[tremor] Ogg/Vorbis report, FFT optimizations

Johannes Sandvall js at sandvall.nu
Thu Mar 11 12:55:21 PST 2004

I wrote to the list earlier about optimizations of the
tremor. Specially replacing the IMDCT with a N/4 FFT.

The report is available here: http://www.sandvall.nu/thesis.pdf

Short summary:
Optimization of the Tremor code under 50kB for a "split" decoder version.
~44 MIPS. Huffman highly unoptimized. IMDCT ~ 8 MIPS.
Quick overview of the Ogg/Vorbis format and a psycho acoustic

I've send code to the list about the FFT but that seems to have
disappeared somehow... Maybe the attachments got lost somewhere.

Most of the code is free, all of the stuff in the report. The parts
developed in cooperation with Ericsson mobile platforms is not

Give me feedback if any parts of the code is of interest.

If there is any questions please send them but check in the report
first if the answer is there.


/ Johannes Sandvall, Erik Montnemery

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