[v13inc]

Why would Cloudfront cause the player to stop buffering the video? Does it happen with a HTTP Download distribution, or the RTMP streaming distribution? I've used both CloudFront and Akamai for serving video, and I don't remember running into those issues. I have only tested it with normal HTTP Download distributions, however.

[jcampbell1]

Cloudfront serves an invalid HTTP response, thus Chrome/Firefox refuse to cache the data. The theory is, it is better to not risk caching bad data. Chrome will still play the video served from Cloudfront, but it wont write any of the data to the media cache. Thus when you pause and buffer, it will only buffer a few seconds of video in the current playback window. It never writes to the cache so buffering must stop.

To see this in action, play a video with chrome://media-internals/ open.

A video served from S3 will get saved to the media cache, and the full video can buffer when paused. A video served from cloudfront will only buffer a few seconds of video.

Update:

It is probably just easier to see for yourself:

Here is a video served from S3. Pause the video in chrome, and you will see the whole video gets buffered:

http://s3.amazonaws.com/jctest20080526/test/test.mp4

Here is the same video served from Cloudfront. Start the video, and pause it, and notice how it doesn't buffer more than a few seconds:

http://d3oocspv43fsel.cloudfront.net/test/test.mp4

[StavrosK]

Oh is that why my Coursera videos suddenly won't buffer for more than a few seconds? I figured it was an optimization, like with YouTube, so they don't waste bandwidth loading videos for people who have the tabs open but won't watch them.

Do you know of any workarounds client-side?

[jcampbell1]

> Do you know of any workarounds client-side?

I don't think there is one. You can't even compile a custom Chromium because it doesn't have h264 codecs. I even spend a day reading the Chrome source code, hoping there was some combination of headers that could trick Chrome into using the media cache, but I didn't find anything. I probably should have just spent the day finding a better CDN.

[StavrosK]

Ugh, that's too bad. Thank you for the reply.

[v13inc]

Thanks for the info, thats very informative. Can you recommend any CDNs that work well with online video? It would be great to find one that is as easy to configure as cloudfront that doesn't have this issue.

I'm not a big fan of Akamai's control panel -- setting up new distributions is way to complicated (albeit more flexible), and configuration changes were taking almost a day to propogate.

[jcampbell1]

I haven't had the time to find another vendor, thus can't recommend one.

Amazon promised a fix, but then back tracked. Their explanation was something along the lines of "an old version of Squid has the same problem, thus it is okay". I cannot comprehend the logic system they employ to think that is a good reason to live with the bug.

[micro-ram]

Both buffer while paused on Chrome iOS.

[mikeash]

Note that Chrome on iOS is basically unrelated to every other version of Chrome. Due to Apple's silly rules, it's essentially just a reskinned Safari.

[jcampbell1]

Chrome on iOS is probably using Apple's AVPlayer, which makes sense because there is probably no other way to access the dedicated decoding hardware. Apple is not afraid to Cache an HTTP 1.0 206 response.

[nkoren]

Both are buffering fine for me on Chrome for Android, too.