From 1c3a3a4ec66f66306013d5038b13dabffcf9f5d9 Mon Sep 17 00:00:00 2001
From: Paul B Mahol <onemda@gmail.com>
Date: Sun, 23 Aug 2020 11:40:40 +0200
Subject: avcodec/notchlc: add initial alpha support

---
 libavcodec/notchlc.c | 83 +++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 73 insertions(+), 10 deletions(-)

(limited to 'libavcodec/notchlc.c')

diff --git a/libavcodec/notchlc.c b/libavcodec/notchlc.c
index 9e6534339f..f9e03fdded 100644
--- a/libavcodec/notchlc.c
+++ b/libavcodec/notchlc.c
@@ -51,7 +51,7 @@ typedef struct NotchLCContext {
     unsigned y_data_offset;
     unsigned uv_data_offset;
     unsigned y_data_size;
-    unsigned uv_count_size;
+    unsigned a_data_offset;
     unsigned uv_count_offset;
     unsigned a_count_size;
     unsigned data_end;
@@ -62,7 +62,7 @@ typedef struct NotchLCContext {
 
 static av_cold int decode_init(AVCodecContext *avctx)
 {
-    avctx->pix_fmt = AV_PIX_FMT_YUV444P12;
+    avctx->pix_fmt = AV_PIX_FMT_YUVA444P12;
     avctx->color_range = AVCOL_RANGE_JPEG;
     avctx->colorspace = AVCOL_SPC_RGB;
     avctx->color_primaries = AVCOL_PRI_BT709;
@@ -196,11 +196,11 @@ static int decode_blocks(AVCodecContext *avctx, AVFrame *p, ThreadFrame *frame,
     if (s->y_data_size >= UINT_MAX / 4)
         return AVERROR_INVALIDDATA;
 
-    s->uv_count_size = bytestream2_get_le32(gb);
-    if (s->uv_count_size >= UINT_MAX / 4)
+    s->a_data_offset = bytestream2_get_le32(gb);
+    if (s->a_data_offset >= UINT_MAX / 4)
         return AVERROR_INVALIDDATA;
-    s->uv_count_size *= 4;
-    if (s->uv_count_size >= uncompressed_size)
+    s->a_data_offset *= 4;
+    if (s->a_data_offset >= uncompressed_size)
         return AVERROR_INVALIDDATA;
 
     s->a_count_size = bytestream2_get_le32(gb);
@@ -218,9 +218,9 @@ static int decode_blocks(AVCodecContext *avctx, AVFrame *p, ThreadFrame *frame,
     if (s->data_end <= s->y_data_size)
         return AVERROR_INVALIDDATA;
     s->y_data_offset = s->data_end - s->y_data_size;
-    if (s->y_data_offset <= s->uv_count_size)
+    if (s->y_data_offset <= s->a_data_offset)
         return AVERROR_INVALIDDATA;
-    s->uv_count_offset = s->y_data_offset - s->uv_count_size;
+    s->uv_count_offset = s->y_data_offset - s->a_data_offset;
 
     if ((ret = ff_thread_get_buffer(avctx, frame, 0)) < 0)
         return ret;
@@ -266,13 +266,76 @@ static int decode_blocks(AVCodecContext *avctx, AVFrame *p, ThreadFrame *frame,
         }
 
         dsty += 4 * ylinesize;
-        dsta += 4 * alinesize;
     }
 
     rgb = *gb;
     dgb = *gb;
-    bytestream2_seek(&rgb, s->uv_offset_data_offset, SEEK_SET);
     bytestream2_seek(gb, s->a_control_word_offset, SEEK_SET);
+    if (s->uv_count_offset == s->a_control_word_offset) {
+        for (int y = 0; y < avctx->height; y++) {
+            for (int x = 0; x < avctx->width; x++)
+                dsta[x] = 4095;
+            dsta += alinesize;
+        }
+    } else {
+        for (int y = 0; y < avctx->height; y += 16) {
+            for (int x = 0; x < avctx->width; x += 16) {
+                unsigned m = bytestream2_get_le32(gb);
+                unsigned offset = bytestream2_get_le32(gb);
+                unsigned alpha0, alpha1;
+                uint64_t control;
+
+                if (offset >= UINT_MAX / 4)
+                    return AVERROR_INVALIDDATA;
+                offset = offset * 4 + s->uv_data_offset + s->a_data_offset;
+                if (offset >= s->data_end)
+                    return AVERROR_INVALIDDATA;
+
+                bytestream2_seek(&dgb, offset, SEEK_SET);
+                control = bytestream2_get_le64(&dgb);
+                alpha0 = control & 0xFF;
+                alpha1 = (control >> 8) & 0xFF;
+                control = control >> 16;
+
+                for (int by = 0; by < 4; by++) {
+                    for (int bx = 0; bx < 4; bx++) {
+                        switch (m & 3) {
+                        case 0:
+                            for (int i = 0; i < 4; i++) {
+                                for (int j = 0; j < 4; j++) {
+                                    dsta[x + (i + by * 4) * alinesize + bx * 4 + j] = 0;
+                                }
+                            }
+                            break;
+                        case 1:
+                            for (int i = 0; i < 4; i++) {
+                                for (int j = 0; j < 4; j++) {
+                                    dsta[x + (i + by * 4) * alinesize + bx * 4 + j] = 4095;
+                                }
+                            }
+                            break;
+                        case 2:
+                            for (int i = 0; i < 4; i++) {
+                                for (int j = 0; j < 4; j++) {
+                                    dsta[x + (i + by * 4) * alinesize + bx * 4 + j] = (alpha0 + (alpha1 - alpha0) * (control & 7)) << 4;
+                                }
+                            }
+                            break;
+                        default:
+                            return AVERROR_INVALIDDATA;
+                        }
+
+                        control >>= 3;
+                        m >>= 2;
+                    }
+                }
+            }
+
+            dsta += 16 * alinesize;
+        }
+    }
+
+    bytestream2_seek(&rgb, s->uv_offset_data_offset, SEEK_SET);
 
     dstu = (uint16_t *)p->data[1];
     dstv = (uint16_t *)p->data[2];
-- 
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