PDA

View Full Version : SB3 chokes on 24/96



deepblu
2006-01-28, 11:39
I have recorded a DVD-Audio (Peter Green Live at the BBC) in original format 24bit 96kHz.
When I stream (wired) to my SqeezeBox v3 (6.2.2) it plays just fine then chokes.
Audio stutters and slows.
Any thoughts?

Mark Lanctot
2006-01-28, 12:16
What format did you record in? WAV?

WAV is the highest bitrate of all formats. If it
plays then stutters, this may be more of a
bandwidth/buffer filling issue than anything.

Try compressing to FLAC using the command-line or
a FLAC frontend.

deepblu wrote:
> I have recorded a DVD-Audio (Peter Green Live at the
BBC) in original
> format 24bit 96kHz.
> When I stream to my SqeezeBox v3 (6.2.2) it plays
just fine then
> chokes.
> Audio stutters and slows.
> Any thoughts?
>
>

--
___________________________________


Mark Lanctot
___________________________________

deepblu
2006-01-28, 12:27
Thanks for the advise.
I have recorded to a .wav file then transcoded to FLAC.
Still chokes at the same spot.
I have full duplex 100mbps wired network.
When I play the track on any other media (PowerDvd,Nero etc) it plays fine.

seanadams
2006-01-28, 12:47
96KHz isn't supported - I'm surprised you get any sound at all!

Is this a DTS rip or something?

deepblu
2006-01-28, 12:52
Not ripped - direct stereo record off the DVD using Wavelab5 through my onboard 24bit DAC
Same symptom applies to the same recording downsampled to 48kHz

deepblu
2006-01-28, 14:40
Should I report this issue as a possible bug?

kdf
2006-01-28, 14:52
deepblu wrote:
> Should I report this issue as a possible bug?
>
http://bugs.slimdevices.com/show_bug.cgi?id=1394

and note, internally (firmware include) sb2 and sb3 are basically identical.

-kdf

deepblu
2006-01-28, 15:14
Maybe a menmber might like to see if he can reproduce the problem.

Also, for pcm .wav files, what are the specs for the unit?

MrD
2007-05-14, 16:21
I have the read the Bug 1394 report. I see that the newer SB firmware, downsamples a 96khz signal.

I am trying to play some linn 24/96 flac files on my SB3 (firmware 81). The sound is normal, but, I get a lot of stutter with these files. The SB3 is hooked up via the analog connections (i.e. I am using the SB3 DAC).

Should the SB3 be able to play these flac files correctly?

NB these files play fine on my transporter, as expected.

Edit:

I guess these are related

http://bugs.slimdevices.com/show_bug.cgi?id=4311
http://bugs.slimdevices.com/show_bug.cgi?id=4886

On a separate note; are there plans to have a per player convert.conf file?

Ron F.
2007-05-14, 17:08
This has been discussed to some degree in the audiophile thread (Linn Records now doing Flac) http://forums.slimdevices.com/showthread.php?t=34985

Bascially, you can play "24/96" flac files on the SB3 if you recode them in real-time as compression-level-0 as they are streaming. See comment #10 in bug #4886.

While this essentially works, I feel the performance is worse than the same material playing at "16/44.1" if using an SB3. I find the noise floor rises considerably as a result of the way the SB3 down-samples a 96kHz stream to 48 kHz.

I would down-sample the file using Audacity to 48 kHz and stream that result to the SB3.

-Ron

MrD
2007-05-14, 18:28
Thanks!

Yep, I tried the convert.conf thing and the SB3 plays appropriately.

There *is* an audible hiss in the material, however during quiet passages, I am not sure if this is in the source or not.

I would have to compare it with my transporter.

Ron F.
2007-05-14, 19:04
MrD,

I think you will likely find that the hiss you hear will not be present when the same file is played through your transporter.

I suspect the SB3 firmware lacks an adequate decimation filter for receiving a 96 kHz stream, (I suspect maybe there is none at all) ... maybe there is not enough room in the SB3 for such an addition?

-Ron

mswlogo
2007-05-14, 21:36
No hiss when I play 24/96 on Stock SB3 over SPDIF.

Eye in the Sky HDAD sounds great !!!

Ron F.
2007-05-15, 08:04
mswlogo,

That is interesting. What kind of file format are you streaming? In all of my experiments I have been streaming FLAC, and I have not tried other formats, such as WAV.

I wonder if it is possible to get the SB3 to stream 96 kHz out of digital port without down-sampling it to 48 kHz first? I get the same hiss whether I stream over SPDIF or the SB3's analog output, so I am pretty sure I am not getting a straight pass-through.

What did you use to rip the HDAD disk?

Thanks,
Ron

Ron F.
2007-05-18, 12:57
An update...

I looked at a sample of one the Linn Records 96kHz 24bit FLAC files I downloaded. What I found was a significant noise hump centered at about 40 kHz, it appears to peak at -64 dB. It begins at about 24 kHz and cuts off sharply of course at 48 kHz.

When files like this are sent to the SB3, that noise hump is going to be aliased into the audio spectrum, centered at 20kHz? That noise hump is very audible after the SB3 gets done decimating the 96kHz stream to 48kHz. There is a significant amount of energy in that hump - why is it there? What purpose does it serve? When played through a Transporter, is anything gained by its presence? It is fairly constant and does not appear to carry any content that is coherent with the music stream.

A 96kHz file cost approximately twice what a 44.1kHz file cost. Why? Why is that noise hump so expensive?

Anyway, The SB3 needs an FIR that cuts off at 24kHz before decimating a 96 kHz stream.

-Ron

MrD
2007-05-26, 17:29
An update...

I looked at a sample of one the Linn Records 96kHz 24bit FLAC files I downloaded. What I found was a significant noise hump centered at about 40 kHz, it appears to peak at -64 dB. It begins at about 24 kHz and cuts off sharply of course at 48 kHz.

When files like this are sent to the SB3, that noise hump is going to be aliased into the audio spectrum, centered at 20kHz? That noise hump is very audible after the SB3 gets done decimating the 96kHz stream to 48kHz. There is a significant amount of energy in that hump - why is it there? What purpose does it serve? When played through a Transporter, is anything gained by its presence? It is fairly constant and does not appear to carry any content that is coherent with the music stream.

A 96kHz file cost approximately twice what a 44.1kHz file cost. Why? Why is that noise hump so expensive?

Anyway, The SB3 needs an FIR that cuts off at 24kHz before decimating a 96 kHz stream.

-Ron

higher order harmonics?