Re: SPDIF audio in DVD Player
Re: SPDIF audio in DVD Player
- Subject: Re: SPDIF audio in DVD Player
- From: Jeff Moore <email@hidden>
- Date: Mon, 1 Aug 2005 12:09:59 -0700
On Aug 1, 2005, at 8:35 AM, Fabian Renn wrote:
Hello Jeff,
i've gotten SPDIF audio to work on my device. Now i'm having
problems with my clipping routine 'clipOutputSamples'. This routine
always crashes. Now, in what format do i get the ac-3 samples. As 2
channel floats? Or as 16 bit ints? ( So, the IOProc format, not the
physical format )
Non-mixable formats like AC-3 are delivered to your device raw, in
the format your driver publishes to the HAL.
Second Question: When i use spdif output in the dvd player,
playback really slows down ( to about 1 - 2 fps ) and the playback
time starts going crazy. Do i need to have some sort of special
sample buffer size ( like in VLC )? Are my inaccurate time stamps
causing the trouble?
The DVD Player does that when it's IOProc isn't getting called by the
HAL. Have you take a look at the IO cycle telemetry from the DVD
Player? I imagine the HAL is waiting for something, such as the
signal from the driver to start or the first time stamp. It's hard to
say.
Fabian Renn
Hello Jeff,
thank you for the quick answer. Unfortunately it wasn't the solution.
No device is "hogging" the device, at least that's what HALLab is
telling me. I also must correct myself the error message i'm getting
is that the device was "removed". It might have something to do with
other problems i'm experiencing with my driver, described in a
different mail 'kIOAudioDeviceTransportTypeUSB has strange effects',
which i am sending at the same time with this respond.
Fabian
Message: 1
Date: Mon, 25 Jul 2005 12:50:57 -0700
From: Jeff Moore <email@hidden>
Subject: Re: SPDIF audio in DVD Player
To: CoreAudio API <email@hidden>
Message-ID: <email@hidden>
Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed
When a device is switched to a non-mixable format, the HAL also
enforces hog mode (aka exclusive access to the device) in a first
come, first served way. So, what is likely going on here is that some
other process has acquired hog mode before the DVD Player can. This
leaves the DVD Player to fall back to non-encoded output on the
default device.
HALLab can tell you which process owns hog mode for your device.
Plus, it can do so without forcing the HAL to grab hog mode provided
you don't do any IO with the device in HALLab.
On Jul 23, 2005, at 12:28 PM, Fabian Renn wrote:
Dear list members,
i'm programming an audio driver for an external usb 2.0 device. The
device has a spdif connecter and i'd like dvd player to support it.
I added the audio format kIOAudioStreamSampleFormat1937AC3 to the
list of supported formats and i can select in the DVD player, yet
when i play a dvd it gives me the error message: 'digital audio
device no longer available switching to standard output!'. What
else do i need to implement that the dvd player will use my device
correctly? All other audio works fine.
Greetings from Germany
Fabian Renn
--
Jeff Moore
Core Audio
Apple
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--
Jeff Moore
Core Audio
Apple
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