Wowza Community

HLS chunks start with brief moment of mono audio

Problem

With most clients, HLS chunks sound fine except for the very first fraction of a second, which sounds like it’s in mono. So in VLC for example, every ten seconds you hear very obvious “audio corruption”.

What surprises me is that I can’t replicate this listening to the stream on QuickTime Player on Mac OS X. However, if I download a chunk and play it, even in QuickTime, I can clearly hear the moment of mono audio.

Configuration summary

I’m using 3.6.4 build 9641. RTMP streams are pushed to a origin HLS packetizer, from which a live repeater is publishing. The packetizer and repeater are different apps on the same instance (to support failover, but that’s not enabled while trying to figure out this problem).

Source => RTMP => origin (packetizer) => live (repeater) => Client

Sample

Here’s a chunk to listen to: http://bethesignal.org/misc/media_147.aac

The file type of the chunk being .aac indicates that this is an audio only stream. You might benefit from this method of writing .ts files instead

Have you tested without the edge, i.e. direct from the origin?

Richard

Do you have the same problem when you playback directly from the origin?

I can hear the anomaly you describe in that .aac chunk.

Run another test, first restart the origin, start the stream, let it packetize for a minute or two, and test HLS playback directly from the origin and from the edge. Then zip up the origin’s /conf and the current access log showing the restart and tests and send to support@wowza.com. Include a link to this thread for reference.

Also, are you able to upgrade to the latest Wowza 4? If this is a Wowza problem it may be fixed in the latest Wowza 4.

Richard

Thanks for your response.

I noticed and tried the .ts approach, however the stream doesn’t play at all in VLC, and is incredibly choppy in QuickTime Player (that’s probably fixable with some configuration, but not working in VLC is a bigger problem).