Gradual Audio Sync - Man, I thought I knew how to do this LOL

I have an avi file that I'm trying to convert to play on my standalone DVD player. I was using NeroVisionExpress to encode to MPEG2 and create menus etc, but it created a final product which would gradually lose sync throughout the movie until the audio was significantly ahead of the video by the end. The original avi plays fine all the way through using VLC Media Player on my PC.

I'm no expert, but I've tried to do as much digging around on the forum as I possible could before finally admitting defeat and asking your guys for some help. Here is what I have and what I have done so far, using VirtualDubMod, TMPGenc and FfmpegGUI

This is the relevant file info that VDubMod gives me for the avi:

[bold]Video Stream[/bold]
Frame size: 608x336, 23.976 fps
FourCC code: [XVID] XviD MPEG-4
Decopmpressor: XviD MPEG-4 Codec
Data rate 1020kbps (0.45% overhead)

[bold]Audio Stream[/bold]
Sampling Rate: 44100Hz
Channels: 2 (Stereo)
Audio tag: 0x0055, Decodable MPEG-1 Layer 3 (MP3)
Compression: Unknown (tag 0055)
Min/avg/max/total frame size: 313/397/835 (23620K)
Data rate: 122 kbps (5.69% overhead)

This is what I did to try and sort out my sync problem:

When the avi is opened in VirtualDubMod I get a "VBR audio stream detected" telling me to decompress to a WAV file and then recompress with a constant bitrate of 127+ - 13.8kbps. It asks me if I want to re-write the header, to which I say no. I extracted the WAV file, then used FfmpegGUI to recompress the WAV to a 128kbps MP2 file.

The avi looks to me like an NTSC Film avi, so I used TMPGenc to create an NTSC DVD using the 3:2 pulldown Encode Mode on the Video tab. I also unchecked "Inverse Telecine (convert to 24fps: Non-interlace source)" on the Advanced tab. As far as I can tell this should maintain the same fps so as to keep the audio in sync. I encoded to an m2v file (and mp2 which I won't use because I'm using the recompressed MP2 from FfmpegGUI as the audio stream).

To test my encoded file I multiplexed the m2v and the mp2 using TMPGenc tools. When played back in VLC Media Player the audio gradual goes out of sync.

I tried re-encoding the WAV file to various MP2 bitrates as well as AC3 audio of different bitrates. I found I had the least sync error with 192kbit AC3 audio, but it's nevertheless still out of sync and frustratingly not right.

Does anyone have any ideas as to what I should have done/not done to get this encode working in sync? Any advice most gratefully received.

Thanks

Simon

 

Well VBR MP3 audio will allways go out of Sync after encodeing, to Solve this you just decompress the audio in your AVI file before encodeing....

This tool will decompress the audio for you...

http://www.megaupload.com/?d=J7HNW11I


Also if your AVI file is 23.976fps and are encodeing in Tmpgenc all you have to do so it encodes to a NTSC Mpeg-2 file with a Frame Rate of 23.976fps with 3:2 Pulldown is First set the "Encode Mode" setting under the "Video" settings to "3:2 Pulldown When Playback" and then set the "Frame Rate" setting to "23.976fps (Internally 29.976fps)" and then you will get a Proper encode that should be in Perfect sync, and "Inverse Telicline" Should NOT be used on this Type of Video....

You don"t not have to Worry about re-compressing the audio in the AVI file unless after encodeing you want to encode the WAV audio to AC3 or MP2...Pluss Most Freeware AC3 encoders that I have tried have caused me Sync problems so it might be a Good Idea to get a Proper AC3 encoder or even the AC3 encoder Plugin for Tmpgenc is Good But I prefer to use "Sony Vegas Video 6" as it can encode to Dolby 5.1...

Good Luck

 

Cheers Minion, that's much appreciated. I'll take a look at that and let you know how it goes.

One thought though - if I don't re-compress the WAV audio to MP2 or AC3 then surely the audio will take up loads of space on my DVD which could otherwise be used for video? I don't really want to put the uncompressed WAV file on my DVD for this reason. Or do I have the wrong end of the stick here?

Thanks again

Simon

 

Tmpgenc Can encode the audio to MP2 while encodeing the Video so you don"t have to Output to wav in tmpgenc.....

Cheers

 

I have played with this myself and noticed that for a 2 channel wav audio file, both compressions (mp2 and AC3) result in the same file size. However, my standalone dvd player wont play back the ac3 audio. If the audio does not is not multi-channel, what is the advantange of using AC3 as compared to mp2?

 

Maybe also I have to use Nero REcode 'cause I own a dvd (Precinct 13) which is out of sync. Video comes prior to the sound. LOL
I prefer VSO's last free version DivXtoDVD for this purpose. If you want most sophisticate solutions start consider bying DVDLab pro.

 

The advantages of AC3 over MP2 is That For NTSC DVD"s the Mp2 Audio Format isn"t 100% DVD Compliant because the NTSC DVD Standard Only Supports MP2 audio when there is a Dolby AC3 stream Present also and the Quality Quality of AC3 is better.....

I can not see why your DVD player doesn"t play DVD"s with Stereo AC3 as it is the Most Compatible Format...Have you checked that your AC3 audio files actually contain audio??

Well anyways you can use MP2 also and it should work even though it isn"t Fully DVD Compliant.....

Cheers

 

well, i converted my auido wav file to both mp2 and ac3. checked the mp2 with winamp and it worked. checked the ac3 with wmp and it played but as if at high speed. when i muxed the mv2 video with ac3 audio and created .vob, .ifo files and burned to dvd+rw it worked fine in my pc. but the standalone dvd player did not work. Ofcourse i do have a pretty crappy standalone player so it may be lacking in terms of audio compatibility.

 

I used the decompressor programme to decompress the audio in the avi file, then dumped the new avi into TMPGenc and it worked!! Brilliant.

Thanks again Minion, much appreciated!

Simon