Wowza Community

Wowza Design Flaw in Live Linear Playback?

Wowza has the capability to play a playlist out of a .smil file. There’s a good tutorial video on the subject. The idea is that you can create an online TV channel, where the video is playing and when a viewer “tunes in” the shows are already in progress.

Pretty cool capability.

However…it seems there’s a design defect in the implementation. If you create a playlist and a video event is scheduled in the past, the video starts playing from the top, from the start of the video file.

Sounds OK, but it’s not.

Suppose you have a TV show called “Trucker Diaries.” Say it’s an hour long. Also say it’s supposed to air at 9PM. So far, so good. Let’s say it’s 9PM and “Trucker Diaries” starts playing as it should. But then at, say, 9:15PM your Wowza server crashes or you have to restart the application for some reason. When you get Wowza back up, the “Trucker Diaries” show should start playing 15 minutes in, not from the very start of the video file!

Has anybody encountered this and found a way to correct for this?

This is a great capability of Wowza but it’s useless if it can’t do what I’m describing.



Thanks for the post and the feedback @Norm Kaiser. So, I spoke with some of the engineers and they first wanted to know if you were playing a VOD as live, because you could implement logic to to jump the re-streaming to the live point.

Can you confirm your workflow? Live or VOD as live?

If it is truly live, then that would require some custom work that perhaps our Pro Services team could discuss building for you.

I’ll look for your reply- thanks.

What do you mean by “VOD as live”? You mean pre-recorded video played back linearly?

It loops an mp4 file and plays it as live through the ServerListenerStreamDemoPublisher.

I’m sorry, looks like that link I had inserted in my first post didn’t work.

This workflow would allow you to implement logic and catch up to the live point should something go wrong. But, for a truly live stream you are correct, we have no option at this time to have it restart at the new live point say 9:15 rather than 9pm at the beginning. But, the engineers did note the request.

The engineers would like to view your workflow and see if they can help set this up for you. They can do that through a support ticket. I am happy to still answer any questions though for you here @Norm Kaiser.

Thanks for all your help so far.

What I am interested in doing is exactly what’s presented here:

The only issue is the flaw I described in my original post. It’s a show stopper.

Hi Norm. What you’re asking for makes sense. The StreamPublisher is a very simple tool. While consistent, it doesn’t have the ability to make a decision, more it executes a playlist, based on instructions from the SMIL file. We do have customers who have leveraged the capability to support a dynamic scheduling workflow, which requires development of custom application logic. In your case, a custom application would need to compare the current time with the schedule and adjust the starting point of the video in the SMIL playlist. An expert Wowza and Java developer (of whom I am not) would likely have even better ideas.

Your concern about a server crash or configuration change, breaking the playlist, is valid - we will never be free from the possibility of a catastrophic event. Inversely, it would be a lot easier to maintain a stable and/or redundant server environment, with supporting change management processes vs. the time and effort required to write an application to customize the scheduler.

Thanks @Tim Dougherty!

Keep in mind @Norm Kaiser that Wowza does offer Professional Services and you’re more than welcome to schedule a call to discuss the possibility of building and implementing this custom Java logic.