L64105 LSI Logic Corporation, L64105 Datasheet - Page 277

• Manufacturer Part Number: L64105
• Description: Mpeg-2 Audio/video Decoder
• Manufacturer: LSI Logic Corporation

8.5 Trick Modes
8.5.1 Skip Frame
The Current Decode Frame bits are updated after the last field of the
currently displayed frame starts displaying. The Current Display Frame
bits are updated at the first vertical sync pulse indicating the start of
display of the first field in the frame.
The L64105 supports a variety of trick modes that are useful for
implementing various functions required in a set top box system. These
include skipping frames, repeating frames, avoiding video channel
underflow by using a programmable “panic threshold,” Rip Forward
mode, support for Broken Link/Open_GOP response, Search For Next
GOP, Display Override Mode, Reconstruction Force Rate Control, and
Single Still Picture display. The following sections describe each of these
functions and the restrictions associated with them.
Three bits in Register 236 control the skip frame feature. Bits [1:0]
(page
skip (see
skipping. When bit 2 is cleared, only one frame is skipped.
Table 8.20
When the host selects a single frame skip, the internal microcontroller
clears bits [1:0] after the frame is skipped to return to normal play. When
the host selects continuous skip, the selected frames are skipped until
Trick Modes
Skip Frame Bits
0b00
0b01
0b10
0b11
Note:
4-50) let the host select skip frame mode and the type of frame to
Table
The Current Display Frame bits are not valid in the Display
Override mode. Refer to
Display Override mode.
Video Skip Frame Modes
8.20). When set, bit 2 in the register causes continuous
Skip Frame Mode
None (normal play)
Skip B frame
Skip P or B frame
Skip any frame
page 4-59
for a description of
8-35