> but it seems that there is some use for rates as high as 384 kHz
Nyquist would suggest otherwise but why let pesky math get in the way of the golden ears. This is just more MHz war, DECT 6.0 style BS. I'm holding out for the dulcet tones of 1Mhz PCM audio myself.
In line with what others have mentioned, there are more uses for "sound" cards than just human ears. Maybe a musician wants to record some ultrasonic insect noise and slow it down to get a unique effect, or a scientist is working with non-human animals with ultrasonic hearing, or a digital restorer is using upper harmonics of noise on a recording to detect the original recording speed (https://en.m.wikipedia.org/wiki/The_Live_Wire:_Woody_Guthrie...).
Another note, since it's too late to edit: this part shows that the PulseAudio people may not know all that much about audio:
> The high rate is just an ALSA quirk originating from the choice of pretending that the compressed data is PCM audio with only two channels, while the compressed data actually carries more channels.
This is almost certainly not a quirk of ALSA, but more likely a reflection of how certain audio formats are (or were) transmitted over an AES or SPDIF digital link.
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And why does PA need to have a 384k hard limit anyway? Just report the driver's supported rates, maybe with a blacklist for drivers like the old BT878(?) that support silly high sample rates (presumably for non-audio purposes).
It wouldn't surprise me if the hardware BOM cost of supporting these high sample rates for playback is basically zero. Any decent audio DAC will oversample internally, so if you don't actually care about fidelity at inaudibly high frequencies, you can just oversample to the same frequency but shove more bits in. Of course, if you do this, you ought to do your oversampling carefully to avoid sounding worse due to leading harmonics of your actual audible signal through your filters into your amp and tweeter.
If you use a bona fide 1-bit DAC, you can sample pretty much as fast as you want if all you care about is your pretty spec sheet. 2+MHz sampling? No problem!
Count me out, of course, but I still think it would be amusing to find a "384 kHz" audio DAC that actually worked at high enough frequencies to transmit AM radio. You'd have to actively exploit insufficiently filtered harmonics to have a chance.
For audio purposes, maybe. Higher sample rates are really handy if you want to - for example - digitise an entire ham radio band at once and feed it to a software radio. (Some external hardware is required to down convert the sinal, such as a Softrock board, but it's quite cheap.)
Nyquist would suggest otherwise but why let pesky math get in the way of the golden ears. This is just more MHz war, DECT 6.0 style BS. I'm holding out for the dulcet tones of 1Mhz PCM audio myself.