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Subject: Re: OggVorbis for CPUs without FPU

Re: OggVorbis for CPUs without FPU

From: Vladimir Pantelic <pan_at_nt.tu-darmstadt.de>
Date: Wed, 04 Sep 2002 11:49:44 +0200

Linus G Larsson wrote:
> Hi all,
>
> I don't want to ask the same question "can we support vorbis" again,
> just tell people who might not know it that Xiph has released Tremor, a
> Vorbis decoder for CPUs that don't have an FPU, under a BSD-like
> license:
> http://www.xiph.org/ogg/vorbis/hardware.html
>
> Anyway, how is the progress going with the exploring of the MAS? Is it
> just na´ve to hope for rockbox to be able to download a new codec into
> the DSP?

A little look into the Tremor sources reveals:

$ grep static window.c
static ogg_int32_t vwin64[32]={
static ogg_int32_t vwin128[64]={
static ogg_int32_t vwin256[128]={
static ogg_int32_t vwin512[256]={
static ogg_int32_t vwin1024[512]={
static ogg_int32_t vwin2048[1024]={ = 4k
static ogg_int32_t vwin4096[2048]={ = 8k
static ogg_int32_t vwin8192[4096]={ = 16k

$ grep static mdct_lookup.h
static ogg_int32_t triglook_64[80]={
static ogg_int16_t bitrevlook_64[16]={
static ogg_int32_t triglook_128[160]={
static ogg_int16_t bitrevlook_128[32]={
static ogg_int32_t triglook_256[320]={
static ogg_int16_t bitrevlook_256[64]={
static ogg_int32_t triglook_512[640]={
static ogg_int16_t bitrevlook_512[128]={
static ogg_int32_t triglook_1024[1280]={
static ogg_int16_t bitrevlook_1024[256]={
static ogg_int32_t triglook_2048[2560]={ = 10k
static ogg_int16_t bitrevlook_2048[512]={ = 1k
static ogg_int32_t triglook_4096[5120]={ = 20k
static ogg_int16_t bitrevlook_4096[1024]={ = 2k
static ogg_int32_t triglook_8192[10240]={ = 40k!!
static ogg_int16_t bitrevlook_8192[2048]={ = 4k

This makes roughly > 100k needed for the tables only!
I doubt that this will fit even in the ROM of the MAS DSP,
not to talk about the RAM that is left for customer code....

Regards,

Vladimir
Received on 2002-09-04

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