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SPDIF audio in DVD Player
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SPDIF audio in DVD Player


  • Subject: SPDIF audio in DVD Player
  • From: Fabian Renn <email@hidden>
  • Date: Mon, 1 Aug 2005 17:35:52 +0200

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 ) 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?

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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