[MPlayer-dev-eng] [PATCH] New commands for loading/unloading audio filters at runtime

[Reimar Döffinger]

On Sun, Apr 11, 2010 at 08:13:46PM +0900, Jehan Pagès wrote:
> On Sun, Apr 11, 2010 at 6:27 PM, Reimar Döffinger
> <Reimar.Doeffinger at gmx.de> wrote:
> > Uh, I think he means crashing when he says "crashing", not just "does not play
> > audio".
> 
> In fact, when I start a file with the filter lavcac3, it would display
> the same errors and exits directly, though you are probably right, in
> this case, this is probably a clean exit (because mplayer see it
> cannot run with such a filter), not a crash (where mplayer loads the
> filter anyway, still see it cannot run with it — hence the errors —
> but continues anyway — hence the crash).

It should continue playing the video (assuming there is any), if not that's a bug.

> > Dynamically inserting lavcac3 just can not work (at least not this way) since
> > the ao does not get reconfigured, so the output at the very end of the
> > filter chain can not change.
> > This means two things: 1) adding or removing lavcac3 can not work since (at least
> > for adding) we would need a AC3 decoder filter somewhere to get back to the
> > same format
> > 2) even if it worked, it wouldn't make any sense.
> 
> Probably if you say so, though I do not understand much what this
> filter is about from the description.

It converts audio to compressed AC3. Given that there is no _filter_ that decodes
AC3, there is no way to get the 16 bit PCM the ao needs after such a filter was
inserted, thus the whole filter chain is broken - unless you added code to also
reinitialize the ao, which might cause some other issues.