One of the key features in dynamic adaptive streaming over HTTP (DASH) systems is the ability to monitor Quality of Experience (QoE) at the client side. This allows the system to manage streaming performance and detect and debug failures.
The 3rd Generation Partnership Project (3GPP) has adopted QoE metrics for adaptive bitrate streaming (ABS) services as part of their DASH specifications. It provides mechanisms for triggering QoE measurements at the client side and protocols/formats for delivery of the measured QoE values to the network servers. The sequence of events is: The server sends a QoE request to the client, then the client measures the requested metrics and reports back.
The set of QoE metrics that are specified in 3GPP DASH are:
- List of HTTP request/response transactions
- List of representation switch events (e.g. changing bitrate)
- Average throughput
- Initial playout delay when streaming began
- List of buffer level measurements
- List of playback periods during which media was streaming
- MPD information (servers without access to MPD can request it)
In 3GPP DASH, QoE reports are formatted using extensible markup language (XML).