Video Input Filtering

3.5.2Chrominance Resampling Operation

Chrominance resampling computes chrominance values at sample points midway between the input luminance samples based on the input co-sited chrominance samples. This filter performs the horizontal portion of a conver- sion between YCbCr 4:2:2 format and YCbCr 4:2:0 format. The vertical portion of the conversion must be performed in software.

The chrominance resampling filters calculate the implied value of Cb and Cr in between luminance sample points based upon nearby co-sited Cb and Cr samples. The resulting values are clamped to between 01h and FEh and sent to the Cb and Cr capture buffers. Chrominance resampling is shown in Figure 3–12.

Figure 3–12. Chrominance Resampling

a b c d e

YCbCr 4:2:2 co-sited input samples

chroma-resampled capture results

Luma (Y)

Chroma (Cb/Cr)

– sample

samples

3.5.3Scaling Operation

f

g

h

i

j

k

l

Cb’ef = (–3Cbc+ 101Cbe+ 33Cbg–3Cbi) / 128 Cr’ef = (–3Crc+ 101Cre+ 33Crg– 3Cri) / 128

The ½-scaling mode is used to reduce the horizontal resolution of captured luminance and chrominance data by a factor of two. For applications that require only CIF or lower resolutions, this reduces the video capture buffer memory requirements (and the bandwidth needed to write the buffer) by a factor of two. Vertical scaling must be performed in software. (The bandwidth to load in the buffer is again reduced by 50% over the nonhorizontal scaled case.)

The filtering for the luminance portion of the scaling filter changes depending on if chrominance resampling is also enabled. (By changing the luminance filter, the chrominance filters can remain the same.) The resulting values are clamped to between 01h and FEh and sent to the Y, Cb, and Cr capture buffers. Scaling for co-sited capture is shown in Figure 3–13 and scaling for chromi- nance resampling is shown in Figure 3–14.

SPRU629

Video Capture Port

3-27

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Texas Instruments TMS320C64x DSP manual Chrominance Resampling Operation, Scaling Operation
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TMS320C64x DSP specifications

The TMS320C64x DSP family from Texas Instruments represents a significant milestone in the realm of digital signal processing. Launched as part of the C6000 series, the C64x DSPs are designed for high-performance applications requiring intensive computational capabilities, such as telecommunications, audio processing, video processing, and industrial control systems.

One of the standout features of the TMS320C64x DSP is its VLIW (Very Long Instruction Word) architecture, which allows for an exceptionally high level of parallelism. This architecture enables multiple instructions to be executed simultaneously, boosting the overall throughput and allowing for complex data processing tasks to be completed more quickly than with conventional DSPs.

The C64x DSPs also boast an impressive clock frequency range, typically up to 1 GHz, delivering substantial computational power for real-time processing goals. Additionally, these processors feature extensive on-chip memory, including L1 and L2 cache, which significantly enhances data access speeds and helps reduce bottlenecks during high-demand processing tasks.

Another key characteristic of the TMS320C64x family is its support for advanced instruction sets optimized for specific applications. These include SIMD (Single Instruction, Multiple Data) capabilities, allowing for efficient handling of large datasets often involved in multimedia processing or complex signal manipulation.

For connectivity, these DSPs often integrate advanced interfaces such as EMIF (External Memory Interface) and McBSP (Multichannel Buffered Serial Port), facilitating seamless interaction with a variety of peripheral devices. This ensures that the DSP can suit different application needs and integrate well into various system architectures.

Texas Instruments emphasizes low power consumption with the C64x DSPs, making them ideal for portable or energy-sensitive applications. Advanced power management techniques and technologies, such as dynamic voltage and frequency scaling, are incorporated to further enhance energy efficiency without compromising performance.

In summary, the Texas Instruments TMS320C64x DSP family stands out due to its high-performance capabilities driven by a VLIW architecture, high clock speeds, extensive memory options, a rich instruction set, and advanced connectivity features, all while maintaining power efficiency. These characteristics make it an exceptional choice for developers looking to integrate robust digital signal processing into their applications, whether in telecommunications, audio and video processing, or embedded control systems.
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