Question

I’m developing a service where people can stream multiple audio files at the same time.

Unfortunately, when streaming about 4 streams simultaneously, Chrome’s HTTP connection limit seems to kick in: new stream requests only arive at the server when a previous connection was closed.

Interestingly enough, I can play 10+ videos at the same time on YouTube.

What kind of technique could YouTube have used here to circumvent the browser’s simultaneous http connection limit?

Answer 1

The crucial point here I suppose is that YouTube streams are not directly controlled by the browser, they are embedded Flash players which use streams that are handled by Flash. If you want to hand off the streaming process to an external app/library (Flash, Java etc) you can circumvent these limitations quite easily.

The other point is that YouTube has a huge CDN, so there is no guarantee you’re getting any two videos from the same server, which would also help to circumvent concurrency limitations (to a point, at least).

I’m not surprised that Chrome stops you after a while because Google did a load of research and experiments regarding browser concurrency and relative efficiency a while ago, and I remember reading somewhere that they concluded that 3-4 concurrent connections to the same server represented the the most efficient data transfer architecture over straight HTTP. Annoyingly, I can’t find a reputable source to reference with that (although I got it from one in the first place), however this is related and probably part of the same research program.

This is also the sort of research Facebook get quite heavily involved in, and you might find some useful information in over at http://developers.facebook.com/ if you can be bothered sifting through the rubbish to find it…