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View Full Version : 24/96 PCM to SB3 not so good.



mswlogo
2007-04-13, 22:46
I thought SB3 would smoothly downsample 24/96 down to 24/48.

I know I can reduce it in software but I didn't want to keep 2 copies and want to keep the original 24/96.

It plays choppy sometimes on 24/96 music.

Same file plays fine using foobar2000.

Tried wired and wireless. Server is wired.

Everything else plays fine (DTS, DD, PCM 16/44).

File is encoded in FLAC.

ymilner
2007-04-13, 22:50
http://bugs.slimdevices.com/show_bug.cgi?id=4886
See the description; there is a workaround - not ideal, but should solve the problem

mswlogo
2007-04-14, 14:23
I added my vote.

Sounds like it's not truly fixable.

The best fix sounds like to downsample it off line.

mswlogo
2007-04-14, 21:49
They added a note tonight on the bug and are trying to make the decoder more efficient so that this may get fixed with existing horse power.

ymilner
2007-04-14, 23:44
They added a note tonight on the bug and are trying to make the decoder more efficient so that this may get fixed with existing horse power.

Actually, it was Josh Coalson, FLAC inventor, who added this note:) Nice to know he is following SB development so closely!
The next step would be for slim devices (Logitech) to embedd the new library in the firmware!

Rangdo
2007-04-15, 00:08
In the meantime, why not just decode on the server side and stream WAV?

ymilner
2007-04-15, 03:17
In the meantime, why not just decode on the server side and stream WAV?
Yes, came to my mind too; but no luck:

http://bugs.slimdevices.com/show_bug.cgi?id=4311

Rangdo
2007-04-15, 03:47
Oops, good point - I raised that bug too :D

What I've done for now is just retain the WAV file until that one is fixed - it's been a little while so I'd forgotten.

Obviously I lose the tag information on those tracks but otherwise they play fine.

mswlogo
2007-04-15, 07:30
The best workaround for me right now is to just down sample the flac file. It will sound perfect as the SB3 is capable of and I don't like having scan FF/RW not work due to transcoding. That was the whole reason I switched my library from wma lossless to flac.

ymilner
2007-04-15, 11:00
The best workaround for me right now is to just down sample the flac file. It will sound perfect as the SB3 is capable of and I don't like having scan FF/RW not work due to transcoding. That was the whole reason I switched my library from wma lossless to flac.

Yes, that's what I did too with those few 24/94 rips I have. I just keep the original files off-line, waiting for SD to fix the firmware (or for transporter, if this day will ever come:) ).
BTW, what do you use for downsampling?

Mark Lanctot
2007-04-15, 13:23
I just keep the original files off-line, waiting for SD to fix the firmware (or for transporter, if this day will ever come:) ).

The Transporter plays 24/96 natively, in both WAV and FLAC form.

In FLAC, the only limitation is you can't use ReplayGain and the spectrum analyzer screensaver at the same time, the CPU hits the wall.

http://bugs.slimdevices.com/show_bug.cgi?id=4463

The Squeezebox did play 24/96 fine by dropping every other sample and playing at 24/48, but there have been problems with this recently.

jt25741
2007-04-15, 16:07
Yes, that's what I did too with those few 24/94 rips I have. I just keep the original files off-line, waiting for SD to fix the firmware (or for transporter, if this day will ever come:) ).
BTW, what do you use for downsampling?

Hi Ymilner, have you tried different downsampling tools? From what I read going from 96K->48K is not rocket science and any reasonable downsampler will work well. I have used PPHS and SRC codecs in Foobar with success. For whatever reason, SRC seems to sound better to me...dont know why. Maybe due to its superior low-past filter to filter above the new Nyquist frequency(which gets reduced by 1/2 with the downsampling) Now going from 96 to 44.1 is not an even multiple, so rocket science is involved -- and I dont think any public domain(free) resamplers do a good job. r8brain is an example of one that costs over $70, but does a great job. You can seach on that if interested. There have been posts on this subject that have been very informative. The good news is that the SB does 24/48 native, so getting very high quality from 24/96 material is possible by downsampling and easy. I think pre-processing the file is better than letting the SB do it in firmware because the low-power SB implementation doesn't filter out the introduced artifacts by the bit reduction(no low-pass filtering). I think most of the perceived improvements seem to be obtained from 16/44.1 to 24/48 anyways(HUGE improvement)....to 24/96 possibly is a bit overkill...open to debate I guess -- I have not done extensive listening tests, but some here.

Pale Blue Ego
2007-04-15, 20:30
I agree that the greater bit-depth seems to improve the sound more than a higher sampling rate. I spent this afternoon listening to some very enjoyable 24/48 files (and comparing them with the same tracks in 16/44.1). The SB3 did a great job, never choked once even though I used ReplayGain.

As to the original question, why not decode the 24/96 files to wav, then recode to FLAC using a lower compression setting like 0 or 1?

mswlogo
2007-04-16, 11:34
I saw posts saying that lowering FLAC compression helps but does not eliminate so I didn't bother.

I use dbPowerAmp to convert.

But it had to convert to wav then back to flac in two steps and I lost the tags.