JC,
If you are using a TCXO then your best option is to go ASYNC mode and
yes that will work with IOS and macOS as well as Windows and Linux. In
ASYNC you are the total master and the rate will be perfect.
Knowing the TAS1020B, PCM2902 and some of the other older chips from
products I made decades ago. These products only use the XO input to
create a PLL Master Clock (and USB clock). The Adaptive rate is then
based on the SOF from the HOST and that timing is matched to the
internal clock which then changes the Master Clock and the sampling
speed to match the host. So using a quality TXCO to accomplish a really
good 48K sample rate is not really going to accomplish your goal. The
true rate is going to be controlled from the host.
You could use the TAS1020B or TUSB3200, which goes out of production at
some point. It is used in too many products to predict when. You would
need the Kiel 8051/52 development system and probably the eval board.
Probably a better idea would be a Microchip PIC32MX270 processor. The
dev is cheap and they have sample code for some of the operation.
Thanks,
Gordon
On 8/21/16 3:57 PM, Jean-Charles Rousset wrote:
Thanks for your reply Gordon.
What we have been trying to do is to RECORD sounds in iOS/macOS with our USB
device as the master clock (TCXO) and iOS/macOS devices as the slave in order
to get perfect samples.
If I have understood correctly :
- It cannot be achieved with ASYNC IN, as the sink (iOS) will be master.
- Of course, it cannot be achieved by SYNC mode.
- In ADAPTIVE mode, iOS should adapt its rate to what the USB device send.
Maybe I understood it wrongly, but then, I have no idea how to send audio to
iOS with iOS being clock slave.
As I’m not recording audio for music but for timing measurement tool, I don’t
need an ultra-high-quality audio. 16 bits / 48KHz is totally ok. But these
48KHz must be absolutely perfect (48.0000KHz..)
Thanks !
JC
Le 21 août 2016 à 21:26, Gordon Rankin <[email protected]> a écrit :
JC,
Adaptive of course will add jitter to either the input or output device because
of it's flow control being that of changing the Master Clock. Which in turn
changes the speed of the clocked device (I2S, L/RJ whatever). Parts like the
PCM2902 and really early TI parts were done (even early TAS1020 code) before
anyone really could take a look the consequences of the protocols used.
The XMOS software only works in ASYNC mode. You can use input, output both
etc...
Maybe a better approach maybe to tell us what you are trying to accomplish and
maybe we could help you look for a better solution. Price or not, ASYNC or SYNC
is a much better ADC way than Adaptive.
Brian is correct on the Windows front, unless you are only trying to accomplish
Full Speed UAC1 type products.
Thanks,
Gordon
--
J. Gordon Rankin
Owner and Chief Scientist
====== Wavelength Audio, ltd ======
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Coreaudio-api mailing list ([email protected])
Help/Unsubscribe/Update your Subscription:
https://lists.apple.com/mailman/options/coreaudio-api/archive%40mail-archive.com
This email sent to [email protected]
