Re: Using MidiMan Delta 66 drivers.
Re: Using MidiMan Delta 66 drivers.
- Subject: Re: Using MidiMan Delta 66 drivers.
- From: Jeff Moore <email@hidden>
- Date: Thu, 13 Dec 2001 11:10:04 -0800
on 12/13/01 12:08 AM, Markus Handell <email@hidden> wrote:
>
But the formats returned from the USB Audio Devices all return zeroes
>
for supported sample rate (and that means that the device performs it's
>
own sample rate tricks, if I understand it correctly?) so I don't think
>
it is comparable.
It is.
The header documentation for AudioStreamBasicDescription says the following:
kAudioStreamAnyRate = 0
// the format can use any sample rate (usually because it does
// its own rate conversion). Note that this constant can only
// appear in listings of supported descriptions. It should never
// appear in the current description as a device must always
// have a "current" nominal sample rate.
What this means in practice, is that you can set the sample rate to just
about anything you like and expect the device to do the right thing. It does
not necessarily imply that the device will be doing rate conversion.
>
We have a popup in the driver selection dialog that displays the
>
choosable sample rates. When a device has zero sample rate we read the
>
current format and extract the samplerate from that and install it in
>
the popup. So I'll have to hack that!
The better thing to do when the device reports it can handle any rate is to
populate your popup with a few common rates (something like 22050, 24000,
44100, 48000, etc) and an "other" item that allows the user to enter in a
sample rate in a text field.
--
Jeff Moore
Core Audio
Apple