Graphics display system with anti-flutter filtering and vertical scaling feature

• US 6,738,072 B1
• Filed: 11/09/1999
• Issued: 05/18/2004
• Est. Priority Date: 11/09/1998
• Status: Expired due to Term

• Current Assignee: Broadcom Corporation (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: MacInnis, Alexander G., Tang, Chengfuh Jeffrey, Kranawetter, Greg A., Patterson, James T., Xie, Xiaodong
• Primary Examiner(s): Bella, Matthew C.
• Assistant Examiner(s): Sajous, Wesner
• Application Number:
  US09/437,327
• Time in Patent Office: 1,652 Days
• Field of Search: 345/636, 345/643, 345/660, 345/501, 345/503, 345/505-506, 345/519, 345/694, 345/698, 345/629, 345/630, 348/441, 348/446, 348/447-448, 348/455, 348/456-457, 348/459-461, 348/490, 348/492, 348/497, 348/624-630, 348/666-668, 348/701, 348/711, 348/581, 348/458, 348/453, 348/384, 382/279, 382/265
• US Class Current: 345/629
• CPC Class Codes: G06F 3/0611 in relation to response time
• CPC Class Codes: G06F 3/0653 Monitoring storage devices or systems
• CPC Class Codes: G06F 3/0659 Command handling arrangements, e.g. command buffers, queues, command scheduling
• CPC Class Codes: G06F 3/0683 Plurality of storage devices
• CPC Class Codes: G06T 1/20 Processor architectures; Processor configuration, e.g. pipelining
• CPC Class Codes: G06T 1/60 Memory management
• CPC Class Codes: G06T 9/00 Image coding bandwidth or redundancy reduction for static pictures H04N1/41; coding or decoding of static colour picture signals H04N1/64; methods or arrangements for coding, decoding, compressing or decompressing digital video signals H04N19/00
• CPC Class Codes: G06T 9/007 Transform coding, e.g. discrete cosine transform
• CPC Class Codes: G09G 2310/0224 Details of interlacing
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 2340/02 Handling of images in compressed format, e.g. JPEG, MPEG
• CPC Class Codes: G09G 2340/0407 Resolution change, inclusive of the use of different resolutions for different screen areas
• CPC Class Codes: G09G 2340/10 Mixing of images, i.e. displayed pixel being the result of an operation, e.g. adding, on the corresponding input pixels
• CPC Class Codes: G09G 2340/125 wherein one of the images is motion video
• CPC Class Codes: G09G 2360/02 Graphics controller able to handle multiple formats, e.g. input or output formats
• CPC Class Codes: G09G 2360/121 using a cache memory
• CPC Class Codes: G09G 2360/125 using unified memory architecture [UMA]
• CPC Class Codes: G09G 2360/126 The frame memory having additional data ports, not inclusive of standard details of the output serial port of a VRAM
• CPC Class Codes: G09G 2360/128 Frame memory using a Synchronous Dynamic RAM [SDRAM]
• CPC Class Codes: G09G 5/001 Arbitration of resources in a display system, e.g. control of access to frame buffer by video controller and/or main processor
• CPC Class Codes: G09G 5/02 : characterised by the way in which colour is displayed details of colour display specific for CRTs G09G1/28; specific for flat matrix panels other than liquid crystal displays G09G3/2003; specific for liquid crystal displays G09G3/3607
• CPC Class Codes: G09G 5/024 : using colour registers, e.g. to control background, foreground, surface filling G09G5/06 takes precedence
• CPC Class Codes: G09G 5/026 : Control of mixing and/or overlay of colours in general G09G5/022 and G09G5/024 take precedence
• CPC Class Codes: G09G 5/06 : using colour palettes, e.g. look-up tables
• CPC Class Codes: G09G 5/12 : Synchronisation between the display unit and other units, e.g. other display units, video-disc players
• CPC Class Codes: G09G 5/14 : Display of multiple viewports
• CPC Class Codes: G09G 5/28 : for enhancement of character form, e.g. smoothing
• CPC Class Codes: G09G 5/346 : for systems having a bit-mapped display memory
• CPC Class Codes: G09G 5/36 : characterised by the display of a graphic pattern, e.g. using an all-points-addressable [APA] memory
• CPC Class Codes: G09G 5/363 : Graphics controllers
• CPC Class Codes: H04N 11/143 : Encoding means therefor H04N11/16 takes precedence
• CPC Class Codes: H04N 11/20 : Conversion of the manner in which the individual colour picture signal components are combined, e.g. conversion of colour television standards
• CPC Class Codes: H04N 19/42 : characterised by implementation details or hardware specially adapted for video compression or decompression, e.g. dedicated software implementation H04N19/635 takes precedence
• CPC Class Codes: H04N 19/423 : characterised by memory arrangements H04N19/433 takes precedence
• CPC Class Codes: H04N 19/436 : using parallelised computational arrangements
• CPC Class Codes: H04N 19/44 : Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder
• CPC Class Codes: H04N 19/59 : involving spatial sub-sampling or interpolation, e.g. alteration of picture size or resolution
• CPC Class Codes: H04N 19/61 : in combination with predictive coding
• CPC Class Codes: H04N 21/42204 : User interfaces specially adapted for controlling a client device through a remote control device; Remote control devices therefor constructive details of casings for the remote control device H01H9/0235; user interfaces for controlling a tuning device of a television receiver through a remote control H03J9/00; remote control of peripheral devices connected to a television receiver through the remote control device of the television receiver H04B1/205
• CPC Class Codes: H04N 21/426 : Internal components of the client ; Characteristics thereof H04N5/44 takes precedence
• CPC Class Codes: H04N 21/42653 : for processing graphics
• CPC Class Codes: H04N 21/4305 : Synchronising client clock from received content stream, e.g. locking decoder clock with encoder clock, extraction of the PCR packets arrangements for synchronising receiver with transmitter by comparing receiver clock with transmitter clock H04L7/0012; arrangements for synchronising receiver with transmitter wherein the receiver takes measures against momentary loss of synchronisation H04L7/0083
• CPC Class Codes: H04N 21/4316 : for displaying supplemental content in a region of the screen, e.g. an advertisement in a separate window
• CPC Class Codes: H04N 21/434 : Disassembling of a multiplex stream, e.g. demultiplexing audio and video streams, extraction of additional data from a video stream; Remultiplexing of multiplex streams; Extraction or processing of SI; Disassembling of packetised elementary stream demultiplexing of data packets for data networks, e.g. RTP/UDP H04L65/00
• CPC Class Codes: H04N 21/440263 : by altering the spatial resolution, e.g. for displaying on a connected PDA
• CPC Class Codes: H04N 21/4438 : Window management, e.g. event handling following interaction with the user interface
• CPC Class Codes: H04N 21/47 : End-user applications
• CPC Class Codes: H04N 5/04 : Synchronising for television systems using pulse code modulation H04N7/56
• CPC Class Codes: H04N 5/126 : whereby the synchronisation signal indirectly commands a frequency generator
• CPC Class Codes: H04N 5/14 : Picture signal circuitry for video frequency region cameras or camera modules comprising electronic image sensors, or control thereof H04N23/00
• CPC Class Codes: H04N 5/44504 : Circuit details of the additional information generator, e.g. details of the character or graphics signal generator, overlay mixing circuits
• CPC Class Codes: H04N 5/45 : Picture in picture , e.g. displaying simultaneously another television channel in a region of the screen
• CPC Class Codes: H04N 5/46 : for receiving on more than one standard at will deflecting circuits of multi-standard receivers H04N3/27
• CPC Class Codes: H04N 7/0122 : the input and the output signals having different aspect ratios
• CPC Class Codes: H04N 7/0135 : involving interpolation processes interpolation-based image scaling G06T3/4007; interpolation for video coding H04N19/587, H04N19/59
• CPC Class Codes: H04N 9/45 : Generation or recovery of colour sub-carriers
• CPC Class Codes: H04N 9/641 : Multi-purpose receivers, e.g. for auxiliary information H04N9/642 takes precedence
• CPC Class Codes: H04N 9/642 : Multi-standard receivers

Abstract

A graphics integrated circuit chip is used in a set-top box for controlling a television display. The graphics chip processes analog video input, digital video input, and graphics input. The chip includes a single polyphase filter that preferably provides both anti-flutter filtering and scaling of graphics. Anti-flutter filtering may help reduce display flicker due to the interlaced nature of television displays. The scaling of graphics may be used to convert the normally square pixel aspect ratio of graphics to the normally rectangular pixel aspect ratio of video.

Claims

1. A graphics processing system comprising:

a display engine for blending a plurality of graphics images, each graphics image comprising a plurality of pixels each having YUV values and an alpha value, to generate a blended graphics image, wherein the YUV values are blended using the alpha values to generate blended YUV values, and the alpha values are combined independently of the YUV values to generate composite alpha values;

a graphics filter coupled to the display engine for performing anti-flutter filtering on the blended graphics image by scaling it to generate a filtered graphics image, wherein the composite alpha values are scaled in a same way as the blended YUV values so that resulting filtered alpha values correctly correspond to resulting filtered YUV values when the filtered graphics image is blended with a video image; and

a video compositor coupled to the graphics filter for blending the filtered YUV values with the video image using the filtered alpha values to generate an output of blended graphics and video.

2. The graphics processing system of claim 1, wherein the graphics filter comprises a polyphase filter.

3. The graphics processing system of claim 2 wherein the polyphase filter is programmable.

4. The graphics processing system of claim 1 wherein the graphics filter scales the blended graphics image vertically.

5. The graphics processing system of claim 1 wherein the graphics filter scales the blended graphics image horizontally.

6. The graphics processing system of claim 1 wherein the graphics filter has four taps.

7. The graphics processing system of claim 2 wherein the polyphase filter has four taps.

8. The graphics processing system of claim 1 wherein the graphics filter is capable of operating in a field mode wherein every other display line is processed during filtering.

9. The graphics processing system of claim 1 wherein the graphics filter is capable of operating in a frame mode wherein every display line is processed during filtering.

10. The graphics processing system of claim 7 wherein inputs to the four taps of the polyphase filter are provided by four line buffers.

11. The graphics processing system of claim 3, wherein the graphics filter comprises memory suitable for storing horizontal coefficients for programming the polyphase filter.

12. The graphics processing system of claim 3, wherein the graphics filter further comprises memory suitable for storing vertical coefficients for programming the polyphase filter.

13. A method of blending a video image with a plurality of graphics images, each graphics image comprising a plurality of pixels each having YUV values and an alpha value, the method comprising:

blending the YUV values of the graphics images using the alpha values to generate blended YUV values for a blended graphics image;

combining the alpha values independently of the YUV values to generate composite alpha values for the blended graphics image;

performing anti-flutter filtering on the blended graphics image by scaling it using a graphics filter to generate a filtered graphic image, wherein the composite alpha values are scaled in a same way as the blended YUV values so that resulting filtered alpha values correctly correspond to resulting filtered YUV values when the filtered graphics image is blended with the video image; and

blending the filtered YUV values with the video image using the filtered alpha values to generate an output of blended graphics and video.

14. The method of claim 13 wherein the graphics filter comprises a polyphase filter.

15. The method of claim 14 wherein the polyphase filter is a four tap filter.

16. The method of claim 13 wherein the scaling comprises vertical scaling.

17. The method of claim 13 wherein the scaling comprises horizontal scaling.

18. The method of claim 13 wherein blending the YUV values of the graphics images comprises blending lines of the graphics images on different layers into a plurality of line buffers, and providing lines of the blended graphics image in the line buffers to be filtered and scaled.

19. The method of claim 18 wherein contents of four line buffers are provided for filtering and scaling at a time.

20. The method of claim 19 wherein lines of graphics images on different layers are composited to create lines of the blended graphics image in one or more of other line buffers while the lines of the blended graphics image in the four line buffers are being filtered and scaled.