3.Operation overview

The MPEG library has two operating modes for video playback:

(1)Video playback mode

This is the mode for playing videos. There are normal playback state, freeze state, pause state, and pause & freeze state.

(2)Still image playback mode

This mode is for playing still images. You can display 4 banks of images at normal resolution and 1 bank of images at high definition resolution.
Audio can always be played. You can also synchronize video and audio.

Figure 3.1 Operating mode

3.1 Video playback

MPEG video data is read from a CD into a CD buffer and expanded into frame banks by a decoder. A video is created by sequentially displaying the image data developed in this frame bank. There are two ways to display frame bank data: output it directly to VDP2, or transfer it to VRAM using the host and display it. The data flow is shown below.

Figure 3.2 Data flow during video playback

3.2 Still image playback

In still image playback mode, video stream data in the CD buffer can be decoded by specifying the frame bank number. By specifying the frame bank number to be output, it can be output directly to VDP2 or transferred to VRAM and displayed by the host.

Figure 3.3 Data flow during still image playback

3.3 How to output image data

You can create an output window in the image data area in the output frame bank and output the data. There are two ways to output data:

1. VDP2 direct output method

2. Host transfer method

You can create multiple output windows when forwarding to a host area, or just one output window when outputting directly to VDP2.
You can also apply various visual effects to these windows.

Figure 3.4 Output window

video effects

• Trimming (cutting out the image)
• Enlarge/reduce
• fade
• Mosaic/Blur
• luminescence key

3.4 Playing MPEG audio

MPEG audio is played by decoding the stream data read from the CD buffer and outputting it to the sound block.

Figure 3.5 Playing audio