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| author | Michael Niedermayer <michaelni@gmx.at> | 2011-12-09 01:11:06 +0100 |
|---|---|---|
| committer | Michael Niedermayer <michaelni@gmx.at> | 2011-12-09 01:11:06 +0100 |
| commit | 43a36ad2eec6e365fcf9de3eac75da5d9d3cdb38 (patch) | |
| tree | 2963abad72139f82297f2817950a486de01cd5ce /libavcodec/cljr.c | |
| parent | 25b9eef410f4a737250dcf2d17b65f6c0c39cd6a (diff) | |
| download | ffmpeg-43a36ad2eec6e365fcf9de3eac75da5d9d3cdb38.tar.gz | |
cljrenc: Add dither to avoid the banding artifcats caused by the very low
number of bits used to represent brightness levels.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Diffstat (limited to 'libavcodec/cljr.c')
| -rw-r--r-- | libavcodec/cljr.c | 14 |
1 files changed, 8 insertions, 6 deletions
diff --git a/libavcodec/cljr.c b/libavcodec/cljr.c index 183652b3a1..950b46a3f7 100644 --- a/libavcodec/cljr.c +++ b/libavcodec/cljr.c @@ -132,6 +132,7 @@ static int encode_frame(AVCodecContext *avctx, unsigned char *buf, PutBitContext pb; AVFrame *p = data; int x, y; + uint32_t dither= avctx->frame_number; p->pict_type = AV_PICTURE_TYPE_I; p->key_frame = 1; @@ -143,13 +144,14 @@ static int encode_frame(AVCodecContext *avctx, unsigned char *buf, uint8_t *cb = &p->data[1][y * p->linesize[1]]; uint8_t *cr = &p->data[2][y * p->linesize[2]]; for (x = 0; x < avctx->width; x += 4) { - put_bits(&pb, 5, luma[3] >> 3); - put_bits(&pb, 5, luma[2] >> 3); - put_bits(&pb, 5, luma[1] >> 3); - put_bits(&pb, 5, luma[0] >> 3); + put_bits(&pb, 5, (luma[3] + (dither>>29) ) >> 3); + put_bits(&pb, 5, (luma[2] + ((dither>>26)&7)) >> 3); + put_bits(&pb, 5, (luma[1] + ((dither>>23)&7)) >> 3); + put_bits(&pb, 5, (luma[0] + ((dither>>20)&7)) >> 3); luma += 4; - put_bits(&pb, 6, *(cb++) >> 2); - put_bits(&pb, 6, *(cr++) >> 2); + put_bits(&pb, 6, (*(cb++) + ((dither>>18)&3)) >> 2); + put_bits(&pb, 6, (*(cr++) + ((dither>>16)&3)) >> 2); + dither = dither*1664525+1013904223; } } |