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* 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
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#ifdef __cplusplus
extern "C" {
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.
* So in this case,the metadata that the encoder receives
* will have a byte stream that consists of two parts:
* 1. First, there is an integer indicating that it is a GRAlloc
* source (kMetadataBufferTypeGrallocSource)
* 2. This is followed by the buffer_handle_t that is a handle to the
* GRalloc buffer. The encoder needs to interpret this GRalloc handle
* and encode the frames.
* --------------------------------------------------------------
* | kMetadataBufferTypeGrallocSource | sizeof(buffer_handle_t) |
* --------------------------------------------------------------
kMetadataBufferTypeGrallocSource = 1,
// Add more here...
} MetadataBufferType;
#ifdef __cplusplus
} // namespace android