diracdec: add support for 12 bit videos

The DSP lacked a function needed to convert signed to unsigned. This was
ignored when originally adding support and templating for bit depths
greater than 8. The 10 bit function was used for 12 bit pictures and
resulted in an improper conversion.
Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>

libavcodec/diracdec.c

@@ -1839,9 +1839,12 @@ static int dirac_decode_frame_internal(DiracContext *s)
 
         if (!s->num_refs) { /* intra */
             for (y = 0; y < p->height; y += 16) {
+                int idx = (s->bit_depth - 8) >> 1;
                 ff_spatial_idwt_slice2(&d, y+16); /* decode */
-                s->diracdsp.put_signed_rect_clamped[s->pshift](frame + y*p->stride, p->stride,
-                                                               p->idwt_buf + y*p->idwt_stride, p->idwt_stride, p->width, 16);
+                s->diracdsp.put_signed_rect_clamped[idx](frame + y*p->stride,
+                                                         p->stride,
+                                                         p->idwt_buf + y*p->idwt_stride,
+                                                         p->idwt_stride, p->width, 16);
             }
         } else { /* inter */
             int rowheight = p->ybsep*p->stride;

libavcodec/diracdsp.c

@@ -168,6 +168,23 @@ static void put_signed_rect_clamped_10bit_c(uint8_t *_dst, int dst_stride, const
     }
 }
 
+static void put_signed_rect_clamped_12bit_c(uint8_t *_dst, int dst_stride, const uint8_t *_src, int src_stride, int width, int height)
+{
+    int x, y;
+    uint16_t *dst = (uint16_t *)_dst;
+    int32_t *src = (int32_t *)_src;
+    for (y = 0; y < height; y++) {
+        for (x = 0; x < width; x+=4) {
+            dst[x  ] = av_clip(src[x  ] + 2048, 0, (1 << 12) - 1);
+            dst[x+1] = av_clip(src[x+1] + 2048, 0, (1 << 12) - 1);
+            dst[x+2] = av_clip(src[x+2] + 2048, 0, (1 << 12) - 1);
+            dst[x+3] = av_clip(src[x+3] + 2048, 0, (1 << 12) - 1);
+        }
+        dst += dst_stride >> 1;
+        src += src_stride >> 2;
+    }
+}
+
 static void add_rect_clamped_c(uint8_t *dst, const uint16_t *src, int stride,
                                const int16_t *idwt, int idwt_stride,
                                int width, int height)
@@ -197,6 +214,7 @@ av_cold void ff_diracdsp_init(DiracDSPContext *c)
     c->add_rect_clamped = add_rect_clamped_c;
     c->put_signed_rect_clamped[0] = put_signed_rect_clamped_8bit_c;
     c->put_signed_rect_clamped[1] = put_signed_rect_clamped_10bit_c;
+    c->put_signed_rect_clamped[2] = put_signed_rect_clamped_12bit_c;
 
     c->add_dirac_obmc[0] = add_obmc8_c;
     c->add_dirac_obmc[1] = add_obmc16_c;