Support and General Use > Audio Playback, Database and Playlists
-24db Precut Sound Quality on Rockboxxed iPod?
Andhyka:
Of course as I stated on the diagram above, the output will always be some decibels short because Rockbox outputs it on 16-bit audio signal wide to Wolfson DAC.
DIGITAL 16bit -> DSP 16bit on 28bit/32bit -> DAC 14bit on 14bit/16bit (or 12bit, I don't know which one)
As for the signal quality on 32-bit Rockbox internal DSP, there's no depreciation.
If only Rockbox outputs in 24-bit...
Ofcourse, pre-cut on current Rockbox cuts away the 4bit (-24db) of signal data, and I don't intend to use it.
If only Rockbox has normalize/compress algorithm...
Llorean:
If the only operation you're doing in the DSP is the digital gain adjustment, outputting at 24-bit should be no different than 16-bit. Math again.
And I told you already: COMPRESSING IS NOT LOSSLESS.
Mathematically the least you can possible lose is the least significant bit. Please, do some proper research on the audio side, and learn basic math.
Do you know the mathematical difference between "dynamic range compression" and "Reducing the volume"?
And I remind you again, though I already did in PM, that you need to read the rules. This is your last warning on that one.
Andhyka:
I understood everything that Llorean said, and is entirely valid.
What I wrote in the few posts beforehand is my wish that Rockbox could develop this feature in future builds so that to get better sound quality out of iPod.
I did decide not to use pre-cut before (as mentioned in the thread).
Llorean:
I think you don't understand: You cannot magically prevent the loss of data. All you have is a choice of which data will be lost. Why don't you look into what exactly precut does, rather than jumping to a conclusion based on the phrasing a user used, and see and decide for yourself whether that's better or worse than analog volume adjustment.
Andhyka:
Yes I do know the difference.
Dynamic range compression determines the fidelity/clarity/detail of sound, and is related to 16bit/24bit/32bit.
And also, I can get the same quality with any volume as long as I put my ipod line-out on headphone amp.
Just one last question before I bail out of this unconstructive thread ever:
Does Wolfson DAC accepts 24-bit digital signal?
If not, then I'm throwing away everything I know.
If yes, what I am proposing is "reducing the volume" through the use of wide "dynamic range compression" of 32-bit Rockbox DSP.
Therefore I can listen the cleanest signal reproduction iPod can reproduce from my iPod without requiring headphone amp.
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