Hi Wade,
I'm registering the IRQ used by the Ensoniq PARIS PCI card. PARIS is a
20 year old PCI base DAW. Getting multiple PCI cards to operate in sync
with really small buffers was a challenge, but a fun one.
It's working really well at 32 samples, but I can see a need to optimize
the Windows install to limit background processes as much as possible.
I'm hoping that PcAddStreamResource might obviate that.
All the best!
Mike
On 4/16/2018 12:22 PM, Wade Dawson wrote:
Hi Mike. If your underlying transport is usb, and you’re using iso
transfers, 1ms will be the minimum callback timing that you’ll be able to
achieve without jitter. Since (in this case) iso transfer size is ultimately
governed by samplerate, it is not possible to directly instruct usb to
transfer anything other that 44/45, 48, 88/89, etc samples per millisecond.
(Current usb host controller drivers will only Irq on multiples of 8 uFrames,
I.e., 1ms) This mismatch between iso frame size and asio buffer size, is why
asio jitter exists and why some driver designers are forced to call asio
bufferswitch at non-regular intervals (jittery) when running atop a blocking
transfer medium such as usb iso.
Some firmware and driver implementations actually operate in a non class
compliant mode utilizing bulk transfers for audio instead of iso so that they
can drive their processing callback at the asio buffer size period instead of
the usb iso (1ms) callback period.
Btw, what are IRQ are you trying to register?
Sent from my iPhone
On Apr 16, 2018, at 10:28, Mike Audet <mike@xxxxxxxxxxxxx> wrote:******************
Thanks for your reply, Vincent!
I'm getting pretty good results now. It's only when, for example,
Windows updates the desktop wallpaper that I sometimes get a glitch.
It's my understanding that calling SetEvent from kernel mode wakes up
the waiting thread immediately, without waiting for the next sche duler
slot. So, it should be possible (if I understand things right) to go
this low. It's only if Windows handles a high load IRQ, like
networking, video, or hard disk, on the same CPU as the audio IRQ that
there should be a problem (I think). It's my understanding that this
new function is designed for this exact situation.
I'm pretty excited to try this new function to see what impact it has.
But, there is no sample code or description of how to use the function.
There's not even a comment in portcls.h.
All the best!
Mike
On 4/16/2018 9:14 AM, Vincent Burel (VB-Audio) wrote:******************
Hello,
On current Windows O/S, It makes no sense to manage 32 samples buffer size
on ASIO driver (or any audio driver).
First because Windows cannot manage time slot below 1 ms (1ms must be
considered as Real Time Jitter under Windows - from XP to current WIN10 -
but the validated value is more closed to 3ms).
Secondly because interrupt incident (due to multitask, page out etc... can
bring 2 or 3 ms penalty in an audio callback process). so you may consider
buffer size above 2.5 to 5 ms to provide a reliable real time audio stream
(it makes usually 128 to 256 samples at 48kHz).
Some audio board manufacturers already did it, they can provide down to 32
or even 16 samples buffer size but it's a disaster in term or stability and
real time (because they are obliged to call the process several time in the
same time slot, breaking the basic DSP time rules) and finally get a real
latency bigger than on well implemented drivers using 128 or 256 samples
buffer.
Regards
Vincent Burel
-----Message d'origine-----
De : wdmaudiodev-bounce@xxxxxxxxxxxxx
[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] De la part de Mike Audet
Envoyé : lundi 16 avril 2018 14:34
À : wdmaudiodev@xxxxxxxxxxxxx
Objet : [wdmaudiodev] PcAddStreamResource IRQ question
Hi everyone,
Does anyone know how to use the new PcAddStreamResource function to
register an IRQ?
The Interrupt stricture in PCSTREAMRESOURCE_DESCRIPTOR looks like this:
struct {
ULONG Version;
PVOID Generic;
} Interrupt;
I'm not sure what to assign to either Version or Generic.
I've searched online and in the archive, and I've only been able to find
sample code that relates to registering a thread.
I'm trying to make an ASIO driver more robust at a 32 sample buffer size.
Below is some code I've roughed in to my ConnectInterrupt routine.
Thanks so much!
Mike
roughed in code:
PCSTREAMRESOURCE_DESCRIPTOR_INIT(&ResourceDescriptor);
ResourceDescriptor.Pdo = DeviceExtension->PhysicalDeviceObject;
ResourceDescriptor.Type = ePcStreamResourceInterrupt;
ResourceDescriptor.Resource.Interrupt.Version = ???;//no idea at all....
ResourceDescriptor.Resource.Interrupt.Generic =
(PVOID)DeviceExtension->InterruptObject; //just a guess....is this right?
ResourceDescriptor.Resource.ResourceSet = NULL; result =
PcAddStreamResource(DeviceExtension->PhysicalDeviceObject,
NULL, &ResourceDescriptor, &DeviceExtension->irqResourceHandle);
if (!NT_SUCCESS(result))
{
DbgPrint("Error calling PcAddStreamResource: %u", result); }
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