Re: [Jack-Devel] S24_3LE

resolution has nothing to do with bit depth, only with sample rate. basic
signal processing theory, nyquist, etc.


On Sun, Aug 11, 2013 at 3:12 PM, Anders Tornvig <[hidden]>wrote:

> Hi Paul, thanks for your rapid answer!
>
> Ok I see. Float if I want the jack api.
>
> The wordlengths we operate with today may make the discussion less
> relevant, but I don't understand the benefit of adding resolution to
> something which was not converted correspondingly.
>
> Say you have a low- and a high-frequency tone added together. Say the lf
> tone amplitude is 1000 times that of the hf tone. I happen to be only
> interested in the low-amplitude hf tone but the lf tone "steals" the
> resolution to represent it. And that resolution changes with the level of
> the lf tone! Am I right?
>
> With integers I know what resolution I have, no more, no less.
>
> Best, Anders
> Den 11/08/2013 16.03 skrev "Paul Davis" <[hidden]>:
>
>
>>
>>
>> On Sun, Aug 11, 2013 at 7:11 AM, Anders Tornvig <[hidden]>wrote:
>>
>>> Dear list,
>>>
>>> I'm writing a full-duplex program (2in/2out) which will output
>>> something, record it as a block of data (1024-3268 samples), analyze it and
>>> decide what to output next. I'm on Ubuntu, at the moment with a UA-25ex USB
>>> audio interface, speaking S24_3LE.
>>>
>>> The Jack API looks fantastic except for one thing: I prefer working with
>>> integers and not float. In ALSA I can set the sample format to
>>> SND_PCM_FORMAT_S24_3LE and then I can give it data in that format directly,
>>> 3 bytes per sample per channel. On the capture side, I receive nice 24-bit
>>> integers.
>>>
>>
>> You should know that almost all audio software on almost every platform
>> these days using floating point. Even platforms that used to use fixed
>> point (e.g. protools DSP boxes) now use floating point.
>>
>> Adding a new data type to JACK is not particularly hard if it is intended
>> only for client-to-client communication. Adding a new data type to JACK
>> that involves the backends is a major undertaking.
>>
>>  You really should try to get over your attachment to integers - they
>> are fundamentally inappropriate for working with audio, something it has
>> taken the industry 10-20 years to realize but is now accepted by almost
>> everyone.
>>
>> --p
>>
>>
>>

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