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mpeg12.h
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1 /*
2  * MPEG1/2 common code
3  * Copyright (c) 2007 Aurelien Jacobs <aurel@gnuage.org>
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 #ifndef AVCODEC_MPEG12_H
23 #define AVCODEC_MPEG12_H
24 
25 #include "mpegvideo.h"
26 
27 #define DC_VLC_BITS 9
28 #define TEX_VLC_BITS 9
29 
30 extern VLC ff_dc_lum_vlc;
31 extern VLC ff_dc_chroma_vlc;
32 
33 typedef struct Mpeg1Context {
35  int mpeg_enc_ctx_allocated; /* true if decoding context allocated */
36  int repeat_field; /* true if we must repeat the field */
37  AVPanScan pan_scan; /**< some temporary storage for the panscan */
39  int swap_uv;//indicate VCR2
42  AVRational frame_rate_ext; ///< MPEG-2 specific framerate modificator
43  int sync; ///< Did we reach a sync point like a GOP/SEQ/KEYFrame?
44  int tmpgexs;
46 } Mpeg1Context;
47 
49 
51 void ff_mpeg12_init_vlcs(void);
52 
53 static inline int decode_dc(GetBitContext *gb, int component)
54 {
55  int code, diff;
56 
57  if (component == 0) {
58  code = get_vlc2(gb, ff_dc_lum_vlc.table, DC_VLC_BITS, 2);
59  } else {
60  code = get_vlc2(gb, ff_dc_chroma_vlc.table, DC_VLC_BITS, 2);
61  }
62  if (code < 0){
63  av_log(NULL, AV_LOG_ERROR, "invalid dc code at\n");
64  return 0xffff;
65  }
66  if (code == 0) {
67  diff = 0;
68  } else {
69  diff = get_xbits(gb, code);
70  }
71  return diff;
72 }
73 
75 
76 #endif /* AVCODEC_MPEG12_H */