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Ad insertion causes buffering

We're using ID3 tags to trigger client side ad insertion via VAST/DFP. The ads are mid roll video ads that we insert into a live HLS stream. We are seeing some unexpected buffering both before and after an ad plays as follows. This is happening with JWplayer 7 in Chrome.

1: Just before the ad starts playing a spinning wheel appears on the screen for a split second. This is surprising because the player is holding 30 seconds of HLS segments so it should just keep rendering it until the video ad has been loaded. Why the spinning wheel?

2: Once the ad is completed and the live stream resumes we see more buffering. I used the browser dev tools to capture the packet flow, and a condensed version is included below. As you can see JWplayer continues to retrieve the chunk list while the ad is playing, so it’s well positioned to resume loading media segments once the ad is complete. But instead of resuming it abandons and starts over by requesting the play list. Why?

4:24:59 PM Get chunklist
4:24:59 PM Get segment 451
4:25:01 PM Ad starts
4:25:05 PM Get chunklist
4:25:11 PM Get chunklist
4:25:17 PM Get chunklist
4:25:20 PM Ad stops
4:25:20 PM Get playlist
4:25:21 PM Get chunklist
4:25:21 PM Get segment 455

1 Community Answers

Up Down

George

JW Player Support Agent  
0 rated :

Hi,

I’ll address your questions below:

1: Just before the ad starts playing a spinning wheel appears on the screen for a split second. This is surprising because the player is holding 30 seconds of HLS segments so it should just keep rendering it until the video ad has been loaded. Why the spinning wheel?
1A. The player is making the ad request and loading the ad content. At that time the player is technically buffering.

2: Once the ad is completed and the live stream resumes we see more buffering. I used the browser dev tools to capture the packet flow, and a condensed version is included below. As you can see JWplayer continues to retrieve the chunk list while the ad is playing, so it’s well positioned to resume loading media segments once the ad is complete. But instead of resuming it abandons and starts over by requesting the playlist. Why?
2A. The player loads the manifests, but not the .ts segments so it will buffer as it loads the video. Also, it will request the manifest once more to ensure it has the most recent manifest.

Please let me know if you have any other questions or concerns.

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