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4349 | Serge | 1 | /* |
2 | * MPEG4 Video frame extraction |
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3 | * Copyright (c) 2003 Fabrice Bellard |
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4 | * Copyright (c) 2003 Michael Niedermayer |
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5 | * |
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6 | * This file is part of FFmpeg. |
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7 | * |
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8 | * FFmpeg is free software; you can redistribute it and/or |
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9 | * modify it under the terms of the GNU Lesser General Public |
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10 | * License as published by the Free Software Foundation; either |
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11 | * version 2.1 of the License, or (at your option) any later version. |
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12 | * |
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13 | * FFmpeg is distributed in the hope that it will be useful, |
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14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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16 | * Lesser General Public License for more details. |
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17 | * |
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18 | * You should have received a copy of the GNU Lesser General Public |
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19 | * License along with FFmpeg; if not, write to the Free Software |
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20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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21 | */ |
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22 | |||
23 | #define UNCHECKED_BITSTREAM_READER 1 |
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24 | |||
25 | #include "parser.h" |
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26 | #include "mpegvideo.h" |
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27 | #include "mpeg4video.h" |
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28 | #include "mpeg4video_parser.h" |
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29 | |||
30 | struct Mp4vParseContext { |
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31 | ParseContext pc; |
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32 | struct MpegEncContext enc; |
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33 | int first_picture; |
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34 | }; |
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35 | |||
36 | int ff_mpeg4_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size){ |
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37 | int vop_found, i; |
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38 | uint32_t state; |
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39 | |||
40 | vop_found= pc->frame_start_found; |
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41 | state= pc->state; |
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42 | |||
43 | i=0; |
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44 | if(!vop_found){ |
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45 | for(i=0; i |
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46 | state= (state<<8) | buf[i]; |
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47 | if(state == 0x1B6){ |
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48 | i++; |
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49 | vop_found=1; |
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50 | break; |
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51 | } |
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52 | } |
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53 | } |
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54 | |||
55 | if(vop_found){ |
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56 | /* EOF considered as end of frame */ |
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57 | if (buf_size == 0) |
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58 | return 0; |
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59 | for(; i |
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60 | state= (state<<8) | buf[i]; |
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61 | if((state&0xFFFFFF00) == 0x100){ |
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62 | pc->frame_start_found=0; |
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63 | pc->state=-1; |
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64 | return i-3; |
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65 | } |
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66 | } |
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67 | } |
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68 | pc->frame_start_found= vop_found; |
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69 | pc->state= state; |
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70 | return END_NOT_FOUND; |
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71 | } |
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72 | |||
73 | /* XXX: make it use less memory */ |
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74 | static int av_mpeg4_decode_header(AVCodecParserContext *s1, |
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75 | AVCodecContext *avctx, |
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76 | const uint8_t *buf, int buf_size) |
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77 | { |
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78 | struct Mp4vParseContext *pc = s1->priv_data; |
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79 | MpegEncContext *s = &pc->enc; |
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80 | GetBitContext gb1, *gb = &gb1; |
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81 | int ret; |
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82 | |||
83 | s->avctx = avctx; |
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84 | s->current_picture_ptr = &s->current_picture; |
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85 | |||
86 | if (avctx->extradata_size && pc->first_picture){ |
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87 | init_get_bits(gb, avctx->extradata, avctx->extradata_size*8); |
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88 | ret = ff_mpeg4_decode_picture_header(s, gb); |
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89 | } |
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90 | |||
91 | init_get_bits(gb, buf, 8 * buf_size); |
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92 | ret = ff_mpeg4_decode_picture_header(s, gb); |
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93 | if (s->width && (!avctx->width || !avctx->height || !avctx->coded_width || !avctx->coded_height)) { |
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94 | avcodec_set_dimensions(avctx, s->width, s->height); |
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95 | } |
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96 | if((s1->flags & PARSER_FLAG_USE_CODEC_TS) && s->avctx->time_base.den>0 && ret>=0){ |
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97 | av_assert1(s1->pts == AV_NOPTS_VALUE); |
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98 | av_assert1(s1->dts == AV_NOPTS_VALUE); |
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99 | |||
100 | s1->pts = av_rescale_q(s->time, (AVRational){1, s->avctx->time_base.den}, (AVRational){1, 1200000}); |
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101 | } |
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102 | |||
103 | s1->pict_type= s->pict_type; |
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104 | pc->first_picture = 0; |
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105 | return ret; |
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106 | } |
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107 | |||
108 | static av_cold int mpeg4video_parse_init(AVCodecParserContext *s) |
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109 | { |
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110 | struct Mp4vParseContext *pc = s->priv_data; |
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111 | |||
112 | ff_mpeg4videodec_static_init(); |
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113 | |||
114 | pc->first_picture = 1; |
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115 | pc->enc.quant_precision=5; |
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116 | pc->enc.slice_context_count = 1; |
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117 | pc->enc.showed_packed_warning = 1; |
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118 | return 0; |
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119 | } |
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120 | |||
121 | static int mpeg4video_parse(AVCodecParserContext *s, |
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122 | AVCodecContext *avctx, |
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123 | const uint8_t **poutbuf, int *poutbuf_size, |
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124 | const uint8_t *buf, int buf_size) |
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125 | { |
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126 | ParseContext *pc = s->priv_data; |
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127 | int next; |
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128 | |||
129 | if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){ |
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130 | next= buf_size; |
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131 | }else{ |
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132 | next= ff_mpeg4_find_frame_end(pc, buf, buf_size); |
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133 | |||
134 | if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) { |
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135 | *poutbuf = NULL; |
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136 | *poutbuf_size = 0; |
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137 | return buf_size; |
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138 | } |
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139 | } |
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140 | av_mpeg4_decode_header(s, avctx, buf, buf_size); |
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141 | |||
142 | *poutbuf = buf; |
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143 | *poutbuf_size = buf_size; |
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144 | return next; |
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145 | } |
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146 | |||
147 | |||
148 | AVCodecParser ff_mpeg4video_parser = { |
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149 | .codec_ids = { AV_CODEC_ID_MPEG4 }, |
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150 | .priv_data_size = sizeof(struct Mp4vParseContext), |
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151 | .parser_init = mpeg4video_parse_init, |
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152 | .parser_parse = mpeg4video_parse, |
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153 | .parser_close = ff_parse_close, |
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154 | .split = ff_mpeg4video_split, |
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155 | };>8)><8)>8)><8)> |