Re: [Jack-Devel] S24_3LE

Also, keep in mind that if you keep the value in the range -1 to 1, you are basically using a 24-bit integer (in the mantissa).  No loss of precision.  

Thanks,
Bill Gribble

On Aug 11, 2013, at 15:23, Paul Davis <[hidden]> wrote:

> 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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1376249326.7732_0.ltw:2,a <FDB560EF-A6C0-40BE-8896-3ABE8096762A at billgribble dot com>