Hardware vs. Software Graphics on Video Overlay Devices
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Hardware Overlay |
Software Overlay (Video I/O Devices) |
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On-board dedicated Hardware ICs do the Graphics and Video Mixing |
Host PC’s CPU and GPU do the Graphics and Video Mixing |
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No Video Frames sent back & forth across the PCI/PCIe Bus for graphics mixing and output |
Video Frames must be sent back & forth across the PCI/PCIe Bus for graphics mixing and output |
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Low and fixed delays between incoming video and output video+graphics overlay regardless PC status |
Long and in-deterministic delays between incoming video and output video+graphics overlay, depending on Host PC status |
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Low requirement on host PC's CPU, GPU, Graphics Card & PCIe Bus: 1XLane Gen 1 PCIe Slot OK for HD |
High requirement on host PC's CPU, GPU, Graphics Card & PCIe Bus: Min. 2XLane PCIe Slot for HD |
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On-board overlay memory buffer available directly for application software to write/read overlay pixels |
Continuous video frames sending to and receiving from host PC for any pixel overlay |
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Easy and instant overlay programming: just write 4-bytes ARGB for each video pixel overlay |
Complicated and slow overlay process: even one pixel overlay requires successive full video frame data sent back and forth over the PCIe bus for host to mix |
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Support multiple overlay cards (even dozens) in one PC without degradation of host PC performance |
Difficult to support multiple cards since each will consume significant CPU/GPU power to read/write continuous video frames |
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Using Separate Sockets to Simultaneously output Video with Overlay and Overlay Only (Key for external mixer) |
Cannot do so |
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