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SAA7127H Datasheet(PDF) 6 Page - NXP Semiconductors |
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SAA7127H Datasheet(HTML) 6 Page - NXP Semiconductors |
6 / 40 page 1999 May 31 6 Philips Semiconductors Product specification Digital video encoder SAA7126H; SAA7127H FUNCTIONAL DESCRIPTION The digital video encoder encodes digital luminance and colour difference signals into analog CVBS, S-video and simultaneously RGB or Cr-Y-Cb signals. NTSC-M, PAL B/G and sub-standards are supported. Both interlaced and non-interlaced operation is possible for all standards. The basic encoder function consists of subcarrier generation, colour modulation and insertion of synchronization signals. Luminance and chrominance signals are filtered in accordance with the standard requirements of “RS-170-A” and “ITU-R BT.470-3”. For ease of analog post filtering the signals are twice oversampled with respect to the pixel clock before digital-to-analog conversion. The total filter transfer characteristics are illustrated in Figs 3 to 8. The DACs for Y, C and CVBS are realized with full 10-bit resolution; 9-bit resolution for RGB output. The Cr-Y-Cb to RGB dematrix can be bypassed optionally in order to provide the upsampled Cr-Y-Cb input signals. The 8-bit multiplexed Cb-Y-Cr formats are “CCIR 656” (D1 format) compatible, but the SAV and EAV codes can be decoded optionally; when the device is operated in slave mode. Two independent data streams can be processed, one latched by the rising edge of LLC1, the other latched by the falling edge of LLC1. The purpose of that is e.g. to forward one of the data streams containing both video and On Screen Display (OSD) information to the RGB outputs, and the other stream containing video only to the encoded outputs CVBS and S-video. For optimum display of RGB signals through a euro-connector TV set, an early composite sync pulse (up to 31LLC1 clock periods) can be provided optionally on the CVBS output. It is also possible to connect a Philips digital video decoder (SAA7111, SAA7711A, SAA7112 or SAA7151B) to the SAA7126H; SAA7127H. Information concerning the actual subcarrier, PAL-ID and (with SAA7111 and newer types) definite subcarrier phase can be inserted via the RTCI pin, connected to the RTCO pin of a decoder. The SAA7126H; SAA7127H synthesizes all necessary internal signals, colour subcarrier frequency and synchronization signals from that clock. Wide screen signalling data can be loaded via the I2C-bus and is inserted into line 23 for standards using a 50 Hz field rate. VPS data for program dependent automatic start and stop of such featured VCR’s is loadable via the I2C-bus. The IC also contains closed caption and extended data services encoding (line 21), and supports anti-taping signal generation in accordance with Macrovision. It is also possible to load data for copy generation management system into line 20 of every field (525/60 line counting). A number of possibilities are provided for setting different video parameters such as: • Black and blanking level control • Colour subcarrier frequency • Variable burst amplitude etc. During reset (RESET = LOW) and after reset is released, all digital I/O stages are set to the input mode and the encoder is set to PAL mode and outputs a ‘black burst’ signal on CVBS and S-video outputs, while RGB outputs are set to their lowest output voltages. A reset forces the I2C-bus interface to abort any running bus transfer. Data manager In the data manager, alternatively to the external video data, a pre-defined colour look-up table located in this block can be read out in a pre-defined sequence (8 steps per active video line), achieving a colour bar test pattern generator without need for an external data source. Encoder VIDEO PATH The encoder generates out of Y, U and V baseband signals luminance and colour subcarrier output signals, suitable for use as CVBS or separate Y and C signals. Luminance is modified in gain and in offset (latter programmable in a certain range to enable different black level set-ups). After insertion of a fixed synchronization pulse tip level, in accordance with standard composite synchronization schemes, a blanking level can be set. Other manipulations used for the Macrovision anti-taping process such as additional insertion of AGC super-white pulses (programmable in height) are supported by SAA7126H only. In order to enable easy analog post filtering, luminance is interpolated from 13.5 MHz data rate to 27 MHz data rate, providing luminance in 10-bit resolution. The transfer characteristic of the luminance interpolation filter are illustrated in Figs 5 and 6. Appropriate transients at start/end of active video and for synchronization pulses are ensured. |
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