Default Sample rate for Pulse Audio/Jack etc.

[Len Ovens]

On Sun, January 6, 2013 11:38 pm, ttoine wrote:
> Len,
>
> 48khz is good for audio production, recording, etc... But think that most
> of what we are listening, from audio cd to mp3, ogg, etc... are stored in
> 44.1kjz files. I often listen to 44.1khz music (pulse audio apps) while
> having a jack session at 48khz or 96khz. It needs a lot more CPU than if
> jack is in 44.1khz.

Pulse should be set to 48K even more than jack. The HW in todays computers
is optimized for 48K. That is even 44.1k files will sound better if the HW
is run at 48k. I would only suggest 96k if (big IF) I had control of the
hardware being used. As Ubuntu Studio we don't, but the base rate for all
PC hard ware since the PCI interface started appearing on mother boards is
48k.

Here is and excerpt for an Email on LAU:
"48 kHz is the standard rate in audio broadcasting as well, apart from
TV and movies.

Something like 25-30 years ago,when I was working at BRT, the Belgian
public radio/TV network, the first radio studios were being converted
to digital. All 48 kHz, even if the only digital signals at that time
were from the CD players - they were just resampled before entering
the mixer (this required an expensive 1U rack equipment for each CD
player, don't remember the type or brand). DAT players were only added
later.

About a year later the music studios went digital, again all 48 kHz.
Can't could the number of CDs I mixed there.

Even that long ago 44.1 kHz was considered 'legacy', an unfortunate
compromise made for pragmatic reasons when the CD format was defined.
There's really no reason why it should still be used today."


> Today, the industry standards are 48khz and 96khz for music and films.
> Some
> people will record at 292khz for oversampling, in order to play very slow
> samples without problems. But think about the weight of files, the cpu
> needed to handle them, and the cpu to handle low latency effects. It is
> not
> time to set 96khz as default. And a lot of sound cards can just not run at
> that rate.

Again, I did not suggest setting the default to 96k but 48k. 96k might be
ideal for live work, but we don't (as you say) control our user's HW. I
would suggest one of the problems with Linux audio in general is defaults
of 44.1k on HW that is designed for 48k use... the Windows PC. I have not
noticed a change in CPU use at all on either of my generally slow/low
memory PCs, one of them 10 years old. 48k audio files are not that much
bigger.

If Ubuntu Studio is made for Pro audio production, for broadcast (even
streaming), for video. We should use the standard... 48k In 1991 when the
adat came out it was 48k... only.

If we want audio that fits best with the audio hardware inside most PCs,
we should be using 48k.

> Maybe we can let 44.1khz for Pulse Audio because most of what we are
> listening to are this way. And when someone will work on an audio project,
> then he/she will choose the good rate when starting jack. That said, Pulse
> Audio is able to connect to jack very easily, no matter the rate.

Nope, pulse should be 48k. That is what the internal HW in most PCs is
designed for. (look through the design spec for ac97 or HDA, they are
centered on 48k) The SB Live! had problems with anything but 48K. They had
enough problems with 44.1 that they recommended only ever recording at 48K
(see http://en.wikipedia.org/wiki/Sound_Blaster_Live! ).

two weeks ago I wouldn't have said any of this... :)  But I can still
learn new (or old) things.




-- 
Len Ovens
www.OvenWerks.net