Rockbox.org home
release
dev builds
extras
themes manual
wiki
device status forums
mailing lists
IRC bugs
patches
dev guide



Rockbox mail archive

Subject: Re: WAV Codec for Archos

Re: WAV Codec for Archos

From: Bluechip <csbluechip_at_gmail.com>
Date: 2006-01-26

Just a moment to support Jorg's comments.

>Before the myths start outgrowing the facts:
>
>The MAS is downloadable, but its internal memory is very small.

Indeed - for, most other formats, most noteably OGG are ...well, I hate the
word "impossible" they were attributed to WAV and Video playback once upon
a time ...but for now I cannot think of a better word.

>The feature was meant for voice codec download.

Interesting point ...did MAS/Archos/whoever spill the beans on those codecs
too?

>Only very small codecs would fit, not
>"any one you'd like". The PCM "codec" is of course the most trivial one,
>just pumping data to/from the DAC/ADC. The MAS as a DSP is too esoteric,
>undocumented and proprietary to reasonably start your own codec development.

Yes, a *LOT* of effort in research/"hacking" the internals would be
required to _develop_ codecs.

>Patching the PCM codec into Rockbox for Archos is not not a trivial task.

I must say, that when I made my first comment re "trivial" I had not
considered as far as elements such as "bitswapping" and "WAVE stamping"
...which although, alone, are not "major" certainly breaches my earlier
prefix "trivial" ...Kinda glad I patched in a "should be" [and I _did_, go
back and add it in before hitting 'send'] ...LOL

>If done properly, it's an opportunity to renovate the playback+recording code,

NOW it becomes major :)

>like keeping the bitswap away from the big buffer, a different concept for
>metadata of buffered files,

How do the new HP/ipod/etc platforms handle multiple codecs? Surely there
must already exist a LoadCodec() ...Sorry for any mistake there, I have not
checked the source.

>a frame walker for mp3,

May I politely suggest that as we now have a util to resolve this issue
retrospectively, it may acquire a lower priority. I am NOT demoting this
feature to "plug my program" - the code is free-as-in-free(tm), in fact
I've not even got a download counter on it! (yet) ...What I AM doing is
promoting features that are as yet not available at ANY stage.

>trick modes, etc. I'd liked to have done that, but other priorities got in
>the way.

We need to get that 25hr clock from Zakk back :) LOL

>For full quality wav pumping, our poor CPU would be pretty busy with
>bitswapping. Don't let your expectations fly too high about running codecs
>on it, too. The disk will be busy, too, having 8 MB helps.
>I'm not worried about audio quality. When using S/PDIF, it's 1:1, as much as
>you can get.

I'm still up for a Rockbox MOD player :) All low-samplerates,
low-bitrates, limited-channels, etc :) ...even have a plugin mod file
sequencer to while away those bored hours on a train ...ejay anyone?

I still hold my hopes higher than others for a basic speech-synth to avoid
building all those voice clips - No, it would not be as slick as a 2Gb
install of <synthname here> but if it works for Stephen Hawkins...
...How about adding "DJ Scripts" ... LOL ... "DJ-Shuffle-Mode back with you
after that <genre> music. Bringing you next <songname>; a <random adverb>
piece of <genre> music by <artist> ...hit it!" LOL ...sorry, I am amused
easily ;)

Mixed stereo sound effects for plugins/games ...how about some "blind
games" - from what I could tell from my previous research, they are mainly
based on stereo positioning and reflex. Although in fairness you can do
stereo mixing of, for example, sound effects over backing music in a game
with Stereo-MP3 files already.

I wonder how easy it would be to pick out the 'fundamental' from a WAV and
write a Guitar Tuner :O

I wonder what effort is required to play SID files.

How about .tap files ...I always wanted to travel back in time and say "in
this box I have every 'speccy' game ever written" ...and show the dir
listing :) Heck, on the higher model machines I would be amazed if a full
4Mhz Z80 emulator were not possible!?

Ahh, the ideas are, as ever, more abundant than the time available.

BC
Received on Thu Jan 26 08:30:24 2006


Page was last modified "Jan 10 2012" The Rockbox Crew
aaa