radio sample rates.

[Jim web]

In article <575c0faa39219d3bb67632d5d8ea7962 at custommade.org.uk>,
   Christopher Woods <christopher at custommade.org.uk> wrote:
> On 2015-03-15 22:23, Tris wrote:
> > I'm not sure if this is connected but two or three weeks ago I was
> > still on v2.89 (I think) and all radio downloading suddenly became
> > unavailable.
> >
> > Things all started working again after I updated to 2.91 which had all
> > the changes in it for the upcoming changes to BBC streaming methods
> > (which had obviously just happened when things stopped for me).
> >
> > Maybe this change to BBC methods is also when the file rates became
> > 48k for you?
> >
> > Tris


> Audio Factory encodes at the audio's native 48 kHz; this is what the
> stations operate at internally.

Understood.

> 44.1 kHz was a legacy thing and to be honest was unnecessary; after
> stations went all-digital at 48 kHz it effectively gave us three
> resampling steps (48 -> 44.1 -> 48).

That raises some questions. Ever since I've used the FireFox + Flash plugin
it has output 44.1k. I've understood the conversion was 'at source'. i.e.
coyopa sent 44.1k. But the closed nature of Flash makes it hard for me to
tell. When I measured test stream mumble years ago they showed the levels
of artifacts were low. Admittedly that was in the 'nemesis' era. :-)

So when I now get 44.1k is that being sent by the server? Or is the Flash
plugin doing it? And are uses of the RTMP/Flash plugin stuck with it? I'm
asking here but if you can't say I'll raise it with someone else off this
public list.

And the situation that alerted me is that I seem to have found that gip
2.90 got me 44.1k files, but 2.91 gets me 48k files with a different
filename syntax. Were both types always present, and can I take it that the
48k version would avoid a conversion? i.e. the 44.1k is downstream of the
48k? Or the reverse?

> Now we have zero additional resampling steps (save for anything like
> commercial music, which will have been resampled once from 44.1 kHz
> source to 48 kHz).

However I get 44.1k from FF+Flash - just like gip until a short time ago.
Which raises the above questions.


Jim

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