Gapless AAC

Wowza Streaming Engine
1

Hi

Does Wowza support reading the information in AAC audio files created by Nero (or Itunes) for gapless playback ?

Thanks

Ruben Chadien

2

Hi Ruben,

I’m not sure what you mean by “reading the information”. Wowza does support the AAC audio codec.

Are you saying that you’ve tried streaming AAC audio files with Nero and Itunes, and the playback through Wowza contains gaps?

3

Hi

Well actually I’m not sure if it does due to the Metadata within the itunes wrapper, this may give itunes instruction on how to playback the files with gapless playback.

If it was the gapless playback that you wanted then you can try the playlist schedule method,

https://www.wowza.com/docs/how-to-schedule-streaming-with-wowza-streaming-engine-streampublisher

Jason

4

Ruben,

Try adding this Property to the /conf/[app-name]/Application.xml /Streams /Properties list:

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

Richard

5

Well, it is worth a try, but on 2nd thought this might not apply to vod.

Richard

6

Yes, when encoding an AAC file the encoder adds a few MS of silence in the beginning of the songs, see http://en.wikipedia.org/wiki/Gapless_playback

Nero AAC encoder and also Itunes encoder supports adding information to the AAC file that tells the player to skip this silence.

I tried playing two files with Flex:

soundInstance.play(“mp4:1.mp4”,0,-1,true);

soundInstance.play(“mp4:2.mp4”,0,-1,false);

and a small gap is heard between the files, these files were encoded with iTunes.

So is it possible to get Wowza to skip the silence based on the information in the AAC files ?

Thanks

Ruben Chadien

7

Think your right , did not help :frowning:

Is this something a can extend Wowza with myself ? Writing some kind of plugin that reads the AAC information and skips the silence.

/Ruben

8

Yes, there are several ways to play a VOD file starting at a certain time: https://www.wowza.com/docs/how-to-specify-a-play-start-time-and-duration-for-http-streaming

If you can figure out how to get your flash player to play an HTTP URI in that format, maybe this will be your solution.

Or you can create a very small module to override the play function to specify this start time for all of your VOD files. From the above link look at the “Server-side API” section. There is mentioned a method called onHTTPSessionCreate(). Here is an example that shows how to invoke this method which you may be able to adapt to your needs: https://www.wowza.com/docs/how-to-limit-playback-by-ip-address-moduleoverrideplayrestrictip