[openal] Questions about OpenAL Soft's Resampler
metalcaedes at gmail.com
Tue Nov 7 14:41:50 EST 2017
Have you looked at libsamplerate:
Apparently you can change the samplerate (or ratio between source and
dest rate) during conversion.
Also, since 2016 it's released under BSD license.
On 07.11.2017 20:10, Ethan Lee wrote:
> Hey there!
> I'm currently working on a reimplementation of Microsoft's XACT runtime,
> called FACT...
> ... and one of the things we have to deal with is resampling Wave data,
> similar to how OpenAL has to resample buffers to match the output
> frequency. Since we're using SDL for audio output I gave SDL's own
> resampler a try, and it actually works for basic output...
> ... but I also have to factor in pitch changes, which SDL_AudioStream
> doesn't account for (it only expects one input frequency for the
> duration of its existence).
> Normally I'd just use OpenAL for this sort of thing, but part of FACT's
> job is mimicking XAudio2 accurately, which unfortunately makes the two
> incompatible in really subtle ways (and fixing them would mean ripping
> up the library for what is essentially one exact use case and nothing
> else). I'd still like to use OpenAL's ideas though, but to keep the
> permissive license intact I'd have to, at most, look at papers/documents
> that explain how it's done, rather than just using the code directly.
> TL;DR: How does OpenAL's resampler work with adjustable pitch changes,
> and are there any resources online that were used as references for the
> resampler? I'm not too concerned about the resampling function itself
> (we'll probably just use a linear resampler), but I'm a lot more
> concerned about stuff like weird step sizes, fractions of samples,
> padding buffer sizes (for both resampling and possibly for output...?),
> handling wildly fluctuating pitches, little details like that.
> openal mailing list
> openal at openal.org
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