Texas Instruments SPRAA56 appendix Important Benchmarks for Video Applications, Figures

SPRAA56
	Figures
Figure 1. Basic Data Flow of the Video Application		4
Figure 2. Detailed Application Data Flow Showing Memory Buffers		8
Figure 3. Task Partitioning in the Modified Application		9
Figure 4.	CPU Load Measurement at Run-Time	15
Figure 5.	External ↔ Internal Memory Transfers, YUV4:2:0 to 4:2:2 Conversion Function ....	16
Figure 6.	Workspace Including RTA Windows	22
Figure 7.	Statistics View Showing Benchmark Measurements	23

1Important Benchmarks for Video Applications

Diverse video applications often require similar benchmarks to quantify their performance. Some of the most commonly needed benchmarks are as follows:

•Frame rate

•Resolution

•End-to-end latency

•Processor utilization

•Bitrate*

•Quantization factor*

•Frame type*

•Group-of-pictures (GOP) structure*

Items marked with an asterisk are of importance in applications where encoders or decoders are involved. This application note provides a method for measuring many of these benchmarks during the capture, processing, and display phases of the example video application.

Frame rate is the rate at which frames are captured, processed, and displayed. The capture, process, and display frame rates can differ by design or under overloaded conditions where frames are “dropped.” Therefore, it is important to measure all three frame rates separately.

Resolution is the size in pixels of the capture, processing, and display. Resolution is typically static at run-time, so it is not usually benchmarked with real-time tools. However, it is important to know the capture, processing, and display resolutions of the system design. For example, the H.263 loopback application used in this application note captures and displays video in D1 resolution and processes in 4CIF resolution.

End-to-end latency is a measurement of the time between the capture of a video frame in real- time and the display of that same video frame some number of milliseconds later.

Processor utilization is the percentage of DSP resources used by an algorithm. In video applications, the significant benchmarks of processor utilization include not only the number of CPU cycles used, but also the memory bus utilization since such large amounts of data must be moved from external memory to L2 and back repeatedly.

Bitrate is the number of bits per second output by a video encoder, or delivered to a video decoder. Higher bitrates are generally associated with higher quality video. The bitrate often varies with the complexity and motion in a video source, so it is important to measure bitrate dynamically in video applications.

2 DSP/BIOS Real-Time Analysis (RTA) and Debugging Applied to a Video Application