1/* 2 * Canopus common routines 3 * Copyright (c) 2015 Vittorio Giovara <vittorio.giovara@gmail.com> 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#include <stdint.h> 23 24#include "libavutil/rational.h" 25 26#include "avcodec.h" 27#include "bytestream.h" 28#include "canopus.h" 29 30int ff_canopus_parse_info_tag(AVCodecContext *avctx, 31 const uint8_t *src, size_t size) 32{ 33 GetByteContext gbc; 34 int par_x, par_y, field_order; 35 36 bytestream2_init(&gbc, src, size); 37 38 /* Parse aspect ratio. */ 39 bytestream2_skip(&gbc, 8); // unknown, 16 bits 1 40 par_x = bytestream2_get_le32(&gbc); 41 par_y = bytestream2_get_le32(&gbc); 42 if (par_x && par_y) 43 av_reduce(&avctx->sample_aspect_ratio.num, 44 &avctx->sample_aspect_ratio.den, 45 par_x, par_y, 255); 46 47 /* Short INFO tag (used in CLLC) has only AR data. */ 48 if (size == 0x18) 49 return 0; 50 51 bytestream2_skip(&gbc, 16); // unknown RDRT tag 52 53 /* Parse FIEL tag. */ 54 bytestream2_skip(&gbc, 8); // 'FIEL' and 4 bytes 0 55 field_order = bytestream2_get_le32(&gbc); 56 switch (field_order) { 57 case 0: avctx->field_order = AV_FIELD_TT; break; 58 case 1: avctx->field_order = AV_FIELD_BB; break; 59 case 2: avctx->field_order = AV_FIELD_PROGRESSIVE; break; 60 } 61 62 return 0; 63} 64