It’s no secret that a few years ago, Counter Strike’s audio was terrible. The HRTF update
last year improved things massively by helping you to pinpoint which direction sounds were
coming from. This occlusion update further builds upon the sound model by muffling and
quietening sounds that come from behind walls. Firstly I’d like to talk about a bug that
was discovered last month, which I believe could have been responsible for this update.
In a popular reddit post, Jambo revealed that footsteps from behind walls wouldn’t be
heard if the player model wasn’t being rendered. I wonder if this was a trade-off that Valve
were aware of. You see, there was an EVEN OLDER update that
was introduced to stop cheaters. Wallhacks can be used to see people through walls. The
update made it so that information about other players would only be sent to a player’s
PC if they had a direct line of sight to them. These visibility calculations are all done
server-side, meaning that the cheater’s computer would be getting literally no information
about players behind walls, rendering the cheats ineffective.
You may have encountered this anti-cheat method if you’ve ever played a match with a high
ping. Sometimes you’ll run around a corner and enemies take a while to ‘pop’ into
view because it takes a while for the server to realise you need the other players’ information.
It doesn’t seem fair, but in a way it’s more so. And it shows that the anti-cheat
is doing its job. However, with this information block in place, it does mean that footstep
sounds are also out of the question, unless the server decides to send you them separately.
This link between this anti-cheat and the footstep bugs is just speculation on my part.
But what I do know is that footsteps can now be heard even when a player’s model isn’t
being drawn. This fix was rolled out just days after the bug was discovered and is separate
from the occlusion update. This isn’t necessarily the case, but I wonder if the footstep fix
was just a temporary solution and if the new occlusion method is a more robust, cheat-resistant
method of tackling the problem. But I’d like to make it super clear, this is all just
speculation. It could just be that Valve are nice and want to treat us to better audio
and that its timing with the other bug is just a coincidence.
Any way. Even without enabling occlusion I can show that this bug has been fixed and
that the footsteps play regardless of whether the character model is being drawn or not.
Just to make sure, I made my own worst-case-scenario level comprising of 2 separate rooms. When
I say these are separate, I mean it! There’s empty space between them. Pure NOTHINGNESS-
a complete vacuum! Technically, sound shouldn’t be able to pass through this in the first
place but, for the sake of maps, it should be able to since there is often an empty space
like this between areas on a map. And indeed, it does. Even without occlusion,
so it shows that the footstep update is doing its job. I also noticed an awful lot of headshot
sounds that shouldn’t have been there- turns out that if you fire a gun in a vacuum on
CS:GO then not only does it violate the laws of thermodynamics but you also get quantum
bullets that are seemingly in 2 positions at once or something. Either that or 2kliksphilip
is cheating. It’s been 3 minutes 24 seconds and I haven’t
even started with the occlusion yet. But I will now. If this same sequence I just showed
is played again but with occlusion enabled, you can hear the difference that it makes.
The sounds are muffled and bassier. According to Valve’s blog, this isn’t
just a cheap trick- it distorts the sounds based on the materials it’s travelling through!
And it’s impressive stuff- the material type does make a difference, as does its thickness.
Strangely, wood doesn’t muffle as much as stone when both are 16 units thick, yet does
a much better job when they’re both 128! The sound even takes into account indirect
paths, it seems. I’ve kept the closest wall transparent just so you know what’s going
on behind. Adding a roof didn’t make much difference in this case, though if he were
higher up towards the top of them then it would have.
All in all from the testing I did I was impressed with the system. It’s just that everything
I tested raised more questions and I didn’t have time to delve too deeply into everything.
Just know that what Valve have done is pretty cool.
Next up I made ANOTHER map to test the direction the sound comes from. Will it come directly
from the shooter, or can we hear echoes in this game? Because in reality, if you’re
stood here, looking directly through the wall towards the shooter, then the sound should
appear to come from the left as it’s bouncing off the walls to reach you. The ingame sound
debugger shows this isn’t the case, and here’s a clip for you to hear it yourself.
In other words, this is a limitation with the occlusion model. It always comes from
the direction of the shooter, when in reality the sound would appear to come from somewhere
else. I’m not complaining though- do we really want it to be harder to tell where
sounds are coming from?! We’ve spent years moaning about that very issue!
Honestly I’m very impressed with this new sound system. It nicely calculates the distance
and type of sound it is, and muffles it according to the number, thickness, material type and
position of the walls around it. It’s not quite as flashy as the Aureal A3D demo but
it suits CS:GO’s sound requirements nicely. It’s better than I first gave it credit
for, too: I repeatedly think that I’ve tricked it, only to find with further testing that
I haven’t and it’s more advanced than I expected. It doesn’t just take into account
the direct line between you and the sound-source, but also the surroundings and it muffles and
distorts the said sounds accordingly. I don’t know how else to put it, it sounds RIGHT.
Though I suspect that at first, some people may not like it. Just like with HRTF. You’ll
just have to get used to the new sound system and to master the maps you wish to play on.
Do this and I believe this new occlusion system will make the sound design more intuitive
and precise than it has ever been before in Counter Strike’s history.
This change is still in beta for now, but once it’s rolled out for real I’d expect
it to be forced on for all players to keep it fair and balanced. Occlusion does make
distant sounds quieter, especially if heard through surfaces, which will reduce what we
can expect to hear from where we are within the level. Not that this is a bad thing. I
think this update is a step in the right direction! It makes the audio more realistic, but only
in the good ways. Much like HRTF, I think we’ll soon take it for granted, but it will
have a small but positive effect on every round of CS:GO that’s played from now on,
especially on Nuke, which I’ll end this video with examples of. It’s a welcome improvement.