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Code Issues Releases Activity

Factorize decode_postfix() out.

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Originally committed as revision 12873 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer
2008-04-17 03:08:25 +00:00
parent c49c5e23dc
commit 5a5a27c5de
1 changed files with 22 additions and 32 deletions
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54
libavcodec/alac.c
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@@ -145,6 +145,26 @@ static inline int count_leading_zeros(int32_t input)
return 31-av_log2(input); return 31-av_log2(input);
} }
static inline int decode_postfix(GetBitContext *gb, int x, int k, int limit){
if (k >= limit)
k = limit;
if (k != 1) {
int extrabits = show_bits(gb, k);
/* multiply x by 2^k - 1, as part of their strange algorithm */
x = (x << k) - x;
if (extrabits > 1) {
x += extrabits - 1;
skip_bits(gb, k);
} else
skip_bits(gb, k - 1);
}
return x;
}
static void bastardized_rice_decompress(ALACContext *alac, static void bastardized_rice_decompress(ALACContext *alac,
int32_t *output_buffer, int32_t *output_buffer,
int output_size, int output_size,
@@ -172,27 +192,11 @@ static void bastardized_rice_decompress(ALACContext *alac,
x = get_bits(&alac->gb, readsamplesize); x = get_bits(&alac->gb, readsamplesize);
} else { } else {
/* standard rice encoding */ /* standard rice encoding */
int extrabits;
int k; /* size of extra bits */ int k; /* size of extra bits */
/* read k, that is bits as is */ /* read k, that is bits as is */
k = 31 - count_leading_zeros((history >> 9) + 3); k = 31 - count_leading_zeros((history >> 9) + 3);
x= decode_postfix(&alac->gb, x, k, rice_kmodifier);
if (k >= rice_kmodifier)
k = rice_kmodifier;
if (k != 1) {
extrabits = show_bits(&alac->gb, k);
/* multiply x by 2^k - 1, as part of their strange algorithm */
x = (x << k) - x;
if (extrabits > 1) {
x += extrabits - 1;
skip_bits(&alac->gb, k);
} else
skip_bits(&alac->gb, k - 1);
}
} }
x_modified = sign_modifier + x; x_modified = sign_modifier + x;
@@ -222,24 +226,10 @@ static void bastardized_rice_decompress(ALACContext *alac,
block_size = get_bits(&alac->gb, 16); block_size = get_bits(&alac->gb, 16);
} else { } else {
int k; int k;
int extrabits;
k = count_leading_zeros(history) + ((history + 16) >> 6 /* / 64 */) - 24; k = count_leading_zeros(history) + ((history + 16) >> 6 /* / 64 */) - 24;
if (k >= rice_kmodifier) block_size= decode_postfix(&alac->gb, x, k, rice_kmodifier);
k = rice_kmodifier;
x = (x << k) - x;
extrabits = show_bits(&alac->gb, k);
if (extrabits < 2) {
skip_bits(&alac->gb, k - 1);
} else {
x += extrabits - 1;
skip_bits(&alac->gb, k);
}
block_size = x;
} }
if (block_size > 0) { if (block_size > 0) {