Rockbox Player - Project to design and build a Free/Open hardware audio player

[AlexP]

How about multichannel (e.g. 5ch) audio output? Rockbox does support AC3 (Dolby Digital). Is analog or digital out preferred for multichannel audio?

For analog, would you not have to have three jacks and decode on-board?  If such a feature were available, digital would seem the obvious choice.  However, were a digital output available, would this be a software thing, patching rockbox to just output the stream over digital?

interesting. what are you using it for?

To have a high quality connection to my amp (and speakers) which is of better quality than the one in the H100

(note: $ refers to USD)
Basically, *most* needs of Rockbox users can be met by existing players on the marked. ... You can get a c200 or e200 for <$50 - $60, sometimes less than $20 and they feature radio, recording, internal mic, and MicroSDHC.

Thats not a precise information, actual selling Sansas are V2 models and Rockbox do not work with them.

They are still available, be it new from a few stores, refurbs, on ebay etc.  What Llorean said was perfectly true, although yes, you must watch out for v2.  However, it is perfectly possible (and I would have thought in the long term probable) that Rockbox will run on them.

[Llorean]

Digital(optical) for multichannel, almost absolutely I would think.

Honestly, if I were to list every feature I want in a player for it to qualify as an "upgrade" from things I've got already:
PERSONAL WISHLIST TIME
-Software USB w/ USB host potential
-Full size SD slot
-FM Radio
-320x240 16-bit screen (or better, portrait acceptable instead it's the number of pixels that counts)
-Tactile input as buttons. No sticks, knobs, or touch sensitive bits. Just real, physical buttons: Play, Power, Vol+, Vol-, Left, Right, Up, Down, Menu, Select as a minimum selection of buttons.
-Potential for a remote (I can't begin to speak about how much I like the iRiver LCD remotes)
-Disk based storage (you can replace it with flash more easily than you can replace soldered flash with a disk, and this also means if the storage fails this part of the player is easy to replace)
-Digital line In and Out
-Analog line out (not just the headphone out)
-Analog line in
-A processor equal or greater in speed than the Gigabeat F (300mhz ARM of some sort). This may seem like overkill, but I guarantee Rockbox is going to offer more and more CPU intensive DSP ops over time, as well as expanding the video codecs supported so a fast, general purpose CPU gives the player room to become more as Rockbox becomes more. I'd rather pay more for something that gives Rockbox room to grow, since I can already have players that do everything Rockbox can currently do.
-USB charging
-LiPoly/LiIon battery that's easy to replace

Really nice extras:
-Remote actually made to go with it.
-Bluetooth 2.0 (wireless headphones and limited file transfer, it's a portable device so WiFi seems a little wrong to me)
-Video out potential (again that whole room for improvement thing)
-Hardware hold switch
-Some form of integrated screen protector or an easy to replace "screen" over the LCD itself
-Real time clock
-integrated mic

While I believe I can get each of the first list of feature from at least one of my players, the ideal would basically be to have a player that has hardware for all the existing Rockbox functionality, while offering enough processing power to allow the software to expand. Hardware mostly abstracts into "input" and "output" and there's just not TOO many variants on that theme, it's what you accept in, and what you put out, that allows the uniqueness I think.

You may also notice I've not mentioned "small size" or "light weight." I'm probably in the minority on this one, but I find anything that comes out around the size of a Archos Jukebox Recorder V1 or smaller acceptable. And weight is irrelevant as long as it doesn't win against my belt.

[spark]

Thanks Llorean, that was a very comprehensive list of features. I've copied it to a file for easy reference 

Having all these features makes larger size and weight inevitable. But we don't want to build just another player that does just the same thing what others do.

One suggestion. instead of having so much packed into a single unit. does it make sense to split some of them into accessories? e.g. assuming we have a USB host port on board, things like bluetooth, Digital in/out, SD/flash card could be accessories over USB. This solves dual purpose, ur belt is lighter, and at the same time you have all features when you need them.

[Llorean]

Personally, I would accept digital in/out, video out (and in?), analog in, line out (separate from headphone out) all as part of a single connector like the iPod dock connector, with an adapter or adapters for accessing those features. It's not ideal but it does mean that you don't have a dozen ports on the side. The actual USB jack needs to be standard though (you should never need to depend on a single specialty cable, it's frustrating to have a player disabled if you damage the cable and most people have a half dozen spare USB cables). I think SD would be preferable internally more or less because it's nice to be able to carry a card around in your player and be able to easily exchange a few files or songs with a friend, without having to pocket dongles. Bluetooth is pretty much "internal or none" anyway, since wireless headphones aren't much good if you've got this odd wired bluetooth dongle flopping around out there. Maybe make sure it's SDIO capable? That covers, possibly, WiFi or bluetooth from a second angle anyway, and makes them more or less internal.

[spark]

Yes. Dock connector is neat.

Connector list
* 1 Headphones/line out
* SD slot
* Dock connector (line in, line out, digital in/out, remote control, USB, maybe video out also)
* mini USB connector

We can keep the connector somewhat compatible with Ipod so that accessories like amp-speakers can be used.

http://ipodlinux.org/Dock_Connector

Does rockbox firmware support any bluetooth peripheral yet?

[Llorean]

Just a note, "Headphones" and "Line out" are two separate things. So it really should just be "1 headphone"

There's no player with any way of handling bluetooth yet. It'd fall into one of those "future ideas" kinds of things, which does make it well suited for an SDIO card rather than something internal (less work to just get the built-in hardware of the player up and running with Rockbox).

I'm not wholly sure duplicating the iPod dock connector is the best idea. For one, it'll be partially useless for things that expect a certain form factor. For another, it's possible that any pins where we differ (and there will be some if we decide to offer features they don't) might cause problems with some accessories.

If it were at all possible, what I'd do is try to have pins to coincide with all of those, but in a unique dock connector. Then follow up to see if it can be made to contain the pins of other dock connectors we support. There probably won't be too many more pins than just that of the iPod. Then you're left with a connector than can be adapted into an iPod or a Sansa or a whatever dock connector by the users, because it contains a superset, but allows for access to features beyond just what the iPod has. Just, y'know, a "given a perfect world" case for what I'd like to see regarding this sort of thing. As it is we really don't go out of our way to support iPod accessories at the moment, so basically anything that's expecting more than a line out and a bit of power really won't work anyway.

[ZincAlloy]

bluetooth is not really important when designing a product for audiophiles, though. I expect audiophiles to use cable bound headphones. you might want to do some research at an audiophile kind of forum, for example the audio hardware section of http://www.stevehoffman.tv/forums/ .
while a larger than average size sure will be accepted you will still need to be careful to make it not too bulky. we're talking about a portable device here.
I think bootleggers would prefer to have digital and line inputs directly on the player and not in a dock..
An SD slot might not be important anymore if the device has usb on the go..

[Llorean]

This product isn't only for audiophiles. If it were we'd probably leave out a screen entirely since updates can generate very small increases in noise, etc.

I'm not sure there's a particularly relevant reason to design for bootleggers when we're copyright respecting folk around here.

And you completely missed my reasoning for having an internal SD slot. USB on the go requires cables or dongles, and a card reader or external flash drive, neither of which can be stored inside the player so you don't have to carry other things around.

[petur]

talking about bootleggers when discussing recording is something that will offend almost everybody  in the taping scene.

bootleggers record shows and sell them, 100% illegally
tapers make recordings for their own or for sharing (for free), most of the time this is known and allowed by the bands.

And apart from that, there are many other legal uses for line-in. So if you're scrapping line-in from the design because of bootleggers, I'd remove the headphone/line-out of it too because many people have illegally ripped CD's on there anyway...

edit: so to clarify, normal standard connectors on the main body please

[Llorean]

The suggestion wasn't "remove the line in" but whether or not it should be directly on the unit, or accessed by way of a dongle / special connector to keep the size of the main unit down somewhat. Perhaps the headphone out could double as a line-in like some iPods?

[spark]

i think we'll rather start work on the hardware. Some features may have to be added/removed as the design progresses.

The most critical component is the CPU. There has already been a vast amount of discussion about this, and we had finalized the AT91SAM9620/9621. This CPU has 200MIPS of power. 
The selection of this CPU was done considering a number of points such as long term availability, features, open community support, documentation.

We have already started research & development using this CPU, so it may be a difficult to go for a change now.

FYI: Gigabeat F/X uses Samsung S3C2440 CPU which is hard to get in small quantities, and no much documentation available.

[markun]

FYI: Gigabeat F/X uses Samsung S3C2440 CPU which is hard to get in small quantities, and no much documentation available.

I'm not saying you should use the S3C2440, but I think the documentation is quite good:

http://www.rockbox.org/twiki/pub/Main/DataSheets/um_s3c2440a_rev10.pdf

[casainho]

FYI: Gigabeat F/X uses Samsung S3C2440 CPU which is hard to get in small quantities, and no much documentation available.

I'm not saying you should use the S3C2440, but I think the documentation is quite good:

http://www.rockbox.org/twiki/pub/Main/DataSheets/um_s3c2440a_rev10.pdf

We can read on Samsung web page of that product:
To download the product information, go through the registration process and log in and then ask for the file you want.
You can ask for information on products we provide all at once through "request", and it will take a maximum of 24 hours for your request to be confirmed. We will let you know whether your request is confirmed through your registered email and you will be able to download the approved file through "download".

I don't see any application notes, codes, for that MCU on Samsung product page.

In Atmel product page for the AT91SAM9620, we can immediately and directly download the datasheet, application notes examples, codes and even Atmel stimulates a Linux port. Thats why I think Atmel gives good information for the AT91SAM9620 and others Atmel MCUs.

[spark]

Samsung is not that friendly to people with small volume requirements. They don't even provide appnotes and sample code freely. On the other hand Atmel is very good in terms of support. See the list of appnots that are available
http://www.atmel.com/dyn/products/app_notes.asp?family_id=605

Again, i cannot find the Samsung part on digikey/mouser. If i contact Samsung to send me a sample, they will just ignore me cause i'm not from a big company. So i guess we should avoid using such parts.

I hope there is no problem with at91sam9260/61. Casainho has already purchased a dev board.
* 12Mbps USB is a problem here, but there is always scope to add an external Hi-Speed OTG controller (NXP's ISP1761)
* 200MIPS is sufficient i guess. (we are talking about a decent rockbox player and not some high end video processing engine or game console)

I'm skeptical about providing video out option. It shouldn't be a priority.

[casainho]

I agree with ZincAlloy, when he says:

just being designed for Rockbox IS a unique feature in my humble opinion. just take a look at the unsurpassed set features that Rockbox has to offer.

add to that a digital input, great audio quality, a decent screen, a large capacity hard drive and put it into a sturdy casing and you've got an Ipod killer. The audiophile crowd will love it for sure - and not only them. A player that focuses on great music playback is what many music enthusiasts are looking for.

I DO think that it is worth spending time, effort and money on this idea. And I'm sure you will be able to sell far more than 100 players.

Another advantage of this player would be an open and standard hardware, long life. In my guess, Sandisk did change the hardware to Sansas v2 just to cut prices and that is bad for us consumers, because we don't have Rockbox for V2 and we don't know how many times Sandisk will change hardware. Sandisk is like the others that change hardware to continue to have "good" prices and add new neat features - as example, what Pasen said about their new products every 2 or 3 months.
If we see Arduino, we know that the base hardware should not see new versions just to cut prices or all the code and hardware available on internet made by communities and companies will not work with new versions.
Arduino is made with Atmel 8 bits MCU because(my guess) Atmel have a lots of information, example codes, application notes and stimulates de GCC-AVR and AVR-Libc.

About my work
I am being very busy, putting a lot of my free time, life, in the project and I am learning a lot, as I pretended in the beginning.

I made a simple ¨flash LED¨ program for the development board, however I could not test it because I do not have, right now, the necessary tools. I quickly created a project page in code google, as I pretend to use that svn for share the first codes to having the hardware working until be able to launch Rockbox firmware. http://code.google.com/p/rockboxplayer/

A short list of technologies that I had to learn, read some tutorials, etc:
- jtag cable -- I bought the USBprog and I am setting up it in hope to use it to program the u-boot on the dev. board.
- dev. board -- I had to search and read information about u-boot, put the dev. board to work. I bought some USB <-> RS232 serial cable + null cable modem.
- u-boot -- I did some reads about u-boot and using stand alone programs with it, also find a way to upload programs, TFTP, USB, serial kermit...
- make -- I did read some tutorials about making files, compiling and ELF files... I did a simple make file for the flash LED code.
- SVN -- I am reading bout SVN and I want starting using it for sharing all the code.
- I bought a cheap, ultra portable pc, with Linux, the eee pc -- I can and I am now reading and coding while on the train (going and backing to/from work) or on the lunch times, as I am doing right now ;-)