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another bitstream extraction to optimize: fixed-length motion vectors 

Originally committed as revision 4286 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Mike Melanson 2005-05-21 01:12:41 +00:00
parent 3f2bf07ba7
commit 7f9926a45e
2 changed files with 22 additions and 0 deletions
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11
libavcodec/vp3.c
View File

@ -1540,9 +1540,15 @@ static int unpack_vectors(Vp3DecodeContext *s, GetBitContext *gb)
motion_y[0] = get_motion_vector_vlc(gb);
#endif
} else {
#if 1
motion_x[0] = fixed_motion_vector_table[get_bits(gb, 6)];
motion_y[0] = fixed_motion_vector_table[get_bits(gb, 6)];
#else
motion_x[0] = get_motion_vector_fixed(gb);
motion_y[0] = get_motion_vector_fixed(gb);
#endif
}
for (k = 1; k < 6; k++) {
motion_x[k] = motion_x[0];
motion_y[k] = motion_y[0];
@ -1572,8 +1578,13 @@ static int unpack_vectors(Vp3DecodeContext *s, GetBitContext *gb)
motion_y[k] = get_motion_vector_vlc(gb);
#endif
} else {
#if 1
motion_x[k] = fixed_motion_vector_table[get_bits(gb, 6)];
motion_y[k] = fixed_motion_vector_table[get_bits(gb, 6)];
#else
motion_x[k] = get_motion_vector_fixed(gb);
motion_y[k] = get_motion_vector_fixed(gb);
#endif
}
motion_x[4] += motion_x[k];
motion_y[4] += motion_y[k];

11
libavcodec/vp3data.h
View File

@ -163,6 +163,17 @@ static const int motion_vector_table[63] = {
24, -24, 25, -25, 26, -26, 27, -27, 28, -28, 29, -29, 30, -30, 31, -31
};
static const int8_t fixed_motion_vector_table[64] = {
0, 0, 1, -1, 2, -2, 3, -3,
4, -4, 5, -5, 6, -6, 7, -7,
8, -8, 9, -9, 10, -10, 11, -11,
12, -12, 13, -13, 14, -14, 15, -15,
16, -16, 17, -17, 18, -18, 19, -19,
20, -20, 21, -21, 22, -22, 23, -23,
24, -24, 25, -25, 26, -26, 27, -27,
28, -28, 29, -29, 30, -30, 31, -31
};
/* only tokens 0..6 indicate eob runs */
static const int eob_run_base[7] = {
1, 2, 3, 4, 8, 16, 0