Increase audio bitrate to 48kbps

[Stoppedpuma]

One of the annoyances I have with Signal is that audio quality in calls sounds significantly worse than other platforms, this has been a common complaint between those I use signal with. This is noticeable on both Mobile and Desktop platforms, especially Desktop. This PR aims to alleviate the problem a bit. In this PR I've increased the audio bitrate from 32kbps to 48kbps, I believe this is a good balance of increased quality while not increasing data usage by much.

I'm not familiar with the Signal codebase so please let me know if there's any other places that I would have to also make this change at.

[adel-signal]

Thank you for submitting a PR. In the past, we tuned these audio settings to prioritize stability. We later made several improvements to uphold quality and we are investigating further improvements. While we won’t merge in this PR, we will consider this feedback in our future work. Please continue to submit feedback and bugs about issues you are having and we will take a look. Feel free to include files or recordings if possible.

Thanks,
Adel @ Signal

[Stoppedpuma]

Hi, thanks for the response! Whilst I do understand where concerns with slightly higher data usage could affect the stability of those on slower networks, I'm equally as much in belief that this would be another good improvement to have regarding the quality of Signal. The other major popular platforms use a bitrate that is higher than the 32kbps that Signal currently uses. Signal already has a low data mode for users in those situations or with highly limited data plans. I think it would be a good improvement for Signal to be able to match those platforms in quality, or to at least get closer than Signal currently is. The two major issues that have commonly come up in discussion with those I use Signal with are Audio and Video quality.

To throw some numbers into this discussion, here are a few popular chat applications and their default audio bitrate (either by their specification or estimate from my research):

FaceTime Audio: ~40-64 kbps
Discord: 64 kbps
WhatsApp (pre-mlow): 24-40 kbps

I believe that meeting quality standards closer to more popular solutions on regular data modes would be well received. Those on slower and or more data limited connections can always use the low data mode.

I'm curious if a high data mode has ever come up in discussion as this could be another good option that would work on both sides of this discussion. In my experiences, the call quality issues (Both Audio and Video) that Signal currently has results in using other applications besides Signal for calls.