Choosing video bitrates

Site Operators
1

(I’m not sure if this is the channel for video technology questions, let me know if there’s a better place).

What bitrates are folks typically using for HLS video streaming?

We use AWS elastic transcode, and you can see what we’ve chosen to do at https://github.com/mitodl/odl-video-service/blob/master/config/et_presets.json

We have been getting complaints recently from some users that our videos are taking a long time to load, or pausing in the middle. We’re using HLS video, so in theory the bitrate should be adjusting to available bandwidth, but something is going wrong. One thing I’d like to validate is whether our bitrates are sensible.

Maybe we need to add another, lower bitrate? I think I saw that edX has an audio-only bitrate – does that really help?

Thanks for any advice.

Peter Pinch
MIT Open Learning

2

I don’t know if it’s the actual reason for it, but I remember early discussions about wanting to be able to play things on your phone while on the run. Many videos are useful with only audio.

Dave

3

Answering my own question, we decided to go with some of the AWS Elastic Transcode Service presets, described in the docs at https://docs.aws.amazon.com/elastictranscoder/latest/developerguide/system-presets.html

The five HLS presets have worked fairly well, although we still have occasional users complaining about stuttering or blurry video – particularly when the video has a lot of text and formulas in it.