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.