AN00127 frame rate limitation

[pmjobin]

Hi,

I've been testing the USB Video Class Device application note (AN00127) on the XK-EVK-XU316 and was wondering what might be limiting the frame rate to around 30 fps. The host negotiates a speed of 480 Mbps, so I would expect the maximum achievable frame rate for a resolution of 480x270 YUV422 to be:

(12 header bytes/line + 480 pixels/lines * 2 bytes/pixels) * 270 lines/frames * 8 bits/byte = 2.1 Mbits/frames

480 Mbps / 2.1 Mbits/frames = 228 frames/sec.

This is significantly higher than the observed 30 fps. It doesn't seem like the frame rate is being limited by a timer or similar mechanism. Instead, the transmission speed appears to be the bottleneck, as reducing the vertical resolution increases the frame rate proportionally.

Is there anything that can be done to achieve a frame rate of 60 fps for this demo?

Thanks,
P-M