Merge "Add extended metadata buffer support by defining different types of metadata buffers"

/*

 * Copyright (C) 2011 The Android Open Source Project

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

#ifndef METADATA_BUFFER_TYPE_H

#define METADATA_BUFFER_TYPE_H

namespace android {

/*

 * MetadataBufferType defines the type of the metadata buffers that

 * can be passed to video encoder component for encoding, via Stagefright

 * media recording framework. To see how to work with the metadata buffers

 * in media recording framework, please consult HardwareAPI.h

 *

 * The creator of metadata buffers and video encoder share common knowledge

 * on what is actually being stored in these metadata buffers, and

 * how the information can be used by the video encoder component

 * to locate the actual pixel data as the source input for video

 * encoder, plus whatever other information that is necessary. Stagefright

 * media recording framework does not need to know anything specific about the

 * metadata buffers, except for receving each individual metadata buffer

 * as the source input, making a copy of the metadata buffer, and passing the

 * copy via OpenMAX API to the video encoder component.

 *

 * The creator of the metadata buffers must ensure that the first

 * 4 bytes in every metadata buffer indicates its buffer type,

 * and the rest of the metadata buffer contains the

 * actual metadata information. When a video encoder component receives

 * a metadata buffer, it uses the first 4 bytes in that buffer to find

 * out the type of the metadata buffer, and takes action appropriate

 * to that type of metadata buffers (for instance, locate the actual

 * pixel data input and then encoding the input data to produce a

 * compressed output buffer).

 *

 * The following shows the layout of a metadata buffer,

 * where buffer type is a 4-byte field of MetadataBufferType,

 * and the payload is the metadata information.

 *

 * --------------------------------------------------------------

 * |  buffer type  |          payload                           |

 * --------------------------------------------------------------

 *

 */

typedef enum {

    /*

     * kMetadataBufferTypeCameraSource is used to indicate that

     * the source of the metadata buffer is the camera component.

     */

    kMetadataBufferTypeCameraSource  = 0,

    /*

     * kMetadataBufferTypeGrallocSource is used to indicate that

     * the payload of the metadata buffers can be interpreted as

     * a buffer_handle_t.

     */

    kMetadataBufferTypeGrallocSource = 1,

    // Add more here...

} MetadataBufferType;

}  // namespace android

#endif  // METADATA_BUFFER_TYPE_H