Originally ticket 5900.

Update:

fix the issue mentioned earlier with channels mapping being incorrect between ALSA and AC3. The problem occurred when using analog outputs.

This patch generalises the upmix / AC-3 (re)encode functionality. Main thing is that it makes upmix and encode to DD5.1 work.

Also:

* Fix resampler clipping

* Turn on resampler where sr != 48k [1]

* Fix passthru where main dev:subdev == passthru dev:subdev [2]

* Add keybind (Ctrl+U) / OSD menu option to toggle upmixing

* Preserve timestretch across stream changes / upmix toggles

* Small change to freesurround params

[1] Recent versions of ALSA will do this if we don't. The SRC we use is much better quality.

[2] Like my nvidia CK804

Following is a set of updates for 0.21-fixes, 0.21-fixes with VDPAU backport and trunk..

What those patches do is merge the original mythtv audio code, with the newer AC3 upmixer one so you can fully turn off the upmixer.

Some people have reported issues with the AC3 upmixer with the channel mapping being incorrect.

This patch adds a new entry in Setup -> General -> Audio, adding a new AC3 upmixer entry. If unckecked (the default) this runs the original mythtv code; if checked the new AC3 upmix is used.

0.21-fixes

0.21-fixes with VDPAU backport

0.22-trunk

Also, check ticket 6279 which adds full software volume control, including on 5.1 audio