H.261 Datasheet, PDF (17/31 Pages) List of Unclassifed Manufacturers – LINE TRANSMISSION OF NON-TELEPHONE SIGNALS

MVD
–16 & 16
–15 & 17
–14 & 18
–13 & 19
–12 & 20
–11 & 21
–10 & 22
o–9 & 23
o–8 & 24
o–7 & 25
o–6 & 26
o–5 & 27
o–4 & 28
o–3 & 29
o–2 & 30
o–1 & 23
o–0 & 23
o–1 & 23
o–2 & –30
o–3 & –29
o–4 & –28
o–5 & –27
o–6 & –26
o–7 & –25
o–8 & –24
o–9 & –23
–10 & –22
–11 & –21
–12 & –20
–13 & –19
–14 & –18
–15 & –17
TABLE 3/H.261
VLC table for MVD
Code
0000 0011 001
0000 0011 011
0000 0011 101
0000 0011 111
0000 0100 001
0000 0100 011
0000 0100 111
0000 0101 011
0000 0101 111
0000 0111 111
0000 1001 110
0000 1011 110
0000 1111 110
0001 1111 110
0011 1111 110
0111 0100 110
1000 0100 110
01000 0100 1
0010 1111 111
0001 0111 111
0000 1101 111
0000 1010 111
0000 1000 110
0000 0110 110
0000 0101 100
0000 0101 001
0000 0100 101
0000 0100 010
0000 0100 000
0000 0011 110
0000 0011 100
0000 0011 010
4.2.4 Block layer
A macroblock comprises four luminance blocks and one of each of the two colour difference blocks (see Figure 10).
Data for a block consists of codewords for transform coefficients followed by an end of block marker (see Figure 11). The
order of block transmission is as in Figure 10.
4.2.4.1 Transform coefficients (TCOEFF)
Transform coefficient data is always present for all six blocks in a macroblock when MTYPE indicates INTRA. In other
cases MTYPE and CBP signal which blocks have coefficient data transmitted for them. The quantized transform coefficients
are sequentially transmitted according to the sequence given in Figure 12.
The most commonly occurring combinations of successive zeros (RUN) and the following value (LEVEL) are encoded with
variable length codes. Other combinations of (RUN, LEVEL) are encoded with a 20-bit word consisting of 6 bits ESCAPE, 6
bits RUN and 8 bits LEVEL. For the variable length encoding there are two code tables, one being used for the first
transmitted LEVEL in INTER, INTER+MC and INTER+MC+FIL blocks, the second for all other LEVELs except the first
one in INTRA blocks which is fixed length coded with 8 bits.
14
Recommendation H.261 (03/93)