[pulseaudio-discuss] [PATCH 2/2] pulse: Bump PA_RATE_MAX to 384 kHz

[Arun Raghavan]

On 31 December 2015 at 11:15, Tanu Kaskinen <tanuk at iki.fi> wrote:
> On Thu, 2015-12-31 at 09:42 +0530, arun at accosted.net wrote:
>> From: Arun Raghavan <git at arunraghavan.net>
>>
>> This will likely be needed in the future when we start supporting high
>> bitrate passthrough, and there actually seem to be people 352/384 kHz
>> out there (potentially as an intermediate production step).
>
> What's your source for claiming that there seems to be people with such
> PCM files (I'm assuming you implied PCM files)? If it's only used as an
> intermediate production step, is there any evidence that people would
> want to play that intermediate stuff via pulseaudio?
>
> The mpv bug was about a dsf file (which means a dsd stream from sacd?).

My source is the Internet. :)

https://en.wikipedia.org/wiki/Digital_eXtreme_Definition

> Supposedly the stream contents were non-PCM data containing more than 2
> channels, meant to be played in passthrough mode. And I guess alsa has
> specified that such content should be wrapped in a 2-channel 384 kHz
> float fake-PCM stream? I don't like extending the rate range for PCM
> streams just because alsa's passthrough implementation happens to
> specify such parameters for fake-PCM streams, but maybe there aren't
> any better options...

I certainly don't know of better options. FWIW, some HDA codecs do
report support for this rate as well. Presumably either the DAC
supports it (I'd be curious to find out why), or it's supported for
HBR passthrough. Either way, we'll probably need to end up supporting
this.

-- Arun