Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[ksigman]

I use a PS AUDIO DirectStream DAC, and a MAC Mini (USB) for music server (running OS10.9.3).
When I was using Media Center 19.0.124 for quite some time now and played CD rips (16/44.1), the DAC displayed just as that (16/44.1) and passed a bit-perfect test (a FLAC file that PS AUDIO supplies).

However, recently after downloading a newer version of Media Center, all would be displayed as 24 bit even though the input was 16 bit.
I found out that that is normal, that the newer versions of Media Center always go to 24 bit in the processing
and is explained well in here:  http://wiki.jriver.com/index.php/Audio_Bitdepth

BUT:  I re-downlaoded the version 19.0.24, had both that version and the newest version 20.0.29 available to me upon demand, and now BOTH
yield 16 bit (not 24) and both versions pass the bit perfect test with the DAC......

This persisted even after restarting the computer and opening either version alone.

I then threw out the version 19.0.24 altogether, restarted the computer and yet version 20.0.29 still results in sending out as 16 bit.


Baffled. I should add that all other files (24/44.1, 24/96, 24/192, etc.) play out on the DAC exactly as they are/should.

[6233638]

Media Center will always select the highest bit-depth that your DAC supports.
The reason for this is that a 16-bit file played over a 24-bit output is just the 16-bit track with a number of zeros added to the end, padding the output to 24-bit.
1111111111111111         becomes
111111111111111100000000
 
The reason for doing this, is that as soon as you make a change to a 16-bit file, you require more than 16-bit to avoid losing any quality.
 
For example, if you have a 16-bit track and reduce the volume by 6dB, that is equivalent to reducing the file from 16-bit to 15-bit. (1-bit is equal to approximately 6.01dB)
1111111111111111 becomes
0111111111111111 with that lower bit being lost

If you reduce the volume of a 16-bit track by 6dB inside a 24-bit signal, however, you still have the full 16-bit resolution. (but are now using 17-bits of information)
It's not until you have more than 48dB of attenuation (8-bits) that you start losing quality again.
111111111111111100000000 becomes
011111111111111110000000 with no loss in quality
000000001111111111111111 as you can see here, you can do 48dB (8-bits) of volume attenuation without a loss in quality.
 
So it is never harmful to use more bits than the source material, but it can be harmful if you are using the same number of bits as the source material on output.
If you are not making any adjustments, 16-bit inside a 24-bit container should remain bit-perfect. My DAC will identify 16-bit (CD) or 20-bit tracks (HDCD) inside a 24-bit container from Media Center if I am not making any adjustments to them.
 
As soon as I touch the volume control, the DAC sees it as a 24-bit signal. (as it should)
And with lossy tracks (MP3, AAC etc.) Media Center will always use the full bit-depth.
Lossy tracks use floating-point data rather than integer, so even if you started with a 16-bit track, it will require greater than 16-bit output for the highest quality playback.

[ksigman]

Thanks: But when I increase the volume (even up to the loudest), the DAC still says it is 16 bit.
The perplexing thing is why is this doing this on version 20.0.29 which is 24 bit, and why did it "flip" back to 16 bit after exhibiting 24 bit for awhile.....
(The sound quality is fine, that is not an issue, I am just wanting to know what is causing this "bug" in the communication between my DAC and Media Center.)