Please excuse me for starting just another "questionable" thread discussing differences in perceived sound of bit-perfect playback ;-)
Before we had LAV Audio I used ffdshow together with JRiver MC for audio decoding. Back then I perceived a difference in "sound signature" when selecting 32bit fp output instead of 16bit/24bit int in ffdshow. The situation is just the same since using LAV audio. I discussed this matter with nevcairiel over at Doom9 some time ago and he suggested to keep the source bit depth untouched for output (therefor letting LAV audio auto-selecting the output bit-depth, because LAV audio's int->float converter is rudimentary and just intended as fallback for hardware not supporting certain formats). With lossless audio this is 24bit int (in very few cases 16bit int). So far so good. After we got convolution integrated into MC now I decided to do another comparison.
My playback chain: source is bdmv in most cases (lossless audio tracks) -> decoded by LAV audio (with the ARCSOFT dts decoder used for DTS HD tracks) -> in Media Center I use convolution (using 64bit fp Acourate filter) and "room correction" DSP for setting the channel levels. No other DSPs are used. Output is to a Prism Sound Orpheus Firewire interface via ASIO. 7.1 speaker setup using Danley SH-50 and Genelecs 1037Cs.
I am comparing LAV audio decoding with 24bit int output (native source format of my lossless sample tracks) and 32bit fp output (be forcing this output in LAV Audio).
I want to suggest the following:
- the final audio output of these two options is quite different.
- Subjectively I would describe the difference as following: in famous audiophile terms the 24bit decoding (with MC doing the int-float conversion) is sounding "rather smooth and laid back" in comparison. Forcing LAV Audio to output 32bit fp into the MC audio engine results in a more "aggressive, coarse" sound signature. My personal preference (sadly) is for later. Logic suggests that doing this int->fp conversion once with the JRiver audio engine is the "better" way to handle this necessary step. But no matter how often I switch between these two options with a large variety of content I continue to prefer the 32bit fp output from LAV audio (subjectively).
So, I should be happy and just use the option I like better, right? ;-)
Well, I want to understand why there is a sound difference. I am willing to provide samples and record the output of both options to make my point. But anybody trying these two options should be able to hear the difference (given you have a very accurate, revealing speaker setup).
If we can agree that int->fp conversion really makes a difference whe might learn something in order to improve payback with LAV audio and JRiver media center. But wait, it is all bit-perfect playback ;-)
For the time being I enjoy my placebo effect and keep forcing LAV audio to output 32bit fp ;-)
@ nevcairiel: Would it be much effort to implement 64bit fp as output option in LAV audio? On the one hand this would likely make my placebo effect even stronger (larger numbers are always better...) and on the other hand this is the native format JRiver including convolution (and my FIR filters) does all its internal processing. I would very much appreciate it although I am aware that you don't see much sense in such an option.