[mythtv-users] Not getting Dolby Prologic out of s/pdif

Matt skd5aner at gmail.com
Thu Mar 16 02:23:35 UTC 2006


On 3/15/06, Steven Adeff <adeffs.mythtv at gmail.com> wrote:
> On 3/15/06, Matt <skd5aner at gmail.com> wrote:
> > On 3/15/06, Steve Skarda <steveskarda at gmail.com> wrote:
> > > Make sure you have use video as timebase turned off in the playback
> > > settings.   Having it checked will allow digital signals to work but AC3
> > > passthrough won't.   Not sure if that is related to your problem or not.
> >
> > It is turned off.
> >
> > Let me just try to quickly sum up my issue:
> >
> > 1) I receive HDTV OTA ATSC signal via HD5000
> > 2) The first audio track says it's AC3 5.1
> > 3) Receiver set to "AFD" - Auto Format Decode
> > 4) When it receives the signal, the LCD on the receiver doesn't do
> > anything (doesn't say what kind of signal it is receiving" and I can
> > hear noice out of my left and right channels, but never the full
> > signal (missing voices, etc).
> > 5) If I switch the receiver to "Normal Surround" I'll get the
> > channels, but the receiver NEVER says it's decoding AC3.
> > 6) If I play a Standard Def recording from my PVR250/500, the receiver
> > will get the signal and say it's playing a PCM signal.
> >
> > I think I'm going to submit a ticket, but before I do that, what else
> > should I do/try/troubleshoot?
> >
> > Thanks!
> > Matt
>
> sounds like you don't have ALSA set up to pass AC3 signals, thus they
> are being sent as stereo pcm. search the list/wiki and you should find
> information on how to enable AC3 using .asoundrc
>

Correct me if I'm wrong, but I believe I do.  Here's my .asoundrc:

Here's my .asoundrc file:

# Override the default output used by ALSA.
# If you do not override the default, your default
# device is identical to the (unmixed) analog device
# shown below. If you prefer mixed and/or digital
# output, uncomment the appropriate four lines below
# (only one slave.pcm line).
pcm.!default {
type plug
## Uncomment the following to use mixed analog by default
# slave.pcm "dmix-analog"
## Uncomment the following to use unmixed digital by default
slave.pcm "digital-hw"
## Uncomment the following to use mixed digital by default
#slave.pcm "dmix-digital"
}
#slave {
#pcm "spdif"
#rate 48000
#format S16_LE
#}
#}
# Alias for analog output on the nForce2/4 (hw:0,0)
# - This is identical to the device named "default"--which
# always exists and refers to hw:0,0 (unless overridden)
# - Therefore, we can specify "hw:0,0", "default", or "analog"
# to access analog output on the nForce2/4
pcm.analog {
type plug
slave.pcm "analog-hw"
}

# Control device (mixer, etc.) for the nForce2 card
ctl.analog {
type hw
card 0
}

# Alias for (rate-converted) mixed analog output on the
# nForce2 (hw:0,0)
# - This will accept audio input--regardless of rate--and
# convert to the rate required for the dmix plugin
# (in this case 48000Hz)
pcm.mixed-analog {
type plug
slave.pcm "dmix-analog"
}

# Control device (mixer, etc.) for the nForce2 card
ctl.mixed-analog {
type hw
card 0
}

# Alias for (rate-converted) digital (S/PDIF) output on the
# nForce2 (hw:0,2)
# - This will accept audio input--regardless of rate--and
# convert to the rate required for the S/PDIF hardware
# (in this case 48000Hz)
pcm.digital {
type plug
slave.pcm "digital-hw"
}

# Control device (mixer, etc.) for the nForce2 card
ctl.digital {
type hw
card 0
}

# Alias for mixed (rate-converted) digital (S/PDIF) output on the
# nForce2/4 (hw:0,2)
# - This will accept audio input--regardless of rate--and
# convert to the rate required for the S/PDIF hardware
# (in this case 48000Hz)
pcm.mixed-digital {
type plug
slave.pcm "dmix-digital"
}

# Control device (mixer, etc.) for the nForce2 card
ctl.mixed-digital {
type hw
card 0
}

# The following devices are not useful by themselves. They
# require specific rates, channels, and formats. Therefore,
# you probably do not want to use them directly. Instead use
# of of the devices defined above.

# Alias for analog output on the nForce2 (hw:0,0)
# Do not use this directly--it requires specific rate,
# channels, and format
pcm.analog-hw {
type hw
card 0
# The default value for device is 0, so no need to specify
}

# Control device (mixer, etc.) for the nForce2/4 card
ctl.analog-hw {
type hw
card 0
}

# Alias for digital (S/PDIF) output on the nForce2/4 (hw:0,2)
# Do not use this directly--it requires specific rate,
# channels, and format
pcm.digital-hw {
type hw
card 0
device 2
}
# Control device (mixer, etc.) for the nForce2/4 card
ctl.digital-hw {
type hw
card 0
}

# Direct software mixing plugin for analog output on
# the nForce2/4 (hw:0,0)
# Do not use this directly--it requires specific rate,
# channels, and format
pcm.dmix-analog {
type dmix
ipc_key 1234
slave {
pcm "analog-hw"
period_time 0
period_size 1024
buffer_size 4096
rate 48000
}
}

# Control device (mixer, etc.) for the nForce2/4 card
ctl.dmix-analog {
type hw
card 0
}

# Direct software mixing plugin for digital (S/PDIF) output
# on the nForce2/4 (hw:0,2)
# Do not use this directly--it requires specific rate,
# channels, and format
pcm.dmix-digital {
type dmix
ipc_key 1235
slave {
pcm "digital-hw"
period_time 0
period_size 1024
buffer_size 4096
rate 48000
}
}

# Control device (mixer, etc.) for the nForce2/4 card
ctl.dmix-digital {
type hw
card 0
}

I've tried myth on "ALSA:spdif" and "ALSA:Digital" with the same results.


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