OpenIV 2.6.4 - Now with audio
As the developers commented on the update:
Over the past few weeks we've been working on one of the most requested features for the PC version of GTA V. And today we are pleased to announce the release of OpenIV 2.6.4 with support for playing GTA V audio files on PC. You can open any audio file or export its contents to .wav format. Audio playback is a cool feature, but you know what's even cooler? Audio editing. Yes, a lot of people want to change the sounds of guns or cars, and now, thanks to the power of openFormats, they can do it. Now, you can edit any audio file in the game. Of course, there is still unknown data in the audio files, but you can study or even try to change it to help understand what the data is responsible for.
Here's a simple video showing the basics of editing audio files in GTA V: