Mike Frisch (mfrisch@xxxxxxxxxx): > > I see the lack of reasonable TV output drivers as being critical for > > building a PVR. > > What would a V4L2 interface provide that simply using a regular video > card with TV-out would not? When you say using a regular video card with TV-out, do you mean just running X at 720x[480,576] and drawing frames full-screen? If you draw an interlaced frame to the screen in this manner, you have no way of knowing what order the fields will be shown. Not only that, if you don't know the clock the card is using to output the fields, if you don't draw the next frame in time it could loop between the two current fields (motion jumping back in time!). Not only that, but you have no control over how the hardware scaling might affect your image. If you blit an interlaced frame at 640x480 for example, if the hardware decides to do a filtered scale to 720x480 for output to TV, you may see image data bleed into the other field. Ugh. When I record an interlaced video stream, I need to make sure the field sequence being output is correct. So far, the only API anyone has suggested that can handle this is v4l2, and so far, nothing supports it afaict. -- Billy Biggs vektor@xxxxxxxxxxxx
