[mythtv-users] .24 Audio results: mixed

Douglas Peale Douglas_Peale at comcast.net
Fri Jun 25 04:19:40 UTC 2010

On 06/24/2010 06:48 PM, Jean-Yves Avenard wrote:
> Hi
> On 18 June 2010 14:52, Douglas Peale <Douglas_Peale at comcast.net> wrote:
>> New problems have arisen:
>> Without changing any settings, I got sound for a pre-recorded standard definition show (mythbusters)
>> Tried liveTV, HD was silent, switch to a SD channel, got sound.
>> went into settings changed from 5.1 Alsa:default to 7.1 PulseAudio:default
>> Now entering liveTV locks up mythTV. It happens to be tuned to an HD channel, but of course I can't change the channel since it
>> locks up.
>> The backend is recording something right now and it is a combined frontend/backend system, so I don't want to try too much right
> If you upgrade to trunk as of today, I have implemented what we had
> discussed here...
> The settings will now only show options supported by the selected hardware...
> Go in the Setup -> General, go to the Audio page.... (maybe I should
> move the audio settings out of general config)
> By default, the settings is now filled up only with the current audio
> output device as last used.
> There is a new scan button located to the right of the audio device
> drop box list.
> The scan button has two purposes:
> 1- Scan the list of all audio output available on the machine. The
> list isn't static anymore and will only show devices that are actually
> present *and* known to work. So if PulseAudio isn't running, option
> for pulse will not be shown. Same with the JACK output etc... For alsa
> device, it checks what alsa reports (same as aplay -L) and then try
> them individually.
> 2- Check the capabilities of the selected device. So if you want to
> use a custom device, you type it, like ALSA:foo ; then press the scan
> button. A pop-up will tell you if this device is usable or not and if
> it is, the PCM, AC3, DTS, number of speakers and upmix will be enabled
> or disabled accordingly
> You still have to set the AC3, DTS and PCM checkbox accordingly, as
> the system can not know what your amplifier or TV can handle.
> The other change, which would fix the previous hang you had ; the
> PulseAudio server is now suspended on an as-needed basis.
> Before the PulseAudio server would be suspended when mythfrontend got
> started, and re-enabled when you would leave. If you changed the audio
> configuration during that time, from say Alsa to Pulse, it would then
> hang.
> If you could try and report what you are seeing now that would be
> great. Any suggestions on how to improve how it's working now are
> welcome.
> I have noticed that the Alsa audio mixer do not work when the pulse
> audio server is running (even if suspended)
> _______________________________________________

Switching to pulseaudio:default no longer causes a hang confirmed.
Selecting "ALSA:iec958:CARD=Intel,DEV=0" still gets me noise for Dolby Digital signals
Selecting "ALSA:default" still requires toggling the mute button in the mixer application to get digital pass through to work
(though stereo signals always work).

Niggling little details:
For output devices like HDMI and SPDIF, isn't the speaker configuration handled by the other end of the cable? (eg my receiver
can handle multiple different speaker configurations, routing sound to the speakers I have regardless of the channels in the
input stream), so in the case of these outputs I'm really choosing between stereo and digital pass through rather than between
stereo and 5.1. And when I select digital pass through, I am letting my receiver handle the routing of sound from input signal
to speakers. I guess all I'm really suggesting here is change "5.1" to "digital pass through" in the drop down menu for Speaker
Configuration when an HDMI or SPDIF output is selected.

Audio output device selection box lists output device names. Unfortunately those names don't mean a whole lot to people
unfamiliar with the Linux sound architecture. I am aware that if I select any of them, a description of that input shows up at
the bottom, but there is lots of room in that drop down box to add a short comment after the name (perhaps after a "#" to
indicate it is not part of the device name itself) that indicated the physical type of connector the device implied: analog,
HDMI, SPDIF. This might help people select the correct device on the first attempt.

A test button for each of the various "Audio Processing Capabilities" check boxes that would send short test signals of the
specified types to the receiver would help people get their setup correct the first time.

Take the above as suggestions you can ignore if you want to, not demands. What you've done is a significant improvement over
what was there. Thank you.

More information about the mythtv-users mailing list