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FFmpeg/libavcodec/ccaption_dec.c
Pavel Koshevoy b51c2c48c1 avcodec/ccaption_dec: Make real-time latency configurable 
Un-hardcode the 200ms minimum latency between emitting subtitle events
so that those that wish to receive a subtitle event for every screen
change could do so.

The problem with delaying realtime output by any amount is that it is
unknown when the next byte pair that would trigger output will happen.
It may be within 200ms, or it may be several seconds later -- that's
not realtime at all.
2021-06-18 19:20:03 -06:00

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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 "internal.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};
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 bg_attribs[8] = // Color
{
CCCOL_WHITE,
CCCOL_GREEN,
CCCOL_BLUE,
CCCOL_CYAN,
CCCOL_RED,
CCCOL_YELLOW,
CCCOL_MAGENTA,
CCCOL_BLACK,
};
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+1][SCREEN_COLUMNS+1];
uint8_t charsets[SCREEN_ROWS+1][SCREEN_COLUMNS+1];
uint8_t colors[SCREEN_ROWS+1][SCREEN_COLUMNS+1];
uint8_t bgs[SCREEN_ROWS+1][SCREEN_COLUMNS+1];
uint8_t fonts[SCREEN_ROWS+1][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;
int real_time;
int real_time_latency_msec;
int data_field;
struct Screen screen[2];
int active_screen;
uint8_t cursor_row;
uint8_t cursor_column;
uint8_t cursor_color;
uint8_t bg_color;
uint8_t cursor_font;
uint8_t cursor_charset;
AVBPrint buffer[2];
int buffer_index;
int buffer_changed;
int rollup;
enum cc_mode mode;
int64_t buffer_time[2];
int screen_touched;
int64_t last_real_time;
uint8_t prev_cmd[2];
int readorder;
} CCaptionSubContext;
static av_cold int init_decoder(AVCodecContext *avctx)
{
int ret;
CCaptionSubContext *ctx = avctx->priv_data;
av_bprint_init(&ctx->buffer[0], 0, AV_BPRINT_SIZE_UNLIMITED);
av_bprint_init(&ctx->buffer[1], 0, AV_BPRINT_SIZE_UNLIMITED);
/* taking by default roll up to 2 */
ctx->mode = CCMODE_ROLLUP;
ctx->bg_color = CCCOL_BLACK;
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[0], NULL);
av_bprint_finalize(&ctx->buffer[1], NULL);
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->bg_color = CCCOL_BLACK;
ctx->cursor_charset = 0;
ctx->active_screen = 0;
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[0]);
av_bprint_clear(&ctx->buffer[1]);
}
/**
* @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 *color = screen->colors[ctx->cursor_row];
char *bg = screen->bgs[ctx->cursor_row];
char *charset = screen->charsets[ctx->cursor_row];
if (col < SCREEN_COLUMNS) {
row[col] = ch;
font[col] = ctx->cursor_font;
color[col] = ctx->cursor_color;
bg[col] = ctx->bg_color;
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 {
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(const uint8_t *cc_data_pair, uint8_t *hi)
{
uint8_t cc_valid = (*cc_data_pair & 4) >>2;
uint8_t cc_type = *cc_data_pair & 3;
*hi = cc_data_pair[1];
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])) {
*hi = 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;
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->bgs[i_row], screen->bgs[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);
}
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;
enum cc_color_code prev_color = CCCOL_WHITE;
enum cc_color_code prev_bg_color = CCCOL_BLACK;
const int bidx = ctx->buffer_index;
av_bprint_clear(&ctx->buffer[bidx]);
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++)
{
if (CHECK_FLAG(screen->row_used, i)) {
const char *row = screen->characters[i];
const char *font = screen->fonts[i];
const char *bg = screen->bgs[i];
const char *color = screen->colors[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[bidx], "{\\an7}{\\pos(%d,%d)}", x, y);
for (; j < SCREEN_COLUMNS; j++) {
const char *e_tag = "", *s_tag = "", *c_tag = "", *b_tag = "";
if (row[j] == 0)
break;
if (prev_font != font[j]) {
switch (prev_font) {
case CCFONT_ITALICS:
e_tag = "{\\i0}";
break;
case CCFONT_UNDERLINED:
e_tag = "{\\u0}";
break;
case CCFONT_UNDERLINED_ITALICS:
e_tag = "{\\u0}{\\i0}";
break;
}
switch (font[j]) {
case CCFONT_ITALICS:
s_tag = "{\\i1}";
break;
case CCFONT_UNDERLINED:
s_tag = "{\\u1}";
break;
case CCFONT_UNDERLINED_ITALICS:
s_tag = "{\\u1}{\\i1}";
break;
}
}
if (prev_color != color[j]) {
switch (color[j]) {
case CCCOL_WHITE:
c_tag = "{\\c&HFFFFFF&}";
break;
case CCCOL_GREEN:
c_tag = "{\\c&H00FF00&}";
break;
case CCCOL_BLUE:
c_tag = "{\\c&HFF0000&}";
break;
case CCCOL_CYAN:
c_tag = "{\\c&HFFFF00&}";
break;
case CCCOL_RED:
c_tag = "{\\c&H0000FF&}";
break;
case CCCOL_YELLOW:
c_tag = "{\\c&H00FFFF&}";
break;
case CCCOL_MAGENTA:
c_tag = "{\\c&HFF00FF&}";
break;
}
}
if (prev_bg_color != bg[j]) {
switch (bg[j]) {
case CCCOL_WHITE:
b_tag = "{\\3c&HFFFFFF&}";
break;
case CCCOL_GREEN:
b_tag = "{\\3c&H00FF00&}";
break;
case CCCOL_BLUE:
b_tag = "{\\3c&HFF0000&}";
break;
case CCCOL_CYAN:
b_tag = "{\\3c&HFFFF00&}";
break;
case CCCOL_RED:
b_tag = "{\\3c&H0000FF&}";
break;
case CCCOL_YELLOW:
b_tag = "{\\3c&H00FFFF&}";
break;
case CCCOL_MAGENTA:
b_tag = "{\\3c&HFF00FF&}";
break;
case CCCOL_BLACK:
b_tag = "{\\3c&H000000&}";
break;
}
}
prev_font = font[j];
prev_color = color[j];
prev_bg_color = bg[j];
override = charset_overrides[(int)charset[j]][(int)row[j]];
if (override) {
av_bprintf(&ctx->buffer[bidx], "%s%s%s%s%s", e_tag, s_tag, c_tag, b_tag, override);
seen_char = 1;
} else if (row[j] == ' ' && !seen_char) {
av_bprintf(&ctx->buffer[bidx], "%s%s%s%s\\h", e_tag, s_tag, c_tag, b_tag);
} else {
av_bprintf(&ctx->buffer[bidx], "%s%s%s%s%c", e_tag, s_tag, c_tag, b_tag, row[j]);
seen_char = 1;
}
}
av_bprintf(&ctx->buffer[bidx], "\\N");
}
}
if (!av_bprint_is_complete(&ctx->buffer[bidx]))
return AVERROR(ENOMEM);
if (screen->row_used && ctx->buffer[bidx].len >= 2) {
ctx->buffer[bidx].len -= 2;
ctx->buffer[bidx].str[ctx->buffer[bidx].len] = 0;
}
ctx->buffer_changed = 1;
return 0;
}
static void update_time(CCaptionSubContext *ctx, int64_t pts)
{
ctx->buffer_time[0] = ctx->buffer_time[1];
ctx->buffer_time[1] = pts;
}
static void handle_bgattr(CCaptionSubContext *ctx, uint8_t hi, uint8_t lo)
{
const int i = (lo & 0xf) >> 1;
ctx->bg_color = bg_attribs[i];
}
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];
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) {
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, ' ');
}
}
static int handle_edm(CCaptionSubContext *ctx)
{
struct Screen *screen = ctx->screen + ctx->active_screen;
int ret;
// In buffered mode, keep writing to screen until it is wiped.
// Before wiping the display, capture contents to emit subtitle.
if (!ctx->real_time)
ret = capture_screen(ctx);
screen->row_used = 0;
ctx->bg_color = CCCOL_BLACK;
// In realtime mode, emit an empty caption so the last one doesn't
// stay on the screen.
if (ctx->real_time)
ret = capture_screen(ctx);
return ret;
}
static int handle_eoc(CCaptionSubContext *ctx)
{
int ret;
ctx->active_screen = !ctx->active_screen;
// In buffered mode, we wait til the *next* EOC and
// capture what was already on the screen since the last EOC.
if (!ctx->real_time)
ret = handle_edm(ctx);
ctx->cursor_column = 0;
// In realtime mode, we display the buffered contents (after
// flipping the buffer to active above) as soon as EOC arrives.
if (ctx->real_time)
ret = capture_screen(ctx);
return ret;
}
static void handle_delete_end_of_row(CCaptionSubContext *ctx)
{
struct Screen *screen = get_writing_screen(ctx);
write_char(ctx, screen, 0);
}
static void handle_char(CCaptionSubContext *ctx, char hi, char lo)
{
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);
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 int process_cc608(CCaptionSubContext *ctx, uint8_t hi, uint8_t lo)
{
int ret = 0;
if (hi == ctx->prev_cmd[0] && lo == ctx->prev_cmd[1]) {
return 0;
}
/* 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 == 0x10 && lo >= 0x20 && lo <= 0x2f)) {
handle_bgattr(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);
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);
break;
case 0x2d:
/* carriage return */
ff_dlog(ctx, "carriage return\n");
if (!ctx->real_time)
ret = capture_screen(ctx);
roll_up(ctx);
ctx->cursor_column = 0;
break;
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");
ret = handle_eoc(ctx);
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);
} else if (hi >= 0x20) {
/* Standard characters (always in pairs) */
handle_char(ctx, hi, lo);
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);
}
} else {
/* Ignoring all other non data code */
ff_dlog(ctx, "Unknown command 0x%hhx 0x%hhx\n", hi, lo);
}
return ret;
}
static int decode(AVCodecContext *avctx, void *data, int *got_sub, AVPacket *avpkt)
{
CCaptionSubContext *ctx = avctx->priv_data;
AVSubtitle *sub = data;
int64_t in_time = sub->pts;
int64_t start_time;
int64_t end_time;
int bidx = ctx->buffer_index;
const uint8_t *bptr = avpkt->data;
int len = avpkt->size;
int ret = 0;
int i;
for (i = 0; i < len; i += 3) {
uint8_t hi, cc_type = bptr[i] & 1;
if (ctx->data_field < 0)
ctx->data_field = cc_type;
if (validate_cc_data_pair(bptr + i, &hi))
continue;
if (cc_type != ctx->data_field)
continue;
ret = process_cc608(ctx, hi & 0x7f, bptr[i + 2] & 0x7f);
if (ret < 0)
return ret;
if (!ctx->buffer_changed)
continue;
ctx->buffer_changed = 0;
if (!ctx->real_time && ctx->mode == CCMODE_POPON)
ctx->buffer_index = bidx = !ctx->buffer_index;
update_time(ctx, in_time);
if (ctx->buffer[bidx].str[0] || ctx->real_time) {
ff_dlog(ctx, "cdp writing data (%s)\n", ctx->buffer[bidx].str);
start_time = ctx->buffer_time[0];
sub->pts = start_time;
end_time = ctx->buffer_time[1];
if (!ctx->real_time)
sub->end_display_time = av_rescale_q(end_time - start_time,
AV_TIME_BASE_Q, ms_tb);
else
sub->end_display_time = -1;
ret = ff_ass_add_rect(sub, ctx->buffer[bidx].str, ctx->readorder++, 0, NULL, NULL);
if (ret < 0)
return ret;
ctx->last_real_time = sub->pts;
ctx->screen_touched = 0;
}
}
if (!bptr && !ctx->real_time && ctx->buffer[!ctx->buffer_index].str[0]) {
bidx = !ctx->buffer_index;
ret = ff_ass_add_rect(sub, ctx->buffer[bidx].str, ctx->readorder++, 0, NULL, NULL);
if (ret < 0)
return ret;
sub->pts = ctx->buffer_time[1];
sub->end_display_time = av_rescale_q(ctx->buffer_time[1] - ctx->buffer_time[0],
AV_TIME_BASE_Q, ms_tb);
if (sub->end_display_time == 0)
sub->end_display_time = ctx->buffer[bidx].len * 20;
}
if (ctx->real_time && ctx->screen_touched &&
sub->pts >= ctx->last_real_time + av_rescale_q(ctx->real_time_latency_msec, ms_tb, AV_TIME_BASE_Q)) {
ctx->last_real_time = sub->pts;
ctx->screen_touched = 0;
capture_screen(ctx);
ctx->buffer_changed = 0;
ret = ff_ass_add_rect(sub, ctx->buffer[bidx].str, ctx->readorder++, 0, NULL, NULL);
if (ret < 0)
return ret;
sub->end_display_time = -1;
}
*got_sub = sub->num_rects > 0;
return ret;
}
#define OFFSET(x) offsetof(CCaptionSubContext, x)
#define SD AV_OPT_FLAG_SUBTITLE_PARAM | AV_OPT_FLAG_DECODING_PARAM
static const AVOption options[] = {
{ "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 },
{ "real_time_latency_msec", "minimum elapsed time between emitting real-time subtitle events", OFFSET(real_time_latency_msec), AV_OPT_TYPE_INT, { .i64 = 200 }, 0, 500, SD },
{ "data_field", "select data field", OFFSET(data_field), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, 1, SD, "data_field" },
{ "auto", "pick first one that appears", 0, AV_OPT_TYPE_CONST, { .i64 =-1 }, 0, 0, SD, "data_field" },
{ "first", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = 0 }, 0, 0, SD, "data_field" },
{ "second", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = 1 }, 0, 0, SD, "data_field" },
{NULL}
};
static const AVClass ccaption_dec_class = {
.class_name = "Closed caption Decoder",
.item_name = av_default_item_name,
.option = options,
.version = LIBAVUTIL_VERSION_INT,
};
const 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,
.capabilities = AV_CODEC_CAP_DELAY,
.caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
};
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