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Bitzie running at 16bit on windows

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Delfalex View Drop Down
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    Posted: 10 Oct 2019 at 2:32pm
Hi,

I'm getting my new Bitzie setup on my Windows 7/10 work computers (up until it's been running from a iPhone), and I noticed that under its USB Audio Codec properties, it shows up as having a maximum input range of 16bit/48kHz. Now I was under the impression for the USB it was 24bit and so am wondering if I'm missing something Ermm any clues?

Cheers,

Alex
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 10 Oct 2019 at 4:24pm
It will accept 24 bits unless a source prevents it. The USB preamble includes device, configuration and string descriptors from which the operating system decides what to do with. In the case of native drivers it might therefore see it as 16 bits because that's what its S/PDIF output does. If you look at the specification for the Majestic USB input, it is qualified thus:

The following measurements taken at 24 bits and sampling rates of
Coax inputs: 192kHz
Optical inputs: 96kHz (192 kHz to order - optical input 1)
USB input: 48kHz

The Audio Precision audio analyser through ASIO4ALL overrides the operating system (Windows 8 in this case) so the USB output works at 24 bits.

The same USB circuit is used in the Bitzie and the only difference is that the Bitzie is bus powered.

It will also be noted (Majestic spec.) that the dynamic range measured 96dB which is 16 bit because that is the conversion bit depth of the S/PDIF output measured by the AP.

However, the input is specified to receive all bit rates, and in the Audio Precision test, which was performed by AP's James Kelly during training here, the input was 24 bits. I did question James about this at the time, and he pointed to the AP display which was reading 24 bits.

At the time of writing the Bitzie specification I was dubious about declaring 24 bit input depth because we didn't have the APX525 analyser, and my only evidence was from data, and in running ASIO4ALL from an XP machine. Colleagues tried the Bitzie on other operating systems on which some indicated 24 bits. It wasn't until APX525 training coincided with the Majestic spec. testing that I was able to see it accepting 24 bits.


Edited by Graham Slee - 10 Oct 2019 at 4:36pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote John C Quote  Post ReplyReply Direct Link To This Post Posted: 10 Oct 2019 at 6:13pm
The datasheet for the USB chip used states:

The following data formats are accepted by the S/PDIF input and output. All other data formats are unable to use S/PDIF.
• 48-kHz 16-bit stereo
• 44.1-kHz 16-bit stereo
• 32-kHz 16-bit stereo
Mismatch between input data format and host command may cause unexpected results except in the following conditions.
• Record monaural format from stereo data input at the same data rate
• Record 8-bit format from 16-bit data input at the same data rate
A combination of the above conditions is not accepted.
For the playback, all possible data rate source is converted to 16-bit stereo format.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 10 Oct 2019 at 6:29pm
Computers are like Marxism. You want to do something, but you cannot unless it conforms to the list.

You might want to send 24 bit audio, but the dynamic link libraries and/or drivers (.dll, .drv) will cross reference a descriptor to whatever is written in them, even if it is mistaken.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 10 Oct 2019 at 6:31pm
Originally posted by John C John C wrote:

The datasheet for the USB chip used states:

The following data formats are accepted by the S/PDIF input and output. All other data formats are unable to use S/PDIF.
• 48-kHz 16-bit stereo
• 44.1-kHz 16-bit stereo
• 32-kHz 16-bit stereo
Mismatch between input data format and host command may cause unexpected results except in the following conditions.
• Record monaural format from stereo data input at the same data rate
• Record 8-bit format from 16-bit data input at the same data rate
A combination of the above conditions is not accepted.
For the playback, all possible data rate source is converted to 16-bit stereo format.


This refers to the S/PDIF converter.

The 24 bit claim is simply that the input will accept 24 bits, and not about how it processes them.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 10 Oct 2019 at 8:04pm
What we could have done is to use a PROM equipped UART to change descriptors, and if a .dll or .drv didn't look likely to exist, write our own.

This would then have won us extra sales by being able to claim asynchronous USB.

We could have learnt bit stuffing, which should the USB-for-real chip have had sufficient buffer length, would have allowed us to switch to 96kHz input whilst still sampling at 48kHz.

This would have also won us more sales.

But we'd have been cheating all along, unless, that is, the sales volumes were enough to stick the lot into one package where nobody would have guessed.

Even so, it might have been possible for somebody to detect that final conversion was still isochronous...

…which is exactly what somebody found with a well-known People's Republic USB chip!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Delfalex Quote  Post ReplyReply Direct Link To This Post Posted: 12 Oct 2019 at 12:20pm
Hi Guys,

Thanks for illuminating me about this
Originally posted by Graham Slee Graham Slee wrote:

It will accept 24 bits unless a source prevents it. The USB preamble includes device, configuration and string descriptors from which the operating system decides what to do with. In the case of native drivers it might therefore see it as 16 bits because that's what its S/PDIF output does. 
Phew!! I thought that I might had been connecting or configuring things wrong (even though plug'n play), or even worse; something brokenCry

Originally posted by Graham Slee Graham Slee wrote:


The Audio Precision audio analyser through ASIO4ALL overrides the operating system (Windows 8 in this case) so the USB output works at 24 bits.

I remember looking at ASIO4ALL a few years back when first encountering audo streaming. So I've installed it and fiddled around to set it as my main playback device for audio (pointing it to the Bitzie), for when using Foobar2000. I confess I haven't really noticed much difference in the SQ between ASIO4ALL & W. USB Audio Codec.

Anyways it's probably a moot exercise because in just seeing that most of the FLACs I listen to are 16bit/41kHz, whilst the musical sound quality of the Bitzie is so enjoyable, "not uptight" and pleasing, the numbers to me are now proving rather irrelevant as I've found what I've wanted for

..and the Bitzie is working how it's meant to Beer


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