1/*
2 * 3GPP TS 26.245 Timed Text encoder
3 * Copyright (c) 2012  Philip Langdale <philipl@overt.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#include <stdarg.h>
23#include "avcodec.h"
24#include "libavutil/avassert.h"
25#include "libavutil/avstring.h"
26#include "libavutil/intreadwrite.h"
27#include "ass_split.h"
28#include "ass.h"
29
30typedef struct {
31    ASSSplitContext *ass_ctx;
32    char buffer[2048];
33    char *ptr;
34    char *end;
35} MovTextContext;
36
37
38static av_cold int mov_text_encode_init(AVCodecContext *avctx)
39{
40    /*
41     * For now, we'll use a fixed default style. When we add styling
42     * support, this will be generated from the ASS style.
43     */
44    static uint8_t text_sample_entry[] = {
45        0x00, 0x00, 0x00, 0x00, // uint32_t displayFlags
46        0x01,                   // int8_t horizontal-justification
47        0xFF,                   // int8_t vertical-justification
48        0x00, 0x00, 0x00, 0x00, // uint8_t background-color-rgba[4]
49        // BoxRecord {
50        0x00, 0x00,             // int16_t top
51        0x00, 0x00,             // int16_t left
52        0x00, 0x00,             // int16_t bottom
53        0x00, 0x00,             // int16_t right
54        // };
55        // StyleRecord {
56        0x00, 0x00,             // uint16_t startChar
57        0x00, 0x00,             // uint16_t endChar
58        0x00, 0x01,             // uint16_t font-ID
59        0x00,                   // uint8_t face-style-flags
60        0x12,                   // uint8_t font-size
61        0xFF, 0xFF, 0xFF, 0xFF, // uint8_t text-color-rgba[4]
62        // };
63        // FontTableBox {
64        0x00, 0x00, 0x00, 0x12, // uint32_t size
65        'f', 't', 'a', 'b',     // uint8_t name[4]
66        0x00, 0x01,             // uint16_t entry-count
67        // FontRecord {
68        0x00, 0x01,             // uint16_t font-ID
69        0x05,                   // uint8_t font-name-length
70        'S', 'e', 'r', 'i', 'f',// uint8_t font[font-name-length]
71        // };
72        // };
73    };
74
75    MovTextContext *s = avctx->priv_data;
76
77    avctx->extradata_size = sizeof text_sample_entry;
78    avctx->extradata = av_mallocz(avctx->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);
79    if (!avctx->extradata)
80        return AVERROR(ENOMEM);
81
82    memcpy(avctx->extradata, text_sample_entry, avctx->extradata_size);
83
84    s->ass_ctx = ff_ass_split(avctx->subtitle_header);
85    return s->ass_ctx ? 0 : AVERROR_INVALIDDATA;
86}
87
88static void mov_text_text_cb(void *priv, const char *text, int len)
89{
90    MovTextContext *s = priv;
91    av_assert0(s->end >= s->ptr);
92    av_strlcpy(s->ptr, text, FFMIN(s->end - s->ptr, len + 1));
93    s->ptr += FFMIN(s->end - s->ptr, len);
94}
95
96static void mov_text_new_line_cb(void *priv, int forced)
97{
98    MovTextContext *s = priv;
99    av_assert0(s->end >= s->ptr);
100    av_strlcpy(s->ptr, "\n", FFMIN(s->end - s->ptr, 2));
101    if (s->end > s->ptr)
102        s->ptr++;
103}
104
105static const ASSCodesCallbacks mov_text_callbacks = {
106    .text     = mov_text_text_cb,
107    .new_line = mov_text_new_line_cb,
108};
109
110static int mov_text_encode_frame(AVCodecContext *avctx, unsigned char *buf,
111                                 int bufsize, const AVSubtitle *sub)
112{
113    MovTextContext *s = avctx->priv_data;
114    ASSDialog *dialog;
115    int i, len, num;
116
117    s->ptr = s->buffer;
118    s->end = s->ptr + sizeof(s->buffer);
119
120    for (i = 0; i < sub->num_rects; i++) {
121
122        if (sub->rects[i]->type != SUBTITLE_ASS) {
123            av_log(avctx, AV_LOG_ERROR, "Only SUBTITLE_ASS type supported.\n");
124            return AVERROR(ENOSYS);
125        }
126
127        dialog = ff_ass_split_dialog(s->ass_ctx, sub->rects[i]->ass, 0, &num);
128        for (; dialog && num--; dialog++) {
129            ff_ass_split_override_codes(&mov_text_callbacks, s, dialog->text);
130        }
131    }
132
133    if (s->ptr == s->buffer)
134        return 0;
135
136    AV_WB16(buf, strlen(s->buffer));
137    buf += 2;
138
139    len = av_strlcpy(buf, s->buffer, bufsize - 2);
140
141    if (len > bufsize-3) {
142        av_log(avctx, AV_LOG_ERROR, "Buffer too small for ASS event.\n");
143        return AVERROR(EINVAL);
144    }
145
146    return len + 2;
147}
148
149static int mov_text_encode_close(AVCodecContext *avctx)
150{
151    MovTextContext *s = avctx->priv_data;
152    ff_ass_split_free(s->ass_ctx);
153    return 0;
154}
155
156AVCodec ff_movtext_encoder = {
157    .name           = "mov_text",
158    .long_name      = NULL_IF_CONFIG_SMALL("3GPP Timed Text subtitle"),
159    .type           = AVMEDIA_TYPE_SUBTITLE,
160    .id             = AV_CODEC_ID_MOV_TEXT,
161    .priv_data_size = sizeof(MovTextContext),
162    .init           = mov_text_encode_init,
163    .encode_sub     = mov_text_encode_frame,
164    .close          = mov_text_encode_close,
165};
166