rocDecode api defintions added for decoder and parser (#6)

* rocDecode api defintions added for decoder and parser

* addressed review comments and changed struct names to CamelCase

* minot reformatting

src/rocdecode/vaapi/vaapi_videodecoder.h

@@ -0,0 +1,59 @@
+/*
+Copyright (c) 2023 - 2023 Advanced Micro Devices, Inc. All rights reserved.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+*/
+
+#pragma once
+
+
+// class implementing highlevel vaapi decoder
+/***********************************************************************************************************/
+//! requirement is as follows
+//!
+//! In order to minimize decode latencies, there should be always at least enough pictures (min 2) in the decode
+//! queue at any time, in order to make sure that all VCN decode engines are always busy.
+//! In addition to the reqular create and destroy: the decoder needs to have a task-Q for submitting decoding jobs from the high level
+//!
+//! Overall data flow:
+//!  - GetCaps(...)
+//!  - CreateVideoDecoder(...)
+//!  - For each picture:
+//!    + submitDecodeTask(0)        /* submit first frame for decoding */
+//!    + ...                        /* submit next frame for decoding */
+//!    + submitDecodeTask(N)        /* N is determined based on available HW decode engines in the system */
+//!
+//!    + QueryStatus(N-4)           /* Query the decode status of N-4 frame */
+//!    + MapVideoFrame(N-4)
+//!    + do some processing in HIP
+//!    + UnmapVideoFrame(N-4)
+//!    + submitDecodeTask(N+1)
+//!    + MapVideoFrame(N-3)
+//!    + ...
+//!  - DestroyVideoDecoder(...)
+//!
+//! NOTE:
+//! - The decoder has to maintain a Q for decode jobs with associated picture buffers
+//! - An intenal thread has to pick up the next available job: If none wait for the Q to fill
+/***********************************************************************************************************/
+
+class vaapiVideoDecoder {
+public:
+
+};