opus - Dec 2015 - How to make opus work on a low end device ?

hi,   
    I am porting opus encoder to a low end device with  32K ram, 256K flash and
32MHz  arm M3 mcu.
But  opus seems consume too much.   To make it work , what I can think of
1,   Only  fixed point supported
2,   Only  mono voice application supported
3,   Set complexity to  zero
4,   Support only one sample rate,  like  16KHz
5,   Silk mode only  or  Celt mode only

My question is ,  before I start,  Shall  I choose silk mode or celt mode ?
and  beside I mention above,  what else can I do to reduce the complexity (rom,
ram, MCU),
even compromise the voice quality...

Thanks, 



jensenchen
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Hi,

The specs you're listing are pretty low, but I *think* running Opus
encoding should be achievable at 16 kHz. CELT should require less CPU
for encoding than SILK, but for voice, you will need a higher bitrate
with CELT than with SILK to achieve equivalent quality (e.g. 24-40 kb/s
with CELT instead of 16-24 kb/s with SILK).

Cheers,

	Jean-Marc

On 12/28/2015 12:11 PM, jensenchen wrote:
> hi,   
>     I am porting opus encoder to a low end device with  32K ram, 256K
> flash and 32MHz  arm M3 mcu.
> But  opus seems consume too much.   To make it work , what I can think of
> 1,   Only  fixed point supported
> 2,   Only  mono voice application supported
> 3,   Set complexity to  zero
> 4,   Support only one sample rate,  like  16KHz
> 5,   Silk mode only  or  Celt mode only
> 
> My question is ,  before I start,  Shall  I choose silk mode or celt mode ?
> and  beside I mention above,  what else can I do to reduce the
> complexity (rom, ram, MCU), 
> even compromise the voice quality...
> 
> Thanks, 
> 
> ------------------------------------------------------------------------
> jensenchen
> 
> 
> _______________________________________________
> opus mailing list
> opus at xiph.org
> http://lists.xiph.org/mailman/listinfo/opus
>

On 12/28/15 9:11 AM, jensenchen wrote:
> hi,   
>     I am porting opus encoder to a low end device with  32K ram, 256K
> flash and 32MHz  arm M3 mcu.
Don't do this.  The delta in cost between a 32K/256K/32MHz and a
128K/256K/100MHz processor borders on zero.  Implementing Opus on the
second is work but not excessive amounts of it.  Implementing it on the
first is nothing but pain.

If you're stuck with this configuration because, say, you are stuck with
a Nordic bluetooth chip, stop now.  You will not be able to use
Bluetooth and encode.  There just aren't enough cycles.

Overall, you will not be able to do anything other than move data in on
SPI, encode it and move it out on SPI pretty much at any frequency below
about 80MHz--64MHz if I'm being excessively charitable.  And you better
have DMA engines handling the SPI transfers.

-a

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