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

Matt skd5aner at gmail.com
Fri Mar 17 00:26:33 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, Steven Adeff <adeffs.mythtv at gmail.com> wrote:
> > > On 3/15/06, Matt <skd5aner at gmail.com> wrote:
> > > > 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"
> > > > }
> > >
> > > Here's my asoundrc file, as well I have "ALSA:digital" for my audio
> > > output device in MythTV...
> > >
> > > # 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"
> > > # slave.pcm "digital-hw"
> > > ## Uncomment the following to use mixed digital by default
> > > # slave.pcm "dmix-digital"
> > > }
> > >
> > > # Alias for analog output on the nForce2 (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
> > > 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 (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 card
> > > ctl.analog-hw {
> > >  type hw
> > >  card 0
> > > }
> > >
> > > # Alias for digital (S/PDIF) output on the nForce2 (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 card
> > > ctl.digital-hw {
> > >  type hw
> > >  card 0
> > > }
> > >
> > > # Direct software mixing plugin for analog output on
> > > # the nForce2 (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 card
> > > ctl.dmix-analog {
> > >  type hw
> > >  card 0
> > > }
> > >
> > > # Direct software mixing plugin for digital (S/PDIF) output
> > > # on the nForce2 (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 card
> > > ctl.dmix-digital {
> > >  type hw
> > >  card 0
> > > }
> > >
> > > --
> > > Steve
> >
> > I copied and pasted as is, and it didn't make any difference.  I still
> > think the AC3 track that is being "passed through" is bogus in some
> > fashion.  I'm more than happy to send the recording to someone for
> > them to play with.  In fact, I can record a short 5 mins of any HD
> > track with AC3 5.1 and send it so it's not so big.  Anyone interested?
> >
> > Matt
>
> oh and what sound chipset do you have?
>
> --


cat /proc/asound/version
Advanced Linux Sound Architecture Driver Version 1.0.9 (Sun May 29
07:31:02 2005 UTC).


cat /proc/asound/cards
0 [nForce2        ]: NFORCE - NVidia nForce2
                     NVidia nForce2 with ALC650F at 0xe0080000, irq 10

cat /proc/asound/devices
 18: [0- 2]: digital audio playback
 25: [0- 1]: digital audio capture
 16: [0- 0]: digital audio playback
 24: [0- 0]: digital audio capture
  0: [0- 0]: ctl
 33:       : timer


cat /proc/asound/modules
0 snd_intel8x0


Thanks!
Matt

P.S. Steven, I'll e-mail you off list with how you can get to the
file... thanks!


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