2.Basics

2.1 Terminology

Table 2.1 defines the terms used.

Table 2.1 Definition of terms

term	meaning
MPEG buffer	Memory area managed by MPEG/VideoLSI.
frame buffer	The area where decoded image data is stored. Area. Consists of multiple frame banks. usually Configuration of 4 banks for resolution and 1 bank for high-definition resolution It becomes.
frame bank	An image of one picture of an MPEG video stream The area where the data will be expanded.
VBV buffer	Used to decode MPEG video streams. area where you are. Allocated within the MPEG buffer.
display window	A rectangular area on a TV monitor where MPEG video is output. The frame buffer window data is output. Masu.
frame buffer window	A rectangular area set for the frame buffer. This area will be the output target.
Bright spot	The smallest visible unit on the display.
pixel	2 x 2 bright spots in normal resolution, 1 x 1 bright spot in high definition resolution A display unit consisting of.
image data	Decoded color data. 16 to host area Transferred as bit color data.
MPEG window	Display window and frame buffer window An object for controlling windows.
MPEG video handle	Object for controlling MPEG videos.
MPEG still image handle	Object for controlling MPEG still images.
MPEG handle	A general term for MPEG video handles and MPEG still image handles.
MPEG report	Data that represents the status of the MPEG system. For details, refer to the CD communication interface manual.

2.2 MPEG Stream

(1) What is MPEG?

MPEG is an international standard for video compression and compresses video to 1.5Mbit/sec. Image data is compressed to approximately 1/50 and audio data to approximately 1/10, and can be recorded on standard speed CDs.

(2) Picture type

The following three types of pictures are constructed based on the video compression method.

Table 2.2 Picture types

picture type	explanation
I picture (Intra-coded Picture)	An image that can be decoded only from its own information. Compression effect Although the rate is bad, this image is inserted at regular intervals. Random access is also possible.
P picture (Predictive-coded Picture)	Use other already decoded pictures as predicted images. Image using cha(I,P).
B picture (Bidirectionally predictive-coded picture)	Use two pictures (I, P) before and after as predicted images image to do. The compression efficiency is the best.

Figure 2.1 Prediction relationship between pictures

(3)G.O.P.

A GOP (Group Of Picture) is composed of one or more I pictures and zero or more non-I pictures. A GOP is a basic editing unit and can be played independently.
In order to decode a B picture, the I picture or P picture, which is the predicted picture, must be decoded first. Therefore, the input order of pictures to the decoder and the actual display order will be swapped.

Figure 2.2 Order on CD-ROM and playback image order