In a new blog post,Instagram has detailed the technical challenges behind its recent move to allow users to post videos up to 60 seconds in length — a bump from the previous limit of 15 seconds.
Essentially, Instagram says it had to completely change the way it serves videos in the Android app. With the 15-second cap, the app would download the full video in the background before playing. Now that videos can be up to a minute in length, however, that method would result in some unsavory wait times. To combat this, Instagram says that it switched to a proxy method that allows the video file to be downloaded and played at the same time. This has a number of benefits, Instagram says, but the two that stick out the most are:
- Playback is no longer blocked by the video download, i.e. it plays as soon as there's enough content.
- Playback is no longer dependent on disk space. Even if the disk cache malfunctions, it would just be treated as a cache miss and streamed directly from the server.
In real terms, Instagram says that it has observed that videos start 20-25% faster with the new system compared to the old.