The MPEG-1 Codec - A Practical Guide to Video and Audio Compression - page 209

187 -29 -34 15 -2 7 5 1
190 33 -75 28 -6 -1 -1 1
-40 107 -59 22 -2 -7 -2 -1
-39 18 16 -13 14 -9 8 -3
3 -10 3 -9 10 -7 5 -1
-3 7 -5 -13 7 -5 -1 2
-1 2 10 -9 -2 1 -1 2
-4 3 3 1 1 3 -3 0

DCT output

Figure 10-17 DCT-coded macroblock.

8 pixels, and so the luma macroblock is com-
posed of 4 DCT encodings while the two color-difference channels only require one each
in this example. Figure 10-17 shows the output of a DCT-coded block of 8

DCT coding works on blocks of 8 ×

× 8 pixels. This

time the results are shown as decimal values.
Note that the values in the top left seem to be markedly larger than the ones in the
lower right.

10.8.2 Coefficient Ordering

Now let's arrange those in a 1-dimensional array, ordering them according to the frequency
of the coefficient. Traverse the coefficients in a zigzag fashion as shown in Figure 10-18:

Figure 10-18 Zigzag scanning.