Why does an Interruption to a HTTP Live Stream (HLS) cause the recorded version to play ?

Question

We have set up Adobe Media Server to stream HLS. It all works great but when the stream is interupted and we start it again it draws in the recorded asset instead of continuig the live stream. What are we doing wrong?

Answer 1

Hi ariestav,
This is known to have some initial lag in the http streaming. HTTP streaming unlike RTMP requires a playlist to be generated first. Since we don't store any playlist on to the disk, this is generated just-in-time as you request. Also, HTTP unlike RTMP requires generated a particular size chunk and downloading. But most solutions around HTTP don't bother from this, because they are supposed to be run behind a HTTP caching system. So lag and all is just for the first user. You can't imagine 1000 HTTP subscribers all hitting the origin server.
Though I might give you some hints to reduce the lags. For this you try reducing the HTTP chuck size. This is by default configured at 8 seconds. You may try setting it around 4 seconds. You can edit HLSMediaFileDuration in httpd.conf under hls-vod tag to 4000.
For better seeking purpose, please try keeping the keyframe interval in your file a factor of HLSMediaFileDuration. Hope this helps http://knowfms.wordpress.com/2011/09/22/best-practices-for-setting-ios-media-file-duration /
Though I said above some initial lag is known, but that doesn't mean it should be too much to be unbearable. If you feel this is too huge, please consider sending me your test file. I will test it out for any possible bugs. You can send me at [email protected]
Good news is that we are working on improving the performance as max possible.
For other issues like artifacts/ choppy playback, also please provide the details about
1. file encoding settings
2. Device and ios-version on which you tested.