MICROTRONIX DX-2200, User Manual

Page: 82 / 103

DX-2200
– SD/HD-SDI Text & Graphics Inserter – User Manual
Page 82 of 103
6 Text Writing Performance Measurements
The text writing speed of the DX-2200-TI has been benchmarked at 1080p30 and 720p60 video resolutions
using a program on a PC to deliver text strings and commands to the SD/HD-SDI Text & Graphics Inserter
unit. The PC program uses Standard Graphic Overlay Control Commands (per commands of Table 12) and
also Low Level Overlay Control Commands (per commands of Table 13).
With the standard Graphic Overlay Commands, all of the video text is rendered (i.e. generated in the active
display buffer) when Fields are changed. However, with the Low Level Overlay Commands, the user
program first renders the static (i.e. non-changing) text to both the active and spare buffer and then updates
only the changing text string into the spare (background) buffer and then simply swaps the buffers (upon the
user Serial Command). To maximize the speed of text updates, text in the new background buffer is not
cleared after the swap and only changing Text Fields are rendered in the background buffer. The results of
the two methods are provided in the following sections.
6.1 Standard Text String Update Benchmark Measurements
In this test a number of characters were written through the Serial Port of the DX-2200-TI for OSD using
three font sizes: the F001 (small 26 pixel height), F002 (medium 40 pixel height) and F003 (large 78 pixel
height). A total of 20 of the characters were subsequently changed for each update. The time required to
update the output display was measured in frames of delay. The results are summarized below.
Table 25: Update Rate for Standard Text String Commands
Font Video
# of Characters
Frames to Update
Output
Written Changing
F001 720p60 147 20 13
F001 720p60 294 20 20
F001 720p60 588 20 33
F001 1080p30 323 20 15
F001 1080p30 664 20 22
F001 1080p30 1328 20 37
F002 720p60 64 20 13
F002 720p60 128 20 19
F002 720p60 256 20 31
F002 1080p30 18 20 13
F002 1080p30 288 20 22
F002 1080p30 576 20 36
F003 720p60 18 20 13
F003 720p60 36 20 19
F003 720p60 72 20 32
F003 1080p30 40 20 14
F003 1080p30 80 20 22
F003 1080p30 120 20 23