add nativeapis

Signed-off-by: Nzengyawen <zengyawen1@huawei.com>

en/application-dev/reference/native-apis/_o_h___a_v_codec_buffer_attr.md

+# OH_AVCodecBufferAttr
+
+
+## Overview
+
+Defines the buffer attributes of an **OH_AVCodec** instance.
+
+\@syscap SystemCapability.Multimedia.Media.CodecBase
+
+**Since:**
+9
+
+**Related Modules:**
+
+[CodecBase](_codec_base.md)
+
+
+## Summary
+
+
+### Member Variables
+
+| Name | Description | 
+| -------- | -------- |
+| [pts](_codec_base.md#pts) | Presentation timestamp of the buffer, in microseconds.| 
+| [size](_codec_base.md#size) | Size of the data contained in the buffer, in bytes. | 
+| [offset](_codec_base.md#offset) | Start offset of valid data in the buffer. | 
+| [flags](_codec_base.md#flags) | Buffer flag, which is a combination of multiple **OH_AVCodecBufferFlags**.  |