Hello, On Friday, November 04, 2011 2:08 PM Jonghun Han wrote:
> I'm not sure the meaning of variables in v4l2_pix_format and v4l2_plane. > Especially bytesperline, sizeimage, length and bytesused. > > v4l2_pix_format.width = width > v4l2_pix_format.height = height > v4l2_pix_format.bytesperline = bytesperline [in bytes] > v4l2_pix_format.sizeimage = bytesperline * buf height -> Is this > right ? Yes, I would expect it to be calculated this way for formats where bytesperline can be defined (for macroblock format bytesperline is hard to define). > > v4l2_plane.length = bytesperline * buf height -> Is this right ? > I don't which is right. > v4l2_plane.bytesused = bytesperline * (top + height) > v4l2_plane.bytesused = bytesperline * height > v4l2_plane.bytesused = width * height * bytesperpixel > v4l2_plane.bytesused = bytesperline * (top + height) - (pixelperline - > (left + width)) * bytesperpixel bytesused should indicate how many bytes have been modified from the beginning of the buffer, so memcpy(dst, buf->mem, byteused) will copy all the video data. So probably the most appropriate value for bytesused is: v4l2_plane.bytesused = bytesperline * (top + height) I hope my assumptions are correct, but I would also like Hans to comment on this. > I assumed the following buffer. > > | | > |<--------------------- bytesperline --------------------->| > | | > +----------------------------------------------------------+----- > | ^ | ^ > | | | | > | | | > | t | | > | o | | > | p | | > | | | > | | | | > | V |<--------- width ---------->| | | > |<-- left -->+----------------------------+ - | | > | | | ^ | > | | | | | b > | | | | | u > | | | | f > | | | h | > | | | e | h > | | | i | e > | | | g | i > | | | h | g > | | | t | h > | | | | t > | | | | | > | | | | | | > | | | v | | > | +----------------------------+ - | | > | | | > | | | > | | v > +----------------------------------------------------------+----- Best regards -- Marek Szyprowski Samsung Poland R&D Center -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
