STV2310_04 Datasheet, PDF (22/112 Pages) STMicroelectronics – Multistandard TV Digital Video Decoder with Adaptive Comb Filter and RGB/YCrCb Input

Functional Description
STV2310
should be identified. If two entries are identified by error, the standard recognition sequence will re-
start from the beginning of the table and no standard will be identified.
The DDECCONT4[5:0], DDECCONT3[5:0], DDECCONT2[5:0], and DDECCONT1[5:0] registers
are used to program the Automatic Standard Recognition table.
After the sequence search, a second step (also called a confirmation step) is performed by the
algorithm. It is performed on the single identified Automatic Standard Recognition table entry. It is
possible to program the number of fields where the standard identification must be confirmed before
the status flags are modified. The confirmation code is described in Table 8.
Table 8: Confirmation Codes
Confirmation
Code
000
001
010
011
Number of Successive Fields
with Correct Identification
1
3 (Default)
7
10
The confirmation code is programmed in the STI_NB_FIELDS_CONFIRM[2:0] bits of the
DDECCONT17 register.
After the confirmation step has been successful, the standard is considered as identified. The
TVSTID flag is set in the DDECSTAT2 register and the code of the identified standard is set in the
TVSTD[2:0] bits of the DDECSTAT2 register.
4.6 Standard Identification
The input signal standard is automatically recognized using a proprietary ST patented algorithm. It
avoids false identification and ensures a good recognition of the color standard, even in bad signal
conditions.
4.7 Chroma Demodulation
4.7.1
General Description
The Chroma PLL and the Input SRC are the main hardware blocks involved in chroma
demodulation. The Chroma PLL is locked to the input video burst signal in frequency and phase.
Demodulation is performed on the chroma samples positioned in the virtual 4 x f_SC clock domain.
Dedicated demodulation hardware is used for SECAM demodulation (frequency modulated
signals). Demodulated chroma components are low pass filtered and matrixed into Cr and Cb
components.
The Chroma Demodulator also includes an Automatic Chroma Control (ACC) which rescales the
chroma components from -20 dB to +6 dB. The color is killed (output Cr Cb components to 80h
value) until the standard is identified. ACC is disabled (fixed gain) in SECAM standard.
If NTSC M or NTSC 4.43 standards are identified, the Chroma Demodulator also incorporates a
Hue Control mechanism and a Flesh Tone Correction mechanism. The Hue Control is a
programmable fixed offset in the demodulation angle and is only operational in the active line.
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