Wave/Mp3 Recorder and Player (DIGICIII-Digic II)?

[RaduP]

Sure, but is it the main CPU that does that, or is it done by some specialized chips that only do those things?

[LjL]

The heavy duty processing is done by the DIG!C chip, but the main processor is an ARM that most likely does 200MHz or so, enough for MP3...

[whim]

@LjL

all IDA dumps I've looked at so far (40+) contain the following strings:

LClock=72MHz
LClock=36MHz
LClock=18MHz
HClock=72MHz
HClock=36MHz
HClock=18MHz
MClock=72MHz
MClock=36MHz
MClock=18MHz

so I think 200 MHz is on the optimistic side ...

wim

[LjL]

Ah, well... I'm familiar with ARM processors from other devices, which all tend to be clocked at around 200MHz.

Anyway, I also have a Psion 5mx with a 36MHz ARM processor; it can play MP3 at 8Khz, 8 bit (that's also a soundcard limitation), probably no more than 64Kbps or so, but I'm not really sure. I don't even remember if the thing used to be open-source... it's a bit lost in cyberspace now. The names to search for are "ENoteM" and "EPlayM", anyway, developed by Alexander Zavorine (who doesn't seem to have a website anymore).

[cybercom]

FWIW,

My TX-1's record and playback *.wav files at 44-, 22-, and 11-kHz up to the full capacity of the SDHC card. An 8GB card indicates 120 minutes recording available at 44.1 kHz, 16-bit, stereo - which is CD quality audio.

HTH,

[LjL]

Right, but encoding and decoding MP3 is very much more processor intensive...

[cybercom]

[RaduP]

I am not sure why exactly are you asking this question. Obviously, the mp3 at any bit rate is much more CPU intensive than uncompressed sound, because the uncompressed sound doesn't use the CPU.

[LjL]

Yes, I'm really not sure either. All the stuff you're putting in bold talks about bitrate, i.e. memory taken on a storage device or bandwidth needed for transfering over a network.

Neither is what anyone was talking about. I think we know pretty well how much MP3 encoded audio fits in a SD card, as well as how much (less, obviously) fits as 44KHz, 16bit encoded.

Decoding PCM data involves reading a word and feeding it to the D/A.

Decoding MP3 involves taking Fourier transforms and things like that.

If you need a proof that the latter is more computationally intensive, well, I'm not sure I know of a place that can has it - I generally don't Google for completely obvious things.

[frank]

I've read somewhere that it's 72Mhz
another point: if that is possible, could it be possible to hear the music with in-ear headphones via the video ouput? ;the plug would fit in it..

[albuemil]

Well, i'm not so sure it would be such a good ideea to have an MP3 player on the camera, after all the baterries diy up quite fast if you make a lot of shots and i bet listening to music would eat up baterries just as fast (if not even faster since the decoding would need to be done constantly).
Even having games on the camera seems a little out of the scope of the device.
I'm not saying that it wouldn't be nice to have a camera that does everyhting (maybe even coffee ) but we have to think about the practicality of those stuff and especially how much would all those "features" influence (in a negative way) the original use of the device (in this case taking pictures).

[LjL]

Actually, my own opinion is more like "who cares". Nobody is certainly forcing anyone to use their camera as an MP3 player... but for those who want to, more power to them. I don't think I'm in the position to make their penny-counting for them.

Then of course, something like this needs developers, and it all depends on whether or not they are interested.

[frank]

For beginning, maybe just convert songs into the wav-format of the camera.
Can be difficult because the camera taken sounds are in a special wav-format.
Don't know if that format is different on different Canon cameras (Videos can only be shown by the camera model they are taken with)

[kuku]

maybe someone will try to port rockbox to digic cameras - it would be simplier to port something than write from scratch

rockbox is running on hardware with as low as 2MB of ram on hardwaer with arm cpu and has a lot of features - look at
http://www.rockbox.org/twiki/bin/view/Main/WhyRockbox

The guys at rockbox are working even on a possibility to run rockbox as an app on hardware that has an api (windows mobile, symbian) so we could try to port it to the chdk elf edition
http://www.rockbox.org/twiki/bin/view/Main/SummerOfCode2008#Rockbox_as_an_Application

(sorry my poor english)

[harvald]

Mp3 player in camera have two main advantages. First AA bateries. You can buy them anywhere and can have many with you. Mp3 in cellphone don't give that and no one wants to be without phone. Second is memory card. In this days they are huge. Not many mp3 players have memory cards, so they have hard limit for capacity. Additionally one device is more comfortable than couple.