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Author Topic: ASIO Question  (Read 947 times)

runes

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ASIO Question
« on: June 03, 2018, 04:25:59 am »

When playing to a DAC using ASIO drivers should the sound be exclusive to the DAC during playback like in WASAPI or it should be possible to play to the DAC using a web browser for example. Because if I play to the DAC with MC using ASIO the device is not locked during playback.
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RD James

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Re: ASIO Question
« Reply #1 on: June 03, 2018, 08:10:23 am »

It depends on the DAC. ASIO is not always exclusive, and does not always bypass the system volume level.
The latter can cause issues for DSD bitstreaming.
 
You are probably better off using WASAPI Exclusive Mode instead.
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JimH

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Re: ASIO Question
« Reply #2 on: June 03, 2018, 08:13:46 am »

Depends on the driver might be more accurate.
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RD James

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Re: ASIO Question
« Reply #3 on: June 03, 2018, 09:31:34 am »

Depends on the driver might be more accurate.
True - though you typically don't get a choice.
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runes

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Re: ASIO Question
« Reply #4 on: June 03, 2018, 09:43:07 am »

I used ASIO because my DAC can play DSD files up to 4X DSD256 natively. Now after changing to WASAPI per RD James advice I have problem playing DSD files which are DSD256. I can play DSD64 and also DSD128 and MC shows that it plays bit perfect streaming in DOP format (which I don't care if it is natively or not) but if I try playing DSD256 files MC displays a message "The output format may not be supported by your hardware". Is it the current  limitation of WASAPI or MC?
Is it possible to play DSD files which are higher than 128FS with WASAPI or is there a different way to play high rate DSD files as well as PCM without using the ASIO drivers?

Thank you
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dtc

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Re: ASIO Question
« Reply #5 on: June 03, 2018, 10:47:19 am »

Each 24 bit PCM DoP sample contains 16 DSD bits. So, the DoP process decreases the sample rate by a factor of 16. So, 2.822MHz converts to 176 KHz, 5.6Mz to 352 KHz. So, 4x DSD converts to 705 KHz DoP. 

You probably cannot play 4x because your DAC does not accept 705 KHz PCM.  Which means you need to use ASIO to play 4X DSD.
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runes

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Re: ASIO Question
« Reply #6 on: June 03, 2018, 11:05:57 am »

Each 24 bit PCM DoP sample contains 16 DSD bits. So, the DoP process decreases the sample rate by a factor of 16. So, 2.822MHz converts to 176 KHz, 5.6Mz to 352 KHz. So, 4x DSD converts to 705 KHz DoP. 

You probably cannot play 4x because your DAC does not accept 705 KHz PCM.  Which means you need to use ASIO to play 4X DSD.
Please forgive my ignorance but isn't DOP is different from Native by packing the DSD stream to PCM and it should be completely transparent and lossless without any conversion of the DSD stream? Shouldn't DOP be the same as Native format?

Thanks
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RD James

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Re: ASIO Question
« Reply #7 on: June 03, 2018, 11:10:36 am »

Please forgive my ignorance but isn't DOP is different from Native by packing the DSD stream to PCM and it should be completely transparent and lossless without any conversion of the DSD stream? Shouldn't DOP be the same as Native format?
Yes, the audio quality is exactly the same.
Some DACs can only handle certain DSD rates via DSD or DoP though. Many DACs only support DoP.
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dtc

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Re: ASIO Question
« Reply #8 on: June 03, 2018, 11:39:26 am »

DoP is completely lossless. It packs 16 DSD bits into each 24 bit sample and the DAC unpacks it back to the original DSD string.  I should have said "pack" rather than "convert". DoP does convert but it is a lossless conversion. Packing is a less confusing term.

This link describes the packing in more detail.

http://dsd-guide.com/dop-open-standard
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