HLS livestream multistream switching problem

Wowza Streaming Engine
1

hello,

I’m running wowza HLS livestream with 3 different qualities that I’m pulling from CDN.

With iOS devices, switching of qualities works just fine.

But there is a problem with smart TV devices (LG). Here is what I’ve found out:

Live stream starts to play. After cca. 20 seconds when quality should change from lower to higher, the stream simply freezes and it doesn’t continue to play.

The problem is that somehow player wants to access the same filename (.ts) on stream to which he is switching, and if that stream doesn’t have that file it simply refuses to play, example:

This is how it looks the playlist from 3 different qualities:

Low:
media_859.ts?wowzasessionid=490125569
media_860.ts?wowzasessionid=490125569
media_861.ts?wowzasessionid=490125569


Medium:
media_858.ts?wowzasessionid=490125569
media_859.ts?wowzasessionid=490125569
media_860.ts?wowzasessionid=490125569


High:
media_855.ts?wowzasessionid=966022614
media_856.ts?wowzasessionid=966022614
media_857.ts?wowzasessionid=966022614

As you can see the sequence numbers in each stream do not match. The problem is solved by restarting wowza, and the player works fine

This is how it looks like after restart, which is OK:

Low:
media_3.ts?wowzasessionid=945643668
media_4.ts?wowzasessionid=945643668
media_5.ts?wowzasessionid=945643668


Medium:
media_3.ts?wowzasessionid=246305015
media_4.ts?wowzasessionid=246305015
media_5.ts?wowzasessionid=246305015


High:
media_3.ts?wowzasessionid=1410221705
media_4.ts?wowzasessionid=1410221705
media_5.ts?wowzasessionid=1410221705

After about 30min of running wowza, the problem is present again.

Can you please tell me what is causing this unusual behaviour?

Thank you

2

As a place to start, you can enable debugging to test multi-bitrate key frame alignment:

How to debug encoder multi-bitrate key frame alignment

Salvadore

3

thanks for the link.

Now that i know that frames are not alined and that using “chunkBreakOnPTS” parameter does not solve the problem, anybody have any other idea why this is happening?

The most interesting thing here is that when sequence numbers are different for each stream, i download a video chank from each stream and they are a match although the sequence numbers on each stream are totally different!

Anyone here care to explain this? :slight_smile:

thanks

4

Using Wowza Transcoder AddOn is the only way you can get this to work properly? There is really no other way?

5

:frowning: is it possible to get a trial version of the add-on? I would like to test this 1st.

6

btw, I came across this article:

https://www.wowza.com/docs/how-to-enable-advanced-monitoring-and-resetting-of-mediacaster-streams

Isn’t this exactly what would solve my problem? resetting the stream when multistream would get out of sync?

7

The Transcoder Addon is available when using a Wowza trial license.

Here is the direct URL for the Trial license request: https://www.wowza.com/pricing/trial

Zoran

8

The only way to guarantee alignment of the key frames is to pull the highest quality stream from the CDN through the Wowza Transcoder AddOn.

From that source stream you can create a set of key frame aligned renditions for Adaptive bit rate switching.

Salvadore

9

There is no other way within Wowza to sort out the key frame mis-alignment.

Salvadore