| 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? | 20:24 |
|---|---|---|
| zumbi | I was thinking on cortex-m based thingy | 20:25 |
| zumbi | maybe something fpga based is better | 20:26 |
| 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 ? | 20:29 |
| 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 | 20:30 |
| 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) | 20:32 |
| ysionneau | so even a 75 MHz PIC32 might be able do to it | 20:35 |
| ysionneau | to do it* | 20:35 |
| 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 | 20:37 |
| zumbi | thanks guys.. I wanted to play streams, so better if I add some audio decoding chip | 20:43 |
| zumbi | and leave CPU for network activity | 20:44 |
| zumbi | however I am looking to that helix libs | 20:44 |
| zumbi | sounds interesting | 20:44 |
| acathla | external decoding chip was used in firsts MP3 players, now acceleration is integrated in the µP | 20:48 |
| acathla | and hardware decoder decodes ONLY what's it's designed for, like only MP3 | 20:49 |
| zumbi | acathla: I was thinking on VS1053 | 20:50 |
| zumbi | Ogg Vorbis / MP3 / AAC / WMA / FLAC / MIDI Audio Codec Chip | 20:51 |
| 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 | 20:52 |
| zumbi | davidc__: I was thinking on some ARM based device running some kind of linux, but, I was targeting a device per room | 20:56 |
| 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* | 20:57 |
| acathla | ? | 20:58 |
| acathla | what's the link between audio quality and decoding from a chip or another? | 20:59 |
| acathla | the quality will be made by our DAC and amplifier | 21:00 |
| zumbi | well, yes, I meant DAC on ARM dev boards is usually bad | 21:04 |
| acathla | using an external decoding chip won't solve the problem, unless it has an embedded DAC | 21:06 |
| zumbi | cortex-m4 can do 32-bit single cycle MAC ops | 21:09 |
| 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 (Ive 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. | 21:38 |
| Hawk777 | (and zumbi) | 21:39 |
| zumbi | nah! it does not have ethernet.. I know those boards | 21:42 |
| Action: zumbi needs to review class D speaker driver | 21:42 | |
| Hawk777 | Oh, I didnt know Ethernet was a requirement. | 21:43 |
| Hawk777 | Whoops. | 21:43 |
| Hawk777 | The MCU does though, so if youre thinking of custom boards its still on the table. | 21:44 |
| zumbi | I am being deviated to something based on raspberry pi and use hdmi audio | 22:00 |
| --- Tue Sep 24 2013 | 00:00 | |
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