Tandy sound quality in AGI games

[almeath]

I have noticed an apparent problem with Tandy sound emulation in some AGI games, especially the DOS version of King's Quest 2. I have tested this in ScummVM 1.6 through 2.0 in macOS and I get the same results.

When compared to DOSBox, there is significant background noise or hissing, particularly during the introduction music to King's Quest 2. Certain sound effects are also distorted, such as the waves in the first scene.

In DOSBox I can get perfect Tandy sound with no hissing by setting the output to 49716 hz, but in ScummVM changing the output has no audible effect.

Is there anything else I can do with the settings to improve the quality of the Tandy sound, or is this a known limitation with the current emulator?

[envisaged0ne]

I just played the DOS version of KQ2,using the latest ScummVM daily snapshot, and the Tandy sounds sound perfectly fine to me. I went back and forth several times (about 4 times) between DOSBox & ScummVM, and honestly couldn't tell the difference. Both sounded nice and clear

[tsoliman]

What OS are you both using?

[almeath]

I am using the latest version of macOS - 10.13.6

This is how it sounds in DOSBox:

http://userweb.eftel.com/~almeath/mac/kq2_dosbox.mp3

Compared to ScummVM 2.0:

http://userweb.eftel.com/~almeath/mac/kq2_scummvm.mp3

A noticeable amount of extra hissing or static in the ScummVM playback.

That is why I thought this had something to do with the output setting, but unfortunately that does not seem to be the case. It actually sounds like it is being played back at 22050 or lower, but I experienced no difference when manually setting it to 44100.

I will try with the latest SVN build to see if there is any improvement.

[tsoliman]

I couldn't hear the difference until I put on earbuds.

I can confirm that the latest (self-compiled) sounds like the ScummVM 2.0 clip that almeath posted.

[envisaged0ne]

I'm using Windows 10. I can hear the difference in his mp3 samples, but again I don't hear a difference when I play them through ScummVM or DOSBox. Maybe it's not a problem in the Windows port

[almeath]

It happens across the board with all the AGI games, and I have tested it in both the macOS and Windows builds. Speaker configuration or quality might make the issue more or less noticeable. I have not found any settings adjustments that will help.

It seems that the Tandy / PCjr sound output in ScummVM is just a bit noiser than the DOSBox equivalent. I am not sure why this would be the case but I presume the underlying sound emulators are different.

I wish I had a real Tandy system to hear which one is more authentic.

[Chilly Willy]

I have a Tandy 1000 HX. Maybe I can hook the output of my Tandy to my input of my PC and record something later tonight.

[Chilly Willy]

I went ahead and dropped what I was doing and recorded it from my Tandy 1000 HX.

http://www.posemotion.com/audio/KQ2_Tandy_1000_HX.mp3
http://www.posemotion.com/audio/KQ2_Tandy_1000_HX.wav

As you can hear. Neither one is 100% correct. The DOSBox versions notes are too rolled or smooth. ScummVM is the closet between the two. Plus listen to the ending of that tune. It chops up a bit on a real machine.

Now lets look at the recordings. Both (ScummVM & Tandy 1000) recorded with peaks not exceeding -1 to -2 db. ScummVM at the top and the Tandy 1000 at the bottom. As you can see, ScummVM leaves no room for dynamics and is literally screaming. Therefor, has harsh sounding audio.

I did not post my ScummVM recording here as it is in another post by almeath, five post above.

[almeath]

Now lets look at the recordings. Both (ScummVM & Tandy 1000) recorded with peaks not exceeding -1 to -2 db. ScummVM at the top and the Tandy 1000 at the bottom. As you can see, ScummVM leaves no room for dynamics and is literally screaming. Therefor, has harsh sounding audio.

Thanks for performing those tests. Very interesting findings.

Yes, I agree that the ScummVM emulation sounds closer to the real thing, and seems to fix a few glitches too. It is just a pity about the harshness of the output. Perhaps there is a way to address that in future releases. However, I do not know if that is a part of the code that is being actively looked at by anyone? I suppose it is a niche area of interest, but for the sake of posterity it would be great to see it addressed.

[Chilly Willy]

Thanks for performing those tests. Very interesting findings.

No problem.

I guess it should be reported so that they can fix it. It appears that maybe there's just a gain/compression issue on the output audio. Maybe just set too high?

[almeath]

Alright then, I will report it.

[Chilly Willy]

Alright then, I will report it.

[filipetolhuizen]

SDL 2.0.6, 2.0.7 and 2.0.8 had severe sound issues as well. 2.0.9 fixed all the stuttering and hissing that were not related to specific hardware emulation.

[CaptainJei]

SDL 2.0.6, 2.0.7 and 2.0.8 had severe sound issues as well. 2.0.9 fixed all the stuttering and hissing that were not related to specific hardware emulation.

Oh, thank god. Everything sounds great again!