Here's today's Twitter post:
Some good news: we’ve made updates to improve video quality.— Twitter Support (@TwitterSupport) September 24, 2021
Starting today, videos you upload to Twitter will appear less pixelated for a better watching experience. pic.twitter.com/lJPI14PVRV
Helpfully, AndroidCommunity has a little more detail:
Finally, they will be making changes to the backend process that causes the poor quality of the videos and while it will still not be HD, it should bring a huge improvement to videos you’ll be uploading in the future. Unfortunately, the fix will not be applied to videos you’ve previously uploaded so either you’ll have to make do with it or re-upload it once the update has rolled out.
...The problem apparently stems from a pre-processing step that splits the video you’re trying to upload into smaller pieces for easier processing. Unfortunately, this has resulted in the video quality being massively reduced. So the fix has been to simply remove that pre-processing step. Twitter has not said if there is another effect by removing this but for now, what we can expect is that the video quality should be less compressed if viewing in full screen. It should also have a quicker adjustment when you switch screen sizes.
All server side, so there's nothing you need to do to take advantage of this for future video uploads in the Twitter applications on Windows 10 Mobile (though this is no longer available in the Store for new installs - use the Edge browser instead), Android and iOS. Note that:
- some parts of Twitter's online infrastructure may take a few days to show the higher quality videos.
- again, none of this applies to videos uploaded to Twitter in the past, since these have already been processed.