Wowza Community

recorded streams audio sync problem

I am experiencing some strange thing and can’t figure out why this is happening.

If I use TERADEK - LIVE:AIR Solo app to stream, the recorded mp4 file audio gets out of sync (audio before the video) when watching with VLC player,

if I open it in browser like Firefox or Chrome it seems to be fine.

With Wowza GoCoder I don’t experience this problem, or if I turn off the Trescoder then TERADEK mp4 seems to be in sync when playing in VLC.

Any idea what setting can cause or fix this ?

Hello there and welcome to the Wowza support forum.

What you describe is generally a problem with the source, the encoder. You can enable this Property so you can debug alignment:

How to debug AAC or MP3 timecode issues with Apple HLS packetization

Be sure to add “cupertinostreamingpacketizer” to /Streams /LiveStreamPacketizers

Also, can an you clarify what you mean by out of sync? How out of sync? Does it drift out of sync over time and is back in sync if you stop playing and start again? Is the stream out of sync when played back using Wowza Server?

What is the key frame interval set to? If it is very long that might be a problem. Try adding this Property to the Application.xml /Streams /Properties list:

<Property>
<Name>recordWaitForVideoKeyFrame</Name>
<Value>true</Value>
<Type>Boolean</Type>
</Property>

Regards,

Salvadore

Hi,

It’s odd that your recordings are in sync on some players and not others. It would seem to point to something external to Wowza but if you open a support ticket and include steps to reproduce as well as a copy of the recording we can take a closer look.

Regards,

Paul

Hello thx for the replay.

By out of sync I mean when I watch it with VLC the sound is 1-2s before the video.

I could not find the property what you mentioned in the WowzaStreamingEngine_ConfigurationReference.pdf, but there is a property in

StreamRecorder => streamRecorderStartOnKeyFrame

The server is a Wowza 4.5

These are the app video settings for the keyframe:

Wowza go coder - Keyframe Interval 30

Live Air Solo - Key Frame Interval 2s