AC3 conversion problem

[phinsman]

On advice from a forum user I am trying to convert the audio for my DVD to AC3. I used BeSweet's GUI which produced the following command line:

"g:\Graphics and Sound\BeSweet\BeSweet\BeSweet.exe" -core( -input "m:\Video Temp\greg_phil.wav" -output "m:\Video Temp\greg_phil.ac3" ) -ac3enc( -b 128 )

Sorry that path is so long.

Anyway, the conversion works fine, and I also converted to the 192 and 256 bitrates.

The problem is, the resulting AC3 file doesn't play correctly. I do have AC3Filter installed. When I play the clip, the audio sounds very slow, like it's about 1/4 speed or so.

The source audio is fine, and it is 48 KHz, so I don't need to use SSRC as the guide on this site said to.

I played the file back on Zoom Player and PowerDVD (after authoring a test DVD).

Thanks,
Dale

[phinsman]

OK, I kept trying some things and also discovered that BeSweet keeps a log. Check this out, and note the requested bitrate in the command line, and actual average bitrate in the output file.

BeSweet v1.5b19 by DSPguru.
--------------------------
Using AC3enc.dll v0.2 by Gerard Lantau & Dg (http://ffmpeg.org).

Logging start : 07/21/03 , 12:09:02.

g:\Graphics and Sound\BeSweet\BeSweet\BeSweet.exe -core( -input m:\Video Temp\greg_phil.wav -output m:\Video Temp\greg_phil.ac3 -logfilea G:\Graphics and Sound\BeSweet\BeSweet.log ) -ac3enc( -b 256 )

[00:00:00:000] +------- BeSweet -----
[00:00:00:000] | Input : m:\Video Temp\greg_phil.wav
[00:00:00:000] | Output: m:\Video Temp\greg_phil.ac3
[00:00:00:000] | Floating-Point Process: No
[00:00:00:000] | Source Sample-Rate: 48.0KHz
[00:00:00:000] +------- AC3ENC ------
[00:00:00:000] | Bitrate method : CBR
[00:00:00:000] | AC3 bitrate : 256
[00:00:00:000] | Channels Mode : 5.1
[00:00:00:000] | Error Protection: Yes
[00:00:00:000] +---------------------
[00:00:36:736] Conversion Completed !
[00:00:36:736] Actual Avg. Bitrate : 512kbps
[00:00:02:000] <-- Transcoding Duration

Logging ends : 07/21/03 , 12:09:04.

That's why it sounds slow...the player thinks the audio is 256, but it's actually 512. Also, I noticed the length of the source wav file is 36 seconds, and the converted AC3 file is about 72.

Now...what the heck is that about? Why is it encoding at twice the bitrate?

Dale

[funkguy4]

Maybe the actual bitrate is 512kbps, but your header says to playback at 256kbps. See if there's a program that will fix the header.

[phinsman]

I actually tried using a hex editor to change it, but it's not very obvious where in the file the bitrate is specified.

Thanks for the help...

Dale

[ching0]

download CDex from sourceforge.net
under the convert dropdown at the top, go to Strip RIFF-WAV header. see if that will work?

[MOVIEGEEK]

These guides might help:https://www.videohelp.com/guides.php?howtoselect=4;15

[funkguy4]

Phinsman, can I have your comp.....mine's not that much worse, but I want your CPU and RAM count.....:P

[racer-x]

Try using 2.0 chanels and 224 kbps. With these setting, my ac3's come out perfect every time.

[funkguy4]

What's this? 256kbps for 5.1 channel audio? Isn't that kinda low? Bump it up to 384 and see if that helps.

[phinsman]

As a follow-up to this topic, I ended up okay with the AC3 audio. I found the "AC3Machine" and used it instead of the BeSweet GUI. I haven't gone back to look at the command line differences yet but everything worked out. I used the -101 ms delay and the sync problem I was having with DVD-Lab improved.

Dale