Custom motor sound profile tutorial

Ryan Douglas

Administrator
Staff member
I'm not sure what those would do for us. They dealt with the sound of the model cutting through the air, not the motor sounds.

At any rate, we could provide the ability to artificially pitch the motor sounds up or down to fit a certain RPM range. But that's the same thing gibson is talking about doing by manually adjusting the file name so that a recording of RPM A is being used to represent RPM B, where RPM A != RPM B. It wouldn't actually solve any of the problems I described above. Basically, you just get to choose between them: either the samples get stretched and sound bad for that reason, or they sound like the unmodified recording but the pitch is incorrect.

The real answer is to avoid using motor sound profiles beyond their intended RPM range.
 

Kmot

Well-known member
I understand gibson's point of view, because a real radial engine sounds awesome. But there are NO model radial engines that sound like a full size radial.

The Moki engines have the best sound as far as model radial engines go, and I believe that is due mostly to the oversized exhaust ring they designed.

The best I have ever seen a modeler do, for an authentic sound, was to overprop his engine by increasing the diameter and the pitch significantly, allowing him to reduce engine rpm significantly yet create enough thrust to keep the model flying. Sounded the closest to a full size that I have ever heard.

I have thought about going through the process as recommended by KE to capture and create a sound profile of the ASP FS400 radial engine. But there is always too much ambient noise around my house. I would have to drive out to the high desert 100 miles to find a spot that does not have housing and business around it, and then there is no guarentee some modelers, dirt bikers, four wheelers, or even full size airplanes won't show up an ruin the "quiet".

It truly seems to be a daunting task to find an environment without noise already present.
 

12oclockhigh

Well-known member
Has anyone released any new engine profiles?

I think that anyone creating a profile should anticipate the file being used badly as Ryan describes... if the engine only revs to 7600rpm, use the high 7600 profile for 10000, 12000, 15000, 20000 samples... you could do the same on the low end... that way your sounds don't get mangled.
 

willsonman

Well-known member
I still need to buy a decent mic. Other projects have made this cost prohibitive. I would have loved to get one before my trip to warbirds over Delaware this week. Getting a real radial sound into the sim is on my priority list.
 

Groni

New member
How do I change an existing sound from a heli? I want to change the Goblin Sound, cause I have a real goblin recording that I want to insert.

I didn´t find an option to replace heli sound profiles.
 

Flare

New member
Someone could have a sneezing plane!
How about a talking one?

hehe!

I didn't know pepole could use the .wav format. I only knew .ogg was usable, and i never really heard of .ogg before i got RF6.
 

Kmot

Well-known member
Ryan, will there be a discreet way to upload a custom engine sound profile to the swap pages in the future?
 

Kmot

Well-known member
2-strokes are difficult?

Ryan,

I'm having fits trying to make a two stroke sound profile. :(

I have made two 4-stroke profiles and they both turned out quite accurate.

I am now working on a 2-stroke and am using the same process that I used for the other two sound profiles, but the end result just sounds bad and is is completely unsatisfactory to me.

When you (KE) made your 2-stroke sound profiles, were they inherently more difficult to make a good one versus the 4-strokes?

I have tried 4 different attempts. With just actual recordings on some, and with software enhanced recordings on others (where you use the program to change speed for an intermediate rpm file). The best version so far has been with pure recordings only. It also seems to be best with less intermediate files than more.

I have made all my clips as close to 7 seconds as possible. I have made the intermediate steps as close to 25% as possible. But it is just not working out, unlike the 4-stroke sounds did.

Any advice?
 

Ryan Douglas

Administrator
Staff member
I am now working on a 2-stroke and am using the same process that I used for the other two sound profiles, but the end result just sounds bad and is is completely unsatisfactory to me.

When you (KE) made your 2-stroke sound profiles, were they inherently more difficult to make a good one versus the 4-strokes?

I have tried 4 different attempts. With just actual recordings on some, and with software enhanced recordings on others (where you use the program to change speed for an intermediate rpm file). The best version so far has been with pure recordings only. It also seems to be best with less intermediate files than more.

I have made all my clips as close to 7 seconds as possible. I have made the intermediate steps as close to 25% as possible. But it is just not working out, unlike the 4-stroke sounds did.

Any advice?
I saw your other thread about the new engine, which I'll get into below. But to address some specific things you asked here:

I don't expect a 2-stroke engine to be significantly more difficult to capture and put in the sim than a 4-stroke. Whatever is contributing to the problems you're experiencing must have another cause.


We do not recommend artificially adjusting the pitch of your samples. The quality will suffer as a result. You should record as many different RPMs as you need to fill out the sound profile, instead of reusing samples from different parts of the RPM range and altering them to fit your needs.


The ideal number of different samples to use will vary depending on several factors, but particularly the size of the RPM range you're recording (how far apart are the min & max RPM?). Because of the way the individual engine sound samples are crossfaded, each sample will be stretched to reach the nearest sample above and below it.

So if you use too few samples, they will be stretched too far in order to cover all the RPM values in between, and your sound profile will sound bad. For example, let's say you only have 1000.ogg and 11000.ogg and nothing in between them. The 1000.ogg will be used for everything up to 11,000 RPM (albeit very quietly as it approaches that value), and it will be sped way up in order to do it. In the same way, the 11000.ogg sample will be slowed way down and mixed in with the lower sample for RPM values all the way down to 1,000. This would sound absolutely terrible. It's too much to ask of a sample to sound good at even double its original sample rate, let alone 11 times!

On the other hand, too many samples (something like 1200, 1500, 1800, 2100, 2400, 2700, 3000, 3300, etc.) should also be avoided. As described above, each individual sample is used for the RPM range extending to each of the samples adjacent to it (although it is only audible for a subsection of that range, meaning its effective range is actually significantly smaller). So too many samples crowded together will cause each individual sample to barely be used at all. In the example above, you might really only hear each sample within about a 300 RPM range (150 on either side). That's not really going to improve the quality of your sound profile. Each sample should be given a little more room to breathe and do its job. On top of that, I suspect that getting the sample filenames to correctly match the engine RPM value they capture is the area where users will struggle the most. If those are off, then it will sound bad when RealFlight blends between the samples, and having more samples means that crossfading will happen more often. That is, if you haven't yet figured out how to make it sound good when two samples blend, it's only going to make things worse if that happens at 30 different points in your sound profile's RPM range.

So, it's important to find a good middle ground, but it's difficult to tell you exactly what that number should be, because there's no single right answer for all sound profiles.


I don't know what your sample filenames look like, but I think it's worth pointing out that this isn't a tidy business. It is of the utmost importance that you accurately name the samples based on the exact RPM values they represent. It would be very difficult to record an engine at exactly 1000, 2000, 3000, 4000, etc., however, so you can't expect your files to come out looking like that. As an example, here are the exact values for one of our stock sound profiles: 1779, 2439, 3057, 4006, 4980, 6150, 7080, & 8100.


Regarding sample length: In the real world, the engine sound never repeats exactly, even if you do detect a pattern to its thrum. Ideally, each RPM sample in the sim would have something like 10 whole minutes' worth of audio before looping, allowing it to sound incredibly natural and making it nearly impossible to detect the loop point. Obviously we can't actually do that, though.

Long samples are a problem for two reasons:
  1. File size - For stock profiles, that means space on the DVD and space on users' hard drives; for custom content, that means space on our server, space on the hard disk of anyone who downloads your content, plus our bandwidth and their time whenever someone downloads it. For multiple sound profiles, it all adds up.
  2. Consistency - As described in the original tutorial post, it is important for the engine pitch to vary as little as possible over the course of a single sample. Electrics make this considerably easier than glow/gas engines, which make it difficult to keep a precise, constant RPM for, say, 15 or 20 seconds.
Short samples have their own problems, too, of course. The shorter the sample, the more obvious to the listener that the sample is a loop. Further, if the loop points weren't chosen perfectly, meaning there are popping artifacts when it loops, or if there are other noticeable aspects such as an engine burble or a thud at a certain point in the sample, the listener will become painfully aware of them if they happen every 2 seconds. Even worse, these kinds of problems are magnified when the sample is sped up. As the pitch increases, the sample length shrinks, meaning your 3 second sample might only be 2 seconds long at higher RPMs. So if it sounds bad to begin with and there is a large distance between this sample and the next highest one, it's a double whammy. (And if this is the highest sample in your profile? You're really in trouble.)

Therefore, as with so many things, it is necessary to find some kind of middle ground that maximizes the good and minimizes the bad. 7 seconds per sample is just a guideline.

It is worth mentioning that sample length is only important within the context of the individual sample. There is no reason to try making all the different samples in your profile match each other. If one sample is 4 seconds long and the next one is 15, that won't cause any problems that didn't already exist. If they sound bad, cutting the 15 second sample down to only 7 or 4 seconds won't help (unless by doing that you cut out whatever made it sound bad to begin with). By itself, the difference in length between the two will cause no problems whatsoever.


Now, about your GMS 76: From just listening to a recording, and without any insight into the samples you're using, it's difficult to say exactly what's causing you problems here. In fact, without seeing your inputs, it's hard to even know what's going on. Are you blipping the throttle at times, or are those variations actually part of the samples you've created? It would probably help to have the radio gadget visible in the video. At any rate, I agree that what you've got so far doesn't accurately reflect the sound of your engine.

From what I was able to pick out, I'd say the biggest problem is that it sounds like the RPM values you've chosen for at least some of the samples do not accurately reflect the RPM they capture. For example, you might have a file labeled 3500.ogg in which the engine is actually turning 3791 RPM. I'm pretty sure I'm hearing a lot of problems at RPMs in between samples, where two different samples are being blended together, and the pitch of the engine in one sample does not match the pitch of the engine in the other. You can test this for yourself by using the throttle to move slowly through the RPM range, watching the RPM in the NavGuides, and paying attention to where that value falls compared to the sample values whenever you hear problems. For example, let's say for a few of your samples you have 2200.ogg, 2870.ogg, and 3142.ogg. Does the engine sound good around those values, and bad in between them?

As I mentioned above, I think getting those RPM values correct is probably going to be the hardest thing to get right for anyone trying to create their own custom sound profile. It is also one of the most important pieces of the puzzle. I suggest focusing on that part and seeing how far you can get.


Ryan, will there be a discreet way to upload a custom engine sound profile to the swap pages in the future?
Tying them to the existing _EA & _AV types, like we've done with other custom items like visual blades or batteries, simplifies things a whole lot in several ways (some of which aren't immediately obvious from a user's perspective). I don't expect the way that works to change.


I hope this helps! :)
 

Kmot

Well-known member
Thank you!

Thank you, Ryan! Thank you so much for this very in-depth, and insightful post!

You have answered many questions I had, you have illuminated some of the problems I have created, and now I have a MUCH better idea of what to do.

Yes, my RPM values are just guesses. And they are all whole numbers. So that right there is problem #1.

I also thought it was important to have all samples the exact same length. I am happy to learn that is not the case because I spent too much time trimming them needlessly.

I think there may be a software that can identify RPM value from a WAV file. I hope so, as that would help tremendously in getting the samples named as accurately as possible.

Thanks again! :)
 

willsonman

Well-known member
I wonder if there is a logarithmic basis samples could be taken at. We are basically dealing with frequency here. Frequency of explosions essentially. When a frequency is doubled its an octave higher. So basically 1000rpm and 2000 rpm will sound drastically different than 2000 to 3000. So for example basing on tens... 1000, 1250, 1500, 1750, 2000, 2500, 3000. Something to that effect. I would suggest getting your full RPM range with a gauge and create a logarithmic division of the entire range and record at that level. Sorry, this is the music major coming out in me. Mixing frequencies that are further apart in pitch is more difficult than ones that are close obviously. This mathematical approach may give better evenness in the mixing.
 

Adam Taylor

Adam-inistrator
I wonder if there is a logarithmic basis samples could be taken at. We are basically dealing with frequency here. Frequency of explosions essentially. When a frequency is doubled its an octave higher. So basically 1000rpm and 2000 rpm will sound drastically different than 2000 to 3000. So for example basing on tens... 1000, 1250, 1500, 1750, 2000, 2500, 3000. Something to that effect. I would suggest getting your full RPM range with a gauge and create a logarithmic division of the entire range and record at that level. Sorry, this is the music major coming out in me. Mixing frequencies that are further apart in pitch is more difficult than ones that are close obviously. This mathematical approach may give better evenness in the mixing.
Fellow musician & music theorist here. When I record sound profiles for RealFlight, the rule of thumb I try to adhere to is to record at each minor 3rd interval. For example, if the pitch generated by the motor at its lowest RPM is a 'B', then I would rest the motor RPM where it's generating a 'D' and record the next sample, then on to F, G#, B an octave up, and so on until I've covered the full range the motor is capable of. You needn't have perfect pitch in order to be able to do this -- just the aural skills to identify the interval.

For those more mathematically inclined, my rule of thumb would be to have each recorded RPM value roughly 120% of the next lowest RPM. If the lowest RPM you recorded is 1000RPM, then you should include 1200RPM, 1440RPM, 1728RPM and so on. Again, this is just a rule of thumb. These numbers certainly do not need to be exact.

Kmot said:
my RPM values are just guesses
I'd advise against simply guessing. RealFlight mimics a real-life phenomenon where quickly yawing or pitching with an airplane distorts the sound coming from the engine / prop. RealFlight achieves this by mixing in a separate waveform alongside the motor sound, at the same RPM. If the RPM of your custom sound profile's waveforms aren't accurate, you will hear two very separate tones when performing 3D maneuvers, and it will sound silly.

I think there may be a software that can identify RPM value from a WAV file. I hope so, as that would help tremendously in getting the samples named as accurately as possible.
I don't know of any such software to do this automatically, but you can do it by ear with a software tone generator.
 

willsonman

Well-known member
Give TrueRTA a go.
http://www.trueaudio.com/rta_abt1.htm
Spectrum analyzers are very powerful. By using playback on your computer you should be able to get a rough idea of the pitch (aurally) of the sound to correspond with RPM using your general RPM gauge. While the free version may not have the resolution you may need the full version is SUPER powerful. I've been using this software for YEARS for analysis of car audio and home audio applications. it also has a wave generator.
 

Herman Effendi

New member
Custom Motor Sound Profile

Hi Everyone! I just wanted to ask someone to tell me that can create and import DA120 engine sound in RF6.5 Public Beta? I also wanted to ask that can any one send or mail me a video tutorial for creating custom motor sound profile. My gmail is hermanneffendi12345@gmail.com. Please someone help me. Thnx
 
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