1/*
2 * Copyright (C) 2011 The Android Open Source Project
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 METADATA_BUFFER_TYPE_H
18#define METADATA_BUFFER_TYPE_H
19
20#ifdef __cplusplus
21extern "C" {
22namespace android {
23#endif
24
25/*
26 * MetadataBufferType defines the type of the metadata buffers that
27 * can be passed to video encoder component for encoding, via Stagefright
28 * media recording framework. To see how to work with the metadata buffers
29 * in media recording framework, please consult HardwareAPI.h
30 *
31 * The creator of metadata buffers and video encoder share common knowledge
32 * on what is actually being stored in these metadata buffers, and
33 * how the information can be used by the video encoder component
34 * to locate the actual pixel data as the source input for video
35 * encoder, plus whatever other information that is necessary. Stagefright
36 * media recording framework does not need to know anything specific about the
37 * metadata buffers, except for receving each individual metadata buffer
38 * as the source input, making a copy of the metadata buffer, and passing the
39 * copy via OpenMAX API to the video encoder component.
40 *
41 * The creator of the metadata buffers must ensure that the first
42 * 4 bytes in every metadata buffer indicates its buffer type,
43 * and the rest of the metadata buffer contains the
44 * actual metadata information. When a video encoder component receives
45 * a metadata buffer, it uses the first 4 bytes in that buffer to find
46 * out the type of the metadata buffer, and takes action appropriate
47 * to that type of metadata buffers (for instance, locate the actual
48 * pixel data input and then encoding the input data to produce a
49 * compressed output buffer).
50 *
51 * The following shows the layout of a metadata buffer,
52 * where buffer type is a 4-byte field of MetadataBufferType,
53 * and the payload is the metadata information.
54 *
55 * --------------------------------------------------------------
56 * |  buffer type  |          payload                           |
57 * --------------------------------------------------------------
58 *
59 */
60typedef enum {
61
62    /*
63     * kMetadataBufferTypeCameraSource is used to indicate that
64     * the source of the metadata buffer is the camera component.
65     */
66    kMetadataBufferTypeCameraSource  = 0,
67
68    /*
69     * kMetadataBufferTypeGrallocSource is used to indicate that
70     * the payload of the metadata buffers can be interpreted as
71     * a buffer_handle_t.
72     * So in this case,the metadata that the encoder receives
73     * will have a byte stream that consists of two parts:
74     * 1. First, there is an integer indicating that it is a GRAlloc
75     * source (kMetadataBufferTypeGrallocSource)
76     * 2. This is followed by the buffer_handle_t that is a handle to the
77     * GRalloc buffer. The encoder needs to interpret this GRalloc handle
78     * and encode the frames.
79     * --------------------------------------------------------------
80     * |  kMetadataBufferTypeGrallocSource | sizeof(buffer_handle_t) |
81     * --------------------------------------------------------------
82     */
83    kMetadataBufferTypeGrallocSource = 1,
84
85    // Add more here...
86
87} MetadataBufferType;
88
89#ifdef __cplusplus
90}  // namespace android
91}
92#endif
93
94#endif  // METADATA_BUFFER_TYPE_H
95