Dual-scaler architecture for reducing video processing requirements

Abstract

A video signal processor includes an input port adapted to receive an input video signal. The input video signal is characterized by a first horizontal resolution and a first vertical resolution. The video signal processor also includes a prescaler adapted to perform prescaling of the video signal, wherein prescaling converts the input video signal at the first horizontal resolution and the first vertical resolution to a prescaled video signal characterized by a second horizontal resolution and a second vertical resolution. The video signal processor additionally includes a frame buffer coupled to the prescaler. The video signal processor further includes a horizontal scaler adapted to convert the horizontal scale of the prescaled video signal from the second horizontal resolution to a third horizontal resolution and a vertical scaler adapted to convert the vertical scale of the prescaled video signal from the second vertical resolution to a third vertical resolution.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application claims benefit under 35 U.S.C. 119(e) of U.S. provisional application No. 60/558,647, filed Jul. 16, 2004, entitled “System And Method For Use In Video Processing Including A Programmable Input Device, A Pixel Clock Generator, And A Dual Scaler Architecture,” the contents of which is incorporated herein by reference in its entirety.

STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

NOT APPLICABLE

BACKGROUND OF THE INVENTION

The present invention relates generally to integrated circuits (ICs), and more particularly to video processor ICs. More particularly, the present invention relates to an architecture for a video processor IC. Merely by way of example, the invention has been applied to a dual-scaler architecture adapted to reduce the workload of a video processor IC receiving high definition video signals. But it would be recognized that the method and apparatus can be applied to both interlaced and progressive video signals and that the invention has a much broader range of applicability.

Video processing hardware is generally used to perform selected pixel-based and frame-based processing steps on an incoming video stream and then scale the resulting video signal for output on a display. Scaling of the video signal may be used to provide appropriate pixel scale in multi-standard video applications. For example, in some applications, it is desirable to receive a video signal at DVD resolution (720 pixels by 480 pixels), for instance, from a DVD player, and to display the video signal on a VGA display device (resolution of 640 by 480 pixels). In this application, the horizontal resolution of the signal is scaled from 720 pixels to 640 pixels for full-screen display on the television. Generally, to provide for multi-format conversion, a set of vertical and horizontal scalers are provided in video processing ICs.

A variety of standard definition television (SDTV) video formats are currently in use, including NTSC, PAL, and SECAM formats, as well as other conventional and non-conventional SDTV formats. Additionally, a number of high-definition television (HDTV) formats such as 720p, 1080i, and 1080p are also currently in use. In these HDTV formats, the letter “p” represents a progressively scanned signal and the letter “i” represents an interlaced signal. Conversion between these various video formats is usually performed by video processing ICs integrated into the display device, for example, a television or video display device. As discussed above, other formats, including the DVD format and PC formats including VGA, XGA, SXGA, and UXGA are currently in use.

The architecture of some video processing ICs is adapted to process standard interlaced video (SDTV) at a pixel rate of 13.5 MHz. Generally, non-HDTV broadcast signals are included in the formats referred to as SDTV. The extension of these video processing ICs for use in processing HDTV signals is nontrivial. For instance, as the clock rate of the video processing IC and the memory size provided increase, it becomes increasingly difficult to utilize hardware adapted for processing SDTV video signals to process HDTV video signals, while maintaining the resolution of the HDTV video signals.

Therefore, there is in need in the art for a method and apparatus for reducing processor and memory bandwidths in video processing ICs utilized to process multi-format video signals.

SUMMARY OF THE INVENTION

According to the present invention, techniques related to integrated circuits (ICs), and more particularly to video processor ICs, are provided. More particularly, the present invention relates to an architecture for a video processor IC. Merely by way of example, the invention has been applied to a dual-scaler architecture adapted to reduce the workload of a video processor IC receiving high definition video signals. But it would be recognized that the method and apparatus can be applied to both interlaced and progressive video signals and that the invention has a much broader range of applicability.

According to an embodiment of the present invention, a video signal processor is provided. The video signal processor includes an input port adapted to receive an input video signal. The input video signal is characterized by a first horizontal resolution and a first vertical resolution. In some embodiments, the input video signal is an HDTV video signal. The video signal processor also includes a pixel-based processor coupled to the input port and adapted to perform pixel-based processing of the input video signal and generate a processed video signal. The video signal processor further includes a prescaler coupled to the pixel-based processor and adapted to perform prescaling of the processed video signal. In embodiments of the present invention, the prescaling process converts the processed video signal at the first horizontal resolution and the first vertical resolution to a prescaled video signal characterized by a second horizontal resolution and a second vertical resolution. In some embodiments, the second horizontal resolution is less than the first horizontal resolution. In other embodiments, the second vertical resolution is less than the first vertical resolution.

The video signal processor additionally includes a frame-based processor coupled to the prescaler and adapted to perform frame-based processing of the prescaled video signal and a frame buffer coupled to the frame-based processor. Moreover, the video signal processor includes a horizontal scaler coupled to the frame buffer and adapted to convert the horizontal scale of the prescaled video signal from the second horizontal resolution to a third horizontal resolution and a vertical scaler coupled to the horizontal scaler and adapted to convert the vertical scale of the prescaled video signal from the second vertical resolution to a third vertical resolution. In some embodiments, the third horizontal and third vertical resolution is less than the first horizontal and first vertical resolution associated with the input video signal.

According to another embodiment of the present invention, a method of processing a video signal is provided. The method includes receiving a video signal characterized by a first horizontal resolution and a first vertical resolution and performing prescaling of the video signal to change the first horizontal resolution to a second horizontal resolution and the first vertical resolution to a second vertical resolution and produce a prescaled video signal. In some embodiments, the first horizontal resolution is greater than the second horizontal resolution and the first vertical resolution is greater than the second vertical resolution. The method also includes performing storage of the prescaled video signal in a frame buffer. The method further includes performing horizontal scaling of the prescaled video signal to convert the prescaled video signal from the second horizontal resolution to a third horizontal resolution and performing vertical scaling of the prescaled video signal to convert the prescaled video signal from the second vertical resolution to a third vertical resolution. Moreover, the method includes providing an output video signal characterized by the third horizontal resolution and the third vertical resolution.

Numerous benefits are achieved using the present invention over conventional techniques. Some embodiments provide video processor ICs with reduced processor requirements. Additionally, embodiments of the present invention reduce the bandwidth of high definition signals for processing by deinterlacers adapted to process standard definition signals. Moreover, some embodiments of the present invention provide reductions in the manufacturing cost of video processor IC components as well as the cost of internal and external memories utilized in video processing operations. Furthermore, embodiments of the present invention provide methods and apparatus which reduce the power consumption for video processing ICs as well as video processing systems. Depending upon the embodiment, one or more of these benefits may exist. These and other benefits have been described throughout the present specification and more particularly below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified schematic diagram illustrating a video processor architecture according to an embodiment of the present invention;

FIG. 2 is a simplified flowchart illustrating a process flow according to an embodiment of the present invention;

FIG. 3 is a simplified schematic diagram illustrating a video processor architecture according to an alternative embodiment of the present invention;

FIG. 4 is a simplified flowchart illustrating a process flow according to an alternative embodiment of the present invention;

FIG. 5 is a simplified diagram illustrating a prescaling, processing, and scaling operation according to an embodiment of the present invention; and

FIG. 6 is a simplified diagram illustrating another prescaling, processing, and scaling operation according to another embodiment of the present invention.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

According to the present invention, techniques related to integrated circuits (ICs), and more particularly to video processor ICs, are provided. More particularly, the present invention relates to an architecture for a video processor IC. Merely by way of example, the invention has been applied to a dual-scaler architecture adapted to reduce the workload of a video processor IC receiving high definition video signals. But it would be recognized that the method and apparatus can be applied to both interlaced and progressive video signals and that the invention has a much broader range of applicability.

As discussed above, the use of video processing ICs adapted to process SDTV video signals for processing of HDTV video signals presents a number of challenges. For instance, an exemplary deinterlacing algorithm included in a video processing IC utilized to process standard interlaced SDTV signals at a pixel rate of 13.5 MHz operates at a clock rate of 50 MHz for signal processing operations and uses a 32-bit memory system. To extend the capabilities of this video processing IC to an HDTV video signal such as a 1080i signal, a pixel rate of 74.25 MHz is used. Accordingly, the system clock operates at a clock rate of 275 MHz and a 64-bit memory system is generally utilized. In some embodiments, the memories are DDR memories, whereas in other embodiments, the memories are SDRAMs.

Moreover, utilizing embodiments of the present invention, the size of frame buffers utilized during video processing operations is reduced. For example, in some video processors adapted to process HDTV signals, frame buffers with 16 MB capacities are utilized. According to embodiments of the present invention, frame buffers of 8 MB capacity or smaller are utilized to process prescaled HDTV signals. As will be evident to one of skill in the art, the increase in system clock rate generally necessitates a decrease in semiconductor process linewidth, for example from 0.18 μm geometries to 0.13 μm geometries. Moreover, the increased memory requirements result in additional cost increases.

In some video applications, the resolution of the video display device is less than the resolution of the input signal. For example, for some video display devices, such as an XGA display device generally utilized with a PC, content is displayed in a 1024×768 pixel progressively scanned format. Other display devices, including VGA display devices, with resolutions of 640×480 pixels, SXGA display devices, with resolutions of 1280×1024 pixels, and UXGA display devices, with resolutions of 1600×1200 pixels, are included in embodiments of the present invention. If the incoming video signal provided to the XGA display device is an HDTV signal, the XGA display device is not capable of displaying the total resolution provided by the HDTV signal. Although the XGA display device provides a picture quality closer to HDTV than to regular television, the XGA display device will not display either the 1280 pixels present in the horizontal direction in a 720p signal (1280×720 pixels) or the 1920 pixels present in a 1080i format signal (1920×1080 pixels). Thus, for some XGA display devices (or other PC or TV displays), the capability of maintaining the resolution of an HDTV signal does not provide a benefit to the viewer. For these applications, and others, a video processing IC incorporating a prescaler provides a benefit of reducing system bandwidth and memory resources utilized while producing an output signal to the display device appropriate to the display device's resolution.

FIG. 1 is a simplified schematic diagram illustrating a video processor architecture according to an embodiment of the present invention. As illustrated in FIG. 1, video processor 100 includes a number of processor elements and provides a dual-scaler architecture comprising a set of prescalers and a set of scalers. As will be described more fully below, the dual-scaler architecture reduces the signal processing and memory requirements, enabling processing of high resolution signals with standard video processing components and algorithms. An input video signal is received at pixel-based processor 110. Generally, pixel-based processing includes enhancements to video signals such as color adjustments, color conversion, format conversion, and the like.

After pixel-based processing of the input video signal, the signal is provided to a horizontal prescaler 112. In an embodiment, the horizontal prescaler reduces the horizontal pixel count of the input video signal, providing an output in the form of a prescaled video signal. Merely by way of example, the horizontal resolution may be decreased from 1920 pixels to 1024 pixels, this conversion being associated with scaling from HD resolution to XGA resolution. Embodiments of the present invention are not limited to conversion from HD resolutions to XGA resolutions. Merely by way of example, embodiments of the present invention provide for horizontal prescaling of HDTV signals for eventual display at EDTV, SDTV, VGA, XGA, SXGA, and other resolutions.

In embodiments of the present invention, the horizontal prescaler is adaptive and software programmable. These features enable the designer to select a scaling level that is appropriate to existing processor components. In some embodiments, conventional scaling approaches and algorithms, including finite impulse response (FIR) filters and downsampling techniques are utilized for the prescalers.

A vertical prescaler 114 is provided as an element of the video processing IC according to embodiments of the present invention. After processing by the horizontal prescaler, the signal is provided to the vertical prescaler, which performs a scaling operation on the pixels arrayed vertically. In some embodiments, the vertical scale of the video signal is reduced, for example, from that associated with an HDTV signal to that associated with an EDTV signal, an SDTV signal, or others. One of ordinary skill in the art would recognize many variations, modifications, and alternatives.

Embodiments of the present invention provide for prescaling of the input video signal, thereby reducing the pixel count prior to substantial processing of the video signal. Accordingly, embodiments of the present invention provide video processing IC designers with methods and apparatus that utilize processor components developed for SDTV applications to convert and process HDTV video, producing a video signal matched to the resolution of display display devices at resolutions lower than HDTV resolutions.

Although FIG. 1 illustrates both a horizontal and vertical prescalar, embodiments of the present invention are not limited to this particular architecture. In some alternative embodiments, either a horizontal prescaler or a vertical prescaler are provided as appropriate to the particular application. Additionally, a software bypass may be used to select the appropriate prescaling processing, including a resolution conversion factor equal to one. Merely by way of example, in a particular embodiment of the present invention, a horizontal prescaler is utilized to reduce the horizontal pixel count while maintaining the vertical pixel count. For example, in a conversion of a 720p signal to a VGA format, a horizontal prescaler may be utilized to reduce the horizontal pixel count from 1280 to 640, thereby reducing the total pixel count by a factor of two. According to embodiments of the present invention, high bandwidth signals, such as HDTV signals with sampling rates about five times greater than SDTV signals are prescaled prior to some video processing steps. The prescaling step allows for reduction in signal bandwidth to levels suitable for processing by video processing components originally developed for SDTV applications, which are generally characterized by signal bandwidths about five times less than those associated with HDTV signals. Cost savings and other benefits will be evident to one of skill in the art.

In other embodiments, the signal is passed from the pixel-based processor 110 to the vertical prescaler, bypassing the horizontal prescaler as illustrated by processing path 130. As an example, processing path 130 could be appropriate for processing a UXGA signal. Moreover, processing path 132 is illustrated in FIG. 1, whereby the horizontal prescaling is performed on the input signal and the signal is passed to the frame-based processor, bypassing the vertical prescaler. As an example, a 1080i signal is prescaled to generate a 960×1080 pixel signal in an embodiment of the present invention, without vertical prescaling of the signal. Additionally, in some embodiments, another processing path (not illustrated) is provided, in which both prescalers are bypassed and the video signal is passed from the pixel-base processor to the frame-based processor. One of ordinary skill in the art would recognize many variations, modifications, and alternatives.

Frame buffer 116 is provided according to embodiments of the present invention as illustrated in FIG. 1. Frame buffer 116 is a DDR or a SDRAM frame buffer according to particular embodiments of the present invention. Generally, the frame buffer stores multiple frames or fields in memory, enabling subsequent processing at a frame/field level. Additionally, frame-based processor 118 is illustrated in FIG. 1. Frame-based processing includes a number of actions, including interlacing, automatic brightness adjustment, noise measurement and adjustment, and the like. As will be evident to one of skill in the art, frame buffers and frame-based processors may also be utilized to perform frame rate conversion. Deinterlacer 120, a second set of scalers including Horizontal Scaler 122 and Vertical Scaler 124 along with a Display Enhancer 126 are illustrated in FIG. 1. Generally, a display enhancer performs processes including edge enhancement, color enhancement, and the like. In some embodiments, the deinterlacer is combined with the frame-based processor, although this is not required by the present invention. Video output is provided at the output of the display enhancer, generally optimized for the particular display associated with the video processor IC. In some applications, the scalers 122 and 124 convert the signal from the format provided by the deinterlacer 120 to the signal associated with a particular monitor or display device. Thus, embodiments of the present invention are capable of receiving multi-format signals as inputs and outputting a video signal adapted for display on a particular display device, the particular display device being characterized by a vertical and horizontal resolution, contrast ratio, and the like.

Although FIG. 1 illustrates the set of prescalers 112 and 114 as utilized between the pixel-based and frame-based processing steps, this is not required by the present invention. In alternative embodiments, the prescalers are employed prior to or following the pixel-based and frame-based processing steps as appropriate to the particular application. Generally, reduction of the pixel count prior to processing by deinterlacer 120 is provided by embodiments of the present invention. As described throughout the specification, signal processing requirements, for example, in the deinterlacer, are reduced by embodiments of the present invention. Moreover, memory sizes provided and/utilized by the video processing IC are reduced, reducing system cost and complexity.

In a particular embodiment, video processing components, such as a deinterlacer, generally utilized to process SDTV signals are utilized to process prescaled HDTV signals without significant reductions in final image quality. As will be evident to one of skill in the art, the useful lifetime of well-developed processor designs currently in use for SDTV signal processing is extended by utilizing the methods and apparatus provided by embodiments of the present invention. As an example, video processing components designed and fabricated using 0.18 μm technology are utilized to process HDTV signals generally processed using more advanced processor designs, larger die sizes, or smaller linewidth technologies such as 0.13 μm technologies.

As illustrated in FIG. 1, deinterlacer 120 is utilized, but embodiments of the present invention are not limited to interlaced video processing. In other embodiments, progressively scanned video signals are processed according to embodiments of the present invention. One of ordinary skill in the art would recognize many variations, modifications, and alternatives.

FIG. 2 is a simplified flowchart illustrating a process flow 200 according to an embodiment of the present invention. As illustrated in FIG. 2, an input video signal is received in step 210. In some embodiments of the present invention, the input video signal is 25 an HDTV signal, for example a 720p, a 1080i, or a 1080p signal. In alternative embodiments, the video signal is an EDTV video signal or an SDTV video signal. One of ordinary skill in the art would recognize many variations, modifications, and alternatives. Pixel-based processing of the video signal is performed in step 212. In steps 214 and 216, respectively, horizontal and vertical prescaling of the video signal received in step 210 is performed.

As described above, prescaling of high bandwidth video signals, such as HDTV signals, reduces the bandwidth of the video signal, thereby reducing performance requirements for processor components and memory. In step 218, frame buffereing is performed and frame-based processing is performed is performed in step 220. In the embodiment, illustrated in FIG. 2, deinterlacing is performed in step 222. Of course, this step becomes an optional step when progressively scan video signals are utilized. Embodiments of the present invention are not limited to interlaced video signals, but are also applicable to progressively scanned video signals. Moreover, in some embodiments, the frame-based processor and the deinterlacer are combined into a single component. In these embodiments, steps 220 and 222 are combined into a frame-based processing/deinterlacing process.

In step 224, horizontal scaling of the video signal is performed. Generally, this scaling step is accomplished in order to size the video signal for display on an appropriate display device. As an example, consider the processing of a 1080i video signal for display on an XGA display device. As received, the 1080i HDTV signal is characterized by 1,920 horizontal pixels and 1,080 vertical pixels. For this example, during horizontal prescaling in step 214, the horizontal resolution of the signal is decreased by a factor of two, producing a signal with 960 horizontal pixels. In some embodiments, the vertical prescaling step is not performed depending on the particular applications, resulting in a prescaled signal with 960×1080 pixels. After frame based processing/deinterlacing and frame buffering in steps 218 and 220, respectively, the signal (at 960×1080 pixels) is scaled for display on an XGA display device, which supports a resolution of 1024×768 pixels. Scaling of the HD signal to other formats will be evident to one of skill in the art.

Accordingly, in step 224, the number of pixels in the horizontal and vertical direction is scaled by an appropriate factor. As will evident to one of skill in the art, in this example, the prescaling of the video signal provides a reduction in the data bandwidth utilized during processing and memory operations without resulting in degradation of the video signal ultimately displayed. In step 228, the display is enhanced as appropriate to display on the XGA display device and an XGA video output signal is provided in step 230.

In the foregoing example, the resolution of the prescaled video signal was less than the resolution of the input video signal in both the horizontal and vertical dimensions. However, this is not required by embodiments the present invention. In some embodiments, prescaling is performed in a single dimension, for example the horizontal or the vertical dimension. Moreover, in the foregoing example, the resolution of the output video signal was less than the prescaled video signal in both the horizontal and vertical dimensions. Likewise, this scaling relationship is not required by embodiments of the present invention. Depending on the particular applications, the scaling of the video signal will be selected based on the display characteristics of the display device. One of ordinary skill in the art would recognize many variations, modifications, and alternatives.

It should be appreciated that the specific steps illustrated in FIG. 2 provide a particular processing sequence according to one embodiment of the present invention. Other sequence of steps may also be performed according to alternative embodiments. For example, alternative embodiments of the present invention may perform the processing steps outlined above in a different order. For example, the order in which the signals are processed using pixel-based and frame-based processing algorithms may be varied, with these processing steps being performed after the horizontal and vertical prescaling steps. Moreover, the individual steps illustrated by this figure may include multiple sub-steps that may be performed in various sequences as appropriate to the individual step. Furthermore, additional video processing and/or memory operations may be added or removed depending on the particular applications. One of ordinary skill in the art would recognize many variations, modifications, and alternatives.

FIG. 3 is a simplified schematic diagram illustrating a video processor architecture according to an alternative embodiment of the present invention. As illustrated in FIG. 3, a video input is received at an input of the video processor IC 300. Prescaler 310 is utilized to prescale the video signal, thereby changing the horizontal and/or vertical resolution. In some embodiments, the resolution of the video signal as received is reduced by the prescaler, thereby reducing the cost and performance of processing and memory components utilized during subsequent video processing operations. Pixel-based processor 312, frame buffer 314 and frame-based processor/deinterlacer 316 are utilized to further process the prescaled video signal. As illustrated in FIG. 3, the deinterlacer is combined with the frame-based processor, although this is not required by the present invention. In the embodiment illustrated in FIG. 3, the deinterlacer is utilized to generate a progressively scanned signal from an interlaced signal. As will be evident to one of skill in the art, the reduction in pixel count provided by the prescaler may provide significant benefits at the deinterlacing step, as dienterlacing methods and systems developed for SDTV signals may be utilized to process HDTV signals. Embodiments of the present invention are not limited to the use of a deinterlacer, but may also be utilized in processing progressively scanned signals.

Scaler 318 is utilized to scale the resolution of the video signal to the resolution of the display device. For example, for an XGA display device, a resolution of 1024×768 is generated by a scaler. Both the prescaler and scalers provided by embodiments of the present invention are software programmable and adaptive to provide the system designer with multi-format input and output displays. Optional display enhancer 320 is utilized in some embodiments to further process the scaled video signal in preparation for display on a particular display device.

FIG. 4 is a simplified flowchart illustrating a process flow 400 according to an alternative embodiment of the present invention. A video signal is received at step 410 and prescaling of the signal is performed in step 412. As discussed above, the prescaling may be performed in the horizontal direction, the vertical direction, or both. Prescaling generally involves reducing the pixel content of the received video signal to produce a prescaled video signal with reduced pixel content. In steps 414 and 416, the prescaled video signal is processed utilizing pixel-based and frame-based processing algorithms, respectively. Of course, as one of skill in the art will appreciate, these steps may be interchanged as appropriate to a particular application.

In step 418, the video signal is stored into memory utilizing a SDRAM frame buffer. As will be evident to one of skill in the art, other memory devices are utilized in alternative embodiments. Deinterlacing is performed in step 420. In embodiments utilizing progressively scanned input video signals, this step is removed, as the signal is already provided in a progressively scanned format. In step 422, the video signal is scaled utilizing conventional methods to provide an output video signal matched to the display characteristics of the display device. Finally, in step 424, the scaled video signal is enhanced for display, providing an output video signal in step 426.

It should be appreciated that the specific steps illustrated in FIG. 4 provide a particular processing sequence according to one embodiment of the present invention. Other sequence of steps may also be performed according to alternative embodiments. For example, alternative embodiments of the present invention may perform the processing steps outlined above in a different order. For example, the order in which the signals are processed using pixel-based and frame-based processing algorithms may be varied, with these processing steps being performed in reverse order. Moreover, the individual steps illustrated by this figure may include multiple sub-steps that may be performed in various sequences as appropriate to the individual step. Furthermore, additional video processing and/or memory operations may be added or removed depending on the particular applications. One of ordinary skill in the art would recognize many variations, modifications, and alternatives.

FIG. 5 is a simplified diagram illustrating a prescaling, processing, and scaling operation according to an embodiment of the present invention. In the embodiment of the present invention illustrated in FIG. 5, a 1080i input video signal 510 is received by the video processing IC. The resolution of this 1080i signal is 1,920 horizontal pixels by 1,080 vertical pixels. As will be described below, the video processing IC provided by embodiments of the present invention will provide an output signal for display on an XGA video display, such as an LCD display panel. The data rate for this input signal is 74.25 MHz, which is a higher data rate than that typically associated with SDTV video processing. As a result, many video processing ICs optimized for processing of SDTV formats run at data rates less than 74.25 MHz.

In process 515, the 1080i video signal is horizontally prescaled by a factor of 0.5 to generate a video signal 520 at a resolution of 960 horizontal pixels by 1,080 vertical pixels. In some embodiments of the present invention, video signal 520 is referred to as an intermediate interlaced picture. The data rate for the intermediate interlaced picture is 37.125 MHz, half of the data rate of the input video signal 510. In a particular embodiment, horizontal prescaling reduces the pixel rate to a level at which deinterlacing, described more fully below, is performed using hardware typically utilized for processing for 480i video signals.

As illustrated in FIG. 5, the horizontal prescaling performed at process 515 modifies the aspect ratio of the intermediate interlaced picture. In the embodiment illustrated in FIG. 5, vertical prescaling of the input signal is not performed. Referring to FIG. 1, path 132 provides a processing flow in which only horizontal prescaling is performed. In the embodiment illustrated in FIG. 5, no vertical resolution is lost during image processing, as the limiting factor in this embodiment is the resolution of the XGA display panel. In other embodiments, both horizontal and vertical prescaling are performed to reduce the data rate to levels predetermined by the system designer. Of course, vertical prescaling alone is performed in alternative embodiments.

Frame buffer 530 is utilized to store frames or fields associated with the intermediate interlaced picture. As will be evident to one of skill in the art, frame buffering provides data utilized during subsequent frame-based processing steps. At process 535, the interlaced video signal is deinterlaced to generate a progressively scanned image. The progressively scanned image, also referred to as a progressive picture 540 has a resolution of 960 horizontal pixels by 1,080 vertical pixels.

In process 545, the progressive picture 540 is vertically down scaled by a factor of 32/45 to generate a progressively scanned picture 550 with a resolution of 960 horizontal pixels and 768 vertical pixels. Although a vertical scaling factor of 32/45 is utilized in the embodiment of the present invention illustrated in FIG. 5, this is not required by the present invention. As will be evident to one of skill in the art, the vertical scaling factor, along with the horizontal scaling factor discussed below, combined with the initial prescaling factor (in either the horizontal, vertical, or both directions) is selected to provide an appropriate resolution for eventual display. As illustrated in FIG. 5, vertical scaling of progressively scanned picture 540 by a factor of 32/45 results in an image with 768 vertical pixels, matched to the XGA display illustrated in FIG. 5. For applications utilizing alternative display formats, such as SXGA, prescaling and scaling factors are selected as appropriate to the particular application. One of ordinary skill in the art would recognize many variations, modifications, and alternatives.

In process 555, the progressive picture 550 is horizontally upscaled by a factor of 16/15 to generate a progressively scanned picture 560 with a resolution of 1,024 horizontal pixels by 768 vertical pixels. The data rate of the video signal 560 is 65 MHz. Referring to FIG. 5, computationally intensive processes, such as deinterlacing at step 535, are performed on reduced data rate video signals. In the embodiment of the present invention illustrated in FIG. 5, deinterlacing is performed on a signal at a data rate of 37.125 MHz, less than the input data rate of 74.25 MHz. Accordingly, frame-based processing components, such as the deinterlacer, generally utilized for processing of SDTV and PC signals are utilized in embodiments of the present invention, thereby reducing system cost and increasing the range of available component.

FIG. 6 is a simplified diagram illustrating another prescaling, processing, and scaling operation according to another embodiment of the present invention. In the embodiment of the present invention illustrated in FIG. 6, a high-resolution input video signal in the form of a 1080p HDTV signal is received and processed for eventual display on an SVGA panel. The resolution of this 1080p signal is 1,920 horizontal pixels by 1,080 vertical pixels. The data rate for this signal is 148.5 MHz, twice that of the 1080i input video signal illustrated in FIG. 5.

In process 615, the 1080p video signal is horizontally prescaled by a factor of 0.5 to generate a video signal 620 at a resolution of 960 horizontal pixels by 1,080 vertical pixels. The data rate of video signal 620 is 74.25 MHz, one half that of the 1080p video input signal. In some embodiments, video signal 620 is referred to as an intermediate progressive picture A.

In process 625, the intermediate progressive picture A 620 is vertically prescaled by a factor of 0.5 to generate intermediate progressive picture B 630 with a resolution of 960×540 pixels and a data rate of 37.125 MHz. As will be evident to one of skill in the art, intermediate progressive picture B 630 is appropriate for processing using, for example, SDTV components. The aspect ratio of the image 630 is the same as the aspect ratio of the original input video signal 610. Frame buffer 640 is utilized to store frames or fields associated with the intermediate progressive picture B. As a result of the prescaling operations, frame buffer size requirements are reduced by factor of four compared to requirements for the 1080p signal. As the video signal 630 is already progressively scanned, no deinterlacer is utilized in the embodiment illustrated in FIG. 6.

In process 645, intermediate progressive picture B is horizontally downscaled by a factor of ⅚ to generate a progressively scanned picture 650 at a resolution of 800×540. Finally, in process 655, the progressive picture 650 is vertically upscaled by a factor of 10/9 to generate the output video signal 660. As will be evident to one of skill in the art, the combination of horizontal and vertical prescaling, as well as the horizontal and vertical scaling in step 645 and step 655, respectively, are selected based on the resolution of the video signal received and the resolution of the output video signal generated. In the embodiment illustrated in FIG. 6, these prescaling and scaling factors are selected to convert the 1080p HDTV video signal into an SVGA output signal. In alternative embodiments, the prescaling and scaling factors are selected as appropriate to the input and output signals.

Referring to FIGS. 5 and 6, the order in which the horizontal and vertical scalers are utilized is modified, as both orders are included according to embodiments of the present invention. Generally, the scaling order is horizontal prescaling, vertical prescaling, vertical scaling, and horizontal scaling, as this order reduces the minimum line buffer requirement. As illustrated the figures, the scaling order is not limited to the above mentioned order, as embodiments of the present invention provide for a variety of scaling orders. Additionally, the horizontal and vertical scalers illustrated in these figures are general-purpose scalers, providing for both scaling up and scaling down as appropriate to the particular application. As illustrated in the figures, the prescalers are generally limited to downscaling operations, although downscaling is not required by the present invention.

It is also understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application and scope of the appended claims.

Claims

1. A video signal processor comprising:

an input port adapted to receive an input video signal, wherein the input video signal is characterized by a first horizontal resolution and a first vertical resolution;

a pixel-based processor coupled to the input port and adapted to perform pixel-based processing of the input video signal to generate a processed video signal;

a prescaler coupled to the pixel-based processor and adapted to perform prescaling of the processed video signal, wherein prescaling converts the processed video signal at the first horizontal resolution and the first vertical resolution to a prescaled video signal characterized by a second horizontal resolution and a second vertical resolution;

a frame-based processor coupled to the prescaler and adapted to perform frame-based processing of the prescaled video signal;

a frame buffer coupled to the frame-based processor;

a horizontal scaler coupled to the frame buffer and adapted to convert the horizontal scale of the prescaled video signal from the second horizontal resolution to a third horizontal resolution; and

a vertical scaler coupled to the horizontal scaler and adapted to convert the vertical scale of the prescaled video signal from the second vertical resolution to a third vertical resolution.

2. The video signal processor of claim 1 wherein the input video signal is an HDTV signal.

3. The video signal processor of claim 1 wherein the prescaler comprises at least one of a horizontal prescaler or a vertical prescaler.

4. The video signal processor of claim 1 wherein the prescaler comprises both a horizontal prescaler and a vertical prescaler.

5. The video signal processor of claim 1 further comprising a deinterlacer coupled to the frame buffer and a display enhancer coupled to the vertical scaler and adapted to provide an output video signal.

6. The video signal processor of claim 5 wherein the deinterlacer is coupled to the vertical scaler.

7. The video signal processor of claim 1 wherein the second horizontal resolution is less than or equal to the first horizontal resolution.

8. The video signal processor of claim 7 wherein the second vertical resolution is less than or equal to the first vertical resolution.

9. The video signal processor of claim 8 wherein the third horizontal resolution is at least less than the second horizontal resolution, greater than the second horizontal resolution, or equal to the second horizontal resolution.

10. The video signal processor of claim 9 wherein the third vertical resolution is at least less than the second vertical resolution, greater than the second vertical resolution, or equal to the second vertical resolution.

11. The videos signal processor of claim 1 wherein the frame buffer is an SDRAM frame buffer.

12. A method of processing a video signal, the method comprising:

receiving a video signal characterized by a first horizontal resolution and a first vertical resolution;

performing prescaling of the video signal to change the first horizontal resolution to a second horizontal resolution and the first vertical resolution to a second vertical resolution and produce a prescaled video signal;

performing storage of the prescaled video signal in a frame buffer;

performing scaling of the prescaled video signal to convert the prescaled video signal from the second horizontal resolution to a third horizontal resolution and from the second vertical resolution to a third vertical resolution;

providing an output video signal characterized by the third horizontal resolution and the third vertical resolution.

13. The method of claim 12 further comprising:

performing pixel-based and frame-based processing of the prescaled video signal.

14. The method of claim 12 further comprising enhancing the output video signal for display on a display device.

15. The video signal processor of claim 12 further comprising performing deinterlacing of the prescaled video signal.

16. The video signal processor of claim 15 wherein the step of deinterlacing is performed prior to the steps of performing horizontal scaling and vertical scaling of the prescaled video signal.

17. The video signal processor of claim 12 wherein the second horizontal resolution is less than the first horizontal resolution.

18. The video signal processor of claim 17 wherein the second vertical resolution is less than the first vertical resolution.

19. The video signal processor of claim 18 wherein the third horizontal resolution is less than the second horizontal resolution.

20. The video signal processor of claim 19 wherein the third vertical resolution is less than the second vertical resolution.

21. The video signal processor of claim 12 wherein the second horizontal resolution and the third horizontal resolution are equal.

22. The video signal processor of claim 12 wherein the second vertical resolution and the third vertical resolution are equal.