New, also help on dealing with multiple audio streams using gstreamer-rs

[Michael Johnson]

All those warnings are related to not handling the None type, I didn't
think that would have any bearing.

Wait. You're not supposed to use emit? Then why does it exist? Surely you
emit a signal to then be caught by the connect. By the logic of setting the
value of 2 every them then current audio should go -1,-1,2 not -1,-1,-1. It
yields 2 on exit. Which was my point

What is the alternative to using emit then, and why does the alternative
still relate to connect?

On Thu, 17 Dec 2020, 13:36 Sebastian Dröge, <sebastian at centricular.com>
wrote:

> On Thu, 2020-12-17 at 12:28 +0000, Michael Johnson wrote:
>
> As requested a toy example,
> Here we see that the audio-changed emit never activates the connect, maybe
> because it emits before the video has began playing?
>
> I'm probably doing something very wrong
>
>
> Yeah, you're ignoring compiler warnings here that tell you that you're
> ignoring potential errors :)
>
> Make sure to at least `unwrap()` `Result`s instead of ignoring them, then
> you immediately know if you did something wrong there.
> In this case the emitting of the "audio-changed" signal fails because of
> the wrong number of arguments.
>
> But that also doesn't matter here: that signal is supposed to be emitted
> by playbin whenever something changes, not by you.
>
> After removing that line what I get is
>
> current audio track is -1
> number of audio tracks is 1
> current audio track is -1
> number of audio tracks is 2
> current audio track is -1
> number of audio tracks is 3
>
> That looks as expected. Every signal emission you're setting the current
> audio track to 2, but only the last time there actually is a 3rd (0, 1, 2)
> audio track available.
> So in the end it should use the 3rd audio track.
>
> If you change it for example to set it to 1 then you'll see that during
> the last signal emission the current audio track is 1.
>
>
> For getting state into the signal handler closure, take a look at the
> overlay-composition.rs example and what it does with the DrawingContext
> inside the Arc<Mutex<_>> there.
>
> --
>
> Sebastian Dröge, Centricular Ltd · https://www.centricular.com
> <http://www.centricular.com>
>
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