| 1 | /* |
| 2 | * MPEG1 / MPEG2 video parser |
| 3 | * Copyright (c) 2000,2001 Fabrice Bellard |
| 4 | * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at> |
| 5 | * |
| 6 | * This file is part of FFmpeg. |
| 7 | * |
| 8 | * FFmpeg is free software; you can redistribute it and/or |
| 9 | * modify it under the terms of the GNU Lesser General Public |
| 10 | * License as published by the Free Software Foundation; either |
| 11 | * version 2.1 of the License, or (at your option) any later version. |
| 12 | * |
| 13 | * FFmpeg is distributed in the hope that it will be useful, |
| 14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 16 | * Lesser General Public License for more details. |
| 17 | * |
| 18 | * You should have received a copy of the GNU Lesser General Public |
| 19 | * License along with FFmpeg; if not, write to the Free Software |
| 20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 21 | */ |
| 22 | |
| 23 | #include "parser.h" |
| 24 | #include "mpeg12.h" |
| 25 | #include "internal.h" |
| 26 | |
| 27 | struct MpvParseContext { |
| 28 | ParseContext pc; |
| 29 | AVRational frame_rate; |
| 30 | int progressive_sequence; |
| 31 | int width, height; |
| 32 | }; |
| 33 | |
| 34 | |
| 35 | static void mpegvideo_extract_headers(AVCodecParserContext *s, |
| 36 | AVCodecContext *avctx, |
| 37 | const uint8_t *buf, int buf_size) |
| 38 | { |
| 39 | struct MpvParseContext *pc = s->priv_data; |
| 40 | const uint8_t *buf_end = buf + buf_size; |
| 41 | uint32_t start_code; |
| 42 | int frame_rate_index, ext_type, bytes_left; |
| 43 | int frame_rate_ext_n, frame_rate_ext_d; |
| 44 | int top_field_first, repeat_first_field, progressive_frame; |
| 45 | int horiz_size_ext, vert_size_ext, bit_rate_ext; |
| 46 | int did_set_size=0; |
| 47 | int bit_rate = 0; |
| 48 | int vbv_delay = 0; |
| 49 | //FIXME replace the crap with get_bits() |
| 50 | s->repeat_pict = 0; |
| 51 | |
| 52 | while (buf < buf_end) { |
| 53 | start_code= -1; |
| 54 | buf= avpriv_find_start_code(buf, buf_end, &start_code); |
| 55 | bytes_left = buf_end - buf; |
| 56 | switch(start_code) { |
| 57 | case PICTURE_START_CODE: |
| 58 | if (bytes_left >= 2) { |
| 59 | s->pict_type = (buf[1] >> 3) & 7; |
| 60 | if (bytes_left >= 4) |
| 61 | vbv_delay = ((buf[1] & 0x07) << 13) | (buf[2] << 5) | (buf[3] >> 3); |
| 62 | } |
| 63 | break; |
| 64 | case SEQ_START_CODE: |
| 65 | if (bytes_left >= 7) { |
| 66 | pc->width = (buf[0] << 4) | (buf[1] >> 4); |
| 67 | pc->height = ((buf[1] & 0x0f) << 8) | buf[2]; |
| 68 | if(!avctx->width || !avctx->height || !avctx->coded_width || !avctx->coded_height){ |
| 69 | ff_set_dimensions(avctx, pc->width, pc->height); |
| 70 | did_set_size=1; |
| 71 | } |
| 72 | frame_rate_index = buf[3] & 0xf; |
| 73 | pc->frame_rate = avctx->framerate = ff_mpeg12_frame_rate_tab[frame_rate_index]; |
| 74 | bit_rate = (buf[4]<<10) | (buf[5]<<2) | (buf[6]>>6); |
| 75 | avctx->codec_id = AV_CODEC_ID_MPEG1VIDEO; |
| 76 | avctx->ticks_per_frame = 1; |
| 77 | } |
| 78 | break; |
| 79 | case EXT_START_CODE: |
| 80 | if (bytes_left >= 1) { |
| 81 | ext_type = (buf[0] >> 4); |
| 82 | switch(ext_type) { |
| 83 | case 0x1: /* sequence extension */ |
| 84 | if (bytes_left >= 6) { |
| 85 | horiz_size_ext = ((buf[1] & 1) << 1) | (buf[2] >> 7); |
| 86 | vert_size_ext = (buf[2] >> 5) & 3; |
| 87 | bit_rate_ext = ((buf[2] & 0x1F)<<7) | (buf[3]>>1); |
| 88 | frame_rate_ext_n = (buf[5] >> 5) & 3; |
| 89 | frame_rate_ext_d = (buf[5] & 0x1f); |
| 90 | pc->progressive_sequence = buf[1] & (1 << 3); |
| 91 | avctx->has_b_frames= !(buf[5] >> 7); |
| 92 | |
| 93 | pc->width |=(horiz_size_ext << 12); |
| 94 | pc->height |=( vert_size_ext << 12); |
| 95 | bit_rate = (bit_rate&0x3FFFF) | (bit_rate_ext << 18); |
| 96 | if(did_set_size) |
| 97 | ff_set_dimensions(avctx, pc->width, pc->height); |
| 98 | avctx->framerate.num = pc->frame_rate.num * (frame_rate_ext_n + 1); |
| 99 | avctx->framerate.den = pc->frame_rate.den * (frame_rate_ext_d + 1); |
| 100 | avctx->codec_id = AV_CODEC_ID_MPEG2VIDEO; |
| 101 | avctx->ticks_per_frame = 2; |
| 102 | } |
| 103 | break; |
| 104 | case 0x8: /* picture coding extension */ |
| 105 | if (bytes_left >= 5) { |
| 106 | top_field_first = buf[3] & (1 << 7); |
| 107 | repeat_first_field = buf[3] & (1 << 1); |
| 108 | progressive_frame = buf[4] & (1 << 7); |
| 109 | |
| 110 | /* check if we must repeat the frame */ |
| 111 | s->repeat_pict = 1; |
| 112 | if (repeat_first_field) { |
| 113 | if (pc->progressive_sequence) { |
| 114 | if (top_field_first) |
| 115 | s->repeat_pict = 5; |
| 116 | else |
| 117 | s->repeat_pict = 3; |
| 118 | } else if (progressive_frame) { |
| 119 | s->repeat_pict = 2; |
| 120 | } |
| 121 | } |
| 122 | |
| 123 | if (!pc->progressive_sequence) { |
| 124 | if (top_field_first) |
| 125 | s->field_order = AV_FIELD_TT; |
| 126 | else |
| 127 | s->field_order = AV_FIELD_BB; |
| 128 | } else |
| 129 | s->field_order = AV_FIELD_PROGRESSIVE; |
| 130 | } |
| 131 | break; |
| 132 | } |
| 133 | } |
| 134 | break; |
| 135 | case -1: |
| 136 | goto the_end; |
| 137 | default: |
| 138 | /* we stop parsing when we encounter a slice. It ensures |
| 139 | that this function takes a negligible amount of time */ |
| 140 | if (start_code >= SLICE_MIN_START_CODE && |
| 141 | start_code <= SLICE_MAX_START_CODE) |
| 142 | goto the_end; |
| 143 | break; |
| 144 | } |
| 145 | } |
| 146 | the_end: ; |
| 147 | if (avctx->codec_id == AV_CODEC_ID_MPEG2VIDEO && bit_rate) { |
| 148 | avctx->rc_max_rate = 400*bit_rate; |
| 149 | } |
| 150 | if (bit_rate && |
| 151 | ((avctx->codec_id == AV_CODEC_ID_MPEG1VIDEO && bit_rate != 0x3FFFF) || vbv_delay != 0xFFFF)) { |
| 152 | avctx->bit_rate = 400*bit_rate; |
| 153 | } |
| 154 | #if FF_API_AVCTX_TIMEBASE |
| 155 | if (avctx->framerate.num) |
| 156 | avctx->time_base = av_inv_q(av_mul_q(avctx->framerate, (AVRational){avctx->ticks_per_frame, 1})); |
| 157 | #endif |
| 158 | } |
| 159 | |
| 160 | static int mpegvideo_parse(AVCodecParserContext *s, |
| 161 | AVCodecContext *avctx, |
| 162 | const uint8_t **poutbuf, int *poutbuf_size, |
| 163 | const uint8_t *buf, int buf_size) |
| 164 | { |
| 165 | struct MpvParseContext *pc1 = s->priv_data; |
| 166 | ParseContext *pc= &pc1->pc; |
| 167 | int next; |
| 168 | |
| 169 | if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){ |
| 170 | next= buf_size; |
| 171 | }else{ |
| 172 | next= ff_mpeg1_find_frame_end(pc, buf, buf_size, s); |
| 173 | |
| 174 | if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) { |
| 175 | *poutbuf = NULL; |
| 176 | *poutbuf_size = 0; |
| 177 | return buf_size; |
| 178 | } |
| 179 | |
| 180 | } |
| 181 | /* we have a full frame : we just parse the first few MPEG headers |
| 182 | to have the full timing information. The time take by this |
| 183 | function should be negligible for uncorrupted streams */ |
| 184 | mpegvideo_extract_headers(s, avctx, buf, buf_size); |
| 185 | av_dlog(NULL, "pict_type=%d frame_rate=%0.3f repeat_pict=%d\n", |
| 186 | s->pict_type, av_q2d(avctx->framerate), s->repeat_pict); |
| 187 | |
| 188 | *poutbuf = buf; |
| 189 | *poutbuf_size = buf_size; |
| 190 | return next; |
| 191 | } |
| 192 | |
| 193 | static int mpegvideo_split(AVCodecContext *avctx, |
| 194 | const uint8_t *buf, int buf_size) |
| 195 | { |
| 196 | int i; |
| 197 | uint32_t state= -1; |
| 198 | int found=0; |
| 199 | |
| 200 | for(i=0; i<buf_size; i++){ |
| 201 | state= (state<<8) | buf[i]; |
| 202 | if(state == 0x1B3){ |
| 203 | found=1; |
| 204 | }else if(found && state != 0x1B5 && state < 0x200 && state >= 0x100) |
| 205 | return i-3; |
| 206 | } |
| 207 | return 0; |
| 208 | } |
| 209 | |
| 210 | static int mpegvideo_parse_init(AVCodecParserContext *s) |
| 211 | { |
| 212 | s->pict_type = AV_PICTURE_TYPE_NONE; // first frame might be partial |
| 213 | return 0; |
| 214 | } |
| 215 | |
| 216 | AVCodecParser ff_mpegvideo_parser = { |
| 217 | .codec_ids = { AV_CODEC_ID_MPEG1VIDEO, AV_CODEC_ID_MPEG2VIDEO }, |
| 218 | .priv_data_size = sizeof(struct MpvParseContext), |
| 219 | .parser_init = mpegvideo_parse_init, |
| 220 | .parser_parse = mpegvideo_parse, |
| 221 | .parser_close = ff_parse_close, |
| 222 | .split = mpegvideo_split, |
| 223 | }; |