fsger wrote: > Hi Marco, > > Thanks for the great plug-in. It is easy to use and really improves the > sound quality compared to upsampling on my RPI3B+ in picoreplayer. As > you have noted, this partly because the flac is converted to cpm on the > server (a Synology DS218). > > I have a possibly stupid question...I normally set the output level of > the player to be fixed at 100% but I have read that digital volume > control can be better than analogue volume control but only when > dithered. Most of my material is 44.1 KHz, 16bit. If I upsample to > say, 192KHz, is there any point in also converting to 24bit or 32bit > (which I believe just adds zeros), and then applying dithered volume > control? If there is a benefit, is there a way to get LMS to use this > instead of non-dithered volume control? > > I have a DigiOne S/PDIF board in the RPI3B+ that outputs to a 32 bit > DAC, so I would need to do any volume control on the sever. > > Thanks!
cfuttrup wrote: > I'm surprised there should be a difference, since both implementations > use SoX, as far as I understand. Anyone care to explain the differences > here? > > About your question on bit depth. The advantage of adding bits is that > when you use digital (e.g. software) volume control, then the added bits > are used to reduce rounding errors. Here's a presentation from ESS about > it: > http://www.esstech.com/files/3014/4095/4308/digital-vs-analog-volume-control.pdf > > Best regards, > Claus Not sure LMS is using SOX for volume control. As far as I know one of the first advise about using LMS for 'HiFi' is to disable volume control, maybe in not becouse SOX but multiple LOSSY conversions needed when in and out is MP3, I don't know. BTW, even if it's made by SOX, it's inside a separate 'effect chain', so with precision as low as the input bit depth ant that is not good when you have other DSP to be applied (* keep reading). The one implemented in C-3PO - Manual gain reduction (in dB) - is using SOX AFTER the pcm conversion and BEFORE the (optional) conversion to the output format (when a different one is selected) im the same "effect chain" togheter with all the other DSPs. SOX is considered one of the best tool for doing that. Internally all the effect chain is working at 64 bit depth so the 'rounding error' is much, much lower than piping different steps at 16 or even 32 bit, so I really advise NOT to pipe a digital volume control AFTER the C-3PO work, BUT use the provided one instead (that's why *, also). PLEASE ALWAYS leave some headroom (at least 3 db, 6 is better) when upsampling os using any effect. You could also consider the loudness control instead/in combination of gain reduction, it's the same BUT ISOPHONICS curves are applied instead of a 'flat' gain reduction. Used as it should be, is great. Same for ANY other effect, like convolution for instance, much better to use the 'slots' in C-3PO to add SOX effects and the reason is always that inside a single effect chain the 'precision' is 64 bit, rounded (and possibly dithered, depending on your choice) a the selected output precision only once, at the end. Hope is clear and please forgive my english, as usual. Marco. ________________________________________________________________________ Author of C-3PO plugin, Squeezelite-R2, Falcon Web interface - See www.marcoc1712.it ------------------------------------------------------------------------ marcoc1712's Profile: http://forums.slimdevices.com/member.php?userid=34842 View this thread: http://forums.slimdevices.com/showthread.php?t=105309 _______________________________________________ Squeezecenter mailing list [email protected] http://lists.slimdevices.com/mailman/listinfo/squeezecenter
