Re: [Flightgear-devel] Adding engine sounds to AI Aircraft

[James T. <ja...@fl...>]

Hi Ron, welcome and thanks for sharing this

> On 21 Jun 2023, at 20:58, Ron Horn <rc...@gm...> wrote:
> 
> So I created a proof-of-concept (my current git patch here <https://drive.google.com/file/d/14vggup8MZcdygtw1uT18qpy-pXT8KSpn/view?usp=drive_link>).  There are a lot of comments in generic-airliner-exhaust.xml to explain it.
> 
> I tested this heavily on 2020.3.18 and also patched and built on 'next' a few days ago - no crashes or disasters.  (Using Windows 10, by the way).
> 
> Being new, I have more questions than answers, but here are a few:
> What can I do to help this possibly become part of a future FlightGear release?  I've read most of the fg wiki pages I could find on contributing, but still need some guidance on how to proceed.
> I found a strange "zombie" sound issue that I worked around by making sure I silence the sounds BEFORE the AI aircraft parks at the gate after arrival (sometimes gets stuck at 10 kts).  Feels like something is wrong in how "class FGAIAircraft" and related code shuts down the sound fx when parking.  I checked the bug list and did not see anything like this, I assume I can/should file a new ticket once I have good steps to recreate it (not hard).
> Watching AI Traffic on 2020.3.18 is very stable (I let it run overnight, and only observed issues that are documented, such as gridlock, etc).  But on 'next', I see some very strange problems with arriving aircraft: wrong glideslope on final approach, crazy pitch attitude as well during landing.  I'm happy to file a ticket for this too, if it is not already a known issue (I searched and did not see it, but I'm not very familiar with the bug list yet).
> Thanks for reading this far!


For 1, we need to some planning indeed. I can see you current patch needs to modify each AI aircraft,, we need to decide if that’s the right approach (probably it is, so turboprops can have different sounds, etc). But in principle I don’t see an issue here, although my knowledge of the sound code is very basic, hopefully Erik who knows it better can also give some feedback.

I’d also wonder what happens (CPU load, etc) at a busy airport with many active AI aircraft taxiing, I’ve no idea how the XML sound system handles this, maybe you already tried at EHAM or KORD and the answer is it’s just fine? Sometimes sound drivers have a limit on the number of active sound sources, to give one example. 

For 2, there could very easily be a bug here about deleting or cleaning up the corresponding FGFX object, would need a simple test case if we can make one.

For 3, Keith paterson currently works on the traffic code; there are plenty of strange behaviours in the 2020.3 code. The code on next has had some particular areas improved, but I don’t know the overall state. Some tickets on specific issues you see would probably be good, especially if they occur consistently. 

Kind regards,
James