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mctrivia
03-28-2009, 02:48 AM
we now have a great wav player and it has been mention mp3 may be possible here (http://forums.parallax.com/showthread.php?p=695703). I would like to encourage the development of this so I am offering a propmod with uSD card reader and RTC free to the first to develop one capable of playing at minimum 90 kbps mono mp3 on 2 pins. stereo prefered though.

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Need to make your prop design easier or secure? Get a PropMod (http://propmodule.com) has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module with uSD reader, and RTC options.

Rayman
03-28-2009, 04:29 AM
I looked into this into some depth last year, enough to convince myself that it isn't possible with Prop I.

Here's some notes:

http://www.rayslogic.com/propeller/Programming/RaysStuff/MP3/MP3.htm

mctrivia
03-28-2009, 04:44 AM
If programed in pasm over a few cogs the code space could be reused. I am willing to accept that the cog can only be loaded once and must be kept running. Also a 64kb eeprom can be used in place of the normal 32kb giving you more space for code and tables. Though at a lower speed then hub ram.

It is probably difficult but i am sure there is some way to do it.

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Need to make your prop design easier or secure? Get a PropMod (http://propmodule.com) has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module with uSD reader, and RTC options.

Steel
03-28-2009, 04:53 AM
http://www.sparkfun.com/commerce/product_info.php?products_id=8892

mctrivia
03-28-2009, 05:06 AM
i know chips like this exist. even an object in obex for 1 of these chips. I want to add the mp3 player option to a product already build. using wav player now with 2gb uSD card.

Not to mention would be great just to have this as 1 more thing the prop can do without any extra hardware(other then the SD card for file storage and possibly larger eeprom for code storage 64kb are almost same price and pin compatible to 32kb)

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Need to make your prop design easier or secure? Get a PropMod (http://propmodule.com) has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module with uSD reader, and RTC options.

Post Edited (mctrivia) : 3/27/2009 10:28:37 PM GMT

hinv
03-30-2009, 03:07 AM
@Rayman,

Was the main limitation memory? Do you think that with external memory attached the prop would have enough processing prower in 1 or 2 cogs?

Thanks,
Doug

mctrivia
03-30-2009, 03:44 AM
i would be happy with 3 or 4 the prop is powerful enough that mundane task now that i use a whole cog for, for simplicity could easily be interlaced into 1 cog in pasm.

32kb of memory is not very much. but if you can use the upper 32k of an eeprom for slow tables and load faster tables into cog ram over 3 or 4 cogs you could gain a fair bit of extra space.

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Need to make your prop design easier or secure? Get a PropMod (http://propmodule.com) has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module with uSD reader, and RTC options.

Rayman
03-30-2009, 07:10 AM
memory is a problem, but processing power is the fundamental limit. With no single cycle multiply instruction, it just doesn't have processing power for real-time mp3 decode...

mctrivia
03-30-2009, 07:20 AM
ya unfortunately there are no 1 cycle instructions. it takes 64 cycles(16 instructions) to do 8x8 multiply. :(

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Need to make your prop design easier or secure? Get a PropMod (http://propmodule.com) has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module with uSD reader, and RTC options.

QuattroRS4
03-30-2009, 04:48 PM
It would probably make more sense to cater for 'Ogg Vorbis' rather than Mp3 due to licensing issues and associated cost - if and when this becomes a reality - most likely prop2 though.

Regards,
John Twomey

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'Necessity is the mother of invention'

Those who can, do.Those who can’t, teach.

Ale
03-30-2009, 09:27 PM
Vorbis is a bit more processor intensive than mp3 is :-( (AFAIK) so it would not be feasible. I'd like to be proven wrong on this, any takers ?

QuattroRS4
03-30-2009, 10:50 PM
Ale - Have a look at 'Tremor' Implementation of Vorbis .. very doable in prop2..

I am sure any extra code overhead for vorbis far outweighs the associated cost of incorporating Mp3 decoding - with a minimum fee per year - if one decides to sell something that incorporates mp3 decoding. - with a minimum of something like $15,000 PA. !!


http://www.xiph.org/vorbis/

Regards,
John Twomey

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'Necessity is the mother of invention'

Those who can, do.Those who can’t, teach.

Post Edited (QuattroRS4) : 3/30/2009 3:07:15 PM GMT

lonesock
03-30-2009, 10:54 PM
If you are open to other formats, check out CELT (http://celt-codec.org/).

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lonesock
Piranha are people too.