How to "Safely" Convert Audio Framerate?

[kalorx]

Hi all. I've got me a WAV file here, created via BeSweet from an AC3. The problem is, the WAV file was downed to a destination framerate of 23.976. My video isn't 23.976, but rather pure NTSC: 29.97.

I'd drop the video framerate to 23.976 if I could so I could sync the damn thing, but thanks to DeComb's Telecide() and Decimate(), the video, no matter how much I fiddle with settings, is very jerky at anything less than 29.97 (and yes, I'm positive that I have the right field order). Hell, it's still not purely smooth at 29.97, either, but it's far better than at 23.976. I suppose it's better than having an interlaced video.

So anyway, here I have a soundtrack that's looking for a 23.976 video and all I have for it is a 29.97 video. When I tried to use BeSweet's preset to convert the WAV to 29.97, all it did was make everyone sound like chipmunks.

Making matters worse is the fact that I cut 11-point-something seconds off the front of the video, which means that I can't just reconvert the original AC3 (although knowing how to avoid the drop to 23.976 would be useful).

Any help would be greatly appreciated.

Thanks,

Robert Aronson

[kalorx]

You've all got to be kidding -- no one knows anything about this? Not even to offer a minor suggestion? Did I ask a stupid question or something? If so, please, by all means, tell me.

[tebasuna51]

If BeSweet with -soundtouch( -r 23976 29970 ) don't work for you ("like chipmunks"), you can try with Audition or SoundForge.

With Audition you can use:
Menu Effects -> Time/Pitch -> Stretch
Ratio: 100 * 29.97/23.976 = 125
High precision
Mode Time Stretch (preserves pitch)

[kalorx]

I'm afraid I don't have the money for Audition, and the trial probably has limited functionality.

BeSweet has no "Mode Time Stretch" option to preserve the pitch?

Also, perhaps most importantly, I know of no "-soundtouch" option for BeSweet; I use the GUI. When I use a preset, it says:

"-ota( -r 23976 29970 )"

Could this simply be an issue related to outdated software?

Anyway, pitch really is the issue. When I use "-ota( -r 23976 29970 )," everyone sounds like they just sucked on helium. :)

Lastly, how would I convert the AC3 to WAV without a concurrent 29.97->23.976 conversion? I don't see a switch in BeSweet's GUI to shut off that "feature."

[foxyshadis]

Why do you need to modify the audio? Are you speeding up or slowing down the video? (ie, an Film->PAL speedup.) Audio "framerate" is only there for the benefit of the container, it doesn't affect playback speed or length, but resampling definitely will and won't be what you want. (Unless the problem is that they all sound deep and underwater now?)

If you cut 11s off the beginning, you can set the audio delay to -11000ms. (Although tools exist to chop the ac3 directly, since some containers don't like negative delays.)


the video is very jerky at anything less than 29.97

Sounds like pure interlaced, not telecined, so you should use a deinterlacer like TDeint instead.

[tebasuna51]

Also, perhaps most importantly, I know of no "-soundtouch" option for BeSweet; I use the GUI. When I use a preset, it says:

"-ota( -r 23976 29970 )"

Could this simply be an issue related to outdated software?

BeSweetGUI is outdated, try BeLight v0.2.2b9 or last BeSweet v1.5b31 with command line like this:
BeSweet.exe -core( -input D:\in.wav -output D:\out.wav -2ch ) -soundtouch( -r 23976 29970 )

[kalorx]

Sounds like pure interlaced, not telecined, so you should use a deinterlacer like TDeint instead.

Interesting. I've heard that DeComb is the best plugin for deinterlacing things. Perhaps I heard wrong. Is there a reliable method of determining which plugin is better for a film?

I did run into an interesting circumstance that warrants explaination, and your reply may have just done so: I was using Decomb's pattern guidance in a manner in which it suggested for the video, but all it did was screw up certain frames with "interlacy" artifacts. Paradoxically, I found that only by completely killing pattern guidelance did I get a smooth, clean video. The plugin still keeps telling me to use pattern guidance, though. Perhaps this is an issue related to needing to be deinterlaced rather than telecined or somesuch?

I've moved the question regarding DeComb and TDeint question to a more appropriate forum:

http://forum.doom9.org/showthread.php?p=809175#post809175