11Khz Sample Rate audio from deobfuscated game-engine audio content?

[Tks]

I recently managed to rip some of the audio from one of the games I used to play when I was a bit younger, the problem was that even audio was built into the game engine and had to be extracted with a custom solution that the company responsible for the game would obviously never give out.

In light of my recently gravedug post about the point of upsampling I had back in April of this year, I want to take a stab at this question I had about some of the audio I found.

What I found was a bunch of audio, with some tracks that would play on a radio while you drove the car in the game. The majority of audio was in 32Khz, while these other tracks are all 11Khz (16 bit though, as are the rest with respect to bit-depth). The bitrate is a pretty meager ~40kbps. All tracks are seemingly clipping constantly and really do sound like something that would have been playing out of a car radio system.

The only reason I am even able to hear any of this is having JRiver upsample the music. So I guess that's one reason to upsample music, I know of nothing that can play 11Khz audio ;P

So the actual question. What is this 11Khz audio? As in, why does this exist, and how is this even produced, and the better question being why? At first I thought it had something to do with filesize, but that makes no sense, as bitrate is a bigger factor here. Is this some sort of DAW process of trying to have properly analogue-sounding audio for the game itself? I am stumped. Interestingly, the compression seems to be MPEG 2.5 Layer 3 (seemingly for very low sample rates).

 

[pozz]

I've done the same sound extraction from games many times. A lot have turned out to be 8 bit, even in modern games. I think this is to do with custom sound object-based processing for spatialization. Once the mix is established only certain spectra are necessary. And when you extract them the game sound engine isn't involved anymore, so they'll sound more messed up. When I listened to the samples more closely in-game, I noticed the distortion and aliasing beneath all the reverb and filters. Not the first time though, not at all.

Just as a side note, the phone system in my office uses only an 8khz sample rate with custom processing to enhance intelligibility and reduce background noise. I bring it up because these sounds are application-specific, and it makes sense that we don't notice until we dig in and have a sense of what we're looking at.

 

[amirm]

Cheapest way (CPU wise) to lower the storage requirement of audio is to reduce the sample rate/bit depth. 11 kHz gives you 4:1 reduction in data.

Even with codecs like MP3, any bit rate lower than 128 kbps lowers the sample rate. High frequencies are hardest to encode so lowering the sample rate gets rid of those and makes them easier to encode.

While external hardware doesn't usually support sample rate below 32 kHz, it used to be quite common to have PC hardware that could in the old days.

 

[Hayabusa]

I recently managed to rip some of the audio from one of the games I used to play when I was a bit younger, the problem was that even audio was built into the game engine and had to be extracted with a custom solution that the company responsible for the game would obviously never give out.

In light of my recently gravedug post about the point of upsampling I had back in April of this year, I want to take a stab at this question I had about some of the audio I found.

What I found was a bunch of audio, with some tracks that would play on a radio while you drove the car in the game. The majority of audio was in 32Khz, while these other tracks are all 11Khz (16 bit though, as are the rest with respect to bit-depth). The bitrate is a pretty meager ~40kbps. All tracks are seemingly clipping constantly and really do sound like something that would have been playing out of a car radio system.

The only reason I am even able to hear any of this is having JRiver upsample the music. So I guess that's one reason to upsample music, I know of nothing that can play 11Khz audio ;P

So the actual question. What is this 11Khz audio? As in, why does this exist, and how is this even produced, and the better question being why? At first I thought it had something to do with filesize, but that makes no sense, as bitrate is a bigger factor here. Is this some sort of DAW process of trying to have properly analogue-sounding audio for the game itself? I am stumped. Interestingly, the compression seems to be MPEG 2.5 Layer 3 (seemingly for very low sample rates).

MPEG 2.5: It was designed for speech coding at very low bitrates.
You can import 11.025KHz audio in audacity and upsample it to any sample frequency you want.

 

[Tks]

Cheapest way (CPU wise) to lower the storage requirement of audio is to reduce the sample rate/bit depth. 11 kHz gives you 4:1 reduction in data.

Even with codecs like MP3, any bit rate lower than 128 kbps lowers the sample rate. High frequencies are hardest to encode so lowering the sample rate gets rid of those and makes them easier to encode.

While external hardware doesn't usually support sample rate below 32 kHz, it used to be quite common to have PC hardware that could in the old days.

Ahhhh I didn't know bitrate-sample rate relationship extended to the lower end of the spectrum. I thought you could mix and match bit depth and sample rates without one penalizing the other (like forcing a CBR of 320 on something so low samplerate wise).

Makes sense, I just figured out how to get LAME to output even a 8Khz file, and boy, now I know why it sounds perfect for car radios of yesteryear. This basically slashed bandwidth requirements by 10-fold. Took a 43MB, 2700kbps, 96Khz binaural recording down to less than half a megabyte, with a 30kbps average bit rate.

What's also interesting is there doesn't seem to be anything past 5-6K anymore. And also this very weird ethereal humming going on.

Kinda cool.

I've done the same sound extraction from games many times. A lot have turned out to be 8 bit, even in modern games. I think this is to do with custom sound object-based processing for spatialization. Once the mix is established only certain spectra are necessary. And when you extract them the game sound engine isn't involved anymore, so they'll sound more messed up. When I listened to the samples more closely in-game, I noticed the distortion and aliasing beneath all the reverb and filters. Not the first time though, not at all.

Just as a side note, the phone system in my office uses only an 8khz sample rate with custom processing to enhance intelligibility and reduce background noise. I bring it up because these sounds are application-specific, and it makes sense that we don't notice until we dig in and have a sense of what we're looking at.

Yeah this is very facinating to see this process since they use quite a few techniques on mixing all this object based audio.

 

[Tks]

Man, audiophiles really ought to try this, take these sterile, shrill, digitally cold, and soulless tracks of the modern day. Plop them down to 8Khz sample rate with variable bit rate, and see what wonderful warmth and a whole bunch of other coloration this provides. Why stop there? Fire up the old tube, throw that solid state in the trash (keep the totalsix dac tho, since at that price point, they get digital right), and see what real warmth sounds like!

If music was beginning to get old, how about just pure cleari.. I mean pure distortions! Not all of them are good, but you never know what someone else might like!



EDIT: Dont forget to throw it in mono! This stereo becomes a headache after a while.

 

[fsos]

Man, audiophiles really ought to try this, take these sterile, shrill, digitally cold, and soulless tracks of the modern day. Plop them down to 8Khz sample rate with variable bit rate, and see what wonderful warmth and a whole bunch of other coloration this provides. Why stop there? Fire up the old tube, throw that jiofi.local.html tplinklogin is it downsolid state in the trash (keep the totalsix dac tho, since at that price point, they get digital right), and see what real warmth sounds like!

If music was beginning to get old, how about just pure cleari.. I mean pure distortions! Not all of them are good, but you never know what someone else might like!



EDIT: Dont forget to throw it in mono! This stereo becomes a headache after a while.

enhance!!