SAA6750H

2.1 General

The SAA6750H is a new approach towards a stand-alone MPEG2 video encoder IC. It combines high quality SP@ML compliant real time encoding with cost-effectiveness, allowing for the first time the use of an MPEG2 encoder IC in applications and markets with a high cost pressure. SAA6750H has been achieved by means of a number of innovations in architecture and algorithms developed by the Philips Research Laboratories, e.g.:

· The unique motion estimation algorithm supports highly efficient encoding by using only I frame and IP frame mode. B frames need not be used. This leads to a significantly smaller internal circuitry and also reduces DRAM memory requirements from at least 4 to 2 Mbyte. In addition, the absence of B frames simplifies editing of the compressed data stream.
· The patented, motion-compensated temporal noise filtering which was developed by Philips for professional equipment reduces noise in the input video before compression is performed. This technique gives visible improvements in picture quality, especially in the field of home recordings with noisy signal sources where this has proved to be of significant benefit.

Internally the SAA6750H uses a hardware solution for data compression and a specially developed high performance
processor for control purposes.

2.2 Function

The SAA6750H is a stand-alone single chip video encoder performing real time MPEG2 compression of digital video data.

The video data input of the SAA6750H accepts a digital YUV video data stream in ITU-T 601 format. PAL standard at 50 Hz and 720 pixels by 576 lines, as well as NTSC at 60 Hz and 720 pixels by 480 lines, are covered. The video synchronization may either follow ITU-T 656 recommendation or can also be supplied by external signals. The external reference clock of 27 MHz to pin VCLK has to be synchronized to the video data. The product family SAA7111 of Philips Semiconductors provides a suitable video data stream and reference clock. Other sources are also supported by the flexible I2C-bus controlled data input interface of the SAA6750H. See Section 7.3 for detailed information.

An internal 4 : 2 : 2 to 4 : 2 : 0 colour format conversion is performed. Optionally, a ITU-T 601 to SIF format conversion may be activated by the I2C-bus control settings.

The real time data encoding part of the SAA6750H combines high-compression rates with high quality picture performance. This is achieved by the integration of Philips unique motion estimation algorithm and a patented motion-compensated noise filtering. The compression algorithm uses I or IP mode encoding. Normally SAA6750H selects automatically the suitable mode but may also be forced to I mode operating only by the I2C-bus control settings.