Adding Closed caption Support

Signed-off-by: Anshul Maheshwari <anshul.ffmpeg@gmail.com>

To test Closed caption use following command
ffmpeg -f lavfi -i "movie=input.ts[out0+subcc]" -map s output.srt
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/Makefile

@@ -173,6 +173,7 @@ OBJS-$(CONFIG_BRENDER_PIX_DECODER)     += brenderpix.o
 OBJS-$(CONFIG_C93_DECODER)             += c93.o
 OBJS-$(CONFIG_CAVS_DECODER)            += cavs.o cavsdec.o cavsdsp.o \
                                           cavsdata.o mpeg12data.o
+OBJS-$(CONFIG_CCAPTION_DECODER)        += ccaption_dec.o
 OBJS-$(CONFIG_CDGRAPHICS_DECODER)      += cdgraphics.o
 OBJS-$(CONFIG_CDXL_DECODER)            += cdxl.o
 OBJS-$(CONFIG_CINEPAK_DECODER)         += cinepak.o

libavcodec/allcodecs.c

@@ -481,6 +481,7 @@ void avcodec_register_all(void)
     /* subtitles */
     REGISTER_ENCDEC (SSA,               ssa);
     REGISTER_ENCDEC (ASS,               ass);
+    REGISTER_DECODER(CCAPTION,          ccaption);
     REGISTER_ENCDEC (DVBSUB,            dvbsub);
     REGISTER_ENCDEC (DVDSUB,            dvdsub);
     REGISTER_DECODER(JACOSUB,           jacosub);

libavcodec/ccaption_dec.c

+/*
+ * Closed Caption Decoding
+ * Copyright (c) 2015 Anshul Maheshwari
+ *
+ * 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 "ass.h"
+#include "libavutil/opt.h"
+
+#define CHAR_DEBUG
+#define SCREEN_ROWS 15
+#define SCREEN_COLUMNS 32
+
+#define SET_FLAG(var, val) ( var |= ( 1 << (val) ) )
+#define UNSET_FLAG(var, val) ( var &=  ~( 1 << (val)) )
+#define CHECK_FLAG(var, val) ( (var) & (1 << (val) ) )
+
+/*
+ * TODO list
+ * 1) handle font and color completely
+ */
+enum cc_mode {
+    CCMODE_POPON,
+    CCMODE_PAINTON,
+    CCMODE_ROLLUP_2,
+    CCMODE_ROLLUP_3,
+    CCMODE_ROLLUP_4,
+    CCMODE_TEXT,
+};
+
+enum cc_color_code
+{
+    CCCOL_WHITE,
+    CCCOL_GREEN,
+    CCCOL_BLUE,
+    CCCOL_CYAN,
+    CCCOL_RED,
+    CCCOL_YELLOW,
+    CCCOL_MAGENTA,
+    CCCOL_USERDEFINED,
+    CCCOL_BLACK,
+    CCCOL_TRANSPARENT
+};
+
+enum cc_font
+{
+    CCFONT_REGULAR,
+    CCFONT_ITALICS,
+    CCFONT_UNDERLINED,
+    CCFONT_UNDERLINED_ITALICS
+};
+
+static const unsigned char pac2_attribs[][3] = // Color, font, ident
+{
+    { CCCOL_WHITE, CCFONT_REGULAR, 0 },  // 0x40 || 0x60
+    { CCCOL_WHITE, CCFONT_UNDERLINED, 0 },  // 0x41 || 0x61
+    { CCCOL_GREEN, CCFONT_REGULAR, 0 },  // 0x42 || 0x62
+    { CCCOL_GREEN, CCFONT_UNDERLINED, 0 },  // 0x43 || 0x63
+    { CCCOL_BLUE, CCFONT_REGULAR, 0 },  // 0x44 || 0x64
+    { CCCOL_BLUE, CCFONT_UNDERLINED, 0 },  // 0x45 || 0x65
+    { CCCOL_CYAN, CCFONT_REGULAR, 0 },  // 0x46 || 0x66
+    { CCCOL_CYAN, CCFONT_UNDERLINED, 0 },  // 0x47 || 0x67
+    { CCCOL_RED, CCFONT_REGULAR, 0 },  // 0x48 || 0x68
+    { CCCOL_RED, CCFONT_UNDERLINED, 0 },  // 0x49 || 0x69
+    { CCCOL_YELLOW, CCFONT_REGULAR, 0 },  // 0x4a || 0x6a
+    { CCCOL_YELLOW, CCFONT_UNDERLINED, 0 },  // 0x4b || 0x6b
+    { CCCOL_MAGENTA, CCFONT_REGULAR, 0 },  // 0x4c || 0x6c
+    { CCCOL_MAGENTA, CCFONT_UNDERLINED, 0 },  // 0x4d || 0x6d
+    { CCCOL_WHITE, CCFONT_ITALICS, 0 },  // 0x4e || 0x6e
+    { CCCOL_WHITE, CCFONT_UNDERLINED_ITALICS, 0 },  // 0x4f || 0x6f
+    { CCCOL_WHITE, CCFONT_REGULAR, 0 },  // 0x50 || 0x70
+    { CCCOL_WHITE, CCFONT_UNDERLINED, 0 },  // 0x51 || 0x71
+    { CCCOL_WHITE, CCFONT_REGULAR, 4 },  // 0x52 || 0x72
+    { CCCOL_WHITE, CCFONT_UNDERLINED, 4 },  // 0x53 || 0x73
+    { CCCOL_WHITE, CCFONT_REGULAR, 8 },  // 0x54 || 0x74
+    { CCCOL_WHITE, CCFONT_UNDERLINED, 8 },  // 0x55 || 0x75
+    { CCCOL_WHITE, CCFONT_REGULAR, 12 }, // 0x56 || 0x76
+    { CCCOL_WHITE, CCFONT_UNDERLINED, 12 }, // 0x57 || 0x77
+    { CCCOL_WHITE, CCFONT_REGULAR, 16 }, // 0x58 || 0x78
+    { CCCOL_WHITE, CCFONT_UNDERLINED, 16 }, // 0x59 || 0x79
+    { CCCOL_WHITE, CCFONT_REGULAR, 20 }, // 0x5a || 0x7a
+    { CCCOL_WHITE, CCFONT_UNDERLINED, 20 }, // 0x5b || 0x7b
+    { CCCOL_WHITE, CCFONT_REGULAR, 24 }, // 0x5c || 0x7c
+    { CCCOL_WHITE, CCFONT_UNDERLINED, 24 }, // 0x5d || 0x7d
+    { CCCOL_WHITE, CCFONT_REGULAR, 28 }, // 0x5e || 0x7e
+    { CCCOL_WHITE, CCFONT_UNDERLINED, 28 }  // 0x5f || 0x7f
+    /* total 32 entry */
+};
+/* 0-255 needs 256 space */
+static const uint8_t parity_table[256] = { 0, 1, 1, 0, 1, 0, 0, 1,
+                                           1, 0, 0, 1, 0, 1, 1, 0,
+                                           1, 0, 0, 1, 0, 1, 1, 0,
+                                           0, 1, 1, 0, 1, 0, 0, 1,
+                                           1, 0, 0, 1, 0, 1, 1, 0,
+                                           0, 1, 1, 0, 1, 0, 0, 1,
+                                           0, 1, 1, 0, 1, 0, 0, 1,
+                                           1, 0, 0, 1, 0, 1, 1, 0,
+                                           1, 0, 0, 1, 0, 1, 1, 0,
+                                           0, 1, 1, 0, 1, 0, 0, 1,
+                                           0, 1, 1, 0, 1, 0, 0, 1,
+                                           1, 0, 0, 1, 0, 1, 1, 0,
+                                           0, 1, 1, 0, 1, 0, 0, 1,
+                                           1, 0, 0, 1, 0, 1, 1, 0,
+                                           1, 0, 0, 1, 0, 1, 1, 0,
+                                           0, 1, 1, 0, 1, 0, 0, 1,
+                                           1, 0, 0, 1, 0, 1, 1, 0,
+                                           0, 1, 1, 0, 1, 0, 0, 1,
+                                           0, 1, 1, 0, 1, 0, 0, 1,
+                                           1, 0, 0, 1, 0, 1, 1, 0,
+                                           0, 1, 1, 0, 1, 0, 0, 1,
+                                           1, 0, 0, 1, 0, 1, 1, 0,
+                                           1, 0, 0, 1, 0, 1, 1, 0,
+                                           0, 1, 1, 0, 1, 0, 0, 1,
+                                           0, 1, 1, 0, 1, 0, 0, 1,
+                                           1, 0, 0, 1, 0, 1, 1, 0,
+                                           1, 0, 0, 1, 0, 1, 1, 0,
+                                           0, 1, 1, 0, 1, 0, 0, 1,
+                                           1, 0, 0, 1, 0, 1, 1, 0,
+                                           0, 1, 1, 0, 1, 0, 0, 1,
+                                           0, 1, 1, 0, 1, 0, 0, 1,
+                                           1, 0, 0, 1, 0, 1, 1, 0 };
+struct Screen {
+    /* +1 is used to compensate null character of string */
+    uint8_t characters[SCREEN_ROWS][SCREEN_COLUMNS+1];
+    /*
+     * Bitmask of used rows; if a bit is not set, the
+     * corresponding row is not used.
+     * for setting row 1  use row | (0 << 1)
+     * for setting row 15 use row | (1 << 14)
+     */
+    int16_t  row_used;
+};
+
+
+typedef struct CCaptionSubContext {
+    AVClass *class;
+    int row_cnt;
+    struct Screen screen[2];
+    int active_screen;
+    uint8_t cursor_row;
+    uint8_t cursor_column;
+    uint8_t cursor_color;
+    uint8_t cursor_font;
+    AVBPrint buffer;
+    int erase_display_memory;
+    int rollup;
+    enum  cc_mode mode;
+    int64_t start_time;
+    /* visible screen time */
+    int64_t startv_time;
+    int64_t end_time;
+    char prev_cmd[2];
+    /* buffer to store pkt data */
+    AVBufferRef *pktbuf;
+}CCaptionSubContext;
+
+
+static av_cold int init_decoder(AVCodecContext *avctx)
+{
+    int ret;
+    CCaptionSubContext *ctx = avctx->priv_data;
+
+    av_bprint_init(&ctx->buffer, 0, AV_BPRINT_SIZE_UNLIMITED);
+    /* taking by default roll up to 2 */
+    ctx->rollup = 2;
+    ret = ff_ass_subtitle_header_default(avctx);
+    /* allocate pkt buffer */
+    ctx->pktbuf = av_buffer_alloc(128);
+    if( !ctx->pktbuf) {
+        ret = AVERROR(ENOMEM);
+    }
+
+
+    return ret;
+}
+
+static av_cold int close_decoder(AVCodecContext *avctx)
+{
+    CCaptionSubContext *ctx = avctx->priv_data;
+    av_bprint_finalize( &ctx->buffer, NULL);
+    av_buffer_unref(&ctx->pktbuf);
+    return 0;
+}
+/**
+ * @param ctx closed caption context just to print log
+ */
+static int write_char (CCaptionSubContext *ctx, char *row,uint8_t col, char ch)
+{
+    if(col < SCREEN_COLUMNS) {
+        row[col] = ch;
+        return 0;
+    }
+    /* We have extra space at end only for null character */
+    else if ( col == SCREEN_COLUMNS && ch == 0) {
+        row[col] = ch;
+        return 0;
+    }
+    else {
+        av_log(ctx, AV_LOG_WARNING,"Data Ignored since exciding screen width\n");
+        return AVERROR_INVALIDDATA;
+    }
+}
+/**
+ * This function after validating parity bit, also remove it from data pair.
+ * The first byte doesn't pass parity, we replace it with a solid blank
+ * and process the pair.
+ * If the second byte doesn't pass parity, it returns INVALIDDATA
+ * user can ignore the whole pair and pass the other pair.
+ */
+static int validate_cc_data_pair (uint8_t *cc_data_pair)
+{
+    uint8_t cc_valid = (*cc_data_pair & 4) >>2;
+    uint8_t cc_type = *cc_data_pair & 3;
+
+    if (!cc_valid)
+        return AVERROR_INVALIDDATA;
+
+    // if EIA-608 data then verify parity.
+    if (cc_type==0 || cc_type==1) {
+        if (!parity_table[cc_data_pair[2]]) {
+            return AVERROR_INVALIDDATA;
+        }
+        if (!parity_table[cc_data_pair[1]]) {
+            cc_data_pair[1]=0x7F;
+        }
+    }
+
+    //Skip non-data
+    if( (cc_data_pair[0] == 0xFA || cc_data_pair[0] == 0xFC || cc_data_pair[0] == 0xFD )
+         && (cc_data_pair[1] & 0x7F) == 0 && (cc_data_pair[2] & 0x7F) == 0)
+        return AVERROR_PATCHWELCOME;
+
+    //skip 708 data
+    if(cc_type == 3 || cc_type == 2 )
+        return AVERROR_PATCHWELCOME;
+
+    /* remove parity bit */
+    cc_data_pair[1] &= 0x7F;
+    cc_data_pair[2] &= 0x7F;
+
+
+    return 0;
+
+}
+
+static struct Screen *get_writing_screen(CCaptionSubContext *ctx)
+{
+    switch (ctx->mode) {
+    case CCMODE_POPON:
+        // use Inactive screen
+        return ctx->screen + !ctx->active_screen;
+    case CCMODE_PAINTON:
+    case CCMODE_ROLLUP_2:
+    case CCMODE_ROLLUP_3:
+    case CCMODE_ROLLUP_4:
+    case CCMODE_TEXT:
+        // use active screen
+        return ctx->screen + ctx->active_screen;
+    }
+    /* It was never an option */
+    return NULL;
+}
+
+static void handle_textattr( CCaptionSubContext *ctx, uint8_t hi, uint8_t lo )
+{
+    int i = lo - 0x20;
+    int ret;
+    struct Screen *screen = get_writing_screen(ctx);
+    char *row = screen->characters[ctx->cursor_row];
+
+    if( i >= 32)
+        return;
+
+    ctx->cursor_color =  pac2_attribs[i][0];
+    ctx->cursor_font = pac2_attribs[i][1];
+
+    SET_FLAG(screen->row_used,ctx->cursor_row);
+    ret = write_char(ctx, row, ctx->cursor_column, ' ');
+    if(ret == 0)
+        ctx->cursor_column++;
+}
+static void handle_pac( CCaptionSubContext *ctx, uint8_t hi, uint8_t lo )
+{
+    static const int8_t row_map[] = {
+        11, -1, 1, 2, 3, 4, 12, 13, 14, 15, 5, 6, 7, 8, 9, 10
+    };
+    const int index = ( (hi<<1) & 0x0e) | ( (lo>>5) & 0x01 );
+    struct Screen *screen = get_writing_screen(ctx);
+    char *row;
+    int indent,i,ret;
+
+    if( row_map[index] <= 0 )
+        return;
+
+    lo &= 0x1f;
+
+    ctx->cursor_row = row_map[index] - 1;
+    ctx->cursor_color =  pac2_attribs[lo][0];
+    ctx->cursor_font = pac2_attribs[lo][1];
+    ctx->cursor_column = 0;
+    indent = pac2_attribs[lo][2];
+    row = screen->characters[ctx->cursor_row];
+    for(i = 0;i < indent; i++) {
+        ret = write_char(ctx, row, ctx->cursor_column, ' ');
+        if(  ret == 0 )
+            ctx->cursor_column++;
+    }
+
+}
+
+/**
+ * @param pts it is required to set end time
+ */
+static int handle_edm(CCaptionSubContext *ctx,int64_t pts)
+{
+    int i;
+    int ret = 0;
+    struct Screen *screen = ctx->screen + ctx->active_screen;
+
+    ctx->start_time = ctx->startv_time;
+    for( i = 0; screen->row_used && i < SCREEN_ROWS; i++)
+    {
+        if(CHECK_FLAG(screen->row_used,i)) {
+            char *str = screen->characters[i];
+            /* skip space */
+            while (*str == ' ')
+                str++;
+            av_bprint_append_data(&ctx->buffer, str, strlen(str));
+            av_bprint_append_data(&ctx->buffer, "\\N",2);
+            UNSET_FLAG(screen->row_used, i);
+            ret = av_bprint_is_complete(&ctx->buffer);
+            if( ret == 0) {
+                ret = AVERROR(ENOMEM);
+                break;
+            }
+        }
+
+    }
+    ctx->startv_time = pts;
+    ctx->erase_display_memory = 1;
+    ctx->end_time = pts;
+    return ret;
+}
+static int handle_eoc(CCaptionSubContext *ctx, int64_t pts)
+{
+    int ret;
+    ret = handle_edm(ctx,pts);
+    ctx->active_screen = !ctx->active_screen;
+    ctx->cursor_column = 0;
+    return ret;
+}
+static void handle_delete_end_of_row( CCaptionSubContext *ctx, char hi, char lo)
+{
+    struct Screen *screen = get_writing_screen(ctx);
+    char *row = screen->characters[ctx->cursor_row];
+    write_char(ctx, row, ctx->cursor_column, 0);
+
+}
+static void handle_char(CCaptionSubContext *ctx, char hi, char lo, int64_t pts)
+{
+    struct Screen *screen = get_writing_screen(ctx);
+    char *row = screen->characters[ctx->cursor_row];
+    int ret;
+
+    SET_FLAG(screen->row_used,ctx->cursor_row);
+
+    ret = write_char(ctx, row, ctx->cursor_column, hi);
+    if( ret == 0 )
+        ctx->cursor_column++;
+
+    if(lo) {
+        ret = write_char(ctx, row, ctx->cursor_column, lo);
+        if ( ret == 0 )
+            ctx->cursor_column++;
+    }
+    write_char(ctx, row, ctx->cursor_column, 0);
+
+    /* reset prev command since character can repeat */
+    ctx->prev_cmd[0] = 0;
+    ctx->prev_cmd[1] = 0;
+#ifdef CHAR_DEBUG
+    av_log(ctx, AV_LOG_DEBUG,"(%c,%c)\n",hi,lo);
+#endif
+}
+static int process_cc608(CCaptionSubContext *ctx, int64_t pts, uint8_t hi, uint8_t lo)
+{
+    int ret = 0;
+#define COR3(var, with1, with2, with3)  ( (var) == (with1) ||  (var) == (with2) || (var) == (with3) )
+    if ( hi == ctx->prev_cmd[0] && lo == ctx->prev_cmd[1]) {
+    /* ignore redundant command */
+    } else if ( (hi == 0x10 && (lo >= 0x40 || lo <= 0x5f)) ||
+              ( (hi >= 0x11 && hi <= 0x17) && (lo >= 0x40 && lo <= 0x7f) ) ) {
+        handle_pac(ctx, hi, lo);
+    } else if ( ( hi == 0x11 && lo >= 0x20 && lo <= 0x2f ) ||
+                ( hi == 0x17 && lo >= 0x2e && lo <= 0x2f) ) {
+        handle_textattr(ctx, hi, lo);
+    } else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x20 ) {
+    /* resume caption loading */
+        ctx->mode = CCMODE_POPON;
+    } else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x24 ) {
+        handle_delete_end_of_row(ctx, hi, lo);
+    } else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x25 ) {
+        ctx->rollup = 2;
+    } else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x26 ) {
+        ctx->rollup = 3;
+    } else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x27 ) {
+        ctx->rollup = 4;
+    } else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x29 ) {
+    /* resume direct captioning */
+        ctx->mode = CCMODE_PAINTON;
+    } else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x2B ) {
+    /* resume text display */
+        ctx->mode = CCMODE_TEXT;
+    } else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x2C ) {
+    /* erase display memory */
+        ret = handle_edm(ctx, pts);
+    } else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x2D ) {
+    /* carriage return */
+        ctx->row_cnt++;
+        if(ctx->row_cnt >= ctx->rollup) {
+            ctx->row_cnt = 0;
+            ret = handle_edm(ctx, pts);
+            ctx->active_screen = !ctx->active_screen;
+        }
+        ctx->cursor_column = 0;
+    } else if ( COR3(hi, 0x14, 0x15, 0x1C) && lo == 0x2F ) {
+    /* end of caption */
+        ret = handle_eoc(ctx, pts);
+    } else if (hi>=0x20) {
+    /* Standard characters (always in pairs) */
+        handle_char(ctx, hi, lo, pts);
+    } else {
+    /* Ignoring all other non data code */
+    }
+
+    /* set prev command */
+     ctx->prev_cmd[0] = hi;
+     ctx->prev_cmd[1] = lo;
+
+#undef COR3
+    return ret;
+
+}
+static int decode(AVCodecContext *avctx, void *data, int *got_sub, AVPacket *avpkt)
+{
+    CCaptionSubContext *ctx = avctx->priv_data;
+    AVSubtitle *sub = data;
+    uint8_t *bptr = NULL;
+    int len = avpkt->size;
+    int ret = 0;
+    int i;
+
+    if ( ctx->pktbuf->size < len) {
+        ret = av_buffer_realloc(&ctx->pktbuf, len);
+         if(ret < 0) {
+            av_log(ctx, AV_LOG_WARNING, "Insufficient Memory of %d truncated to %d\n",len, ctx->pktbuf->size);
+            len = ctx->pktbuf->size;
+            ret = 0;
+        }
+    }
+    memcpy(ctx->pktbuf->data, avpkt->data, len);
+    bptr = ctx->pktbuf->data;
+
+
+    for (i  = 0; i < len; i += 3) {
+        uint8_t cc_type = *(bptr + i) & 3;
+        if (validate_cc_data_pair( bptr + i) )
+            continue;
+        /* ignoring data field 1 */
+        if(cc_type == 1)
+            continue;
+        else
+            process_cc608(ctx, avpkt->pts, *(bptr + i + 1) & 0x7f, *(bptr + i + 2) & 0x7f);
+        if(ctx->erase_display_memory && *ctx->buffer.str)
+        {
+            int start_time = av_rescale_q(ctx->start_time, avctx->time_base, (AVRational){ 1, 100 });
+            int end_time = av_rescale_q(ctx->end_time, avctx->time_base, (AVRational){ 1, 100 });
+#ifdef CHAR_DEBUG
+            av_log(ctx, AV_LOG_DEBUG,"cdp writing data (%s)\n",ctx->buffer.str);
+#endif
+            ret = ff_ass_add_rect(sub, ctx->buffer.str, start_time, end_time - start_time , 0);
+            if (ret < 0)
+                return ret;
+            sub->pts = av_rescale_q(ctx->start_time, avctx->time_base, AV_TIME_BASE_Q);
+            ctx->erase_display_memory = 0;
+            av_bprint_clear(&ctx->buffer);
+        }
+    }
+
+    *got_sub = sub->num_rects > 0;
+    return ret;
+}
+static const AVOption options[] = {
+    {NULL}
+};
+static const AVClass ccaption_dec_class = {
+    .class_name = "Closed caption Decoder",
+    .item_name  = av_default_item_name,
+    .option     = options,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
+AVCodec ff_ccaption_decoder = {
+    .name           = "cc_dec",
+    .long_name      = NULL_IF_CONFIG_SMALL("Closed Caption (EIA-608 / CEA-708) Decoder"),
+    .type           = AVMEDIA_TYPE_SUBTITLE,
+    .id             = AV_CODEC_ID_EIA_608,
+    .priv_data_size = sizeof(CCaptionSubContext),
+    .init           = init_decoder,
+    .close          = close_decoder,
+    .decode         = decode,
+    .priv_class     = &ccaption_dec_class,
+};