I hope replays will work, unlike with the F-14

[Katmandu]

It's no secret that the F-14 has a completely broken replays function in DCS, with even the simplest short single player missions (like take off, turn round and land) failing to sync.

I personally have never bought this beauty as having (one of) the most beautiful and cinematic airplanes of all time with no replays would frustrate me no end.

The F-4 is also a beaut, and it would be good if Heatlbur could continuously bugcheck the replay sync function as they develop and flesh out F-4's FM.

Edited May 22, 2023 by Katmandu

[Temetre]

Is that really a thing, F-14 replay just dont work?

[draconus]

13 minutes ago, Temetre said:

Is that really a thing, F-14 replay just dont work?

They do work but drift from original more or less depending on inputs.

[Hiob]

That issue is not related or unique to the F-14. It's just more obvious in the F-14 and other very complex aircraft.

Dig a bit into how replays work and you will figure out that is is basically impossible to pull off and why the F-14 is more affected than simpler aircraft.

[Super Grover]

I fixed replays for the F-4 some time ago, and they work like a charm, yay!

Sadly, it's not easy to apply the same fix for the F-14, so it will take some time before the changes are applied to the F-14.

[MAXsenna]

I fixed replays for the F-4 some time ago, and they work like a charm, yay!
Sadly, it's not easy to apply the same fix for the F-14, so it will take some time before the changes are applied to the F-14.

Impressive! How did you do that?

Sent from my MAR-LX1A using Tapatalk

[Temetre]

vor 3 Stunden schrieb draconus:

They do work but drift from original more or less depending on inputs.

Yeah I know that kinda issue from other games replay systems. But theres a difference between "sometimes they get a bit inaccurate", and "replay just breaks after seconds with no recovery".

Are trackfiles itself affected, even in a track viewer? Or just the ingame replay system of DCS?

vor 3 Stunden schrieb Hiob:

Dig a bit into how replays work and you will figure out that is is basically impossible to pull off and why the F-14 is more affected than simpler aircraft.

I know how replays work. Its just a question how bad it is, and sometimes they got ways to "recover" inaccuracies reguarly. The F-14 just seems to instantly break in the clip?

Ive watched me flying F-18 replays to check out stuff recently, and they were fairly accurate. Good enough to get to see what I wanted.

Edited May 22, 2023 by Temetre

[draconus]

7 minutes ago, Temetre said:

Yeah I know that kinda issue from other games replay systems. But theres a difference between "sometimes they get a bit inaccurate", and "replay just breaks after seconds with no recovery".

Are trackfiles itself affected, even in a track viewer? Or just the ingame replay system of DCS?

I already answered that it depends on your inputs so I can only explain this way: when you start on the ground and click things it'll be perfect, if you airstart, put on autopilot and fly straight ahead it can probably be ok for some time, if you start making maneuvers and high alpha stuff on the edge of flight envelope you'll break it in seconds.

Track files and replay are connected systems. DCS saves the track (saves the mission and player inputs) and the replay system plays them back (runs the mission and player inputs). We don't know what fails in this system wrt Tomcat or other modules but since the calculations are always done again (no objects' positions saving*) it can never be perfectly the same especially due to AI nature. There's no way to "recover" tracks that play wrong.

*This only works for server tracks.

[Temetre]

vor 17 Minuten schrieb draconus:

I already answered that it depends on your inputs so I can only explain this way: when you start on the ground and click things it'll be perfect, if you airstart, put on autopilot and fly straight ahead it can probably be ok for some time, if you start making maneuvers and high alpha stuff on the edge of flight envelope you'll break it in seconds.

Yeh I know how tracks generally break, its usually compression and inaccuracies piling up. Tho with F-14 it seems fundamentally broken.

vor 17 Minuten schrieb draconus:

Track files and replay are connected systems. DCS saves the track (saves the mission and player inputs) and the replay system plays them back (runs the mission and player inputs). We don't know what fails in this system wrt Tomcat or other modules but since the calculations are always done again (no objects' positions saving*) it can never be perfectly the same especially due to AI nature. There's no way to "recover" tracks that play wrong.

*This only works for server tracks.

I think track viewer can shows the entire mission as well, its a seperate software that can read track files in DCS and other games? Wouldve been interesting to see if its simplified modeling is more consistent and doesnt break like the ingame replay system. Was just curious if someone had experience with that^^

Would definitely be nice if ED had some regular position saving or so to correct mistakes. 

Edited May 22, 2023 by Temetre

[Hiob]

5 minutes ago, Temetre said:

Yeh I know how tracks generally break, its usually compression and inaccuracies piling up. Tho with F-14 it seems fundamentally broken.

The trackfiles log all relevant parameters. Especially inputs. Problem is that they can do it only with a finite polling rate. Otherwise it would probably a performance killer.

The Tomcat has several factors that play into that. A) By it's nature, it has very complex aerodynamics and control interfacesy, B) The FM is probably among the most complex and sophisticated in DCS and last but not least C) it is dual cockpit.

I'm assuming that the amount of data that needs to be logged in order to replay properly is a magnitude higher with the F-14 than with most other modules (whose replays go haywire, too - sooner or later).

Those are all assumptions. I'm by no means a subject matter expert. But I think those conclusions are not far fetched.

[Katmandu]

4 hours ago, Temetre said:

Is that really a thing, F-14 replay just dont work?

Yep, there was an experiment with no video editing, shot in in a single take. The same simple mission for all planes: take off, turn round, land. Multiple attempts to minimize errors due to chance . All DCS planes had working replays, both single seater and two seater. (F-16 had 4/4 synced replays; AV-8B 4/4; F/A-18 2/2; L-39 4/4)... the F-14 had 0/6 synced replays (!!!).

Part one of the experiment is in the OP, part two is here

 

[Katmandu]

I've repeated the same test (take off , turn round, land) with the current MT version of DCS and same result: 0/3 synced replays with the F-14.

[Temetre]

vor 7 Minuten schrieb Hiob:

The trackfiles log all relevant parameters. Especially inputs. Problem is that they can do it only with a finite polling rate. Otherwise it would probably a performance killer.

The Tomcat has several factors that play into that. A) By it's nature, it has very complex aerodynamics and control interfacesy, B) The FM is probably among the most complex and sophisticated in DCS and last but not least C) it is dual cockpit.

I'm assuming that the amount of data that needs to be logged in order to replay properly is a magnitude higher with the F-14 than with most other modules (whose replays go haywire, too - sooner or later).

Those are all assumptions. I'm by no means a subject matter expert. But I think those conclusions are not far fetched.

Tbf because you only got finite polling, that means you have to do some trickery and smart compression. Its just like compression music or video, you only got limited data, but try to make a reconstruction thats as good as possible.

It doesnt really matter "how" it arrives at the goal, it just has to get there. The DCS track+replay system combo is just not up to the task.

I imagine with the F-14 something is just incorrectly polled or replayed or so, or theres not enough data, or whatever. Might just be a simple bug.

vor 11 Minuten schrieb Katmandu:

Yep, there was an experiment with no video editing, shot in in a single take. The same simple mission for all planes: take off, turn round, land. Multiple attempts to minimize errors due to chance . All DCS planes had working replays, both single seater and two seater. (F-16 had 4/4 synced replays; AV-8B 4/4; F/A-18 2/2; L-39 4/4)... the F-14 had 0/6 synced replays (!!!).

Part one of the experiment is in the OP, part two is here

Thx, thats a lot of testing! Clearly the F-14 is broken in replays in some way.

[Bosun]

I've never understood why DCS replay system is different than other sims.  I've flown flight sims for decades, and even going back to the early aught's, I could record a flight and play it back in other simulations.  

I couldn't jump in and 'take-over' the flight, like you can here when replaying - but that's never, ever why I would 'record' a flight.  I record it to watch it and evaluate, not to take back over and fly it again.  

I have felt, for a long time, that they'd have been better off to create a system that simply records position information and aircraft status at regular intervals and interpolates the steps for a smooth video replay from different angles, rather than try to directly track control inputs, just like many sims have done before.  It may not be elegant, but it would work. I can respect that they wanted to try something innovative - but not all innovation works out.