diff options
author | Reimar Döffinger <Reimar.Doeffinger@gmx.de> | 2011-07-17 15:03:57 +0400 |
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committer | Reimar Döffinger <Reimar.Doeffinger@gmx.de> | 2011-07-18 22:01:43 +0400 |
commit | 47b71eea099b3fe2c7e16644878ad9b7067974e3 (patch) | |
tree | 50cbc59f8bf582d0f9821e1fd02e3d2f0ad8babd /libavcodec/bink.c | |
parent | f04d4345da29782035f241d605de5df3cefbfeda (diff) |
Bink: clip AC coefficients during dequantization.
Fixes artefacts with Neverwinter Nights WOTCLogo.bik
(http://drmccoy.de/zeugs/WOTCLogo.bik).
Fixes trac ticket #352.
Signed-off-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>
Diffstat (limited to 'libavcodec/bink.c')
-rw-r--r-- | libavcodec/bink.c | 20 |
1 files changed, 18 insertions, 2 deletions
diff --git a/libavcodec/bink.c b/libavcodec/bink.c index ef07747dbc..4328a43525 100644 --- a/libavcodec/bink.c +++ b/libavcodec/bink.c @@ -571,6 +571,22 @@ static inline int binkb_get_value(BinkContext *c, int bundle_num) return ret; } +static inline DCTELEM dequant(DCTELEM in, uint32_t quant, int dc) +{ + /* Note: multiplication is unsigned but we want signed shift + * otherwise clipping breaks. + * TODO: The official decoder does not use clipping at all + * but instead uses the full 32-bit result. + * However clipping at least gets rid of the case that a + * half-black half-white intra block gets black and white swapped + * and should cause at most minor differences (except for DC). */ + int32_t res = in * quant; + res >>= 11; + if (!dc) + res = av_clip_int16(res); + return res; +} + /** * Read 8x8 block of DCT coefficients. * @@ -669,10 +685,10 @@ static int read_dct_coeffs(GetBitContext *gb, DCTELEM block[64], const uint8_t * quant = quant_matrices[quant_idx]; - block[0] = (block[0] * quant[0]) >> 11; + block[0] = dequant(block[0], quant[0], 1); for (i = 0; i < coef_count; i++) { int idx = coef_idx[i]; - block[scan[idx]] = (block[scan[idx]] * quant[idx]) >> 11; + block[scan[idx]] = dequant(block[scan[idx]], quant[idx], 0); } return 0; |