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FFmpeg/libavcodec/ccaption_dec.c

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/*
* 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 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)) )
static const AVRational ms_tb = {1, 1000};
/*
* TODO list
* 1) handle font and color completely
*/
enum cc_mode {
CCMODE_POPON,
CCMODE_PAINTON,
CCMODE_ROLLUP,
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,
};
enum cc_charset {
CCSET_BASIC_AMERICAN,
CCSET_SPECIAL_AMERICAN,
CCSET_EXTENDED_SPANISH_FRENCH_MISC,
CCSET_EXTENDED_PORTUGUESE_GERMAN_DANISH,
};
static const char *charset_overrides[4][128] =
{
[CCSET_BASIC_AMERICAN] = {
[0x27] = "\u2019",
[0x2a] = "\u00e1",
[0x5c] = "\u00e9",
[0x5e] = "\u00ed",
[0x5f] = "\u00f3",
[0x60] = "\u00fa",
[0x7b] = "\u00e7",
[0x7c] = "\u00f7",
[0x7d] = "\u00d1",
[0x7e] = "\u00f1",
[0x7f] = "\u2588"
},
[CCSET_SPECIAL_AMERICAN] = {
[0x30] = "\u00ae",
[0x31] = "\u00b0",
[0x32] = "\u00bd",
[0x33] = "\u00bf",
[0x34] = "\u2122",
[0x35] = "\u00a2",
[0x36] = "\u00a3",
[0x37] = "\u266a",
[0x38] = "\u00e0",
[0x39] = "\u00A0",
[0x3a] = "\u00e8",
[0x3b] = "\u00e2",
[0x3c] = "\u00ea",
[0x3d] = "\u00ee",
[0x3e] = "\u00f4",
[0x3f] = "\u00fb",
},
[CCSET_EXTENDED_SPANISH_FRENCH_MISC] = {
[0x20] = "\u00c1",
[0x21] = "\u00c9",
[0x22] = "\u00d3",
[0x23] = "\u00da",
[0x24] = "\u00dc",
[0x25] = "\u00fc",
[0x26] = "\u00b4",
[0x27] = "\u00a1",
[0x28] = "*",
[0x29] = "\u2018",
[0x2a] = "-",
[0x2b] = "\u00a9",
[0x2c] = "\u2120",
[0x2d] = "\u00b7",
[0x2e] = "\u201c",
[0x2f] = "\u201d",
[0x30] = "\u00c0",
[0x31] = "\u00c2",
[0x32] = "\u00c7",
[0x33] = "\u00c8",
[0x34] = "\u00ca",
[0x35] = "\u00cb",
[0x36] = "\u00eb",
[0x37] = "\u00ce",
[0x38] = "\u00cf",
[0x39] = "\u00ef",
[0x3a] = "\u00d4",
[0x3b] = "\u00d9",
[0x3c] = "\u00f9",
[0x3d] = "\u00db",
[0x3e] = "\u00ab",
[0x3f] = "\u00bb",
},
[CCSET_EXTENDED_PORTUGUESE_GERMAN_DANISH] = {
[0x20] = "\u00c3",
[0x21] = "\u00e3",
[0x22] = "\u00cd",
[0x23] = "\u00cc",
[0x24] = "\u00ec",
[0x25] = "\u00d2",
[0x26] = "\u00f2",
[0x27] = "\u00d5",
[0x28] = "\u00f5",
[0x29] = "{",
[0x2a] = "}",
[0x2b] = "\\",
[0x2c] = "^",
[0x2d] = "_",
[0x2e] = "|",
[0x2f] = "~",
[0x30] = "\u00c4",
[0x31] = "\u00e4",
[0x32] = "\u00d6",
[0x33] = "\u00f6",
[0x34] = "\u00df",
[0x35] = "\u00a5",
[0x36] = "\u00a4",
[0x37] = "\u00a6",
[0x38] = "\u00c5",
[0x39] = "\u00e5",
[0x3a] = "\u00d8",
[0x3b] = "\u00f8",
[0x3c] = "\u250c",
[0x3d] = "\u2510",
[0x3e] = "\u2514",
[0x3f] = "\u2518",
},
};
static const unsigned char pac2_attribs[32][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 entries */
};
struct Screen {
/* +1 is used to compensate null character of string */
uint8_t characters[SCREEN_ROWS][SCREEN_COLUMNS+1];
uint8_t charsets[SCREEN_ROWS][SCREEN_COLUMNS+1];
uint8_t colors[SCREEN_ROWS][SCREEN_COLUMNS+1];
uint8_t fonts[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 | (1 << 0)
* for setting row 15 use row | (1 << 14)
*/
int16_t row_used;
};
typedef struct CCaptionSubContext {
AVClass *class;
lavc/ccaption_dec: implement real_time option This new mode is useful for realtime decoding of closed captions so they can be display along with mpeg2 frames. Closed caption streams contain two major types of captions: - POPON captions, which are buffered off-screen and displayed only after EOC (end of caption, aka display buffer) - PAINTON/ROLLUP captions, which are written to the display as soon as they arrive. In a typical real-time eia608 decoder, commands like EOC (end of caption; display buffer), EDM (erase display memory) and EBM (erase buffered memory) perform their expected functions as soon as the commands are processed. This is implemented in the real_time branches added in this commit. Before this commit, and in the !real_time branches after this commit, the decoder cleverly implements its own version of the decoder which is specifically geared towards buffered decoding. It does so by actively ignoring commands like EBM (erase buffered memory), and then re-using the non-display buffer to hold the previous caption while the new one is received. This is the opposite of the real-time decoder, which uses the non-display buffer to hold the new caption while the display buffer is still showing the current caption. In addition to ignoring EBM, the buffered decoder also has custom implementations for EDM and EOC. An EDM (erase display memory) command flushes the existing contents before clearing the screen, and EOC similarly always flushes the active buffer (the previous subtitle) before flipping buffers.
2016-01-09 05:01:22 +02:00
int real_time;
struct Screen screen[2];
int active_screen;
uint8_t cursor_row;
uint8_t cursor_column;
uint8_t cursor_color;
uint8_t cursor_font;
uint8_t cursor_charset;
AVBPrint buffer;
int buffer_changed;
int rollup;
2016-01-06 01:18:09 +02:00
enum cc_mode mode;
int64_t start_time;
/* visible screen time */
int64_t startv_time;
int64_t end_time;
lavc/ccaption_dec: implement real_time option This new mode is useful for realtime decoding of closed captions so they can be display along with mpeg2 frames. Closed caption streams contain two major types of captions: - POPON captions, which are buffered off-screen and displayed only after EOC (end of caption, aka display buffer) - PAINTON/ROLLUP captions, which are written to the display as soon as they arrive. In a typical real-time eia608 decoder, commands like EOC (end of caption; display buffer), EDM (erase display memory) and EBM (erase buffered memory) perform their expected functions as soon as the commands are processed. This is implemented in the real_time branches added in this commit. Before this commit, and in the !real_time branches after this commit, the decoder cleverly implements its own version of the decoder which is specifically geared towards buffered decoding. It does so by actively ignoring commands like EBM (erase buffered memory), and then re-using the non-display buffer to hold the previous caption while the new one is received. This is the opposite of the real-time decoder, which uses the non-display buffer to hold the new caption while the display buffer is still showing the current caption. In addition to ignoring EBM, the buffered decoder also has custom implementations for EDM and EOC. An EDM (erase display memory) command flushes the existing contents before clearing the screen, and EOC similarly always flushes the active buffer (the previous subtitle) before flipping buffers.
2016-01-09 05:01:22 +02:00
int screen_touched;
int64_t last_real_time;
char prev_cmd[2];
/* buffer to store pkt data */
uint8_t *pktbuf;
int pktbuf_size;
int readorder;
} 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->mode = CCMODE_ROLLUP;
ctx->rollup = 2;
ctx->cursor_row = 10;
ret = ff_ass_subtitle_header(avctx, "Monospace",
ASS_DEFAULT_FONT_SIZE,
ASS_DEFAULT_COLOR,
ASS_DEFAULT_BACK_COLOR,
ASS_DEFAULT_BOLD,
ASS_DEFAULT_ITALIC,
ASS_DEFAULT_UNDERLINE,
3,
ASS_DEFAULT_ALIGNMENT);
if (ret < 0) {
return ret;
}
return ret;
}
static av_cold int close_decoder(AVCodecContext *avctx)
{
CCaptionSubContext *ctx = avctx->priv_data;
av_bprint_finalize(&ctx->buffer, NULL);
av_freep(&ctx->pktbuf);
ctx->pktbuf_size = 0;
return 0;
}
static void flush_decoder(AVCodecContext *avctx)
{
CCaptionSubContext *ctx = avctx->priv_data;
ctx->screen[0].row_used = 0;
ctx->screen[1].row_used = 0;
ctx->prev_cmd[0] = 0;
ctx->prev_cmd[1] = 0;
ctx->mode = CCMODE_ROLLUP;
ctx->rollup = 2;
ctx->cursor_row = 10;
ctx->cursor_column = 0;
ctx->cursor_font = 0;
ctx->cursor_color = 0;
ctx->cursor_charset = 0;
ctx->active_screen = 0;
lavc/ccaption_dec: implement real_time option This new mode is useful for realtime decoding of closed captions so they can be display along with mpeg2 frames. Closed caption streams contain two major types of captions: - POPON captions, which are buffered off-screen and displayed only after EOC (end of caption, aka display buffer) - PAINTON/ROLLUP captions, which are written to the display as soon as they arrive. In a typical real-time eia608 decoder, commands like EOC (end of caption; display buffer), EDM (erase display memory) and EBM (erase buffered memory) perform their expected functions as soon as the commands are processed. This is implemented in the real_time branches added in this commit. Before this commit, and in the !real_time branches after this commit, the decoder cleverly implements its own version of the decoder which is specifically geared towards buffered decoding. It does so by actively ignoring commands like EBM (erase buffered memory), and then re-using the non-display buffer to hold the previous caption while the new one is received. This is the opposite of the real-time decoder, which uses the non-display buffer to hold the new caption while the display buffer is still showing the current caption. In addition to ignoring EBM, the buffered decoder also has custom implementations for EDM and EOC. An EDM (erase display memory) command flushes the existing contents before clearing the screen, and EOC similarly always flushes the active buffer (the previous subtitle) before flipping buffers.
2016-01-09 05:01:22 +02:00
ctx->last_real_time = 0;
ctx->screen_touched = 0;
ctx->buffer_changed = 0;
if (!(avctx->flags2 & AV_CODEC_FLAG2_RO_FLUSH_NOOP))
ctx->readorder = 0;
av_bprint_clear(&ctx->buffer);
}
/**
* @param ctx closed caption context just to print log
*/
static void write_char(CCaptionSubContext *ctx, struct Screen *screen, char ch)
{
uint8_t col = ctx->cursor_column;
char *row = screen->characters[ctx->cursor_row];
char *font = screen->fonts[ctx->cursor_row];
char *charset = screen->charsets[ctx->cursor_row];
if (col < SCREEN_COLUMNS) {
row[col] = ch;
font[col] = ctx->cursor_font;
charset[col] = ctx->cursor_charset;
ctx->cursor_charset = CCSET_BASIC_AMERICAN;
if (ch) ctx->cursor_column++;
return;
}
/* We have extra space at end only for null character */
else if (col == SCREEN_COLUMNS && ch == 0) {
row[col] = ch;
return;
}
else {
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av_log(ctx, AV_LOG_WARNING, "Data Ignored since exceeding screen width\n");
return;
}
}
/**
* 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 (!av_parity(cc_data_pair[2])) {
return AVERROR_INVALIDDATA;
}
if (!av_parity(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:
case CCMODE_TEXT:
// use active screen
return ctx->screen + ctx->active_screen;
}
/* It was never an option */
return NULL;
}
static void roll_up(CCaptionSubContext *ctx)
{
struct Screen *screen;
int i, keep_lines;
if (ctx->mode == CCMODE_TEXT)
return;
screen = get_writing_screen(ctx);
/* +1 signify cursor_row starts from 0
* Can't keep lines less then row cursor pos
*/
keep_lines = FFMIN(ctx->cursor_row + 1, ctx->rollup);
for (i = 0; i < SCREEN_ROWS; i++) {
if (i > ctx->cursor_row - keep_lines && i <= ctx->cursor_row)
continue;
UNSET_FLAG(screen->row_used, i);
}
for (i = 0; i < keep_lines && screen->row_used; i++) {
const int i_row = ctx->cursor_row - keep_lines + i + 1;
memcpy(screen->characters[i_row], screen->characters[i_row+1], SCREEN_COLUMNS);
memcpy(screen->colors[i_row], screen->colors[i_row+1], SCREEN_COLUMNS);
memcpy(screen->fonts[i_row], screen->fonts[i_row+1], SCREEN_COLUMNS);
memcpy(screen->charsets[i_row], screen->charsets[i_row+1], SCREEN_COLUMNS);
if (CHECK_FLAG(screen->row_used, i_row + 1))
SET_FLAG(screen->row_used, i_row);
}
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UNSET_FLAG(screen->row_used, ctx->cursor_row);
}
static int capture_screen(CCaptionSubContext *ctx)
{
int i, j, tab = 0;
struct Screen *screen = ctx->screen + ctx->active_screen;
enum cc_font prev_font = CCFONT_REGULAR;
av_bprint_clear(&ctx->buffer);
for (i = 0; screen->row_used && i < SCREEN_ROWS; i++)
{
if (CHECK_FLAG(screen->row_used, i)) {
const char *row = screen->characters[i];
const char *charset = screen->charsets[i];
j = 0;
while (row[j] == ' ' && charset[j] == CCSET_BASIC_AMERICAN)
j++;
if (!tab || j < tab)
tab = j;
}
}
for (i = 0; screen->row_used && i < SCREEN_ROWS; i++)
{
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if (CHECK_FLAG(screen->row_used, i)) {
const char *row = screen->characters[i];
const char *font = screen->fonts[i];
const char *charset = screen->charsets[i];
const char *override;
int x, y, seen_char = 0;
j = 0;
/* skip leading space */
while (row[j] == ' ' && charset[j] == CCSET_BASIC_AMERICAN && j < tab)
j++;
x = ASS_DEFAULT_PLAYRESX * (0.1 + 0.0250 * j);
y = ASS_DEFAULT_PLAYRESY * (0.1 + 0.0533 * i);
av_bprintf(&ctx->buffer, "{\\an7}{\\pos(%d,%d)}", x, y);
for (; j < SCREEN_COLUMNS; j++) {
const char *e_tag = "", *s_tag = "";
if (row[j] == 0)
break;
if (prev_font != font[j]) {
switch (prev_font) {
case CCFONT_ITALICS:
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e_tag = "{\\i0}";
break;
case CCFONT_UNDERLINED:
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e_tag = "{\\u0}";
break;
case CCFONT_UNDERLINED_ITALICS:
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e_tag = "{\\u0}{\\i0}";
break;
}
switch (font[j]) {
case CCFONT_ITALICS:
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s_tag = "{\\i1}";
break;
case CCFONT_UNDERLINED:
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s_tag = "{\\u1}";
break;
case CCFONT_UNDERLINED_ITALICS:
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s_tag = "{\\u1}{\\i1}";
break;
}
}
prev_font = font[j];
override = charset_overrides[(int)charset[j]][(int)row[j]];
if (override) {
av_bprintf(&ctx->buffer, "%s%s%s", e_tag, s_tag, override);
seen_char = 1;
} else if (row[j] == ' ' && !seen_char) {
av_bprintf(&ctx->buffer, "%s%s\\h", e_tag, s_tag);
} else {
av_bprintf(&ctx->buffer, "%s%s%c", e_tag, s_tag, row[j]);
seen_char = 1;
}
}
av_bprintf(&ctx->buffer, "\\N");
}
}
if (!av_bprint_is_complete(&ctx->buffer))
return AVERROR(ENOMEM);
if (screen->row_used && ctx->buffer.len >= 2) {
ctx->buffer.len -= 2;
ctx->buffer.str[ctx->buffer.len] = 0;
}
ctx->buffer_changed = 1;
return 0;
}
static int reap_screen(CCaptionSubContext *ctx, int64_t pts)
{
ctx->start_time = ctx->startv_time;
ctx->startv_time = pts;
ctx->end_time = pts;
return capture_screen(ctx);
}
static void handle_textattr(CCaptionSubContext *ctx, uint8_t hi, uint8_t lo)
{
int i = lo - 0x20;
struct Screen *screen = get_writing_screen(ctx);
if (i >= 32)
return;
ctx->cursor_color = pac2_attribs[i][0];
ctx->cursor_font = pac2_attribs[i][1];
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SET_FLAG(screen->row_used, ctx->cursor_row);
write_char(ctx, screen, ' ');
}
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);
int indent, i;
if (row_map[index] <= 0) {
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av_log(ctx, AV_LOG_DEBUG, "Invalid pac index encountered\n");
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_charset = CCSET_BASIC_AMERICAN;
ctx->cursor_column = 0;
indent = pac2_attribs[lo][2];
for (i = 0; i < indent; i++) {
write_char(ctx, screen, ' ');
}
}
/**
* @param pts it is required to set end time
*/
static void handle_edm(CCaptionSubContext *ctx, int64_t pts)
{
struct Screen *screen = ctx->screen + ctx->active_screen;
lavc/ccaption_dec: implement real_time option This new mode is useful for realtime decoding of closed captions so they can be display along with mpeg2 frames. Closed caption streams contain two major types of captions: - POPON captions, which are buffered off-screen and displayed only after EOC (end of caption, aka display buffer) - PAINTON/ROLLUP captions, which are written to the display as soon as they arrive. In a typical real-time eia608 decoder, commands like EOC (end of caption; display buffer), EDM (erase display memory) and EBM (erase buffered memory) perform their expected functions as soon as the commands are processed. This is implemented in the real_time branches added in this commit. Before this commit, and in the !real_time branches after this commit, the decoder cleverly implements its own version of the decoder which is specifically geared towards buffered decoding. It does so by actively ignoring commands like EBM (erase buffered memory), and then re-using the non-display buffer to hold the previous caption while the new one is received. This is the opposite of the real-time decoder, which uses the non-display buffer to hold the new caption while the display buffer is still showing the current caption. In addition to ignoring EBM, the buffered decoder also has custom implementations for EDM and EOC. An EDM (erase display memory) command flushes the existing contents before clearing the screen, and EOC similarly always flushes the active buffer (the previous subtitle) before flipping buffers.
2016-01-09 05:01:22 +02:00
// In buffered mode, keep writing to screen until it is wiped.
// Before wiping the display, capture contents to emit subtitle.
if (!ctx->real_time)
reap_screen(ctx, pts);
screen->row_used = 0;
lavc/ccaption_dec: implement real_time option This new mode is useful for realtime decoding of closed captions so they can be display along with mpeg2 frames. Closed caption streams contain two major types of captions: - POPON captions, which are buffered off-screen and displayed only after EOC (end of caption, aka display buffer) - PAINTON/ROLLUP captions, which are written to the display as soon as they arrive. In a typical real-time eia608 decoder, commands like EOC (end of caption; display buffer), EDM (erase display memory) and EBM (erase buffered memory) perform their expected functions as soon as the commands are processed. This is implemented in the real_time branches added in this commit. Before this commit, and in the !real_time branches after this commit, the decoder cleverly implements its own version of the decoder which is specifically geared towards buffered decoding. It does so by actively ignoring commands like EBM (erase buffered memory), and then re-using the non-display buffer to hold the previous caption while the new one is received. This is the opposite of the real-time decoder, which uses the non-display buffer to hold the new caption while the display buffer is still showing the current caption. In addition to ignoring EBM, the buffered decoder also has custom implementations for EDM and EOC. An EDM (erase display memory) command flushes the existing contents before clearing the screen, and EOC similarly always flushes the active buffer (the previous subtitle) before flipping buffers.
2016-01-09 05:01:22 +02:00
// In realtime mode, emit an empty caption so the last one doesn't
// stay on the screen.
if (ctx->real_time)
reap_screen(ctx, pts);
}
static void handle_eoc(CCaptionSubContext *ctx, int64_t pts)
{
lavc/ccaption_dec: implement real_time option This new mode is useful for realtime decoding of closed captions so they can be display along with mpeg2 frames. Closed caption streams contain two major types of captions: - POPON captions, which are buffered off-screen and displayed only after EOC (end of caption, aka display buffer) - PAINTON/ROLLUP captions, which are written to the display as soon as they arrive. In a typical real-time eia608 decoder, commands like EOC (end of caption; display buffer), EDM (erase display memory) and EBM (erase buffered memory) perform their expected functions as soon as the commands are processed. This is implemented in the real_time branches added in this commit. Before this commit, and in the !real_time branches after this commit, the decoder cleverly implements its own version of the decoder which is specifically geared towards buffered decoding. It does so by actively ignoring commands like EBM (erase buffered memory), and then re-using the non-display buffer to hold the previous caption while the new one is received. This is the opposite of the real-time decoder, which uses the non-display buffer to hold the new caption while the display buffer is still showing the current caption. In addition to ignoring EBM, the buffered decoder also has custom implementations for EDM and EOC. An EDM (erase display memory) command flushes the existing contents before clearing the screen, and EOC similarly always flushes the active buffer (the previous subtitle) before flipping buffers.
2016-01-09 05:01:22 +02:00
// In buffered mode, we wait til the *next* EOC and
// reap what was already on the screen since the last EOC.
if (!ctx->real_time)
handle_edm(ctx,pts);
ctx->active_screen = !ctx->active_screen;
ctx->cursor_column = 0;
lavc/ccaption_dec: implement real_time option This new mode is useful for realtime decoding of closed captions so they can be display along with mpeg2 frames. Closed caption streams contain two major types of captions: - POPON captions, which are buffered off-screen and displayed only after EOC (end of caption, aka display buffer) - PAINTON/ROLLUP captions, which are written to the display as soon as they arrive. In a typical real-time eia608 decoder, commands like EOC (end of caption; display buffer), EDM (erase display memory) and EBM (erase buffered memory) perform their expected functions as soon as the commands are processed. This is implemented in the real_time branches added in this commit. Before this commit, and in the !real_time branches after this commit, the decoder cleverly implements its own version of the decoder which is specifically geared towards buffered decoding. It does so by actively ignoring commands like EBM (erase buffered memory), and then re-using the non-display buffer to hold the previous caption while the new one is received. This is the opposite of the real-time decoder, which uses the non-display buffer to hold the new caption while the display buffer is still showing the current caption. In addition to ignoring EBM, the buffered decoder also has custom implementations for EDM and EOC. An EDM (erase display memory) command flushes the existing contents before clearing the screen, and EOC similarly always flushes the active buffer (the previous subtitle) before flipping buffers.
2016-01-09 05:01:22 +02:00
// In realtime mode, we display the buffered contents (after
// flipping the buffer to active above) as soon as EOC arrives.
if (ctx->real_time)
reap_screen(ctx, pts);
}
static void handle_delete_end_of_row(CCaptionSubContext *ctx, char hi, char lo)
{
struct Screen *screen = get_writing_screen(ctx);
write_char(ctx, screen, 0);
}
static void handle_char(CCaptionSubContext *ctx, char hi, char lo, int64_t pts)
{
struct Screen *screen = get_writing_screen(ctx);
SET_FLAG(screen->row_used, ctx->cursor_row);
switch (hi) {
case 0x11:
ctx->cursor_charset = CCSET_SPECIAL_AMERICAN;
break;
case 0x12:
if (ctx->cursor_column > 0)
ctx->cursor_column -= 1;
ctx->cursor_charset = CCSET_EXTENDED_SPANISH_FRENCH_MISC;
break;
case 0x13:
if (ctx->cursor_column > 0)
ctx->cursor_column -= 1;
ctx->cursor_charset = CCSET_EXTENDED_PORTUGUESE_GERMAN_DANISH;
break;
default:
ctx->cursor_charset = CCSET_BASIC_AMERICAN;
write_char(ctx, screen, hi);
break;
}
if (lo) {
write_char(ctx, screen, lo);
}
write_char(ctx, screen, 0);
lavc/ccaption_dec: implement real_time option This new mode is useful for realtime decoding of closed captions so they can be display along with mpeg2 frames. Closed caption streams contain two major types of captions: - POPON captions, which are buffered off-screen and displayed only after EOC (end of caption, aka display buffer) - PAINTON/ROLLUP captions, which are written to the display as soon as they arrive. In a typical real-time eia608 decoder, commands like EOC (end of caption; display buffer), EDM (erase display memory) and EBM (erase buffered memory) perform their expected functions as soon as the commands are processed. This is implemented in the real_time branches added in this commit. Before this commit, and in the !real_time branches after this commit, the decoder cleverly implements its own version of the decoder which is specifically geared towards buffered decoding. It does so by actively ignoring commands like EBM (erase buffered memory), and then re-using the non-display buffer to hold the previous caption while the new one is received. This is the opposite of the real-time decoder, which uses the non-display buffer to hold the new caption while the display buffer is still showing the current caption. In addition to ignoring EBM, the buffered decoder also has custom implementations for EDM and EOC. An EDM (erase display memory) command flushes the existing contents before clearing the screen, and EOC similarly always flushes the active buffer (the previous subtitle) before flipping buffers.
2016-01-09 05:01:22 +02:00
if (ctx->mode != CCMODE_POPON)
ctx->screen_touched = 1;
if (lo)
ff_dlog(ctx, "(%c,%c)\n", hi, lo);
else
ff_dlog(ctx, "(%c)\n", hi);
}
static void process_cc608(CCaptionSubContext *ctx, int64_t pts, uint8_t hi, uint8_t lo)
{
if (hi == ctx->prev_cmd[0] && lo == ctx->prev_cmd[1]) {
/* ignore redundant command */
return;
}
/* set prev command */
ctx->prev_cmd[0] = hi;
ctx->prev_cmd[1] = lo;
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 (hi == 0x14 || hi == 0x15 || hi == 0x1c) {
switch (lo) {
case 0x20:
/* resume caption loading */
ctx->mode = CCMODE_POPON;
break;
case 0x24:
handle_delete_end_of_row(ctx, hi, lo);
break;
case 0x25:
case 0x26:
case 0x27:
ctx->rollup = lo - 0x23;
ctx->mode = CCMODE_ROLLUP;
break;
case 0x29:
/* resume direct captioning */
ctx->mode = CCMODE_PAINTON;
break;
case 0x2b:
/* resume text display */
ctx->mode = CCMODE_TEXT;
break;
case 0x2c:
/* erase display memory */
handle_edm(ctx, pts);
break;
case 0x2d:
/* carriage return */
ff_dlog(ctx, "carriage return\n");
lavc/ccaption_dec: implement real_time option This new mode is useful for realtime decoding of closed captions so they can be display along with mpeg2 frames. Closed caption streams contain two major types of captions: - POPON captions, which are buffered off-screen and displayed only after EOC (end of caption, aka display buffer) - PAINTON/ROLLUP captions, which are written to the display as soon as they arrive. In a typical real-time eia608 decoder, commands like EOC (end of caption; display buffer), EDM (erase display memory) and EBM (erase buffered memory) perform their expected functions as soon as the commands are processed. This is implemented in the real_time branches added in this commit. Before this commit, and in the !real_time branches after this commit, the decoder cleverly implements its own version of the decoder which is specifically geared towards buffered decoding. It does so by actively ignoring commands like EBM (erase buffered memory), and then re-using the non-display buffer to hold the previous caption while the new one is received. This is the opposite of the real-time decoder, which uses the non-display buffer to hold the new caption while the display buffer is still showing the current caption. In addition to ignoring EBM, the buffered decoder also has custom implementations for EDM and EOC. An EDM (erase display memory) command flushes the existing contents before clearing the screen, and EOC similarly always flushes the active buffer (the previous subtitle) before flipping buffers.
2016-01-09 05:01:22 +02:00
if (!ctx->real_time)
reap_screen(ctx, pts);
roll_up(ctx);
ctx->cursor_column = 0;
break;
lavc/ccaption_dec: implement real_time option This new mode is useful for realtime decoding of closed captions so they can be display along with mpeg2 frames. Closed caption streams contain two major types of captions: - POPON captions, which are buffered off-screen and displayed only after EOC (end of caption, aka display buffer) - PAINTON/ROLLUP captions, which are written to the display as soon as they arrive. In a typical real-time eia608 decoder, commands like EOC (end of caption; display buffer), EDM (erase display memory) and EBM (erase buffered memory) perform their expected functions as soon as the commands are processed. This is implemented in the real_time branches added in this commit. Before this commit, and in the !real_time branches after this commit, the decoder cleverly implements its own version of the decoder which is specifically geared towards buffered decoding. It does so by actively ignoring commands like EBM (erase buffered memory), and then re-using the non-display buffer to hold the previous caption while the new one is received. This is the opposite of the real-time decoder, which uses the non-display buffer to hold the new caption while the display buffer is still showing the current caption. In addition to ignoring EBM, the buffered decoder also has custom implementations for EDM and EOC. An EDM (erase display memory) command flushes the existing contents before clearing the screen, and EOC similarly always flushes the active buffer (the previous subtitle) before flipping buffers.
2016-01-09 05:01:22 +02:00
case 0x2e:
/* erase buffered (non displayed) memory */
// Only in realtime mode. In buffered mode, we re-use the inactive screen
// for our own buffering.
if (ctx->real_time) {
struct Screen *screen = ctx->screen + !ctx->active_screen;
screen->row_used = 0;
}
break;
case 0x2f:
/* end of caption */
ff_dlog(ctx, "handle_eoc\n");
handle_eoc(ctx, pts);
break;
default:
ff_dlog(ctx, "Unknown command 0x%hhx 0x%hhx\n", hi, lo);
break;
}
} else if (hi >= 0x11 && hi <= 0x13) {
/* Special characters */
handle_char(ctx, hi, lo, pts);
2016-01-06 01:18:09 +02:00
} else if (hi >= 0x20) {
/* Standard characters (always in pairs) */
handle_char(ctx, hi, lo, pts);
ctx->prev_cmd[0] = ctx->prev_cmd[1] = 0;
} else if (hi == 0x17 && lo >= 0x21 && lo <= 0x23) {
int i;
/* Tab offsets (spacing) */
for (i = 0; i < lo - 0x20; i++) {
handle_char(ctx, ' ', 0, pts);
}
} else {
/* Ignoring all other non data code */
ff_dlog(ctx, "Unknown command 0x%hhx 0x%hhx\n", hi, lo);
}
}
static int decode(AVCodecContext *avctx, void *data, int *got_sub, AVPacket *avpkt)
{
CCaptionSubContext *ctx = avctx->priv_data;
AVSubtitle *sub = data;
const int64_t start_time = sub->pts;
uint8_t *bptr = NULL;
int len = avpkt->size;
int ret = 0;
int i;
av_fast_padded_malloc(&ctx->pktbuf, &ctx->pktbuf_size, len);
if (!ctx->pktbuf) {
av_log(ctx, AV_LOG_WARNING, "Insufficient Memory of %d truncated to %d\n", len, ctx->pktbuf_size);
return AVERROR(ENOMEM);
}
memcpy(ctx->pktbuf, avpkt->data, len);
bptr = ctx->pktbuf;
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, start_time, *(bptr + i + 1) & 0x7f, *(bptr + i + 2) & 0x7f);
lavc/ccaption_dec: implement real_time option This new mode is useful for realtime decoding of closed captions so they can be display along with mpeg2 frames. Closed caption streams contain two major types of captions: - POPON captions, which are buffered off-screen and displayed only after EOC (end of caption, aka display buffer) - PAINTON/ROLLUP captions, which are written to the display as soon as they arrive. In a typical real-time eia608 decoder, commands like EOC (end of caption; display buffer), EDM (erase display memory) and EBM (erase buffered memory) perform their expected functions as soon as the commands are processed. This is implemented in the real_time branches added in this commit. Before this commit, and in the !real_time branches after this commit, the decoder cleverly implements its own version of the decoder which is specifically geared towards buffered decoding. It does so by actively ignoring commands like EBM (erase buffered memory), and then re-using the non-display buffer to hold the previous caption while the new one is received. This is the opposite of the real-time decoder, which uses the non-display buffer to hold the new caption while the display buffer is still showing the current caption. In addition to ignoring EBM, the buffered decoder also has custom implementations for EDM and EOC. An EDM (erase display memory) command flushes the existing contents before clearing the screen, and EOC similarly always flushes the active buffer (the previous subtitle) before flipping buffers.
2016-01-09 05:01:22 +02:00
if (!ctx->buffer_changed)
continue;
ctx->buffer_changed = 0;
if (*ctx->buffer.str || ctx->real_time)
{
ff_dlog(ctx, "cdp writing data (%s)\n",ctx->buffer.str);
ret = ff_ass_add_rect(sub, ctx->buffer.str, ctx->readorder++, 0, NULL, NULL);
if (ret < 0)
return ret;
sub->pts = ctx->start_time;
if (!ctx->real_time)
sub->end_display_time = av_rescale_q(ctx->end_time - ctx->start_time,
AV_TIME_BASE_Q, ms_tb);
else
sub->end_display_time = -1;
ctx->buffer_changed = 0;
ctx->last_real_time = sub->pts;
lavc/ccaption_dec: implement real_time option This new mode is useful for realtime decoding of closed captions so they can be display along with mpeg2 frames. Closed caption streams contain two major types of captions: - POPON captions, which are buffered off-screen and displayed only after EOC (end of caption, aka display buffer) - PAINTON/ROLLUP captions, which are written to the display as soon as they arrive. In a typical real-time eia608 decoder, commands like EOC (end of caption; display buffer), EDM (erase display memory) and EBM (erase buffered memory) perform their expected functions as soon as the commands are processed. This is implemented in the real_time branches added in this commit. Before this commit, and in the !real_time branches after this commit, the decoder cleverly implements its own version of the decoder which is specifically geared towards buffered decoding. It does so by actively ignoring commands like EBM (erase buffered memory), and then re-using the non-display buffer to hold the previous caption while the new one is received. This is the opposite of the real-time decoder, which uses the non-display buffer to hold the new caption while the display buffer is still showing the current caption. In addition to ignoring EBM, the buffered decoder also has custom implementations for EDM and EOC. An EDM (erase display memory) command flushes the existing contents before clearing the screen, and EOC similarly always flushes the active buffer (the previous subtitle) before flipping buffers.
2016-01-09 05:01:22 +02:00
ctx->screen_touched = 0;
}
}
lavc/ccaption_dec: implement real_time option This new mode is useful for realtime decoding of closed captions so they can be display along with mpeg2 frames. Closed caption streams contain two major types of captions: - POPON captions, which are buffered off-screen and displayed only after EOC (end of caption, aka display buffer) - PAINTON/ROLLUP captions, which are written to the display as soon as they arrive. In a typical real-time eia608 decoder, commands like EOC (end of caption; display buffer), EDM (erase display memory) and EBM (erase buffered memory) perform their expected functions as soon as the commands are processed. This is implemented in the real_time branches added in this commit. Before this commit, and in the !real_time branches after this commit, the decoder cleverly implements its own version of the decoder which is specifically geared towards buffered decoding. It does so by actively ignoring commands like EBM (erase buffered memory), and then re-using the non-display buffer to hold the previous caption while the new one is received. This is the opposite of the real-time decoder, which uses the non-display buffer to hold the new caption while the display buffer is still showing the current caption. In addition to ignoring EBM, the buffered decoder also has custom implementations for EDM and EOC. An EDM (erase display memory) command flushes the existing contents before clearing the screen, and EOC similarly always flushes the active buffer (the previous subtitle) before flipping buffers.
2016-01-09 05:01:22 +02:00
if (ctx->real_time && ctx->screen_touched &&
sub->pts > ctx->last_real_time + av_rescale_q(200, ms_tb, AV_TIME_BASE_Q)) {
ctx->last_real_time = sub->pts;
lavc/ccaption_dec: implement real_time option This new mode is useful for realtime decoding of closed captions so they can be display along with mpeg2 frames. Closed caption streams contain two major types of captions: - POPON captions, which are buffered off-screen and displayed only after EOC (end of caption, aka display buffer) - PAINTON/ROLLUP captions, which are written to the display as soon as they arrive. In a typical real-time eia608 decoder, commands like EOC (end of caption; display buffer), EDM (erase display memory) and EBM (erase buffered memory) perform their expected functions as soon as the commands are processed. This is implemented in the real_time branches added in this commit. Before this commit, and in the !real_time branches after this commit, the decoder cleverly implements its own version of the decoder which is specifically geared towards buffered decoding. It does so by actively ignoring commands like EBM (erase buffered memory), and then re-using the non-display buffer to hold the previous caption while the new one is received. This is the opposite of the real-time decoder, which uses the non-display buffer to hold the new caption while the display buffer is still showing the current caption. In addition to ignoring EBM, the buffered decoder also has custom implementations for EDM and EOC. An EDM (erase display memory) command flushes the existing contents before clearing the screen, and EOC similarly always flushes the active buffer (the previous subtitle) before flipping buffers.
2016-01-09 05:01:22 +02:00
ctx->screen_touched = 0;
capture_screen(ctx);
ctx->buffer_changed = 0;
ret = ff_ass_add_rect(sub, ctx->buffer.str, ctx->readorder++, 0, NULL, NULL);
lavc/ccaption_dec: implement real_time option This new mode is useful for realtime decoding of closed captions so they can be display along with mpeg2 frames. Closed caption streams contain two major types of captions: - POPON captions, which are buffered off-screen and displayed only after EOC (end of caption, aka display buffer) - PAINTON/ROLLUP captions, which are written to the display as soon as they arrive. In a typical real-time eia608 decoder, commands like EOC (end of caption; display buffer), EDM (erase display memory) and EBM (erase buffered memory) perform their expected functions as soon as the commands are processed. This is implemented in the real_time branches added in this commit. Before this commit, and in the !real_time branches after this commit, the decoder cleverly implements its own version of the decoder which is specifically geared towards buffered decoding. It does so by actively ignoring commands like EBM (erase buffered memory), and then re-using the non-display buffer to hold the previous caption while the new one is received. This is the opposite of the real-time decoder, which uses the non-display buffer to hold the new caption while the display buffer is still showing the current caption. In addition to ignoring EBM, the buffered decoder also has custom implementations for EDM and EOC. An EDM (erase display memory) command flushes the existing contents before clearing the screen, and EOC similarly always flushes the active buffer (the previous subtitle) before flipping buffers.
2016-01-09 05:01:22 +02:00
if (ret < 0)
return ret;
sub->end_display_time = -1;
lavc/ccaption_dec: implement real_time option This new mode is useful for realtime decoding of closed captions so they can be display along with mpeg2 frames. Closed caption streams contain two major types of captions: - POPON captions, which are buffered off-screen and displayed only after EOC (end of caption, aka display buffer) - PAINTON/ROLLUP captions, which are written to the display as soon as they arrive. In a typical real-time eia608 decoder, commands like EOC (end of caption; display buffer), EDM (erase display memory) and EBM (erase buffered memory) perform their expected functions as soon as the commands are processed. This is implemented in the real_time branches added in this commit. Before this commit, and in the !real_time branches after this commit, the decoder cleverly implements its own version of the decoder which is specifically geared towards buffered decoding. It does so by actively ignoring commands like EBM (erase buffered memory), and then re-using the non-display buffer to hold the previous caption while the new one is received. This is the opposite of the real-time decoder, which uses the non-display buffer to hold the new caption while the display buffer is still showing the current caption. In addition to ignoring EBM, the buffered decoder also has custom implementations for EDM and EOC. An EDM (erase display memory) command flushes the existing contents before clearing the screen, and EOC similarly always flushes the active buffer (the previous subtitle) before flipping buffers.
2016-01-09 05:01:22 +02:00
}
*got_sub = sub->num_rects > 0;
return ret;
}
lavc/ccaption_dec: implement real_time option This new mode is useful for realtime decoding of closed captions so they can be display along with mpeg2 frames. Closed caption streams contain two major types of captions: - POPON captions, which are buffered off-screen and displayed only after EOC (end of caption, aka display buffer) - PAINTON/ROLLUP captions, which are written to the display as soon as they arrive. In a typical real-time eia608 decoder, commands like EOC (end of caption; display buffer), EDM (erase display memory) and EBM (erase buffered memory) perform their expected functions as soon as the commands are processed. This is implemented in the real_time branches added in this commit. Before this commit, and in the !real_time branches after this commit, the decoder cleverly implements its own version of the decoder which is specifically geared towards buffered decoding. It does so by actively ignoring commands like EBM (erase buffered memory), and then re-using the non-display buffer to hold the previous caption while the new one is received. This is the opposite of the real-time decoder, which uses the non-display buffer to hold the new caption while the display buffer is still showing the current caption. In addition to ignoring EBM, the buffered decoder also has custom implementations for EDM and EOC. An EDM (erase display memory) command flushes the existing contents before clearing the screen, and EOC similarly always flushes the active buffer (the previous subtitle) before flipping buffers.
2016-01-09 05:01:22 +02:00
#define OFFSET(x) offsetof(CCaptionSubContext, x)
#define SD AV_OPT_FLAG_SUBTITLE_PARAM | AV_OPT_FLAG_DECODING_PARAM
static const AVOption options[] = {
lavc/ccaption_dec: implement real_time option This new mode is useful for realtime decoding of closed captions so they can be display along with mpeg2 frames. Closed caption streams contain two major types of captions: - POPON captions, which are buffered off-screen and displayed only after EOC (end of caption, aka display buffer) - PAINTON/ROLLUP captions, which are written to the display as soon as they arrive. In a typical real-time eia608 decoder, commands like EOC (end of caption; display buffer), EDM (erase display memory) and EBM (erase buffered memory) perform their expected functions as soon as the commands are processed. This is implemented in the real_time branches added in this commit. Before this commit, and in the !real_time branches after this commit, the decoder cleverly implements its own version of the decoder which is specifically geared towards buffered decoding. It does so by actively ignoring commands like EBM (erase buffered memory), and then re-using the non-display buffer to hold the previous caption while the new one is received. This is the opposite of the real-time decoder, which uses the non-display buffer to hold the new caption while the display buffer is still showing the current caption. In addition to ignoring EBM, the buffered decoder also has custom implementations for EDM and EOC. An EDM (erase display memory) command flushes the existing contents before clearing the screen, and EOC similarly always flushes the active buffer (the previous subtitle) before flipping buffers.
2016-01-09 05:01:22 +02:00
{ "real_time", "emit subtitle events as they are decoded for real-time display", OFFSET(real_time), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, SD },
{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)"),
.type = AVMEDIA_TYPE_SUBTITLE,
.id = AV_CODEC_ID_EIA_608,
.priv_data_size = sizeof(CCaptionSubContext),
.init = init_decoder,
.close = close_decoder,
.flush = flush_decoder,
.decode = decode,
.priv_class = &ccaption_dec_class,
};