Re: 答复: 答复: S/PDIF audio output
Re: 答复: 答复: S/PDIF audio output
- Subject: Re: 答复: 答复: S/PDIF audio output
- From: Jeff Moore <email@hidden>
- Date: Fri, 15 Jun 2007 11:23:32 -0700
The AC-3 support the tech not mentions is in support of IEC60958.
Basically, you can send AC-3 over a digital interface to be decoded
somewhere else. Our DVD Player supports this as well as several other
apps out there like VLC.
Doing it entails taking each packet of AC-3 data from the media,
massaging it into the form required by IEC60958, and writing the
packet out in your IOProc. Note that AUHAL only supports linear PCM
data, so you will need to drop down and use the HAL directly to send
AC-3 data.
On Jun 14, 2007, at 11:50 PM, ann_chen (陳勇) wrote:
Dear Jeff,
there is one question about S/PDIF continue. Apple's http://developer.apple.com/documentation/Hardware/Conceptual/HWTech_Audio/index.html
talk about S/PDIF can support AC3 audio stream output:
S/PDIF Optical Digital Output
The S/PDIF optical digital output supports a stereo data stream at
bit depths of 16, 20, or 24 bits per sample and at sample rates of
44.100 kHz, 48.000 kHz or 96.000 kHz in PCM format. In addition, the
S/PDIF optical digital output supports a stereo data stream at 16
bits per sample and at sample rates of 44.1 kHz, 48 kHz, or 96 kHz
in AC-3 encoded audio format.
that mean: when my audio content is AC3, I need not decoder AC3 to
PCM and send the AC3 stream data to S/PDIF output directly. is
right? then , how Audio Unit to realize like this?
And I search S/PDIF by Google, Find some other software deal with S/
PDIF like this http://faq.elgato.com/index.php/faq/more/71
Many DVD VOB files contain Dolby Digital™ AC-3 sound. EyeHome does
not decode this sound format to the analog sound outputs. However,
EyeHome passes AC-3 through the S/PDIF optical interface.
thanks in advance .
--Ann
-----邮件原件-----
发件人: ann_chen (陳勇)
发送时间: 2007年6月15日 9:08
收件人: 'Jeff Moore'
主题: 答复: 答复: S/PDIF audio output
Hi Jeff,
thank you very much
--Ann
-----邮件原件-----
发件人: coreaudio-api-bounces
+ann_chen=email@hidden [mailto:coreaudio-api-bounces+ann_chen=email@hidden
] 代表 Jeff Moore
发送时间: 2007年6月15日 2:54
收件人: CoreAudio API
主题: Re: 答复: S/PDIF audio output
It depends on the hardware. For example, the Edirol USB Audio box I
have here on my desk always sends the audio data to both it's analog
ports and it's SPDIF port. The same is true if I have one of those
special cables plugged into the output of my G5 iMac. On the other
hand, on my MacPro, the SPDIF output is it's own audio device separate
from the line out and built-in speaker. On a MotU 828, the SPDIF
output is actually addressed via the second output stream it publishes
(which is presented alongside and concurrent with the analog output
stream).
On Jun 13, 2007, at 10:52 PM, ann_chen (陳勇) wrote:
> Dear Jeff,
>
> ====Yes. If the piece of hardware has a SPDIF output, it will work
> fine.===
>
> Need I set some attribute to make the Audio Unit use SPDIF output? I
> search the Audio Unit framework, can't find any information about
> SPDIF, only IOkit have "kIOAudioOututPortSubTypeSPDIF" about the
> SPDIF, how make Audio Unit use SPDIF output, if it’s automatic?
>
> my Audio playback is follow apple's Technical Note TN2097
> http://developer.apple.com/technotes/tn2004/tn2097.html
>
> thanks in advance.
>
> Ann
>
>
> -----邮件原件-----
> 发件人: ann_chen (陳勇)
> 发送时间: 2007年5月22日 8:40
> 收件人: 'Jeff Moore'
> 主题: 答复: S/PDIF audio output
>
> Dear Jeff,
>
> Thank you very much.
>
> Ann
>
> -----邮件原件-----
> 发件人: coreaudio-api-bounces
> +ann_chen=email@hidden [mailto:coreaudio-api-bounces+ann_chen=email@hidden
> ] 代表 Jeff Moore
> 发送时间: 2007年5月22日 2:01
> 收件人: CoreAudio API
> 主题: Re: S/PDIF audio output
>
> Yes. If the piece of hardware has a SPDIF output, it will work fine.
>
> On May 21, 2007, at 1:32 AM, ann_chen (陳勇) wrote:
>
>> I use Audio Unit to play back LPCM audio. It can support S/PDIF
>> audio output?
>
> --
>
> Jeff Moore
> Core Audio
> Apple
>
>
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--
Jeff Moore
Core Audio
Apple
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Jeff Moore
Core Audio
Apple
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