App/Music Volume While On Call

While calling, I also want to watch a video, listen to music, or watch a tv show. When I do so, the video/music volume lowers so I can hear the call in better quality. Every app with sound and safari does this. This is a cool feature, but I want to actually hear my music and the video at full volume. There seems to be nothing in the iPhone settings currently to disable this feature from changing the music/video volume during the call.