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lavc/cfhd: add alpha decompanding in rgba12 

Alpha decompanding curve added to post process the decoded alpha channel.
Fixes ticket #6265.
This commit is contained in:
Gagandeep Singh 2018-03-22 15:03:37 +05:30 committed by Paul B Mahol
parent 59347c2474
commit c64c97b972
1 changed files with 19 additions and 0 deletions
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19
libavcodec/cfhd.c
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@ -37,6 +37,9 @@
#include "thread.h"
#include "cfhd.h"
#define ALPHA_COMPAND_DC_OFFSET 256
#define ALPHA_COMPAND_GAIN 9400
enum CFHDParam {
ChannelCount = 12,
SubbandCount = 14,
@ -94,6 +97,20 @@ static inline int dequant_and_decompand(int level, int quantisation)
FFSIGN(level) * quantisation;
}
static inline void process_alpha(int16_t *alpha, int width)
{
int i, channel;
for (i = 0; i < width; i++) {
channel = alpha[i];
channel -= ALPHA_COMPAND_DC_OFFSET;
channel <<= 3;
channel *= ALPHA_COMPAND_GAIN;
channel >>= 16;
channel = av_clip_uintp2(channel, 12);
alpha[i] = channel;
}
}
static inline void filter(int16_t *output, ptrdiff_t out_stride,
int16_t *low, ptrdiff_t low_stride,
int16_t *high, ptrdiff_t high_stride,
@ -792,6 +809,8 @@ static int cfhd_decode(AVCodecContext *avctx, void *data, int *got_frame,
high = s->plane[plane].l_h[7];
for (i = 0; i < lowpass_height * 2; i++) {
horiz_filter_clip(dst, low, high, lowpass_width, s->bpc);
if (act_plane == 3)
process_alpha(dst, lowpass_width * 2);
low += lowpass_width;
high += lowpass_width;
dst += pic->linesize[act_plane] / 2;