gnome-cd skips

[Jonathan Corbet]

Sometime over the last month, a rawhide update bestowed upon me a
version of gnome-cd which skips.  Bits of the audio drop out every 30
seconds or so.

If I play a CD with cdplay, it sounds fine, as always.  So I believe the
problem lies with gnome-cd, rather than elsewhere in the system.

Anybody else seen this?  If there's any useful information I could
extract from the system, please let me know.

Thanks,

jon

[Jef Spaleta]

On Mon, 28 Feb 2005 16:11:25 -0700, Jonathan Corbet
 wrote:
> Sometime over the last month, a rawhide update bestowed upon me a
> version of gnome-cd which skips.  Bits of the audio drop out every 30
> seconds or so.

im not seeing this... i just listened to a whole album.. no problems.
maybe something is spiking cpu usage or memory spike and this is just
a symptom.

-jef"man this gerado album gets better and better everytime i pick it up"spaleta

[Kyrre Ness Sjobak]

tir, 01.03.2005 kl. 00.32 skrev Jeff Spaleta:
> On Mon, 28 Feb 2005 16:11:25 -0700, Jonathan Corbet
>  wrote:
> > Sometime over the last month, a rawhide update bestowed upon me a
> > version of gnome-cd which skips.  Bits of the audio drop out every 30
> > seconds or so.
>
> im not seeing this... i just listened to a whole album.. no problems.
> maybe something is spiking cpu usage or memory spike and this is just
> a symptom.

Dosn't gnome-cd play the cd directly analogly using the nice little
cable between the cdrom and the soundcard?

[Jef Spaleta]

On Wed, 02 Mar 2005 16:08:32 +0100, Kyrre Ness Sjobak
> Dosn't gnome-cd play the cd directly analogly using the nice little
> cable between the cdrom and the soundcard?

it use to... i dont keep up with whether or not gnome-cd is using gst
now and if the rawhide gst has the digitial extraction bits enabled
yet.

If its just playing analogly... where could the problem with playback
for the original reporter be software-wise?

-jef

[Kyrre Ness Sjobak]

ons, 02.03.2005 kl. 16.19 skrev Jeff Spaleta:
> On Wed, 02 Mar 2005 16:08:32 +0100, Kyrre Ness Sjobak
> > Dosn't gnome-cd play the cd directly analogly using the nice little
> > cable between the cdrom and the soundcard?
>
> it use to... i dont keep up with whether or not gnome-cd is using gst
> now and if the rawhide gst has the digitial extraction bits enabled
> yet.
>
> If its just playing analogly... where could the problem with playback
> for the original reporter be software-wise?
>
> -jef

I don't have a clue - but i have also experienced this behaviour. It
happened on an old 200mhz celeron running fc3 *before* some update which
happened just before christmas. After the update, everything was fine...

[Kjartan Maraas]

man, 28,.02.2005 kl. 16.11 -0700, skrev Jonathan Corbet:
> Sometime over the last month, a rawhide update bestowed upon me a
> version of gnome-cd which skips.  Bits of the audio drop out every 30
> seconds or so.
>
> If I play a CD with cdplay, it sounds fine, as always.  So I believe the
> problem lies with gnome-cd, rather than elsewhere in the system.
>
> Anybody else seen this?  If there's any useful information I could
> extract from the system, please let me know.

I filed this today because I was seeing skips with mixed data/audio CDs.
Is the CD you played back by any chance in this category?

http://bugzilla.gnome.org/show_bug.cgi?id=168978

Cheers
Kjartan

[Jonathan Corbet]

Kjartan Maraas  wrote:
> > Sometime over the last month, a rawhide update bestowed upon me a
> > version of gnome-cd which skips.  Bits of the audio drop out every 30
> > seconds or so.
>
> I filed this today because I was seeing skips with mixed data/audio CDs.
> Is the CD you played back by any chance in this category?
>
> http://bugzilla.gnome.org/show_bug.cgi?id=168978

I have such CDs, but *every* CD I play skips, regardless of whether it
has data tracks or not.  So I don't think that's it.

I ran it under strace for a bit today.  As others have guessed, gnome-cd
is not actually dealing with the music stream itself; that goes direct
to the sound card from the play.  I see the gnome-cd process doing two
things:

- Talking with the X server.  Not surprising.

- ioctl(20, CDROM_DRIVE_STATUS, 0x7fffffff) = 4

So now I'm beginning to wonder: might the real problem be a regression
in the kernel such that this ioctl() call perturbs a running CD drive?
*This* is the sort of problem I can try to track down (whereas what goes
on inside GNOME is a deep, dark mystery), so I think I'll try to carve
out a bit of time to dig further.

jon

[Jonathan Corbet]

Jonathan Corbet  wrote:
> Sometime over the last month, a rawhide update bestowed upon me a
> version of gnome-cd which skips.  Bits of the audio drop out every 30
> seconds or so.

Update time: research tells me that gnome-cd is reading the data from
the CD and feeding it to the sound card itself.  At least, when I play a
CD with gnome-cd, the "PCM" mixer control affects the playback volume,
while the "CD" control does not.

If, instead, I play with cdplay or grip, the volume is adjusted with the
"CD" slider.

The gnome-cd people had to go to some effort to make it work that way;
one wonders what advantages they were going for.

Meanwhile, with current rawhide, the skipping problem has gone away.  So
I'm happy...

jon

Jonathan Corbet
Executive editor, LWN.net
[e-mail]

[Alan Cox]

On Thu, Mar 17, 2005 at 05:04:56PM -0700, Jonathan Corbet wrote:
> The gnome-cd people had to go to some effort to make it work that way;
> one wonders what advantages they were going for.

The newer machines don't have an analogue cable for this to save a few cents

[Jonathan Corbet]

Alan Cox  wrote:
> > The gnome-cd people had to go to some effort to make it work that way;
> > one wonders what advantages they were going for.
>
> The newer machines don't have an analogue cable for this to save a few cents

Figures.  It leads to some interesting behavior - like the CD continuing
to play for a couple of seconds after the disc has been ejected.  I
suspect it will drive more users into the "we need extra low latency!"
camp as well.

jon

Jonathan Corbet
Executive editor, LWN.net
[e-mail]