So I’ve built a media pc from a Zotac itx mobo, and it lives in my entertainment center.  An HDMI cable carries the video AND audio from the Nvidia video and audio chipsets to my Sony digital tuner, which is capable of decoding and playing back all manner of digital audio formats.

The media pc doesn’t have an optical drive, though — if I want to play a Blu-Ray or DVD disc, I just use the Sony Blu-Ray player.  The media pc, instead, is for those times I want to play youtube videos, hulu, or other such online formats.

The new pulseaudio system in Fedora 12 handles the audio beautifully… just as long as I don’t try to play back a file with digital audio.  An example situation would be my .avi file of Star Trek IX with 5.1 audio, which I ripped from the dvd for playback alongside the rifftrax .mp3 companion audio.

But to play the movie with the 5.1 soundtrack, I have to suspend pulseaudio and use alsa’s ac3 passthrough capability.

Here’s how to do that:

First, install the pulseaudio-utils package:

# yum install pulseaudio-utils

This gives you the “pasuspender” program…with that, you can run your playback application with pulseaudio suspended, giving you direct access to the alsa device itself.  The command line looks like this:

$ pasuspender — mplayer -ac hwac3 -ao alsa:device=hw=0.3 yourfilehere.avi

Note the double dash right after the pasuspender command — this tells pasuspender to stop interpreting switches, so that the switches only have meaning to mplayer.

You’d use the same command to play a dvd (if your media pc has a dvd drive — mine doesn’t, I was trying to keep moving parts to a minimum).  For instance, after inserting the Star Trek dvd, you’d use the following:

$ pasuspender — mplayer -ac hwac3 -ao alsa:device=hw=0.3 dvdnav://21

BTW, most dvd’s will let you playback with “dvd://21″ — but the Star Trek dvd tries to get in your way, if you try to play back the content that you’ve bought.  “dvdnav:” gets around such idiocy.

And finally, you might be wondering why I’m fiddling around with the legacy DVD, when I could be using the HD video content of a Blu-Ray.  I do own the Blu-Ray, but a) I can’t play it from Linux yet, and b) I’m not ramped-up on ripping Blu-Ray just yet…and I wanted to put together a Star Trek/rifftrax viewing party relatively soon.

But this particular issue — as well as today’s nonsensical balderdash from “Bono” regarding ISP’s and digital content — only serve to underline that there are a lot of folks out there that really don’t understand the digital landscape.  But suffice to say that the content providers are so wound-up about possible unlawful use of their content, they screw-up one-off, lawful, and legal, uses of the content for folks who have these capabilities.

And I see a great need for another post about this.  Coming soon…