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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 4349 | Serge | 1 | /* |
| 2 | * 3GPP TS 26.245 Timed Text decoder |
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| 3 | * Copyright (c) 2012 Philip Langdale |
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| 4 | * |
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| 5 | * This file is part of FFmpeg. |
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| 6 | * |
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| 7 | * FFmpeg is free software; you can redistribute it and/or |
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| 8 | * modify it under the terms of the GNU Lesser General Public |
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| 9 | * License as published by the Free Software Foundation; either |
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| 10 | * version 2.1 of the License, or (at your option) any later version. |
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| 11 | * |
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| 12 | * FFmpeg is distributed in the hope that it will be useful, |
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| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 15 | * Lesser General Public License for more details. |
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| 16 | * |
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| 17 | * You should have received a copy of the GNU Lesser General Public |
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| 18 | * License along with FFmpeg; if not, write to the Free Software |
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| 19 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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| 20 | */ |
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| 21 | |||
| 22 | #include "avcodec.h" |
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| 23 | #include "ass.h" |
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| 24 | #include "libavutil/avstring.h" |
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| 25 | #include "libavutil/common.h" |
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| 26 | #include "libavutil/bprint.h" |
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| 27 | #include "libavutil/intreadwrite.h" |
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| 28 | |||
| 29 | static int text_to_ass(AVBPrint *buf, const char *text, const char *text_end) |
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| 30 | { |
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| 31 | while (text < text_end) { |
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| 32 | switch (*text) { |
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| 33 | case '\r': |
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| 34 | break; |
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| 35 | case '\n': |
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| 36 | av_bprintf(buf, "\\N"); |
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| 37 | break; |
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| 38 | default: |
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| 39 | av_bprint_chars(buf, *text, 1); |
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| 40 | break; |
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| 41 | } |
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| 42 | text++; |
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| 43 | } |
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| 44 | |||
| 45 | av_bprintf(buf, "\r\n"); |
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| 46 | return 0; |
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| 47 | } |
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| 48 | |||
| 49 | static int mov_text_init(AVCodecContext *avctx) { |
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| 50 | /* |
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| 51 | * TODO: Handle the default text style. |
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| 52 | * NB: Most players ignore styles completely, with the result that |
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| 53 | * it's very common to find files where the default style is broken |
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| 54 | * and respecting it results in a worse experience than ignoring it. |
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| 55 | */ |
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| 56 | return ff_ass_subtitle_header_default(avctx); |
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| 57 | } |
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| 58 | |||
| 59 | static int mov_text_decode_frame(AVCodecContext *avctx, |
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| 60 | void *data, int *got_sub_ptr, AVPacket *avpkt) |
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| 61 | { |
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| 62 | AVSubtitle *sub = data; |
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| 63 | int ts_start, ts_end; |
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| 64 | AVBPrint buf; |
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| 65 | const char *ptr = avpkt->data; |
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| 66 | const char *end; |
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| 67 | |||
| 68 | if (!ptr || avpkt->size < 2) |
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| 69 | return AVERROR_INVALIDDATA; |
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| 70 | |||
| 71 | /* |
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| 72 | * A packet of size two with value zero is an empty subtitle |
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| 73 | * used to mark the end of the previous non-empty subtitle. |
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| 74 | * We can just drop them here as we have duration information |
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| 75 | * already. If the value is non-zero, then it's technically a |
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| 76 | * bad packet. |
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| 77 | */ |
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| 78 | if (avpkt->size == 2) |
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| 79 | return AV_RB16(ptr) == 0 ? 0 : AVERROR_INVALIDDATA; |
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| 80 | |||
| 81 | /* |
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| 82 | * The first two bytes of the packet are the length of the text string |
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| 83 | * In complex cases, there are style descriptors appended to the string |
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| 84 | * so we can't just assume the packet size is the string size. |
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| 85 | */ |
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| 86 | end = ptr + FFMIN(2 + AV_RB16(ptr), avpkt->size); |
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| 87 | ptr += 2; |
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| 88 | |||
| 89 | ts_start = av_rescale_q(avpkt->pts, |
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| 90 | avctx->time_base, |
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| 91 | (AVRational){1,100}); |
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| 92 | ts_end = av_rescale_q(avpkt->pts + avpkt->duration, |
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| 93 | avctx->time_base, |
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| 94 | (AVRational){1,100}); |
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| 95 | |||
| 96 | // Note that the spec recommends lines be no longer than 2048 characters. |
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| 97 | av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED); |
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| 98 | text_to_ass(&buf, ptr, end); |
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| 99 | |||
| 100 | if (!av_bprint_is_complete(&buf)) |
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| 101 | return AVERROR(ENOMEM); |
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| 102 | |||
| 103 | ff_ass_add_rect(sub, buf.str, ts_start, ts_end-ts_start, 0); |
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| 104 | *got_sub_ptr = sub->num_rects > 0; |
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| 105 | av_bprint_finalize(&buf, NULL); |
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| 106 | return avpkt->size; |
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| 107 | } |
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| 108 | |||
| 109 | AVCodec ff_movtext_decoder = { |
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| 110 | .name = "mov_text", |
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| 111 | .long_name = NULL_IF_CONFIG_SMALL("3GPP Timed Text subtitle"), |
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| 112 | .type = AVMEDIA_TYPE_SUBTITLE, |
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| 113 | .id = AV_CODEC_ID_MOV_TEXT, |
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| 114 | .init = mov_text_init, |
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| 115 | .decode = mov_text_decode_frame, |
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| 116 | }; |