[ALSA - driver 0001359]: cs46xx DTS pass through works, but AC3/Dolby Digital does not

[bugtrack@alsa-project.org]

The following issue has been SUBMITTED.
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<https://bugtrack.alsa-project.org/alsa-bug/view.php?id=1359> 
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Reported By:                rjh
Assigned To:                
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Project:                    ALSA - driver
Issue ID:                   1359
Category:                   PCI - cs46xx
Reproducibility:            always
Severity:                   major
Priority:                   normal
Status:                     new
Distribution:               Fedora Core 4
Kernel Version:             Linux 2.6.12-1.1398_FC4 (a standard FC4 kernel)
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Date Submitted:             08-22-2005 20:57 CEST
Last Modified:              08-22-2005 20:57 CEST
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Summary:                    cs46xx DTS pass through works, but AC3/Dolby Digital
does not
Description: 
Dear Alsa developers.

I have an interesting situation with my Terratec XFire 1024 and Sony
STR-DB930 external amplifier.

I have a dual boot system. When I use Windows and Windows DVD players,
digital pass-through sound works perfectly. When I switch to Linux FC4 +
Alsa + Xine, only DTS pass-though sound works. In particular, when playing
a typical DVD that uses Dolby Digital sound by default, the amplifier
recognizes that it is receiving Dolby Digital signal (Sony STD DB-930
front panel shows text "Dolby Digital [3/2]", and all the apropriate
status lights are turned on, too), but no sound comes out. Likewise, no
DVD intro sounds that play before and during DVD menus can be heard (but
Sony STD DB-930 front panel shows for example text "Dolby Digital [2/0]").
There is no humming, rattling, popping, or some other artifact sounds
either, just silence.

If I on the other hand select a DTS sound track using Xine DVD menu
functions, the aplifier recognizes that it is now receiving DTS signal
(font panel shows "DTS [3/2]"), and sound plays as it should!

If I configure Xine to do the decoding and output normal stereo sound,
that works too, but without the benefits of surround sound, of course.

It would therefore seem that current ALSA cs46xx driver can almost but not
quite output Dolby Digital sound in a format that the Sony STR-DB930
amplifier recognizes. One the other hand, DTS signal comes through ok. I
hope that these observations will propably limit the number of locations
where the problem may be.

I would also point out that the amplifier status display reacts correctly
to changes in signal type. This propably proves that at least something
does indeed come though correctly. Finally, the fact that everything works
perfectly with Windows drivers shows that the card and amplifier can work
together.

I have also tried to randomly change the control values in Xine iec958
control string (the audio.device.alsa_passthrough_device parameter that
has the default value of "iec958:AES0=0x6,AES1=0x82,AES2=0x0,AES3=0x2) but
without any effect.

I have also tried various control values with 'iecset' utility, but again
without any effect.

I have no custom .asoundrc settings in place.

I have to admit that I have not tried other recent players than Xine
0.99.4-1.2.fc4 yet, mainly because latest mplayer current crashes and I
have had some trouble compiling it, too. However, I have observed the same
problem earlier with older Xine and mplayer version is some older Linux
distribution (and exactly the same hardware).

I would be very thankfull for any advice. I would also be happy to run any
additional tests you might consider usefull.

  Rami
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Issue History
Date Modified  Username       Field                    Change              
======================================================================
08-22-05 20:57 rjh            New Issue                                    
08-22-05 20:57 rjh            Distribution              => Fedora Core 4   
08-22-05 20:57 rjh            Kernel Version            => Linux
2.6.12-1.1398_FC4 (a standard FC4 kernel)
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