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View Full Version : FLAC plays mono on SB1/SS6.0.0



Richard Elen
2005-04-06, 01:23
> From: Mark Bennett <mark (AT) markandliz (DOT) co.uk
> Not sure that the concept of bit rate has very much meaning for
> FLAC, other than for network bandwidth. The quality is totally
> unaffected by bitrate.
This is the figure given by SSQ2 when I ask it. I know it's pretty
meaningless but included it in case it gave useful bandwidth info.
Evidently not. :)
I'm using Michael Facquet's excellent FLAC encoder/Winamp plugin to rip
at default quality, which would appear to be 6 on a scale of 10. (There
are some interesting metadata display issues but that's another thread...)

> However, if you have a bit rate limit set for the SB1 then
> it will transcode to MP3 instead [of WAV]. Do you have a bit rate
> limit set for your SB1?

No, I'm set to "no limit". I don't have LAME installed, incidentally.
It's also interesting that the transcoding of whatever type is deciding
to go into mono (if that's what's happening).

Both stereo WAV and MP3 files play in stereo on the box, suggesting a
server issue.

In fact I need to look at exactly what /is/ being output when I play
FLAC files. I discovered this mono effect late last night and as a
result did not have the chance to look at it really carefully. I am
running the SB via S/PDIF coax into a surround processor with a Trifield
(3-speaker stereo) decode and noticed that on playing these test files
it all came out of the centre front speaker. I do not yet know whether I
am getting L+R or just one or the other, though my first impression
suggests L+R, and the same signal is being output on both S/PDIF channels.

> Slimserver version and platform/version (Win, Mac, Linux)
Linux/RH7.2, SS 6.0.0 (I thought I was downloading 6.0.1 but evidently
not).
> FLAC decoder version
Dunno. Where/what to look for?
> Have you made any edits to convert.conf?
No. Largely because I have limited time to tweak at present (and am
pretty much a newbie with this system), I am playing safe (release
versions, default settings, etc). What should I check here that relates
to this issue?

An aside: does anyone know what happens (with an SB2 of course) if you
rip a DTS CD to FLAC (instead of WAV) and try to decode it?

Thanks for the info and the assistance!

--Richard E

Richard Elen
2005-04-06, 13:38
Last time I noted:
> I don't have LAME installed, incidentally.

Well, I installed LAME and restarted the server; SS said that LAME was
"correctly installed"; and now this problem has gone away.

Doesn't explain why this was happening, but evidently LAME is a good
thing to have on board.

Thanks for the useful comments!
--Richard E

Mark Bennett
2005-04-06, 14:12
On Wed, 2005-04-06 at 09:23 +0100, Richard Elen wrote:
> > From: Mark Bennett <mark@********.co.uk

OT - it would be helpful if your mailer script didn't automatically
quote peoples email addresses when replying - it makes it so much easier
for spam email harvesters......

> > However, if you have a bit rate limit set for the SB1 then
> > it will transcode to MP3 instead [of WAV]. Do you have a bit rate
> > limit set for your SB1?
>
> No, I'm set to "no limit". I don't have LAME installed, incidentally.
> It's also interesting that the transcoding of whatever type is deciding
> to go into mono (if that's what's happening).
>
> Both stereo WAV and MP3 files play in stereo on the box, suggesting a
> server issue.

I agree that this would appear to indicate a server/transcoding issue.

For recent softsqueeze versions there is no transcoding it acts like
an SB2 and decodes the FLAC directly on the local machine, which
further points to a transcoding issue.

> In fact I need to look at exactly what /is/ being output when I play
> FLAC files. I discovered this mono effect late last night and as a
> result did not have the chance to look at it really carefully. I am
> running the SB via S/PDIF coax into a surround processor with a Trifield
> (3-speaker stereo) decode and noticed that on playing these test files
> it all came out of the centre front speaker. I do not yet know whether I
> am getting L+R or just one or the other, though my first impression
> suggests L+R, and the same signal is being output on both S/PDIF channels.

What comes out of the analogue/headphone outputs of the SB1?

Can you switch the fancy DSP off, and just use the external DAC?

> > Slimserver version and platform/version (Win, Mac, Linux)
> Linux/RH7.2, SS 6.0.0 (I thought I was downloading 6.0.1 but evidently
> not).

There have been some comments about SS 6.x.x being unsupported
on RH7.2 due to a broken perl build. I don't know if this could
be related, but it's probably unlikely.

> > FLAC decoder version
> Dunno. Where/what to look for?

For reference try "flac -version" in a command window.

I'm on flac 1.1.0.

> > Have you made any edits to convert.conf?
> No. Largely because I have limited time to tweak at present (and am
> pretty much a newbie with this system), I am playing safe (release
> versions, default settings, etc). What should I check here that relates
> to this issue?

This file defines how the transcoding is done. If you'd made
any changes to this then you could have different transcoding
going on than you had thought. You haven't edited it so this is
unlikely to be the problem.

Another interesting piece of data would be to turn the d_source debug
option on and then try to play a FLAC file. You'll see an entry in the
log looking something like:

2005-04-06 22:04:13.0769 command: [flac] -dcs --force-raw-format
--endian=little --sign=signed --skip=$START$ --until=$END$ -- $FILE$

This will confirm that the correct transcoding is happening.

--
"The biggest problem encountered while trying to design a system that
was completely foolproof, was, that people tended to underestimate the
ingenuity of complete fools." (Douglas Adams)

Mark Bennett
2005-04-06, 14:16
On Wed, 2005-04-06 at 21:38 +0100, Richard Elen wrote:
> Last time I noted:
> > I don't have LAME installed, incidentally.
>
> Well, I installed LAME and restarted the server; SS said that LAME was
> "correctly installed"; and now this problem has gone away.

OK, this is very strange. Are you sure you're not transcoding into
MP3? Check the d_source debug option in my other email to be
certain.

I've often found that problems that are fixed by apparently
unrelated changes often come back - usually when you least
want them to.

> Doesn't explain why this was happening, but evidently LAME is a good
> thing to have on board.

Apparently, but it shouldn't have made any difference...

--
"The biggest problem encountered while trying to design a system that
was completely foolproof, was, that people tended to underestimate the
ingenuity of complete fools." (Douglas Adams)

Richard Elen
2005-04-06, 14:39
Mark Bennett wrote:
> On Wed, 2005-04-06 at 09:23 +0100, Richard Elen wrote:
>>>From: Mark Bennett <mark@********.co.uk
> OT - it would be helpful if your mailer script didn't automatically
> quote peoples email addresses when replying - it makes it so much easier
> for spam email harvesters......

Apologies - that's the setup at work. There, I'm behind a firewall and
can only use certain things. I can edit content manually (and from now
will do), by cutting and pasting.

> For recent softsqueeze versions there is no transcoding it acts like
> an SB2 and decodes the FLAC directly on the local machine, which
> further points to a transcoding issue.

That's all happening correctly, and was before.

> What comes out of the analogue/headphone outputs of the SB1?

I'll never know, now. At the moment it is a rather lower-quality version
of what comes out digitally :)

> Can you switch the fancy DSP off, and just use the external DAC?
Yes, I did this before the problem went away - I just set the mode to
stereo :) - and I got identical outputs from L and R. This is the only
combination that could have given me a signal from CF only in Trifield
mode, so it's what I expected, but I /did/ want to check that half my
system hadn't gone off or something silly. I also tried a different
(2-ch) DAC altogether, same result. I also tried putting other stereo
S/PDIF sources into the same input and they came out in stereo, so it
was definitely a problem in the SS chain. Now everything's in stereo.

> There have been some comments about SS 6.x.x being unsupported
> on RH7.2 due to a broken perl build. I don't know if this could
> be related, but it's probably unlikely.

Would like to know more about this. I /do/ have a problem with starting
SS at boot, but that is not perl-related. I'm glad I didn't know about
this rumour earlier, I wouldn't have tried this version. I /am/ getting
the XML::Parser error referred to in Michael Herger's posts, which /is/
perl-related, but this seems to be innocuous.

>>>FLAC decoder version
> I'm on flac 1.1.0.
And so am I.

> Another interesting piece of data would be to turn the d_source debug
> option on and then try to play a FLAC file. You'll see an entry in the
> log looking something like:
>
> 2005-04-06 22:04:13.0769 command: [flac] -dcs --force-raw-format
> --endian=little --sign=signed --skip=$START$ --until=$END$ -- $FILE$
>
> This will confirm that the correct transcoding is happening.

This is pretty much the sort of entry I'm seeing. Hardly surprising as
it now works.

> I've often found that problems that are fixed by apparently
> unrelated changes often come back - usually when you least
> want them to.

Absolutely! Some other things have suddenly started to work, too,
notably Live365 now logs in to my VIP account as it should - I /never/
had that work on this machine before, even with 5.4.x.

Thanks for all your help on this, anyway. If it recurs, as it surely
will, I'll let you know after having checked the logs as you suggest.

--Richard E

"By Jove, that /is/ odd!" - Sir Henry Jowls, 4th Tower of Inverness