[CELT-dev] fixed point code
J.B. (Jae) Hong
jbhong at broadcom.com
Thu Mar 3 13:46:56 PST 2011
Thanks for your prompt response.
>> ROM tables are already included for frame sizes 120,240,480,960 at 48kHz.
Could you let me know where to find those tables?
From: Jean-Marc Valin [mailto:jmvalin at jmvalin.ca]
Sent: Thursday, March 03, 2011 1:26 PM
To: J.B. (Jae) Hong
Cc: celt-dev at xiph.org
Subject: Re: [CELT-dev] fixed point code
"J.B. (Jae) Hong" <jbhong at broadcom.com> a écrit :
> Could you provide us with fixed-point code for initialization of
> this array? Or you may kindly provide us with ROM tables of the
> array for each possible combination of frame size and sampling
ROM tables are already included for frame sizes 120,240,480,960 at 48
kHz. For the others, you can use the dump_modes utility with the
sampling rate(s) and frame size(s) you need.
>  Usage on global stack memory
> In "arch.h", there is a definition on the following constant for
> global processing memory (stack RAM).
> #define GLOBAL_STACK_SIZE 100000
This "global stack" is only a fall-back when neither C99
variable-length arrays, nor alloca() are available. See if you can use
one of those instead. For that, all you need is define either
VAR_ARRAYS or USE_ALLOCA.
> - Peak state memory (static RAM) size?
> - Peak processing RAM size including local stack RAM
> (100,000 bytes?)?
I have not measured those, but I'm sure it's under 100k. Also, it's
probably possible to make CELT more efficient than it currently is
when it comes to stack size.
> - Minimum input bit-stream buffer size with maximum
> bit-rate per frame considered at 48KHz sampling rate?
If by that you mean the largest compressed packet that can exist, then
the answer is 1275 bytes.
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