hevc: clip pixels when transquant bypass is used

The reconstructed picture should always be clipped (see section 8.6.5),
previously we did not clip coding units where
cu_transquant_bypass_flag == 1.

Sample-Id: 00001325-google
Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>

libavcodec/hevcdsp_template.c

@@ -50,7 +50,7 @@ static void FUNC(transquant_bypass4x4)(uint8_t *_dst, int16_t *coeffs,
 
     for (y = 0; y < 4; y++) {
         for (x = 0; x < 4; x++) {
-            dst[x] += *coeffs;
+            dst[x] = av_clip_pixel(dst[x] + *coeffs);
             coeffs++;
         }
         dst += stride;
@@ -67,7 +67,7 @@ static void FUNC(transquant_bypass8x8)(uint8_t *_dst, int16_t *coeffs,
 
     for (y = 0; y < 8; y++) {
         for (x = 0; x < 8; x++) {
-            dst[x] += *coeffs;
+            dst[x] = av_clip_pixel(dst[x] + *coeffs);
             coeffs++;
         }
         dst += stride;
@@ -84,7 +84,7 @@ static void FUNC(transquant_bypass16x16)(uint8_t *_dst, int16_t *coeffs,
 
     for (y = 0; y < 16; y++) {
         for (x = 0; x < 16; x++) {
-            dst[x] += *coeffs;
+            dst[x] = av_clip_pixel(dst[x] + *coeffs);
             coeffs++;
         }
         dst += stride;
@@ -101,7 +101,7 @@ static void FUNC(transquant_bypass32x32)(uint8_t *_dst, int16_t *coeffs,
 
     for (y = 0; y < 32; y++) {
         for (x = 0; x < 32; x++) {
-            dst[x] += *coeffs;
+            dst[x] = av_clip_pixel(dst[x] + *coeffs);
             coeffs++;
         }
         dst += stride;