1 /*
2 * Copyright 2020 The libgav1 Authors
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #ifndef LIBGAV1_SRC_FRAME_BUFFER_UTILS_H_
18 #define LIBGAV1_SRC_FRAME_BUFFER_UTILS_H_
19
20 #include <cassert>
21 #include <cstdint>
22
23 #include "src/gav1/decoder_buffer.h"
24
25 namespace libgav1 {
26
27 // The following table is from Section 6.4.2 of the spec.
28 //
29 // subsampling_x subsampling_y mono_chrome Description
30 // -----------------------------------------------------------
31 // 0 0 0 YUV 4:4:4
32 // 1 0 0 YUV 4:2:2
33 // 1 1 0 YUV 4:2:0
34 // 1 1 1 Monochrome 4:0:0
35
ComposeImageFormat(bool is_monochrome,int8_t subsampling_x,int8_t subsampling_y)36 inline Libgav1ImageFormat ComposeImageFormat(bool is_monochrome,
37 int8_t subsampling_x,
38 int8_t subsampling_y) {
39 Libgav1ImageFormat image_format;
40 if (subsampling_x == 0) {
41 assert(subsampling_y == 0 && !is_monochrome);
42 image_format = kLibgav1ImageFormatYuv444;
43 } else if (subsampling_y == 0) {
44 assert(!is_monochrome);
45 image_format = kLibgav1ImageFormatYuv422;
46 } else if (!is_monochrome) {
47 image_format = kLibgav1ImageFormatYuv420;
48 } else {
49 image_format = kLibgav1ImageFormatMonochrome400;
50 }
51 return image_format;
52 }
53
DecomposeImageFormat(Libgav1ImageFormat image_format,bool * is_monochrome,int8_t * subsampling_x,int8_t * subsampling_y)54 inline void DecomposeImageFormat(Libgav1ImageFormat image_format,
55 bool* is_monochrome, int8_t* subsampling_x,
56 int8_t* subsampling_y) {
57 *is_monochrome = false;
58 *subsampling_x = 1;
59 *subsampling_y = 1;
60 switch (image_format) {
61 case kLibgav1ImageFormatYuv420:
62 break;
63 case kLibgav1ImageFormatYuv422:
64 *subsampling_y = 0;
65 break;
66 case kLibgav1ImageFormatYuv444:
67 *subsampling_x = *subsampling_y = 0;
68 break;
69 default:
70 assert(image_format == kLibgav1ImageFormatMonochrome400);
71 *is_monochrome = true;
72 break;
73 }
74 }
75
76 } // namespace libgav1
77
78 #endif // LIBGAV1_SRC_FRAME_BUFFER_UTILS_H_
79