The attached file documents the new, experimental, video output overlays. These are for the 2.6.22 kernel.
While I'm happy with how it is used, the one thing that I am not sure about is the name 'video output overlay'. I wonder if I shouldn't rename it to 'Video Output OSD'. In theory at least it is possible to have an MPEG decoder that mixes the video output with an OSD framebuffer and then overlays that with a graphics card framebuffer. Some feedback on this is welcome. Regards, Hans
Documentation for the new, experimental video output overlay buffer type. Add a new section after section 4.3 (Video Output Interface): Section 4.4. Video Output Overlay Interface Status: experimental. Also known as On-Screen Display Video output overlay devices have the ability to mix the output video with a framebuffer image. It is used to achieve the On-Screen Display feature. Contrary to the Video Overlay Interface this framebuffer is normally implemented on the video output board and not in the graphics card. The actual operation of a video output overlay interface is identical to that of the video overlay, see section 4.2 for more information. 4.4.1. Querying Capabilities Devices supporting the video output overlay interface set the V4L2_CAP_VIDEO_OUTPUT_OVERLAY flag in the capabilities field of struct v4l2_capability returned by the VIDIOC_QUERYCAP. ioctl VIDIOC_QUERYCAP: add the following to Table 2 (Device Capabilities Flags): V4L2_CAP_VIDEO_OUTPUT_OVERLAY 0x00000400 The device supports the video output overlay interface. This is typically used for On-Screen Displays. Status: experimental. Section 3.5 (Buffers), Table 3-2 (enum v4l2_buf_type): add the following: V4L2_BUF_TYPE_VIDEO_OUTPUT_OVERLAY 8 Buffer for a video output overlay, see Section 4.4. Status: experimental.
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