JohnSwenson wrote: > Recent tests on the DAC chip I'm using in the CSP hardware have > determined that it is not possible to adjust the interpolation filter > characteristics. This is one of the prime reasons for wanting to use > that chip in the first place, it was supposed to have fully adjustable > parameters. Well it does for everything except the interpolation filter! > > > There is one way to turn off the internal filter which is to feed it 352 > or 384 sample rate data. That means an external upsampler program is > needed before the output to the DAC chip. SOX is a good candidate for > this since it has a very good upsampler with adjustable parameters so it > can be tweaked to get very good sound out of the DAC chip. > > I have done experimentation with this offline (run sox on the file, > output to a new file at higher sample rate, play new file), the results > are very very good when doing this, so I think the concept is sound. We > just have to figure out if it is possible to do this in realtime on the > wandboard. > > I know that SOX can be used with the server, but I want this to be in > the player not the server, so people can continue to use NAS boxes, > pogoplugs etc. for their server. So we need some way to get SOX into a > pipeline with squeezelite. This might be possible with ALSA but I'm not > sure if that is how we want to do this. > > I expect Triode is going to have to be the prime factor in this, so > Triode, any thoughts how this can be done? > > BTW this does not mean we don't need the programming interface for the > DAC chip, there are still other things that need to be programmed into > the DAC chip. > > John S.
I think Clive is already using sox to upsample to 384 on the server. Clive - does this work in real time if the server is on the wandboard? We can probably include libsoxr or libsox in squeezelite if it needs to be in the player. Do you know if libsoxr will do what we need with appropriate quality? ------------------------------------------------------------------------ Triode's Profile: http://forums.slimdevices.com/member.php?userid=17 View this thread: http://forums.slimdevices.com/showthread.php?t=98544 _______________________________________________ unix mailing list unix@lists.slimdevices.com http://lists.slimdevices.com/mailman/listinfo/unix
