libavcodec/libaribb24.c - third_party/ffmpeg - Git at Google

 /*
  * ARIB STD-B24 caption decoder using the libaribb24 library
  * Copyright (c) 2019 Jan Ekström
  *
  * 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 "avcodec.h"
 #include "libavcodec/ass.h"
 #include "libavutil/log.h"
 #include "libavutil/opt.h"

 #include <aribb24/aribb24.h>
 #include <aribb24/parser.h>
 #include <aribb24/decoder.h>

 typedef struct Libaribb24Context {
     AVClass *class;

     arib_instance_t *lib_instance;
     arib_parser_t *parser;
     arib_decoder_t *decoder;

     int read_order;

     char        *aribb24_base_path;
     unsigned int aribb24_skip_ruby;
 } Libaribb24Context;

 static unsigned int get_profile_font_size(int profile)
 {
     switch (profile) {
     case FF_PROFILE_ARIB_PROFILE_A:
         return 36;
     case FF_PROFILE_ARIB_PROFILE_C:
         return 18;
     default:
         return 0;
     }
 }

 static void libaribb24_log(void *p, const char *msg)
 {
     av_log((AVCodecContext *)p, AV_LOG_INFO, "%s\n", msg);
 }

 static int libaribb24_generate_ass_header(AVCodecContext *avctx)
 {
     unsigned int plane_width = 0;
     unsigned int plane_height = 0;
     unsigned int font_size = 0;

     switch (avctx->profile) {
     case FF_PROFILE_ARIB_PROFILE_A:
         plane_width = 960;
         plane_height = 540;
         font_size = get_profile_font_size(avctx->profile);
         break;
     case FF_PROFILE_ARIB_PROFILE_C:
         plane_width = 320;
         plane_height = 180;
         font_size = get_profile_font_size(avctx->profile);
         break;
     default:
         av_log(avctx, AV_LOG_ERROR, "Unknown or unsupported profile set!\n");
         return AVERROR(EINVAL);
     }

     avctx->subtitle_header = av_asprintf(
              "[Script Info]\r\n"
              "; Script generated by FFmpeg/Lavc%s\r\n"
              "ScriptType: v4.00+\r\n"
              "PlayResX: %d\r\n"
              "PlayResY: %d\r\n"
              "\r\n"
              "[V4+ Styles]\r\n"

              /* ASSv4 header */
              "Format: Name, "
              "Fontname, Fontsize, "
              "PrimaryColour, SecondaryColour, OutlineColour, BackColour, "
              "Bold, Italic, Underline, StrikeOut, "
              "ScaleX, ScaleY, "
              "Spacing, Angle, "
              "BorderStyle, Outline, Shadow, "
              "Alignment, MarginL, MarginR, MarginV, "
              "Encoding\r\n"

              "Style: "
              "Default,"             /* Name */
              "%s,%d,"               /* Font{name,size} */
              "&H%x,&H%x,&H%x,&H%x," /* {Primary,Secondary,Outline,Back}Colour */
              "%d,%d,%d,0,"          /* Bold, Italic, Underline, StrikeOut */
              "100,100,"             /* Scale{X,Y} */
              "0,0,"                 /* Spacing, Angle */
              "%d,1,0,"              /* BorderStyle, Outline, Shadow */
              "%d,10,10,10,"         /* Alignment, Margin[LRV] */
              "0\r\n"                /* Encoding */

              "\r\n"
              "[Events]\r\n"
              "Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text\r\n",
              !(avctx->flags & AV_CODEC_FLAG_BITEXACT) ? AV_STRINGIFY(LIBAVCODEC_VERSION) : "",
              plane_width, plane_height,
              ASS_DEFAULT_FONT, font_size, ASS_DEFAULT_COLOR,
              ASS_DEFAULT_COLOR, ASS_DEFAULT_BACK_COLOR, ASS_DEFAULT_BACK_COLOR,
              -ASS_DEFAULT_BOLD, -ASS_DEFAULT_ITALIC, -ASS_DEFAULT_UNDERLINE,
              ASS_DEFAULT_BORDERSTYLE, ASS_DEFAULT_ALIGNMENT);

     if (!avctx->subtitle_header)
         return AVERROR(ENOMEM);

     avctx->subtitle_header_size = strlen(avctx->subtitle_header);

     return 0;
 }

 static int libaribb24_init(AVCodecContext *avctx)
 {
     Libaribb24Context *b24 = avctx->priv_data;
     void(* arib_dec_init)(arib_decoder_t* decoder) = NULL;
     int ret_code = AVERROR_EXTERNAL;

     if (!(b24->lib_instance = arib_instance_new(avctx))) {
         av_log(avctx, AV_LOG_ERROR, "Failed to initialize libaribb24!\n");
         goto init_fail;
     }

     if (b24->aribb24_base_path) {
         av_log(avctx, AV_LOG_INFO, "Setting the libaribb24 base path to '%s'\n",
                b24->aribb24_base_path);
         arib_set_base_path(b24->lib_instance, b24->aribb24_base_path);
     }

     arib_register_messages_callback(b24->lib_instance, libaribb24_log);

     if (!(b24->parser = arib_get_parser(b24->lib_instance))) {
         av_log(avctx, AV_LOG_ERROR, "Failed to initialize libaribb24 PES parser!\n");
         goto init_fail;
     }
     if (!(b24->decoder = arib_get_decoder(b24->lib_instance))) {
         av_log(avctx, AV_LOG_ERROR, "Failed to initialize libaribb24 decoder!\n");
         goto init_fail;
     }

     switch (avctx->profile) {
     case FF_PROFILE_ARIB_PROFILE_A:
         arib_dec_init = arib_initialize_decoder_a_profile;
         break;
     case FF_PROFILE_ARIB_PROFILE_C:
         arib_dec_init = arib_initialize_decoder_c_profile;
         break;
     default:
         av_log(avctx, AV_LOG_ERROR, "Unknown or unsupported profile set!\n");
         ret_code = AVERROR(EINVAL);
         goto init_fail;
     }

     arib_dec_init(b24->decoder);

     if (libaribb24_generate_ass_header(avctx) < 0) {
         ret_code = AVERROR(ENOMEM);
         goto init_fail;
     }

     return 0;

 init_fail:
     if (b24->decoder)
         arib_finalize_decoder(b24->decoder);

     if (b24->lib_instance)
         arib_instance_destroy(b24->lib_instance);

     return ret_code;
 }

 static int libaribb24_close(AVCodecContext *avctx)
 {
     Libaribb24Context *b24 = avctx->priv_data;

     if (b24->decoder)
         arib_finalize_decoder(b24->decoder);

     if (b24->lib_instance)
         arib_instance_destroy(b24->lib_instance);

     return 0;
 }

 #define RGB_TO_BGR(c) (((c) & 0xff) << 16 | ((c) & 0xff00) | (((c) >> 16) & 0xff))

 static int libaribb24_handle_regions(AVCodecContext *avctx, AVSubtitle *sub)
 {
     Libaribb24Context *b24 = avctx->priv_data;
     const arib_buf_region_t *region = arib_decoder_get_regions(b24->decoder);
     unsigned int profile_font_size = get_profile_font_size(avctx->profile);
     AVBPrint buf = { 0 };
     int ret = 0;

     av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);

     while (region) {
         ptrdiff_t region_length = region->p_end - region->p_start;
         unsigned int ruby_region =
             region->i_fontheight == (profile_font_size / 2);

         // ASS requires us to make the colors BGR, so we convert here
         int foreground_bgr_color = RGB_TO_BGR(region->i_foreground_color);
         int background_bgr_color = RGB_TO_BGR(region->i_background_color);

         if (region_length < 0) {
             av_log(avctx, AV_LOG_ERROR, "Invalid negative region length!\n");
             ret = AVERROR_INVALIDDATA;
             break;
         }

         if (region_length == 0 || (ruby_region && b24->aribb24_skip_ruby)) {
             goto next_region;
         }

         // color and alpha
         if (foreground_bgr_color != ASS_DEFAULT_COLOR)
             av_bprintf(&buf, "{\\1c&H%06x&}", foreground_bgr_color);

         if (region->i_foreground_alpha != 0)
             av_bprintf(&buf, "{\\1a&H%02x&}", region->i_foreground_alpha);

         if (background_bgr_color != ASS_DEFAULT_BACK_COLOR)
             av_bprintf(&buf, "{\\3c&H%06x&}", background_bgr_color);

         if (region->i_background_alpha != 0)
             av_bprintf(&buf, "{\\3a&H%02x&}", region->i_background_alpha);

         // font size
         if (region->i_fontwidth  != profile_font_size ||
             region->i_fontheight != profile_font_size) {
             av_bprintf(&buf, "{\\fscx%"PRId64"\\fscy%"PRId64"}",
                        av_rescale(region->i_fontwidth, 100,
                                   profile_font_size),
                        av_rescale(region->i_fontheight, 100,
                                   profile_font_size));
         }

         // TODO: positioning

         av_bprint_append_data(&buf, region->p_start, region_length);

         av_bprintf(&buf, "{\\r}");

 next_region:
         region = region->p_next;
     }

     if (!av_bprint_is_complete(&buf))
         ret = AVERROR(ENOMEM);

     if (ret == 0) {
         av_log(avctx, AV_LOG_DEBUG, "Styled ASS line: %s\n",
                buf.str);

         ret = ff_ass_add_rect(sub, buf.str, b24->read_order++,
                               0, NULL, NULL);
     }

     av_bprint_finalize(&buf, NULL);

     return ret;
 }

 static int libaribb24_decode(AVCodecContext *avctx, void *data, int *got_sub_ptr, AVPacket *pkt)
 {
     Libaribb24Context *b24 = avctx->priv_data;
     AVSubtitle *sub = data;
     size_t parsed_data_size = 0;
     size_t decoded_subtitle_size = 0;
     const unsigned char *parsed_data = NULL;
     char *decoded_subtitle = NULL;
     time_t subtitle_duration = 0;
     int ret = 0;

     if (pkt->size <= 0)
         return pkt->size;

     arib_parse_pes(b24->parser, pkt->data, pkt->size);

     parsed_data = arib_parser_get_data(b24->parser,
                                        &parsed_data_size);
     if (!parsed_data || !parsed_data_size) {
         av_log(avctx, AV_LOG_DEBUG, "No decode'able data was received from "
                                     "packet (dts: %"PRId64", pts: %"PRId64").\n",
                pkt->dts, pkt->pts);
         return pkt->size;
     }

     decoded_subtitle_size = parsed_data_size * 4;
     if (!(decoded_subtitle = av_mallocz(decoded_subtitle_size + 1))) {
         av_log(avctx, AV_LOG_ERROR,
                "Failed to allocate buffer for decoded subtitle!\n");
         return AVERROR(ENOMEM);
     }

     decoded_subtitle_size = arib_decode_buffer(b24->decoder,
                                                parsed_data,
                                                parsed_data_size,
                                                decoded_subtitle,
                                                decoded_subtitle_size);

     subtitle_duration = arib_decoder_get_time(b24->decoder);

     if (avctx->pkt_timebase.num && pkt->pts != AV_NOPTS_VALUE)
         sub->pts = av_rescale_q(pkt->pts,
                                 avctx->pkt_timebase, AV_TIME_BASE_Q);

     sub->end_display_time = subtitle_duration ?
                             av_rescale_q(subtitle_duration,
                                          AV_TIME_BASE_Q,
                                          (AVRational){1, 1000}) :
                             UINT32_MAX;

     av_log(avctx, AV_LOG_DEBUG,
            "Result: '%s' (size: %zu, pkt_pts: %"PRId64", sub_pts: %"PRId64" "
            "duration: %"PRIu32", pkt_timebase: %d/%d, time_base: %d/%d')\n",
            decoded_subtitle ? decoded_subtitle : "<no subtitle>",
            decoded_subtitle_size,
            pkt->pts, sub->pts,
            sub->end_display_time,
            avctx->pkt_timebase.num, avctx->pkt_timebase.den,
            avctx->time_base.num, avctx->time_base.den);

     if (decoded_subtitle)
         ret = libaribb24_handle_regions(avctx, sub);

     *got_sub_ptr = sub->num_rects > 0;

     av_free(decoded_subtitle);

     // flush the region buffers, otherwise the linked list keeps getting
     // longer and longer...
     arib_finalize_decoder(b24->decoder);

     return ret < 0 ? ret : pkt->size;
 }

 static void libaribb24_flush(AVCodecContext *avctx)
 {
     Libaribb24Context *b24 = avctx->priv_data;
     if (!(avctx->flags2 & AV_CODEC_FLAG2_RO_FLUSH_NOOP))
         b24->read_order = 0;
 }

 #define OFFSET(x) offsetof(Libaribb24Context, x)
 #define SD AV_OPT_FLAG_SUBTITLE_PARAM | AV_OPT_FLAG_DECODING_PARAM
 static const AVOption options[] = {
     { "aribb24-base-path", "set the base path for the libaribb24 library",
       OFFSET(aribb24_base_path), AV_OPT_TYPE_STRING, { .str = NULL }, 0, 0, SD },
     { "aribb24-skip-ruby-text", "skip ruby text blocks during decoding",
       OFFSET(aribb24_skip_ruby), AV_OPT_TYPE_BOOL, { .i64 = 1 }, 0, 1, SD },
     { NULL }
 };

 static const AVClass aribb24_class = {
     .class_name = "libaribb24 decoder",
     .item_name  = av_default_item_name,
     .option     = options,
     .version    = LIBAVUTIL_VERSION_INT,
 };

 AVCodec ff_libaribb24_decoder = {
     .name      = "libaribb24",
     .long_name = NULL_IF_CONFIG_SMALL("libaribb24 ARIB STD-B24 caption decoder"),
     .type      = AVMEDIA_TYPE_SUBTITLE,
     .id        = AV_CODEC_ID_ARIB_CAPTION,
     .priv_data_size = sizeof(Libaribb24Context),
     .init      = libaribb24_init,
     .close     = libaribb24_close,
     .decode    = libaribb24_decode,
     .flush     = libaribb24_flush,
     .priv_class= &aribb24_class,
     .wrapper_name = "libaribb24",
 };
	/*
	* ARIB STD-B24 caption decoder using the libaribb24 library
	* Copyright (c) 2019 Jan Ekström
	*
	* 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 "avcodec.h"
	#include "libavcodec/ass.h"
	#include "libavutil/log.h"
	#include "libavutil/opt.h"

	#include <aribb24/aribb24.h>
	#include <aribb24/parser.h>
	#include <aribb24/decoder.h>

	typedef struct Libaribb24Context {
	AVClass *class;

	arib_instance_t *lib_instance;
	arib_parser_t *parser;
	arib_decoder_t *decoder;

	int read_order;

	char *aribb24_base_path;
	unsigned int aribb24_skip_ruby;
	} Libaribb24Context;

	static unsigned int get_profile_font_size(int profile)
	{
	switch (profile) {
	case FF_PROFILE_ARIB_PROFILE_A:
	return 36;
	case FF_PROFILE_ARIB_PROFILE_C:
	return 18;
	default:
	return 0;
	}
	}

	static void libaribb24_log(void p, const char msg)
	{
	av_log((AVCodecContext *)p, AV_LOG_INFO, "%s\n", msg);
	}

	static int libaribb24_generate_ass_header(AVCodecContext *avctx)
	{
	unsigned int plane_width = 0;
	unsigned int plane_height = 0;
	unsigned int font_size = 0;

	switch (avctx->profile) {
	case FF_PROFILE_ARIB_PROFILE_A:
	plane_width = 960;
	plane_height = 540;
	font_size = get_profile_font_size(avctx->profile);
	break;
	case FF_PROFILE_ARIB_PROFILE_C:
	plane_width = 320;
	plane_height = 180;
	font_size = get_profile_font_size(avctx->profile);
	break;
	default:
	av_log(avctx, AV_LOG_ERROR, "Unknown or unsupported profile set!\n");
	return AVERROR(EINVAL);
	}

	avctx->subtitle_header = av_asprintf(
	"[Script Info]\r\n"
	"; Script generated by FFmpeg/Lavc%s\r\n"
	"ScriptType: v4.00+\r\n"
	"PlayResX: %d\r\n"
	"PlayResY: %d\r\n"
	"\r\n"
	"[V4+ Styles]\r\n"

	/* ASSv4 header */
	"Format: Name, "
	"Fontname, Fontsize, "
	"PrimaryColour, SecondaryColour, OutlineColour, BackColour, "
	"Bold, Italic, Underline, StrikeOut, "
	"ScaleX, ScaleY, "
	"Spacing, Angle, "
	"BorderStyle, Outline, Shadow, "
	"Alignment, MarginL, MarginR, MarginV, "
	"Encoding\r\n"

	"Style: "
	"Default," /* Name */
	"%s,%d," /* Font{name,size} */
	"&H%x,&H%x,&H%x,&H%x," /* {Primary,Secondary,Outline,Back}Colour */
	"%d,%d,%d,0," /* Bold, Italic, Underline, StrikeOut */
	"100,100," /* Scale{X,Y} */
	"0,0," /* Spacing, Angle */
	"%d,1,0," /* BorderStyle, Outline, Shadow */
	"%d,10,10,10," /* Alignment, Margin[LRV] */
	"0\r\n" /* Encoding */

	"\r\n"
	"[Events]\r\n"
	"Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text\r\n",
	!(avctx->flags & AV_CODEC_FLAG_BITEXACT) ? AV_STRINGIFY(LIBAVCODEC_VERSION) : "",
	plane_width, plane_height,
	ASS_DEFAULT_FONT, font_size, ASS_DEFAULT_COLOR,
	ASS_DEFAULT_COLOR, ASS_DEFAULT_BACK_COLOR, ASS_DEFAULT_BACK_COLOR,
	-ASS_DEFAULT_BOLD, -ASS_DEFAULT_ITALIC, -ASS_DEFAULT_UNDERLINE,
	ASS_DEFAULT_BORDERSTYLE, ASS_DEFAULT_ALIGNMENT);

	if (!avctx->subtitle_header)
	return AVERROR(ENOMEM);

	avctx->subtitle_header_size = strlen(avctx->subtitle_header);

	return 0;
	}

	static int libaribb24_init(AVCodecContext *avctx)
	{
	Libaribb24Context *b24 = avctx->priv_data;
	void(* arib_dec_init)(arib_decoder_t* decoder) = NULL;
	int ret_code = AVERROR_EXTERNAL;

	if (!(b24->lib_instance = arib_instance_new(avctx))) {
	av_log(avctx, AV_LOG_ERROR, "Failed to initialize libaribb24!\n");
	goto init_fail;
	}

	if (b24->aribb24_base_path) {
	av_log(avctx, AV_LOG_INFO, "Setting the libaribb24 base path to '%s'\n",
	b24->aribb24_base_path);
	arib_set_base_path(b24->lib_instance, b24->aribb24_base_path);
	}

	arib_register_messages_callback(b24->lib_instance, libaribb24_log);

	if (!(b24->parser = arib_get_parser(b24->lib_instance))) {
	av_log(avctx, AV_LOG_ERROR, "Failed to initialize libaribb24 PES parser!\n");
	goto init_fail;
	}
	if (!(b24->decoder = arib_get_decoder(b24->lib_instance))) {
	av_log(avctx, AV_LOG_ERROR, "Failed to initialize libaribb24 decoder!\n");
	goto init_fail;
	}

	switch (avctx->profile) {
	case FF_PROFILE_ARIB_PROFILE_A:
	arib_dec_init = arib_initialize_decoder_a_profile;
	break;
	case FF_PROFILE_ARIB_PROFILE_C:
	arib_dec_init = arib_initialize_decoder_c_profile;
	break;
	default:
	av_log(avctx, AV_LOG_ERROR, "Unknown or unsupported profile set!\n");
	ret_code = AVERROR(EINVAL);
	goto init_fail;
	}

	arib_dec_init(b24->decoder);

	if (libaribb24_generate_ass_header(avctx) < 0) {
	ret_code = AVERROR(ENOMEM);
	goto init_fail;
	}

	return 0;

	init_fail:
	if (b24->decoder)
	arib_finalize_decoder(b24->decoder);

	if (b24->lib_instance)
	arib_instance_destroy(b24->lib_instance);

	return ret_code;
	}

	static int libaribb24_close(AVCodecContext *avctx)
	{
	Libaribb24Context *b24 = avctx->priv_data;

	if (b24->decoder)
	arib_finalize_decoder(b24->decoder);

	if (b24->lib_instance)
	arib_instance_destroy(b24->lib_instance);

	return 0;
	}

	#define RGB_TO_BGR(c) (((c) & 0xff) << 16 \| ((c) & 0xff00) \| (((c) >> 16) & 0xff))

	static int libaribb24_handle_regions(AVCodecContext avctx, AVSubtitle sub)
	{
	Libaribb24Context *b24 = avctx->priv_data;
	const arib_buf_region_t *region = arib_decoder_get_regions(b24->decoder);
	unsigned int profile_font_size = get_profile_font_size(avctx->profile);
	AVBPrint buf = { 0 };
	int ret = 0;

	av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);

	while (region) {
	ptrdiff_t region_length = region->p_end - region->p_start;
	unsigned int ruby_region =
	region->i_fontheight == (profile_font_size / 2);

	// ASS requires us to make the colors BGR, so we convert here
	int foreground_bgr_color = RGB_TO_BGR(region->i_foreground_color);
	int background_bgr_color = RGB_TO_BGR(region->i_background_color);

	if (region_length < 0) {
	av_log(avctx, AV_LOG_ERROR, "Invalid negative region length!\n");
	ret = AVERROR_INVALIDDATA;
	break;
	}

	if (region_length == 0 \|\| (ruby_region && b24->aribb24_skip_ruby)) {
	goto next_region;
	}

	// color and alpha
	if (foreground_bgr_color != ASS_DEFAULT_COLOR)
	av_bprintf(&buf, "{\\1c&H%06x&}", foreground_bgr_color);

	if (region->i_foreground_alpha != 0)
	av_bprintf(&buf, "{\\1a&H%02x&}", region->i_foreground_alpha);

	if (background_bgr_color != ASS_DEFAULT_BACK_COLOR)
	av_bprintf(&buf, "{\\3c&H%06x&}", background_bgr_color);

	if (region->i_background_alpha != 0)
	av_bprintf(&buf, "{\\3a&H%02x&}", region->i_background_alpha);

	// font size
	if (region->i_fontwidth != profile_font_size \|\|
	region->i_fontheight != profile_font_size) {
	av_bprintf(&buf, "{\\fscx%"PRId64"\\fscy%"PRId64"}",
	av_rescale(region->i_fontwidth, 100,
	profile_font_size),
	av_rescale(region->i_fontheight, 100,
	profile_font_size));
	}

	// TODO: positioning

	av_bprint_append_data(&buf, region->p_start, region_length);

	av_bprintf(&buf, "{\\r}");

	next_region:
	region = region->p_next;
	}

	if (!av_bprint_is_complete(&buf))
	ret = AVERROR(ENOMEM);

	if (ret == 0) {
	av_log(avctx, AV_LOG_DEBUG, "Styled ASS line: %s\n",
	buf.str);

	ret = ff_ass_add_rect(sub, buf.str, b24->read_order++,
	0, NULL, NULL);
	}

	av_bprint_finalize(&buf, NULL);

	return ret;
	}

	static int libaribb24_decode(AVCodecContext avctx, void data, int got_sub_ptr, AVPacket pkt)
	{
	Libaribb24Context *b24 = avctx->priv_data;
	AVSubtitle *sub = data;
	size_t parsed_data_size = 0;
	size_t decoded_subtitle_size = 0;
	const unsigned char *parsed_data = NULL;
	char *decoded_subtitle = NULL;
	time_t subtitle_duration = 0;
	int ret = 0;

	if (pkt->size <= 0)
	return pkt->size;

	arib_parse_pes(b24->parser, pkt->data, pkt->size);

	parsed_data = arib_parser_get_data(b24->parser,
	&parsed_data_size);
	if (!parsed_data \|\| !parsed_data_size) {
	av_log(avctx, AV_LOG_DEBUG, "No decode'able data was received from "
	"packet (dts: %"PRId64", pts: %"PRId64").\n",
	pkt->dts, pkt->pts);
	return pkt->size;
	}

	decoded_subtitle_size = parsed_data_size * 4;
	if (!(decoded_subtitle = av_mallocz(decoded_subtitle_size + 1))) {
	av_log(avctx, AV_LOG_ERROR,
	"Failed to allocate buffer for decoded subtitle!\n");
	return AVERROR(ENOMEM);
	}

	decoded_subtitle_size = arib_decode_buffer(b24->decoder,
	parsed_data,
	parsed_data_size,
	decoded_subtitle,
	decoded_subtitle_size);

	subtitle_duration = arib_decoder_get_time(b24->decoder);

	if (avctx->pkt_timebase.num && pkt->pts != AV_NOPTS_VALUE)
	sub->pts = av_rescale_q(pkt->pts,
	avctx->pkt_timebase, AV_TIME_BASE_Q);

	sub->end_display_time = subtitle_duration ?
	av_rescale_q(subtitle_duration,
	AV_TIME_BASE_Q,
	(AVRational){1, 1000}) :
	UINT32_MAX;

	av_log(avctx, AV_LOG_DEBUG,
	"Result: '%s' (size: %zu, pkt_pts: %"PRId64", sub_pts: %"PRId64" "
	"duration: %"PRIu32", pkt_timebase: %d/%d, time_base: %d/%d')\n",
	decoded_subtitle ? decoded_subtitle : "<no subtitle>",
	decoded_subtitle_size,
	pkt->pts, sub->pts,
	sub->end_display_time,
	avctx->pkt_timebase.num, avctx->pkt_timebase.den,
	avctx->time_base.num, avctx->time_base.den);

	if (decoded_subtitle)
	ret = libaribb24_handle_regions(avctx, sub);

	*got_sub_ptr = sub->num_rects > 0;

	av_free(decoded_subtitle);

	// flush the region buffers, otherwise the linked list keeps getting
	// longer and longer...
	arib_finalize_decoder(b24->decoder);

	return ret < 0 ? ret : pkt->size;
	}

	static void libaribb24_flush(AVCodecContext *avctx)
	{
	Libaribb24Context *b24 = avctx->priv_data;
	if (!(avctx->flags2 & AV_CODEC_FLAG2_RO_FLUSH_NOOP))
	b24->read_order = 0;
	}

	#define OFFSET(x) offsetof(Libaribb24Context, x)
	#define SD AV_OPT_FLAG_SUBTITLE_PARAM \| AV_OPT_FLAG_DECODING_PARAM
	static const AVOption options[] = {
	{ "aribb24-base-path", "set the base path for the libaribb24 library",
	OFFSET(aribb24_base_path), AV_OPT_TYPE_STRING, { .str = NULL }, 0, 0, SD },
	{ "aribb24-skip-ruby-text", "skip ruby text blocks during decoding",
	OFFSET(aribb24_skip_ruby), AV_OPT_TYPE_BOOL, { .i64 = 1 }, 0, 1, SD },
	{ NULL }
	};

	static const AVClass aribb24_class = {
	.class_name = "libaribb24 decoder",
	.item_name = av_default_item_name,
	.option = options,
	.version = LIBAVUTIL_VERSION_INT,
	};

	AVCodec ff_libaribb24_decoder = {
	.name = "libaribb24",
	.long_name = NULL_IF_CONFIG_SMALL("libaribb24 ARIB STD-B24 caption decoder"),
	.type = AVMEDIA_TYPE_SUBTITLE,
	.id = AV_CODEC_ID_ARIB_CAPTION,
	.priv_data_size = sizeof(Libaribb24Context),
	.init = libaribb24_init,
	.close = libaribb24_close,
	.decode = libaribb24_decode,
	.flush = libaribb24_flush,
	.priv_class= &aribb24_class,
	.wrapper_name = "libaribb24",
	};