New I2S Audio Interface IP Core Great for High-Def Sound

Numerous customers have used our I²S interface core in a variety applications and products. Now we're offering an even better version from our development partners Evatronix, the I2S-SC.

The CAST S2C-SC supports all the modes in the Philips spec, but it's optimized to give better performance when processing the high-quality sound delivered with HD video and other popular sources.

Instead of eight separate channels, the new core uses just one channel, and employs Time Division Multiplexing (TDM) to efficiently exploit that single channel for multi-channel data flow. Since most consumer devices use just one of the eight channels anyway, this approach is considerably more efficient.

I²S engineer and core developer Pawel Du says:

With the introduction of the TDM, we’re extending this one stereophonic channel into an orchestra of 16 channels, capable of delivering 192 kHz samples each. This is the equivalent of the state-of-the-art Dolby® TrueHD technology that is hitting the shelves on BluRay discs.

The I2S-SC is loaded with features, and an included tool makes it easy to configure them for the best match to your particular application.

If your project needs a high-quality audio interface, check out our new, second-generation core and save yourself some time.

Datasheet:
http://www.cast-inc.com/ip-cores/audio/i2s-sc/

Subsampling Explained

One of the first things we ask a new JPEG or H.264 customer about their requirements is: "What subsampling will you use?"

Many of them respond: "What's subsampling?" Here's a brief explanation.

Sampling is used to represent the Red, Blue, and Green (RBG) information defining each pixel in an image. In a group of 4 x 4 pixels, there are 16 Red samples, 16 Blue samples and 16 Green samples (48 total samples). This is called 4:4:4 format.

One technique for compressing image data is to switch the way an image is represented to a format that can more readily be subsampled.

For example, instead of using RGB, we can represent the exact same image information with values of luminance and chrominance. Luminance values are represented by Y, and chrominance by U and V. Hence this representation is called YUV format.

A perfect, lossless, transformation from RBG 4:4:4 to YUV 4:4:4 still uses the same abount of data for each pixel (16 samples for each channel). It turns out, though, that the human visual system is more sensitive to luminance than it is to chrominance.

We can exploit this fact to use fewer U and V samples -- subsampling -- but still keep the image looking pretty much the same to the human eye.

Three popular YUV subsampling schemes are 4:2:2 (24 samples), 4:2:0 (20 samples), and 4:1:1 (18 samples). They each require less data than the full 4:4:4 format, at the expense of discarding some of the image information (lossy compression). How far an image can be down-sampled and still look good depends on the nature of the image and the definition of "good" for the particular application.

Different compression algorithms work best with different image formats. So that's why one of our first questions as you consider our image and video compression IP cores is "What subsampling will you use?"

This also helps us understand if you might need something like our Color Space Converter core to get the best results in your system.

Richnex Achieves USB-IF Certification with our USB Hi-Speed OTG Controller

CAST mixed-signal IC design partner Richnex recently achieved USB-IF certification for a USB transceiver reference design using our USB Hi-Speed On-The-Go Controller Core.

Richnex worked together with our controller core development partner Evatronix to build the reference design system.

"RN1170 is the only USB High Speed Transceiver IC that features an integrated charge pump capable of supplying 100mA current. With a compact 5mm x 5mm QFN package, it is ideal for embedded host or OTG applications in portable devices. Our complete line up of USB transceiver products including different packages and feature set are USB-IF certified and proven to work flawlessly with the Evatronix High Speed USB OTG controller.” said Larry Huang, Sales & Marketing VP from Richnex Electronics Corporation.

Learn more about Richnex or their RN1170 USB 2.0 ULPI Transceiver with Integrated Charge Pump.