[wdmaudiodev] Re: KS STATE PAUSE and Streaming

  • From: "Neetu Sand" <neetu.freelist@xxxxxxxxx>
  • To: wdmaudiodev@xxxxxxxxxxxxx
  • Date: Mon, 15 Sep 2008 18:57:35 +0530

Hi Tim,

Thanks for your response. I am not sure if I understand what you are saying
: Are you saying that I should be streaming the data queued up in "Pause"
state?? In case that's what you are saying I don't think its a good idea to
do that because:
- DDK says that we should keep the SRBs queued in PAUSE and start streaming
in RUn state.
- If you run DTM tests then some of the audio tests would not pass if you do
that because they check that driver should not be streaming in PAUSE state.

In case you are not suggesting above, please ignore above and explain me
what did you mean to say. Also about KSPIN_FLAG_PROCESS_IN_RUN_STATE_ONLY, I
didn't fing any corresponding flag for streaming minidriver. Flag value is
either ignored or must be zero!

Thanks, Neetu.

On Fri, Sep 12, 2008 at 10:17 PM, Tim Roberts <timr@xxxxxxxxx> wrote:

> Neetu Sand wrote:
> >
> > I have been working on investigating a bug with a application and a
> > driver that I have written. The driver has been written using
> > "Streaming MiniDriver" architecture. Here is what I see:
> >
> > 1. Application opens a stream in driver for render.
> > 2. Application sets state to ACQUIRE->PAUSE.
> > 3. Application queues 2 SRBs to stream. Here driver simply queues
> > those SRBs so that as soon as the state is changed to RUN it can start
> > streaming.
> > 4. On the other hand application does not change state to RUN and
> > start waiting for the return of SRBs. This eventually results in a
> > timeout and SRBs are canceled and returned.
> >
> > I feel this is a wrong behavior from application's side because it is
> > not changing the driver state to RUN and queuing SRBs and expecting
> > them to return. Am I wrong in my understanding here??
> You are wrong.  Many graphs try to "pre-roll" the graph so that data is
> cued up and ready to go immediately on the transition to RUN.  Thus,
> some applications expect to get a few samples during PAUSE.  The stock
> video renderer, as an example, will not complete the transition to
> "paused" state until it gets a video frame.
> A kernel streaming driver can say that it  doesn't support this by
> setting KSPIN_FLAG_PROCESS_IN_RUN_STATE_ONLY in its pin descriptor.  I'm
> not sure of the equivalent for straight stream-class drivers.
> Why are you creating a stream-class minidriver instead of AVStream?
> --
> Tim Roberts, timr@xxxxxxxxx
> Providenza & Boekelheide, Inc.
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