/libavcodec/assenc.c

  1/*
  2 * SSA/ASS encoder
  3 * Copyright (c) 2010  Aurelien Jacobs <aurel@gnuage.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 <string.h>
 23
 24#include "avcodec.h"
 25#include "ass.h"
 26#include "libavutil/avstring.h"
 27#include "libavutil/internal.h"
 28#include "libavutil/mem.h"
 29
 30typedef struct {
 31    int id; ///< current event id, ReadOrder field
 32} ASSEncodeContext;
 33
 34static av_cold int ass_encode_init(AVCodecContext *avctx)
 35{
 36    avctx->extradata = av_malloc(avctx->subtitle_header_size + 1);
 37    if (!avctx->extradata)
 38        return AVERROR(ENOMEM);
 39    memcpy(avctx->extradata, avctx->subtitle_header, avctx->subtitle_header_size);
 40    avctx->extradata_size = avctx->subtitle_header_size;
 41    avctx->extradata[avctx->extradata_size] = 0;
 42    return 0;
 43}
 44
 45static int ass_encode_frame(AVCodecContext *avctx,
 46                            unsigned char *buf, int bufsize,
 47                            const AVSubtitle *sub)
 48{
 49    ASSEncodeContext *s = avctx->priv_data;
 50    int i, len, total_len = 0;
 51
 52    for (i=0; i<sub->num_rects; i++) {
 53        char ass_line[2048];
 54        const char *ass = sub->rects[i]->ass;
 55        long int layer;
 56        char *p;
 57
 58        if (sub->rects[i]->type != SUBTITLE_ASS) {
 59            av_log(avctx, AV_LOG_ERROR, "Only SUBTITLE_ASS type supported.\n");
 60            return AVERROR(EINVAL);
 61        }
 62
 63#if FF_API_ASS_TIMING
 64        if (!strncmp(ass, "Dialogue: ", 10)) {
 65            if (i > 0) {
 66                av_log(avctx, AV_LOG_ERROR, "ASS encoder supports only one "
 67                       "ASS rectangle field.\n");
 68                return AVERROR_INVALIDDATA;
 69            }
 70
 71            ass += 10; // skip "Dialogue: "
 72            /* parse Layer field. If it's a Marked field, the content
 73             * will be "Marked=N" instead of the layer num, so we will
 74             * have layer=0, which is fine. */
 75            layer = strtol(ass, &p, 10);
 76
 77#define SKIP_ENTRY(ptr) do {        \
 78    char *sep = strchr(ptr, ',');   \
 79    if (sep)                        \
 80        ptr = sep + 1;              \
 81} while (0)
 82
 83            SKIP_ENTRY(p); // skip layer or marked
 84            SKIP_ENTRY(p); // skip start timestamp
 85            SKIP_ENTRY(p); // skip end timestamp
 86            snprintf(ass_line, sizeof(ass_line), "%d,%ld,%s", ++s->id, layer, p);
 87            ass_line[strcspn(ass_line, "\r\n")] = 0;
 88            ass = ass_line;
 89        }
 90#endif
 91
 92        len = av_strlcpy(buf+total_len, ass, bufsize-total_len);
 93
 94        if (len > bufsize-total_len-1) {
 95            av_log(avctx, AV_LOG_ERROR, "Buffer too small for ASS event.\n");
 96            return AVERROR_BUFFER_TOO_SMALL;
 97        }
 98
 99        total_len += len;
100    }
101
102    return total_len;
103}
104
105#if CONFIG_SSA_ENCODER
106AVCodec ff_ssa_encoder = {
107    .name         = "ssa",
108    .long_name    = NULL_IF_CONFIG_SMALL("ASS (Advanced SubStation Alpha) subtitle"),
109    .type         = AVMEDIA_TYPE_SUBTITLE,
110    .id           = AV_CODEC_ID_ASS,
111    .init         = ass_encode_init,
112    .encode_sub   = ass_encode_frame,
113    .priv_data_size = sizeof(ASSEncodeContext),
114};
115#endif
116
117#if CONFIG_ASS_ENCODER
118AVCodec ff_ass_encoder = {
119    .name         = "ass",
120    .long_name    = NULL_IF_CONFIG_SMALL("ASS (Advanced SubStation Alpha) subtitle"),
121    .type         = AVMEDIA_TYPE_SUBTITLE,
122    .id           = AV_CODEC_ID_ASS,
123    .init         = ass_encode_init,
124    .encode_sub   = ass_encode_frame,
125    .priv_data_size = sizeof(ASSEncodeContext),
126};
127#endif