USBTrace : Class Decoding : Audio

USB devices which belong to the Audio class can be monitored using the Audio class decoder (Plug-in dll). This class applies to all devices or functions embedded in composite devices that are used to manipulate audio, voice, and sound-related functionality. The decoder will capture, decode and display USB Audio class specific descriptors, requests and data. Both Audio Control (AC) and Audio Streaming (AS) requests are captured. The decoder supports version 1.0 of the USB Audio class specification.

The type of requests captured are:

• Audio Control Requests
• Terminal Control Requests
• Mixer Control Requests
• Selector Unit Control Requests
• Feature Unit Control Requests
• Processing Unit Control Requests
• Extension Unit Control Requests
• Audio Streaming Requests
• Interface Control Requests
• Endpoint Control Requests
• Additional Requests
• Memory Requests
• Status Requests

The following types of audio class descriptors are displayed:

• Audio Control (AC) Interface Descriptors
• Header
• Input Terminal
• Output Terminal
• Mixer Unit
• Selector Unit
• Feature Unit
• Processing Unit
• Extension Unit
• Audio Streaming (AS) General Interface Descriptor
• Audio Streaming (AS) General Endpoint Descriptor

Image below shows an audio request packet, decoded and displayed by USBTrace.