PAL NTSC 詳解和 Focus的設定

PAL 864x625x50Hz = 27,000,000
NTSC 858x525x59.94 ~= 27,000,000


PAL-M (a broadcast standard) however should not be confused with "PAL-60" (a video playback system )

跟PAL-M不一樣, PAL-60 是一種 Video Playback System 而不是一廣播標準
由上圖可知 PAL 的 chrominance subcarrier 為4.43MHz
( 正確值是 4.43361875 MHz ) (NTSC是3.579545 MHz)
在focus 453的 PAL register 設定
CHR_FREQ default 0xCB8A092A
27MHz x 0xCB8A092A / 2^32 = 4.4336187487933
得證


HNDP1 是在 Sync Pulse 的後面 ( Back porch )
HNDP2 是在 Active Area的後面 (H-pulse delay, Front Porch)

而VNDP剛好相反
VNDP1 在 Vertical Sync Pulse 前面, Active Area 的後面
VNDP2 在 Vertical Sync Pulse 後面

Back porch refers to the portion in each scan line of a video signal between the end (rising edge) of the horizontal sync pulse and the start of active video. It is used to restore the black level reference in analog video.

In television broadcasting, the front porch is a brief (about 1.5 microsecond) period inserted between the end of each transmitted line of picture and the leading edge of the next line sync pulse. Its purpose was to allow voltage levels to stabilise in older televisions, preventing interference between picture lines.


在 Focus 453, High Resolution 時 MISC register 的 UIM_DEC bit要設成1, 會先把horizontal line
prescale 一半。

要使用Downscaler 時, 注意 Bypass register CAC_Bypass 和 HDS_Bypass 要設定0