Proceeding
Well stuff is happening. I have been investigating different lossless audio schemes and at the moment the most likely ones are going to be:
FLAC
Bonk
Shorten
ALAC (Apple Lossless Audio Codec)
Shorten
I have gone through ALAC & Bonk and got them going under MSVC using very cut down interfaces that will be suitable for an embedded enviroment. I have also started putting togther some of the core classes for talking to the peripherals on the board. I intend to initially implement stubs for most of the stuff in C++ then if required we will recode bits in Assembler. The processor has some quite neat bit addressing schemes that may speed up some of the interesting bit manipulations that are required for the Rice compression schemes used by most of the lossless codecs.
The hardware has also progressed slightly with the demo board now attached to a sort of motherboard. I have also invested in a extra display that is off a Nokia phone. They are very cheap for what you get and good resolution, 128 x 128 with an SPI interface. I am starting to think that i am going to need to implement this as two fairly tightly coupled processors as even if the core is fast enough i think that we are going to fall off the end of the world with pins! The other option is going to be a PLD or possibly an FPGA. I have a couple of devices that could do the job but i would rather not do it that way...
1 Comments:
This sounds like an interesting project!
I am the developer of the WavPack lossless audio format, and I was wondering why you weren't considering it also. It is completely open (like FLAC), it has an optional lossy mode which might be useful for creating longer playing disks, and I have already done an ARM optimization of the decoder for the Rockbox project. Let me know if you have any questions about it (my e-mail address is on the WavPack website); I'd be happy to help out.
BTW, although I'm from California, I have actually been to Fremantle! I was spending the day on Rottnest (during a 3-day trip to WA) and met a family from Perth and the next day they took me to Fremantle and introduced me to some of the local artists. Very cool little area...
5:51 AM
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