omxVCM4P2_EncodeVLCZigzag_IntraACVLC.c revision 78e52bfac041d71ce53b5b13c2abf78af742b09d 
1/*
2 * Copyright (C) 2007-2008 ARM Limited
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/**
18 *
19 * File Name:  omxVCM4P2_EncodeVLCZigzag_IntraACVLC.c
20 * OpenMAX DL: v1.0.2
21 * Revision:   9641
22 * Date:       Thursday, February 7, 2008
23 *
24 *
25 *
26 *
27 * Description:
28 * Contains modules for zigzag scanning and VLC encoding
29 * for intra block.
30 *
31 */
32
33#include "omxtypes.h"
34#include "armOMX.h"
35#include "omxVC.h"
36
37#include "armVC.h"
38
39
40/**
41 * Function:  omxVCM4P2_EncodeVLCZigzag_IntraACVLC   (6.2.4.5.2)
42 *
43 * Description:
44 * Performs zigzag scan and VLC encoding of AC and DC coefficients for one
45 * intra block.  Two versions of the function (DCVLC and ACVLC) are provided
46 * in order to support the two different methods of processing DC
47 * coefficients, as described in [ISO14496-2], subclause 7.4.1.4,  Intra DC
48 * Coefficient Decoding for the Case of Switched VLC Encoding.
49 *
50 * Input Arguments:
51 *
52 *   ppBitStream - double pointer to the current byte in the bitstream
53 *   pBitOffset - pointer to the bit position in the byte pointed by
54 *            *ppBitStream. Valid within 0 to 7.
55 *   pQDctBlkCoef - pointer to the quantized DCT coefficient
56 *   predDir - AC prediction direction, which is used to decide the zigzag
57 *            scan pattern; takes one of the following values:
58 *            -  OMX_VC_NONE - AC prediction not used.
59 *                             Performs classical zigzag scan.
60 *            -  OMX_VC_HORIZONTAL - Horizontal prediction.
61 *                             Performs alternate-vertical zigzag scan.
62 *            -  OMX_VC_VERTICAL - Vertical prediction.
63 *                             Performs alternate-horizontal zigzag scan.
64 *   pattern - block pattern which is used to decide whether this block is
65 *            encoded
66 *   shortVideoHeader - binary flag indicating presence of
67 *            short_video_header; escape modes 0-3 are used if
68 *            shortVideoHeader==0, and escape mode 4 is used when
69 *            shortVideoHeader==1.
70 *
71 * Output Arguments:
72 *
73 *   ppBitStream - *ppBitStream is updated after the block is encoded, so
74 *            that it points to the current byte in the bit stream buffer.
75 *   pBitOffset - *pBitOffset is updated so that it points to the current bit
76 *            position in the byte pointed by *ppBitStream.
77 *
78 * Return Value:
79 *
80 *    OMX_Sts_NoErr - no error
81 *    OMX_Sts_BadArgErr - Bad arguments:
82 *    -    At least one of the following pointers is NULL: ppBitStream,
83 *              *ppBitStream, pBitOffset, pQDctBlkCoef.
84 *    -   *pBitOffset < 0, or *pBitOffset >7.
85 *    -    PredDir is not one of: OMX_VC_NONE, OMX_VC_HORIZONTAL, or
86 *         OMX_VC_VERTICAL.
87 *    -    VideoComp is not one component of enum OMXVCM4P2VideoComponent.
88 *
89 */
90
91OMXResult omxVCM4P2_EncodeVLCZigzag_IntraACVLC(
92     OMX_U8 **ppBitStream,
93     OMX_INT *pBitOffset,
94     const OMX_S16 *pQDctBlkCoef,
95     OMX_U8 predDir,
96     OMX_U8 pattern,
97     OMX_INT shortVideoHeader
98)
99{
100    OMX_U8 start = 0;
101
102    return armVCM4P2_EncodeVLCZigzag_Intra(
103     ppBitStream,
104     pBitOffset,
105     pQDctBlkCoef,
106     predDir,
107     pattern,
108     shortVideoHeader,
109     start);
110}
111
112/* End of file */
113