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Old 17th January 2021, 16:35   #28  |  Link
hello_hello
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Join Date: Mar 2011
Posts: 4,823
StainlessS,

I converted both stereo and 5.1ch audio as a test, and ran them though AudioSpeed using the settings I suggested earlier, opening the script with foobar2000 and converting to AC3, because fb2k displays the speed relative to real time in the progress window and AC3 is a pretty fast codec. If the output was wave I think my hard drive speed could be a bottleneck. I'm using a 10yo PC.

AudioSpeed(24.0, 27000.0/1001.0, PitchCorrect=true)

2ch audio to AC3 without AudioSpeed in the script ran at roughly 180x real time. With AudioSpeed it was roughly 150x, although it took a few seconds to ramp up to that speed. 5.1ch audio is a whole other kettle of worms. 165x without AudioSpeed, and roughly 28x with it, although still a fair bit faster than real time.

I just realised the 2ch audio I used was 44.1k rather than 48k... sigh... although I doubt that'd change the relative speeds much.

For SSRC, AudioSpeed first attempts to resample using a Try/Catch thingy, suppressing any "SSRC can't do that" error messages and if necessary, moving on to Avisynth's filters instead. I do recall reading that SSRC isn't much better these days, but SSRC also has a fast and slow speed argument, and whether slow produces much better quality than the default of fast, I have no idea, but that lack of idea led me to include SSRC in the function, just in case.

Info=true shows when SSRC isn't used... if PitchCorrect=true or if SSRC fails. Playing around a little now, I had a hard time finding a "reasonable" numerator and denominator that'll cause it to fail. Here's an unreasonable one:

AudioSpeed(122.3674, 24.888)
The Resampling line for Info=true should change to "ResampleAudio", rather than "SSRC", assuming PitchCorrection hasn't been enabled.

Last edited by hello_hello; 17th January 2021 at 16:43.
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