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Re: Coreaudio-api Digest, Vol 14, Issue 39
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Re: Coreaudio-api Digest, Vol 14, Issue 39


  • Subject: Re: Coreaudio-api Digest, Vol 14, Issue 39
  • From: Paweł Gorgoń <email@hidden>
  • Date: Wed, 5 Jul 2017 10:47:11 +0200

Hi Gordon,

Thank you for your answer. AD is recognized in system as 384kHz/32bit device and I would like to record 32bit PCM samples in every rate at first. DSD data is packed in PCM on 32 bit data (DoP needs x2 rate as you wrote) and it is second thing I would like to implement.

The problem is recording as integer. Streams are configured to int and data in inputbuffer given in callback is correct (bit values are the same as in pattern I play for test), but randomly shifted. It is important for me to receive 32bit data, because it is one of application requirements.

Pawel


W dniu 04.07.2017 o 19:43, Gordon Rankin pisze:
Pawel,

What does the AD look like to the OS? What kinds of sample rates does it look like? You may have to change the device to use DoP over PCM 24 bit samples at 2X (i.e. 176.4 for DSD64 and 352.8 for DSD128....) because the drivers may not understand the sample rates and so forth associated with DSD.

Not a huge fan of DoP and I know companies are using DSD data direct at 32bit samples on output devices. But I think they are using standard PCM sample rates.

Thanks,
Gordon

Today's Topics:

    1. Integer mode for input stream (Paweł Gorgoń)


----------------------------------------------------------------------

Message: 1
Date: Mon, 3 Jul 2017 18:53:21 +0200
From: Paweł Gorgoń <email@hidden>
To: email@hidden
Subject: Integer mode for input stream
Message-ID: <email@hidden>
Content-Type: text/plain; charset="utf-8"; Format="flowed"

Hi Everyone,

I'am trying to make some recording application which will be using with
32bit/DSD ADC. It needs 32bit integer mode for input stream. I've done
some steps like enter hog mode, configure stream for unmixable 2-ch
int32 data (physical and virtual), register callback and start device,
but I receive data which are shifted randomly in every callback call.

I was make some more test and:

   * the same configuration for output works properly.
   * changing stream format to int via HALLab and recording using reaper
     DAW causes same issue. Reaper interprets data as floats, but I have
     constant patern generated in device which should be interpreted as
     constant float value, but it doesn't.
   * Receiving floats in my app gives constant values and it is ok.
   * Data is shifted by 2, 4, 6 bytes for stereo device. For 4-channel
     device it is multiple of 4bytes (4bytes, 8bytes ext.).

I've tested it on OSX 10.10.2 and OSX 10.11.6.  Maybe someone has same
issue and can help me.

Thanks.

Pawel


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References: 
 >Re: Coreaudio-api Digest, Vol 14, Issue 39 (From: Gordon Rankin <email@hidden>)

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