Video over IP Measurement techniques

Video over IP quality measurement is important for the growth of video on the internet.

Quality measurement algorithms are divided into two main types: Subjective and objective measurements. Subjective measurements results are not preformed by monitoring devices only by humens Therefore this discussion about monitoring devices algorithms will focus on objective video quality monitoring methods

The objective quality measurements types are further segmented into several algorithm types:
1 Payload based
2 Codec Aware Packet based
3 Codec independent packet based
4 Network parameters

Payload based methods requires a comparison of the video to the source. Those methods are used for lab measurements in which the source stream is available.
The most common Payload Based video quality evaluation methods are PSNR and ITU-T J.144.
In a monitoring (in-service) testing scenario, the source stream is not available; Hence payload based measurements are not used in monitoring equipment.

Monitoring equipment must utilize zero refrence algorithms which could be one or more of the three methods network monitoring, packet based codec aware and packet based codec independent methods.
For regular data oriented communication networks, the raw packet loss and jitter parameters suffice.
In media oriented networks, raw network parameters are not enough and there is a need to measure the effect of the network impairments on the perceived media quality.

The two quality monitoring methods employed in media oriented packet networks are the codec aware and codec unaware packet based algorithms.
The codec unaware algorithms like MDI provide a quality index based only on network parameters without considering the codec type. This type of measurement will provide the same quality index for all codecs, although each codec degrades differently in the presence of network impairments.

The most used methods for media quality in IP networks today is the codec aware packet based method which considers the codec type when grading the quality based on network parameters. For example, while MDI will provide one media quality index for any given packet loss, codec aware methods will consider the codec type.
degradation curve described in the graph above and provide the quality score based on the codec type.

The drawing above presents a rough taxonomy of the monitoring algorithms reviewed and their uses.