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add decode_coeffs()

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Originally committed as revision 19719 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Sascha Sommer 2009-08-26 21:23:21 +00:00
parent f53e96ed41
commit 85fecafe49
1 changed files with 88 additions and 0 deletions
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88
libavcodec/wmaprodec.c
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@ -152,6 +152,94 @@ static void decode_decorrelation_matrix(WMA3DecodeContext *s,
}
}
/**
*@brief Extract the coefficients from the bitstream.
*@param s codec context
*@param c current channel number
*@return 0 on success, < 0 in case of bitstream errors
*/
static int decode_coeffs(WMA3DecodeContext *s, int c)
{
int vlctable;
VLC* vlc;
WMA3ChannelCtx* ci = &s->channel[c];
int rl_mode = 0;
int cur_coeff = 0;
int num_zeros = 0;
const uint16_t* run;
const uint16_t* level;
dprintf(s->avctx, "decode coefficients for channel %i\n", c);
vlctable = get_bits1(&s->gb);
vlc = &coef_vlc[vlctable];
if (vlctable) {
run = coef1_run;
level = coef1_level;
} else {
run = coef0_run;
level = coef0_level;
}
/** decode vector coefficients (consumes up to 167 bits per iteration for
4 vector coded large values) */
while (!rl_mode && cur_coeff + 3 < s->subframe_len) {
int vals[4];
int i;
unsigned int idx;
idx = get_vlc2(&s->gb, vec4_vlc.table, VLCBITS, VEC4MAXDEPTH);
if ( idx == HUFF_VEC4_SIZE - 1 ) {
for (i = 0; i < 4; i += 2) {
idx = get_vlc2(&s->gb, vec2_vlc.table, VLCBITS, VEC2MAXDEPTH);
if ( idx == HUFF_VEC2_SIZE - 1 ) {
vals[i] = get_vlc2(&s->gb, vec1_vlc.table, VLCBITS, VEC1MAXDEPTH);
if (vals[i] == HUFF_VEC1_SIZE - 1)
vals[i] += ff_wma_get_large_val(&s->gb);
vals[i+1] = get_vlc2(&s->gb, vec1_vlc.table, VLCBITS, VEC1MAXDEPTH);
if (vals[i+1] == HUFF_VEC1_SIZE - 1)
vals[i+1] += ff_wma_get_large_val(&s->gb);
} else {
vals[i] = symbol_to_vec2[idx] >> 4;
vals[i+1] = symbol_to_vec2[idx] & 0xF;
}
}
} else {
vals[0] = symbol_to_vec4[idx] >> 12;
vals[1] = (symbol_to_vec4[idx] >> 8) & 0xF;
vals[2] = (symbol_to_vec4[idx] >> 4) & 0xF;
vals[3] = symbol_to_vec4[idx] & 0xF;
}
/** decode sign */
for (i = 0; i < 4; i++) {
if (vals[i]) {
int sign = get_bits1(&s->gb) - 1;
ci->coeffs[cur_coeff] = (vals[i]^sign) - sign;
num_zeros = 0;
} else {
/** switch to run level mode when subframe_len / 128 zeros
were found in a row */
rl_mode |= (++num_zeros > s->subframe_len>>8);
}
++cur_coeff;
}
}
/** decode run level coded coefficients */
if (rl_mode) {
if(ff_wma_run_level_decode(s->avctx, &s->gb, vlc,
level, run, 1, ci->coeffs,
cur_coeff, s->subframe_len, s->subframe_len,
s->esc_len, 0))
return AVERROR_INVALIDDATA;
}
return 0;
}
/**
*@brief Reconstruct the individual channel data.
*@param s codec context