JohnSwenson wrote: > Some quick thinking and back of envelope figures comes up with the > following: > > One board which has CPU, main memory (DDR2 or DDR3), boot rom, ethernet, > USB, S/PDIF out, I2S to a DAC chip, WiFi and HDMI. No onboard display, > no server. > > I have found some very nice new processors that do almost everything > here, have linux distros ready to go which include drivers for all this > (including audio for USB, I2S and S/PDIF). Quick calculations come up > with $170 for board, all parts, and assembly in 25 unit quantities. Of > course price goes down as quantity increases. > > This does NOT include: case, power supply, antenna and final assembly. > > I found a very interesting DAC chip for this. As some of you might have > read in my posts, I am convinced that one of the biggest problems with > getting REALLY good sound from digital audio is the compromised digital > filters in DAC chip. This DAC is uniquein that it has a general purpose > DSP system included which allows you to implement your own filter! (by > default it uses the good old broken design that everybody uses, but you > don't HAVE to use it) Using a non compromised filter will significantly > improve the sound quality over what you can get from say a Touch. It > also has enough power to do things like room correction filters, speaker > crossovers etc. And it costs $9 in singles. It has a direct drive output > so it can directly drive RCA jacks without any caps or op amps etc. > > With this DSP it can easily do things such as what was done in the Boom > without adding any extra circuitry. It can also do other things such as > Dolby digital or DTS decoding. I would add a connector on the main board > so you can add an inexpensive daugther board and get 4 more outputs, you > can then have it do surround sound or digtial crossovers for triamped > speaker systems. With all the processing done inside the DAC chip! > > The WiFi is also rather interesting, I found a little WiFi module which > has it's own processor which has a web server for configuratgion, > supports bridge mode, AP mode AND has a router and DHCP server built in, > all for $30. This means that not only can it connect to an existing > wireless network, it can make it's OWN wireless network so you can use > iPeng (or whatever) without having to have an existing network or > worrying about how to connect this box and your chose remote to > something else. It offloads all the wireless encryption etc from the > main processor, it just looks like a wired ethernet device to the main > processor (it also has a 5 port ethernet switch built in which can even > do VLANs if you REALLY want to do fancy IT stuff) > > Without having to do display or wifi stuff the main processor really > doesn't have all that much to do, just run linux, IP stack, audio > drivers and Squeezelite. It doesn't need to be a very powerful > processor. There are some very nice new processors which are very low > power (electrical wise, not throughput wise) which have two processors > on the same chip, one which is the main processor and the other that is > optimized for peripheral handling which takes care of a lot of the real > time interaction with things such as the ethernet and USB, freeing up > the main processor from having to deal with the low level interactions > with these. The linux drivers deal with all this already. > > With the low power use of everything in the system it might be quite > possible to run this as a battery powered device. It's not going to be > very big either, something like 3x3 inches. > > How does that sound, any thoughts? > > Thanks, > > John S.
Hi John - many thoughts on this.... 1) Anything from an arm5 at 400Mhz or so would be enough for basic flac playback and possibly a limited display, but it would be infinitely preferable to have hardfloat support and armv6, single core would be ok (Pi type class - armv6 or later, 600MHz or more) 2) Floating point means better support of aac and vorbis and allows the standard libfaad, libvorbis to be used 3) Squeezlite has as small a footprint as I could manage, but it would be nice to have a bit more memory if we want to do hdmi user interface. [I have some thoughts in that area too - can you make it 128M at least?] 4) Can we validate it has real ehci usb hardware rather than the s*** that Pi has!) 5) Can we pick something which is arm based so libspotify will work on it? 6) Ability to run some form of server would be nice, long term this need not be LMS! However I think it would be good to have some headroom unless you think this hits the cost too much. ------------------------------------------------------------------------ Triode's Profile: http://forums.slimdevices.com/member.php?userid=17 View this thread: http://forums.slimdevices.com/showthread.php?t=97881 _______________________________________________ discuss mailing list [email protected] http://lists.slimdevices.com/mailman/listinfo/discuss
