20:24 <zumbi> hello! maybe this is not the right channel, but I'll ask, which is good and inexpensive option to be able to play/decode audio streams?

20:25 <zumbi> I was thinking on cortex-m based thingy

20:26 <zumbi> maybe something fpga based is better

20:29 <ysionneau> I don't think you need FPGA to decode audio

20:29 <ysionneau> small cpu can do it I think

20:29 <ysionneau> it depends on the encoding

20:29 <ysionneau> which format do you want to decode ?

20:30 <ysionneau> I don't remember if we tried decoding mp3 on LM32 on FPGA

20:30 <ysionneau> but I bet any arm core can do it with their bunch of hundreds of MHz

20:32 <acathla> there are microcontrolers specialized for that, like the portalplayer µP

20:32 <davidc__> I've done MP3 decoding on a 70mhz ARM7TDMI

20:32 <davidc__> 'twas a portalplayer, actually (they don't have any fancy HW support)

20:35 <ysionneau> so even a 75 MHz PIC32 might be able do to it

20:35 <ysionneau> to do it*

20:37 <davidc__> hardware multiplier and fast barrel shifter are key IIRC. The Helix decode library is quite good (all fixed point) but it has a bit of a funky license

20:43 <zumbi> thanks guys.. I wanted to play streams, so better if I add some audio decoding chip

20:44 <zumbi> and leave CPU for network activity

20:44 <zumbi> however I am looking to that helix libs

20:44 <zumbi> sounds interesting

20:48 <acathla> external decoding chip was used in firsts MP3 players, now acceleration is integrated in the µP

20:49 <acathla> and hardware decoder decodes ONLY what's it's designed for, like only MP3

20:50 <zumbi> acathla: I was thinking on VS1053

20:51 <zumbi> Ogg Vorbis / MP3 / AAC / WMA / FLAC / MIDI Audio Codec Chip

20:52 <davidc__> zumbi: why not just drop down a 200+mhz ARM? They're cheap and have plenty of horsepower.

20:52 <acathla> ou still need a microcontroller, but probably with less code to write

20:56 <zumbi> davidc__: I was thinking on some ARM based device running some kind of linux, but, I was targeting a device per room

20:57 <zumbi> so, low cost and high quality audio is interesting.. but it might be easier to use on of those raspberry pi boards (which does not do hw audio decoding) and most devices quality is crap

20:57 <zumbi> audio quality*

20:58 <acathla> ?

20:59 <acathla> what's the link between audio quality and decoding from a chip or another?

21:00 <acathla> the quality will be made by our DAC and amplifier

21:04 <zumbi> well, yes, I meant DAC on ARM dev boards is usually bad

21:06 <acathla> using an external decoding chip won't solve the problem, unless it has an embedded DAC

21:09 <zumbi> cortex-m4 can do 32-bit single cycle MAC ops

21:38 <Hawk777> acathla: the STM32F4Discovery board (used to be insanely cheap, $15 IIRC) has a nice ARM chip and a “CS43L22, audio DAC with integrated class D speaker driver” on the board, among other things. I have no clue what the audio quality of that chip is (I’ve never used it), but it might help you.

21:38 <Hawk777> The CPU runs up to 168 MHz.

21:38 <Hawk777> No hardware decoder, but it might be beefy enough to run a software decoder.

21:39 <Hawk777> (and zumbi)

21:42 <zumbi> nah! it does not have ethernet.. I know those boards

21:43 <Hawk777> Oh, I didn’t know Ethernet was a requirement.

21:43 <Hawk777> Whoops.

21:44 <Hawk777> The MCU does though, so if you’re thinking of custom boards it’s still on the table.

22:00 <zumbi> I am being deviated to something based on raspberry pi and use hdmi audio