Rockbox

sorry. this patch updates (does not include some files)

   rb_tta_codec_2.patch (60.5 KiB)

Works fine on the Sansa clipv2, but not on coldfire due to endian-ness issues (Coldfire is big endian, x86 and ARM are little endian):

http://www.rockbox.org/irc/log-20100510#00:57:29

I tried removing the extra letoh32/letoh16 calls, and it works on ARM, but so far no one has tested this on Coldfire to see if it fixes the problem.

   ttav2.patch (60.7 KiB)

ttav2.patch works on coldfire, but isn’t realtime. test_codec yields 52.4% realtime for the test track on my iriver H180. Imo it’s ready for initial commit.

I’ll look into assemblerising the filter for coldfire. EMAC should help a lot :)

comment and correction of the endian thanks.

hybrid_filter() is a very slow function, and If this function is not executed, decode speed becomes twice or more.
However, the speed doesn’t change so much even if it rewrite by assembler (in ARM, C to asm about 7 - 8 % speed up at most)

I think that it is necessary to optimize more for not hybrid_filter() but get_samples().

For speed up you should use IRAM for some more variables and buffers. Especially tta[], cache[] and some of the global variables used in bit fiddling (e.g. bitpos, bit_cache, bit_count, …).
I expect that moving tta[] to IRAM will improve the decoding speed quite a lot.

Edit: Forget about my guess. This will speed up decoding by only ~1.4 MHz (unpatched needs 57.5 MHz) on a PP502x.

IRAM is an absolute must on coldfire. As-is, coldfire would need ~240MHz for realtime decoding; I would expect this to be on par with arm, probably even faster, with proper IRAM usage.
However, I do think this work should be done after committing the current patch to svn. Much easier for others to help this way :)

optimize a bit
on iPod video, about +5 % spped up.

But, it is to slow oppositely according to the player.

changes:

get_samples: rice update logic is changed to the function (update_rice()). 

   rb_tta_codec_3.patch (61.2 KiB)

optimize more
maybe all targets speed up.
on iPod, + 8 - 9 % speed up against yesterday’s patch (i.e., decoding speed is 152 - 153 %)

changes:

 get_samples: The decoding logic is optimized by using that the max channels is 2.
 tta_info: deletes HANDLE

   rb_tta_codec_4.patch (61.2 KiB)

commit tta codec.
please, problems concerning TTA must open as other tasks.
After I update the manual, I will close this task.