Even though most of us have a general idea , I still think that a problem description is a good thing.
We want to achieve gapless playback on our apps. This is especially important for classical music (at least I think so) because there are works that actually don't have any stops between movements. Currently, we have a best-effort approach to having a gapless playback experience for users. What this means is that we preload the audio but we're not doing anything to ensure gapless playback.
This is where Media Source Extensions (MSE) API comes in. You can read more about MSE API here but in short it gives the developers a finer level of control over what gets played by the `` tag. This really gives the developers a lot of power and enables us to directly manipulate the audio stream. An important implication of this is that we can make sure that there is only one audio stream and append next