They can only be cut on keyframes or you can have sync problems.

If you change the sample rate of the audio, it won't work as a DVD any more.

[El Heggunte]

My educated guess: it's the WMA stream that is being problematic to Format Factory.

Edited WMA streams are (in)famous for causing synch issues, because not all software knows how to deal with the "gaps" and 'overlaps" allowed by the ASF container:

http://forum.doom9.org/showthread.php?p=1513679#post1513679

Supposing that Movie Maker accepts outputting uncompressed audio together with the WMV stream, then you should try this option.
Otherwise, you should decompress and recompress separately the edited audio --- I recommend wma2wav from Lord Mulder.

http://sourceforge.net/projects/muldersoft/files/wma2wav%20Decoder/

[organic io]

Drop the original video into MediaInfo and tell us what video and audio codec it's using. It's a waste of all our time just to guess.

Some highly compressed codecs can't just be randomly edited. They can only be cut on keyframes or you can have sync problems.

If you change the sample rate of the audio, it won't work as a DVD any more.

OK.I ran MediaInfo and it says:
Format: MPEG-4
Codecs Video: AVC
Codecs Audio: AAC LC-SBR

Also of note the filename says x.264

Is this one of the tricky codecs?

[organic io]

Supposing that Movie Maker accepts outputting uncompressed audio together with the WMV stream, then you should try this option.

I looked through it and the only option is for compressed audio, appears to be mp3.

In that case, I guess I'm screwed with the wmv then?

So now I will see what redwudz says about the codecs, in the meantime I will try to see if I can get a proper h.264 export out of Windows Movie Maker.

[hello_hello]

The file conversions go like this:

1) Original: avi (not sure what codec)

There's several programs which will let you split and join files without re-encoding. There's generally a limitation of only being able to cut on keyframes, so you can't always cut exactly where you want to, but for Xvid/AVI they're generally not too far apart.

If you open the original AVI with VirtualDub as I described previously, you can select start and end points and save a section of it as a new AVI, or you can delete sections and save what's left as a new AVI, or you can append saved sections and re-save them as a single AVI etc. As long as you use "direct stream copy" for the video compression method, there's no re-encoding so it's fairly quick.
There's buttons on the navigation bar with a picture of a key on them. They let you navigate backward and forward between keyframes and there's two buttons for setting the start and end points.
Unfortunately VirtualDub doesn't always display the correct frame when navigating (if you navigate backwards then return to the same spot you might see a different frame in the preview). It depends on the video, but as long as you work out in advance where you want to edit you can ignore the preview if need be.

AVIDemux, has a "copy video" mode for video and audio, which means you can use it to edit like VirtualDub without re-encoding. The buttons with the double arrows on the navigation bar jump between keyframes and it'll let you delete or save sections of video the same as VirtualDub, and with any luck it's preview will be accurate.

Video To Video Converter has a splitter and commercial remover under it's Tools menu for editing video without re-encoding and it's preview tends to be a bit more accurate.

[organic io]

Hey guys!

I found a solution! It was just a matter of running some different programs. I did a little searching, and found this: idealshare videogo which says their software can automatically fix the audio sync on stuff. It has something to do with a setting called "async", which apparently "stitches together" the audio and video, just like I was referring to in my original post. I was a little skeptical, but I figured I would give the demo a try. Indeed it worked! So I broke down and bought the full version, figure it is worth it since I would rather just *get it done* than keep wasting more hours trying to do it with free tools.

I actually have 2 movies I was working on.. For the one which I was asking about originally, I was able to use idealshare Videogo to convert it to xvid/avi just fine and get it to play on the TV with synced audio perfectly.

I had another movie which I did the editing on a year ago, and goes out of sync about halfway through the movie. I tried to convert it to xvid/avi with the exact same settings, and for some reason when I played it on the TV, there was no audio. Crazy.

So I tried exporting it to vob instead. Of course this thing makes like a 3gb vob file instead of dvd compliant 1gb, so I tried to use vobedit and ifoedit to split it and remux it (as I had done in testing with the first movie), but for some reason ifoedit didn't like the file that was created. So I had to go with plan B, which was:

DVD Styler

I used this free tool to import the 3gb vob and author it to a DVD-video standard disc. Played it on the TV to test... Brilliant, the second half is in sync now.

So. Wow. It's been an experience the last week or two, to say the least.. Messing with all these programs and settings. But, with determination I was able to get it to work.

Thank you for all your help and suggestions guys. Hopefully this thread will be useful to someone in the future, and if not I can at least refer to it myself later, when I forget which programs I used... Lol

[Chris K]

I found a solution! It was just a matter of running some different programs. I did a little searching, and found this: idealshare videogo which says their software can automatically fix the audio sync on stuff. It has something to do with a setting called "async", which apparently "stitches together" the audio and video, just like I was referring to in my original post. I was a little skeptical, but I figured I would give the demo a try. Indeed it worked! So I broke down and bought the full version, figure it is worth it since I would rather just *get it done* than keep wasting more hours trying to do it with free tools.

async sounds much like a FFmpeg option. The description on what it does too. I guess many FREE FFmpeg guis could have done this.