MP3 players - Page 1
Forum section: electronics / beginners

author: funfairEE
author_rank: Contributor
timestamp: April 19, 2012, 04:26:55 pm
content: I am wanting to build a simple MP3 player that plays different MP3s with different switches, each switch plays a different mp3. I am thinking that the way it wold probably work is have a micro controller with some form of memory chip, the micro to find the mp3s in the storage, move them into the built in ram on the micro then output it on one of the pins.is there a simpler way?Is there any of the shelf chips that are dedicated to this sort of thing?any information on this subject is much appreciated.thanks a lot funfairEE

author: harnon
author_rank: Regular Contributor
timestamp: April 19, 2012, 11:21:22 pm
content: There are probably a billion mp3 player schematics on the web..... E.g.http://www.opencircuits.com/Music_Player? You may be able to adapt one of these.Most devices use a Chip fromhttp://www.vlsi.fi. These are relatively expensive in small quantities because of the mp3 licensing costs, however Sparkfun sell some of the chips and mp3 shields for Arduino as well, just do a search there.

author: funfairEE
author_rank: Contributor
timestamp: April 21, 2012, 03:43:29 pm
content: are there any similar chips to the vlsi ones that decode a few different formats like mp3 and wav, not having any look finding a UK suppler.

author: amyk
author_rank: Super Contributor
timestamp: April 22, 2012, 10:36:34 am
content: It might be easier and cheaper to modify an existing MP3 player to do this for you.

author: SoftwareSamurai
author_rank: Regular Contributor
timestamp: April 22, 2012, 03:13:24 pm
content: What about...THIS?(Yeah, okay, not out yet, but still...pretty exciting!)

author: funfairEE
author_rank: Contributor
timestamp: April 22, 2012, 07:38:42 pm
content: Quote from: amyk on April 22, 2012, 10:36:34 amIf i was to do that wold probably have to desolder all the components and use them but its a possibility I guess.

author: TerminalJack505
author_rank: Super Contributor
timestamp: April 22, 2012, 07:55:50 pm
content: Are you needing to play MP3s? Or do you just want to play music/sound? If you avoid the whole MP3 patent issue you'll have a lot more options. You can decode the MP3s on your PC into your own format and use that, perhaps? Nice thing about this option is that youmightbe able to get away with using an 8-bit MCU if you keep the encoding simple.If you really need to decode MP3s then you'll need at least a low end 32-bit MCU for the decoding. Then check into projects such as this one:MAD: MPEG Audio DecoderIt's Open Source but there is still the whole MP3 license issue so you're probably expected to pay a fee to someone.Atmel has an application note about using this decoder with their UC3 MCUs:Atmel AVR32840: AVR UC3 Audio Player MAD MP3 DecoderI haven't used the decoder. I just found it doing a little Googling.

author: T4P
author_rank: Super Contributor
timestamp: April 23, 2012, 03:13:44 pm
content: There are codes out there meant for ARM used for MP3 decoding . STM32F4 ... w/eBut STM32F4 being ARM Cortex-M4 means you don't need to deal with a extra DSP if you do need , because it's there already , and a high performance one on top of that .

author: amyk
author_rank: Super Contributor
timestamp: April 24, 2012, 10:00:43 am
content: Actually you don't need that much CPU power to decode MP3.The old common s1mp3 designs (ATJ208x/9x series) mostly had a Z80 and 24-bit DSP running at 72MHz, and that was enough to decode MJPEG too (128x160, 15FPS). If I remember correctly ALi had a design with an 8051 running at ~120MHz and that could do video too

author: T4P
author_rank: Super Contributor
timestamp: April 24, 2012, 03:58:29 pm
content: Quote from: amyk on April 24, 2012, 10:00:43 amBecause it's cheap and available , it isn't a outdated design and it reduces part counts .

author: slateraptor
author_rank: Frequent Contributor
timestamp: April 24, 2012, 05:00:02 pm
content: Quote from: Dave.S on April 24, 2012, 03:58:29 pmWhat does that have to do with anything??Quote from: funfairEE on April 19, 2012, 04:26:55 pmAs harnon has already suggested, the simplest way would to integrate an off-the-shelf mp3 decode ASIC into your design. It's expensive, but without a doubt the simplest.

author: T4P
author_rank: Super Contributor
timestamp: April 24, 2012, 06:57:18 pm
content: Quote from: slateraptor on April 24, 2012, 05:00:02 pmIf he was referring to my post , then it's true . Because off the shelf 8051's cost the same as a STM32F4 ...

author: codeboy2k
author_rank: Super Contributor
timestamp: April 26, 2012, 02:24:34 am
content: If you need MP3 because its a design to be used by others, beyond your control, and it's a design need, then you wouldprobably need to use an off-the-shelf mp3 decoder.However, if you have control over the source files, and are planning to pre-load the device with various sound filesto play at the flip of a switch, then why not use OGG as your source format. It's open source, no royalties, and if youdo have original source material in MP3, you can use a PC to convert it to OGG format for storage on your device.Again, this is only a solution if you have control over the source audio. If you expect others to load clips, and play them,then you probably need to use MP3, unless you can train your uses to first convert files to OGG format.OGG is considered superior to MP3, and is free and open source.

author: amyk
author_rank: Super Contributor
timestamp: April 26, 2012, 09:58:28 am
content: If you're going to convert then why not convert to uncompressed PCM format like WAV. NAND flash is cheap enough these days and if all your device is going to have to handle only several short songs. A 2GB (16Gb) chip can hold more than 6 hours of 16-bit 44.1KHz stereo PCM. That greatly simplifies the hardware and software because all it has to do is read data from the flash and stream it to a DAC.

author: slateraptor
author_rank: Frequent Contributor
timestamp: April 26, 2012, 07:18:16 pm
content: Quote from: amyk on April 26, 2012, 09:58:28 amI'd argue that half the fun is in decoding the MP3.