assenc.c

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/*
 * SSA/ASS encoder
 * Copyright (c) 2010  Aurelien Jacobs <aurel@gnuage.org>
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */
 
#include <string.h>
 
#include "avcodec.h"
#include "ass.h"
#include "internal.h"
#include "libavutil/avstring.h"
#include "libavutil/internal.h"
#include "libavutil/mem.h"
 
static av_cold int ass_encode_init(AVCodecContext *avctx)
{
    avctx->extradata = av_malloc(avctx->subtitle_header_size + 1);
    if (!avctx->extradata)
        return AVERROR(ENOMEM);
    memcpy(avctx->extradata, avctx->subtitle_header, avctx->subtitle_header_size);
    avctx->extradata_size = avctx->subtitle_header_size;
    avctx->extradata[avctx->extradata_size] = 0;
    return 0;
}
 
static int ass_encode_frame(AVCodecContext *avctx,
                            unsigned char *buf, int bufsize,
                            const AVSubtitle *sub)
{
    int i, len, total_len = 0;
 
    for (i=0; i<sub->num_rects; i++) {
        const char *ass = sub->rects[i]->ass;
 
        if (sub->rects[i]->type != SUBTITLE_ASS) {
            av_log(avctx, AV_LOG_ERROR, "Only SUBTITLE_ASS type supported.\n");
            return AVERROR(EINVAL);
        }
 
        len = av_strlcpy(buf+total_len, ass, bufsize-total_len);
 
        if (len > bufsize-total_len-1) {
            av_log(avctx, AV_LOG_ERROR, "Buffer too small for ASS event.\n");
            return AVERROR_BUFFER_TOO_SMALL;
        }
 
        total_len += len;
    }
 
    return total_len;
}
 
#if CONFIG_SSA_ENCODER
const AVCodec ff_ssa_encoder = {
    .name         = "ssa",
    .long_name    = NULL_IF_CONFIG_SMALL("ASS (Advanced SubStation Alpha) subtitle"),
    .type         = AVMEDIA_TYPE_SUBTITLE,
    .id           = AV_CODEC_ID_ASS,
    .init         = ass_encode_init,
    .encode_sub   = ass_encode_frame,
    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
};
#endif
 
#if CONFIG_ASS_ENCODER
const AVCodec ff_ass_encoder = {
    .name         = "ass",
    .long_name    = NULL_IF_CONFIG_SMALL("ASS (Advanced SubStation Alpha) subtitle"),
    .type         = AVMEDIA_TYPE_SUBTITLE,
    .id           = AV_CODEC_ID_ASS,
    .init         = ass_encode_init,
    .encode_sub   = ass_encode_frame,
    .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
};
#endif