Digital Signal Processing Reference
In-Depth Information
8 × 8 DCT coeff block
8 × 8 pixel block
Frame
DCT
Field
DCT
8 × 8 pixel blocks
8 × 8 DCT coeff blocks
Figure 15.1. Frame and
eld DCT.
15.1.1.6 MPEG-2 support for 3:2 pulldown
MPEG-2 allows for compression of video in the 3:2 pulldown
form. Film or movie video is commonly recorded at 24 fps,
progressively. For use in television, it's decoded into 60 fps. This
is done using 3-2 pulldown. Each film frame is replicated either
two or three times, resulting in 60 fps.
24 fps film video sequence: A, B, C, D
.
60 fps 3:2 pulldown sequence: A, A, B, B, B, C, C, D, D, D
.
.
.
This is an optional output
format which the decoder
can provide,
to ensure compatibility with televisions or
monitors.
15.1.1.7 MPEG-2 Aspect Ratio Support
Video recorded and compressed with 16:9 aspect ratio
can be decoded to display the portion of frame corre-
sponding to the 4:3 aspect ratio used in older televisions and
monitors.
