Updated SoundTouch library to 1.8.1 [r198]

[skidau]

Updated the time stretch library to the latest revision and selected the linear algorithm for interpolation. Seems to respond better to a dynamically changing framerate.

[JMC47]

This will allow OpenAL to have a better time stretch option? I'll test it through and see what I can find.

[skidau]

Yes, it seems to be better. The build can be tested here (needs OpenAL backend selected):

https://dl.dolphin-emu.org/prs/pr-953-dolphin-latest-x64.7z
https://dl.dolphin-emu.org/prs/pr-953-dolphin-latest.dmg

[shuffle2]

Shouldn't this be one commit? It looks like the second one is also just updating files in externals...are there any remaining parts that aren't updated for soundtouch?

[skidau]

I split the commit to signify that the second commit is a Dolphin specific modification of the original source code. I kept the changes that were needed for the code to compile in the first commit.

[lioncash]

@skidau Does the SoundTouch API not allow you to specify that though during initialization or something? I'm just saying in case in the future if we update it again, if it isn't you doing it, someone might not know about that slight modification.

[shuffle2]

@skidau ok, I guess the Externals/soundtouch/SoundTouch.h change should still be in the first commit though? and also, what @lioncash said...if it's not configurable, can you add a comment or some notes in a text file (current version, changes, etc).

[skidau]

@lioncash, on closer inspection the configuration change was for a feature that Dolphin does not use. I have removed the second commit. This PR is ready for review.

[lioncash]

@skidau Looks good to me now, feel free to merge.