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SAF7118 Datasheet(PDF) 49 Page - NXP Semiconductors |
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SAF7118 Datasheet(HTML) 49 Page - NXP Semiconductors |
49 / 173 page 2004 Jul 22 49 Philips Semiconductors Product specification Multistandard video decoder with adaptive comb filter and component video input SAF7118 Table 9 Processing trigger and start XDV1 92H[5] XDV0 92H[4] XDH 92H[2] DESCRIPTION Internal decoder: The processing triggers at the falling edge of the V123 pulse [see Figs 28 (50 Hz) and 29 (60 Hz)], and starts earliest with the rising edge of the decoder HREF at line number: 0 1 0 4/7 (50/60 Hz, 1st field), respectively 3/6 (50/60 Hz, 2nd field) (decoder count) 0 0 0 2/5 (50/60 Hz, 1st field), respectively 2/5 (50/60 Hz, 2nd field) (decoder count) 000 External ITU 656 stream: The processing starts earliest with SAV at line number 23 (50 Hz system), respectively line 20 (60 Hz system) (according to ITU 656 count) 8.4.1.2 Task handling The task handler controls the switching between the two programming register sets. It is controlled by subaddresses 90H and C0H. A task is enabled via the global control bits TEA[80H[4]] and TEB[80H[5]]. The handler is then triggered by events, which can be defined for each register set. In the event of a programming error the task handling and the complete scaler can be reset to the initial states by setting the software reset bit SWRST[88H[5]] to logic 0. Especially if the programming registers, related acquisition window and scale are reprogrammed while a task is active, a software reset must be performed after programming. Contrary to the disabling/enabling of a task, which is evaluated at the end of a running task, when SWRST is at logic 0 it sets the internal state machines directly to their idle states. The start condition for the handler is defined by bits STRC[1:0] 90H[1:0] and means: start immediately, wait for next V-sync, next FID at logic 0 or next FID at logic 1. The FID is evaluated, if the vertical and horizontal offsets are reached. When RPTSK[90H[2]] is at logic 1 the actual running task is repeated (under the defined trigger conditions), before handing control over to the alternate task. To support field rate reduction, the handler is also enabled to skip fields (bits FSKP[2:0] 90H[5:3]) before executing the task. A TOGGLE flag is generated (used for the correct output field processing), which changes state at the beginning of a task, every time a task is activated; examples are given in Section 8.4.1.3. Remarks: • To activate a task the start condition must be fulfilled and the acquisition window offsets must be reached. For example, in case of ‘start immediately’, and two regions are defined for one field, the offset of the lower region must be greater than (offset + length) of the upper region, if not, the actual counted H and V position at the end of the upper task is beyond the programmed offsets and the processing will ‘wait for next V’. • Basically the trigger conditions are checked, when a task is activated. It is important to realize, that they are not checked while a task is inactive. So you can not trigger to next logic 0 or logic 1 with overlapping offset and active video ranges between the tasks (e.g. task A STRC[2:0] = 2, YO[11:0] = 310 and task B STRC[2:0] = 3, YO[11:0] = 310 results in output field rate of 50 ⁄3 Hz). • After power-on or software reset (via SWRST[88H[5]]) task B gets priority over task A. 8.4.1.3 Output field processing As a reference for the output field processing, two signals are available for the back-end hardware. These signals are the input field ID from the scaler source and a TOGGLE flag, which shows that an active task is used an odd (1, 3, 5...) or even (2, 4, 6...) number of times. Using a single or both tasks and reducing the field or frame rate with the task handling function, the TOGGLE information can be used to reconstruct an interlaced scaled picture at a reduced frame rate. The TOGGLE flag isn’t synchronized to the input field detection, as it is only dependent on the interpretation of this information by the external hardware, whether the output of the scaler is processed correctly; see Section 8.4.3. |
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