.AC3 Rendering Bugs???

bwarshaw wrote on 3/14/2003, 3:38 PM
Hi,

I've now duplicated the following behavior on 3 machines, so it's time to post it to the forum:

I'm trying to Render .ac3 files using VV4. I select "Sonic Foundry AC-3 (*.ac3)" as the "Save as type:" under "Render As". I use "Stereo DVD" as the Template. I then click on save and have noticed the following:

1. The selected template type/description doesn't always seem to match the .ac3 file produced. Many times I get a 5.1 448Kbps file when I've selected the "Stereo DVD" template.

2. Following up on #1 above, if I selected "Stereo DVD" as the template under "Render As" and then click on "Custom", the "Custom Template" dialog will show parameters consistent with a 5.1 Surround encoding (3/2, 448kbps), even though the template name and description are "Stereo DVD" and "192Kbps, 48,000Hz, Stereo".

3. If I reselect "Stereo DVD" from the "Template" drop down in the "Custom Template" dialog, the parameters reset to 2/0, 48KHz, 192Kbps (which is correct). The file the renders to .ac3 OK.

4. If I reselect "Stereo DVD" as in #3 above, but then change the "Data Rate" to some other value, such as "224 kbps", and then render the .ac3 the file is garbage. By that I mean when I try to play it using PowerDVD all I get is a shrill high speed clicking noise.

5. From experimentation I found that I can change to different data rates in stereo mode (2/0) only by performing the following dance:
a. Bring up the custom template dialog
b. Select the 5.1 Surround DVD template (even though this isn't what I want)
c. Click "OK". A warning dialog is displayed (...not valid with current project settings....).
d. Click "OK" to dismiss the warning dialog.
e. Bring up the custom template dialog again.
f. This time select the "Stereo DVD" template
g. Change the "Data rate:" setting to the desired rate (e.g. 224kbps)
h. Click "OK" to dismiss "Custom Template" dialog.
i. Click "Save" to render the .ac3 file.

Clearly there seems to be some strange bug in the template handling logic for AC-3 rendering. Is this being addressed in a soon to be released patch?

/BILLW

Comments

CDM wrote on 3/14/2003, 4:08 PM
these WILL be fixedin the 4.0b update.

for the moment, here's a supposed workaround:

Bring up the Render As dialog, select AC-3
Select the Stereo template
Hit "Custom"
Append "workaround" to the name, hit save.

From then on, use the "workaround" template.
bwarshaw wrote on 3/14/2003, 6:39 PM
Ok, I tried making a few of my own templates at different data rates. They're all based on the "Stereo DVD" template - I just changed the data rate for each version.

I then tried rendering a region by selecting my new template directly in the "Render As" dialog. No joy - I still get the garbage .ac3 file out unless I do the "dance" described previously.

Hopefully the engineers are aware of the full scope of the template problem and are working on a comprehensive fix in 4b. Until then I have a workaround (the AC-3 "dance") that although cumbersome will suffice.

/BILLW