[mythtv-users] Digital Audio Problems - Noisey, stuttering, skipping
Mike Smith
easygreenus at yahoo.com
Mon Jan 19 22:08:15 UTC 2009
Sorry for the weird description. Machine gun like doesn't sound very technical.
Using Fedora 10.
I'm building a new Mythfrontend box in preparation for capturing HD. I have a
Gigabyte motherboard that uses the Nvidia 9400 chip set. It uses the Realtek
ALC889A chipset. Interesting board for HDTV, if I can get it all working.
It have VGA, VDI, and HDMI outputs to connect to the TV.
For audio, it has an optical SPDIF that I am trying to use. I have connected
an optical cable to it.
bash-3.2$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: NVidia [HDA NVidia], device 0: ALC883 Analog [ALC883 Analog]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 0: NVidia [HDA NVidia], device 1: ALC883 Digital [ALC883 Digital]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 0: NVidia [HDA NVidia], device 3: NVIDIA HDMI [NVIDIA HDMI]
Subdevices: 1/1
Subdevice #0: subdevice #0
bash-3.2$
bash-3.2$
bash-3.2$ aplay -L
front:CARD=NVidia,DEV=0
HDA NVidia, ALC883 Analog
Front speakers
surround40:CARD=NVidia,DEV=0
HDA NVidia, ALC883 Analog
4.0 Surround output to Front and Rear speakers
surround41:CARD=NVidia,DEV=0
HDA NVidia, ALC883 Analog
4.1 Surround output to Front, Rear and Subwoofer speakers
surround50:CARD=NVidia,DEV=0
HDA NVidia, ALC883 Analog
5.0 Surround output to Front, Center and Rear speakers
surround51:CARD=NVidia,DEV=0
HDA NVidia, ALC883 Analog
5.1 Surround output to Front, Center, Rear and Subwoofer speakers
surround71:CARD=NVidia,DEV=0
HDA NVidia, ALC883 Analog
7.1 Surround output to Front, Center, Side, Rear and Woofer speakers
iec958:CARD=NVidia,DEV=0
HDA NVidia, ALC883 Digital
IEC958 (S/PDIF) Digital Audio Output
null
Discard all samples (playback) or generate zero samples (capture)
pulse
PulseAudio Sound Server
default
Default
I followed the steps Mythtv Wiki article
Configuring Digital Sound with AC3 and SPDIF
and
Configuring Digital Sound
I have configured the alsamixer and checked the iec958 and iec958 Default PCM boxes
and can see the laser light come on ( pointed at some white paper, of course. )
I downloaded an ac3 file called Prelude.wav from the net and ran:
bash-3.2$ aplay -D iec958 Prelude.wav
Playing WAVE 'Prelude.wav' : Signed 16 bit Little Endian, Rate 44100 Hz, Stereo
Music plays fine and the DTS light on my receiver goes on.
I downloaded some music tracks that that are .ac3 and they all play fine.
I also ran the speaker test recommended:
bash-3.2$ speaker-test -c6 -t wav
speaker-test 1.0.18
Playback device is default
Stream parameters are 48000Hz, S16_LE, 6 channels
WAV file(s)
Rate set to 48000Hz (requested 48000Hz)
Buffer size range from 32 to 349525
Period size range from 10 to 116509
Using max buffer size 349524
Periods = 4
was set period_size = 87381
was set buffer_size = 349524
0 - Front Left
4 - Center
1 - Front Right
3 - Rear Right
2 - Rear Left
It worked, and the DTS light comes up on my receiver.
I go into the mythtv sound setup. Its the third screen under
"General".
Audio Output Device - Alsa:Default
Passthru Output Device - Default
Max Audio Channels 5.1
Checked "Enable AC3 to SPDIF Passthrough"
Checked "Enable DTS to SPDIF Passthrough"
Checked "Use Internal Volume Controls"
Mixer Device - Alsa:Default
Mixer Controls - Master
I can play my Programs that were captured using MythTV. They are going through
the Optical SPDIF, but they are captured in Analog stereo.
Its the DVDs that I have ripped that have the sound like machine gun fire.
I ripped a new one last night with the AC3 capture checked. Same problem.
Anyone have any ideas?
Thanks,
Mike
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