From 4ea1953b2ceff4ab3be57caf730c9d99a4192238 Mon Sep 17 00:00:00 2001
From: Gagandeep Singh <deepgagan231197@gmail.com>
Date: Tue, 20 Mar 2018 17:54:06 +0530
Subject: [FFmpeg][PATCH] lavc/cfhd: alpha decoding added

some post processing was required
---
 libavcodec/cfhd.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/libavcodec/cfhd.c b/libavcodec/cfhd.c
index a064cd1599..a950dc0f28 100644
--- a/libavcodec/cfhd.c
+++ b/libavcodec/cfhd.c
@@ -94,6 +94,21 @@ 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  -= 16 << 4;
+        channel <<= 8;
+        channel  -= 128;
+        channel  /= 223;
+        channel   = FFMIN(channel, (1 << 12) - 1);
+        channel   = FFMAX(channel, 0);
+        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 +807,8 @@ 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;
--
2.14.1