Angular interpolation error while configuring base64 media source

so I have something like this:

<audio ng-switch-when="audio" controls ng-show="messageContent.retrieved"><source ng-src="{{messageContent.source}}"/></audio>

      

        
        
        
      

    

and the content of the message is defined here:

messageLog.messages[i].messageContent[j].source = "data:audio/mp3;base64," + audioSource;

      

        
        
        
      

    

where audioSource is a base64 string. Compiling this to html gives me this error:

Error: [$interpolate:interr] Can't interpolate: {{messageContent.source}}
Error: [$sce:insecurl] Blocked loading resource from url not allowed by $sceDelegate policy.

      

        
        
        
      

    

Any ideas on why this is happening?