/* * WebVTT subtitle encoder * Copyright (c) 2010 Aurelien Jacobs * Copyright (c) 2014 Aman Gupta * * 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 #include "avcodec.h" #include "libavutil/avstring.h" #include "libavutil/bprint.h" #include "ass_split.h" #include "ass.h" #define WEBVTT_STACK_SIZE 64 typedef struct { AVCodecContext *avctx; ASSSplitContext *ass_ctx; AVBPrint buffer; unsigned timestamp_end; int count; char stack[WEBVTT_STACK_SIZE]; int stack_ptr; } WebVTTContext; #ifdef __GNUC__ __attribute__ ((__format__ (__printf__, 2, 3))) #endif static void webvtt_print(WebVTTContext *s, const char *str, ...) { va_list vargs; va_start(vargs, str); av_vbprintf(&s->buffer, str, vargs); va_end(vargs); } static int webvtt_stack_push(WebVTTContext *s, const char c) { if (s->stack_ptr >= WEBVTT_STACK_SIZE) return -1; s->stack[s->stack_ptr++] = c; return 0; } static char webvtt_stack_pop(WebVTTContext *s) { if (s->stack_ptr <= 0) return 0; return s->stack[--s->stack_ptr]; } static int webvtt_stack_find(WebVTTContext *s, const char c) { int i; for (i = s->stack_ptr-1; i >= 0; i--) if (s->stack[i] == c) break; return i; } static void webvtt_close_tag(WebVTTContext *s, char tag) { webvtt_print(s, "", tag); } static void webvtt_stack_push_pop(WebVTTContext *s, const char c, int close) { if (close) { int i = c ? webvtt_stack_find(s, c) : 0; if (i < 0) return; while (s->stack_ptr != i) webvtt_close_tag(s, webvtt_stack_pop(s)); } else if (webvtt_stack_push(s, c) < 0) av_log(s->avctx, AV_LOG_ERROR, "tag stack overflow\n"); } static void webvtt_style_apply(WebVTTContext *s, const char *style) { ASSStyle *st = ff_ass_style_get(s->ass_ctx, style); if (st) { if (st->bold != ASS_DEFAULT_BOLD) { webvtt_print(s, ""); webvtt_stack_push(s, 'b'); } if (st->italic != ASS_DEFAULT_ITALIC) { webvtt_print(s, ""); webvtt_stack_push(s, 'i'); } if (st->underline != ASS_DEFAULT_UNDERLINE) { webvtt_print(s, ""); webvtt_stack_push(s, 'u'); } } } static void webvtt_text_cb(void *priv, const char *text, int len) { WebVTTContext *s = priv; av_bprint_append_data(&s->buffer, text, len); } static void webvtt_new_line_cb(void *priv, int forced) { webvtt_print(priv, "\n"); } static void webvtt_style_cb(void *priv, char style, int close) { if (style == 's') // strikethrough unsupported return; webvtt_stack_push_pop(priv, style, close); if (!close) webvtt_print(priv, "<%c>", style); } static void webvtt_cancel_overrides_cb(void *priv, const char *style) { webvtt_stack_push_pop(priv, 0, 1); webvtt_style_apply(priv, style); } static void webvtt_end_cb(void *priv) { webvtt_stack_push_pop(priv, 0, 1); } static const ASSCodesCallbacks webvtt_callbacks = { .text = webvtt_text_cb, .new_line = webvtt_new_line_cb, .style = webvtt_style_cb, .color = NULL, .font_name = NULL, .font_size = NULL, .alignment = NULL, .cancel_overrides = webvtt_cancel_overrides_cb, .move = NULL, .end = webvtt_end_cb, }; static int webvtt_encode_frame(AVCodecContext *avctx, unsigned char *buf, int bufsize, const AVSubtitle *sub) { WebVTTContext *s = avctx->priv_data; ASSDialog *dialog; int i; av_bprint_clear(&s->buffer); for (i=0; inum_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(ENOSYS); } #if FF_API_ASS_TIMING if (!strncmp(ass, "Dialogue: ", 10)) { int num; dialog = ff_ass_split_dialog(s->ass_ctx, ass, 0, &num); // TODO reindent for (; dialog && num--; dialog++) { webvtt_style_apply(s, dialog->style); ff_ass_split_override_codes(&webvtt_callbacks, s, dialog->text); } } else { #endif dialog = ff_ass_split_dialog2(s->ass_ctx, ass); if (!dialog) return AVERROR(ENOMEM); webvtt_style_apply(s, dialog->style); ff_ass_split_override_codes(&webvtt_callbacks, s, dialog->text); ff_ass_free_dialog(&dialog); #if FF_API_ASS_TIMING } #endif } if (!av_bprint_is_complete(&s->buffer)) return AVERROR(ENOMEM); if (!s->buffer.len) return 0; if (s->buffer.len > bufsize) { av_log(avctx, AV_LOG_ERROR, "Buffer too small for ASS event.\n"); return -1; } memcpy(buf, s->buffer.str, s->buffer.len); return s->buffer.len; } static int webvtt_encode_close(AVCodecContext *avctx) { WebVTTContext *s = avctx->priv_data; ff_ass_split_free(s->ass_ctx); av_bprint_finalize(&s->buffer, NULL); return 0; } static av_cold int webvtt_encode_init(AVCodecContext *avctx) { WebVTTContext *s = avctx->priv_data; s->avctx = avctx; s->ass_ctx = ff_ass_split(avctx->subtitle_header); av_bprint_init(&s->buffer, 0, AV_BPRINT_SIZE_UNLIMITED); return s->ass_ctx ? 0 : AVERROR_INVALIDDATA; } AVCodec ff_webvtt_encoder = { .name = "webvtt", .long_name = NULL_IF_CONFIG_SMALL("WebVTT subtitle"), .type = AVMEDIA_TYPE_SUBTITLE, .id = AV_CODEC_ID_WEBVTT, .priv_data_size = sizeof(WebVTTContext), .init = webvtt_encode_init, .encode_sub = webvtt_encode_frame, .close = webvtt_encode_close, };