giro Posted June 5, 2014 Share Posted June 5, 2014 *Purely Experimental* - Back to basics - I'm after a music player that is strictly fixed point front-to-back in order to emulate the process Philips employed for getting 16bit performance out of a 14bit mulitbit. However instead of 14bit, I want to experiment with 8bit (which is not far from vinyl hifi performance regarding SNR). Essentially I want to emulate vinyl. I did research and discovered fixed point decoder MPEG audio decoder (MAD) CoolPlayer is an option but no re-sampling or dither plugins are available for it. I'm sure it wouldn't be too hard to impliment sox plugin for it eitherway. I also found MAD plugin for winamp, I'm sure to achieve "8bit", the plugin upsamples x64 and dithers down for clean 8bit out - though it would be nice to know what it's going on internally and change resampler to sox (also mad based). As I say, the mad plugin for winamp probably is my best bet but incorporating sox would top it off nicely - i'm contacting the developer for more info. Unsure if winamp is fixed point front to back though ~ ? Any thoughts? Cheers Link to comment
iago Posted June 5, 2014 Share Posted June 5, 2014 I'm not quite sure where your journey is leading you, but kindly allow me to question a few of your assumptions. If you are referring to the first generation of Phillips DAC chips, these were not multi-bit. They used R-2R networks and were simply limited to 14 bit resolution. I think you are aming too low with the 8-bit resolution for Vinyl. This would give you a SNR of 48 dB. I would assume at least 60-70 dB noise floor for a standard turntable assembly, which would give you around 11 bit resolution. As far as I know, Philips was decoding the CD in a normal way (I think you have no choice, because of the necessary format translation from Reed Solomon to LPCM). Only the final D/A conversion was 14 bit. To overcome this limitation they used 4x oversampling, which gained them 1 bit in resolution. Ideally you should create your own plugin for WinAmp, first upsampling the original data and afterwards decimating the resolution. You could also do it on file level; upsampling is fairly easy, but I'm not sure if the available software allows you to arbitrarily manipulate the resolution (there may be hardware or file format restrictions also). Primary ::= Nabla music server | Mutec MC-3+USB w/ Temex LPFRS-01 RB clock | WLM Gamma Reference DAC; Secondary ::= Nabla music server | WaveIO | PrismSound Lyra Link to comment
Skeptic Posted June 5, 2014 Share Posted June 5, 2014 I'm not sure why you would want this, but JRiver has a bitdepth simulator you can enable in the Parametric EQ DSP. This can be set to any bit-depth you want from 4 to 24 bit, with dithering being optional. Link to comment
giro Posted June 19, 2014 Author Share Posted June 19, 2014 Ok, thanks for the response. y Link to comment
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