For my book I wanted to see if there is a way to see the performance impact of various settings. So I launched the Energy Diagnostics instrument for the first time. I was not able to conclusively demonstrate the impact of any capture setting, but I did see something odd. Even though my barcode scanner sample app does not have any need for audio data AV Foundation appears to insist on capturing and processing it.
As the energy diagnostics performance instrument indicates, this causes energy usage for “Audio Processing” even though for the purpose of scanning barcodes audio is not needed. In the least developers should be able to indicate to iOS that they have no use for audio processing so that the system can conserve this energy.
This bug report is filed as rdar://16389364 and on Open Radar.