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/* dectx3gsub.c
Copyright (c) 2003-2013 HandBrake Team
This file is part of the HandBrake source code
Homepage: <http://handbrake.fr/>.
It may be used under the terms of the GNU General Public License v2.
For full terms see the file COPYING file or visit http://www.gnu.org/licenses/gpl-2.0.html
*/
/*
* Converts TX3G subtitles to UTF-8 subtitles with limited HTML-style markup (<b>, <i>, <u>).
*
* TX3G == MPEG 4, Part 17 (ISO/IEC 14496-17) == 3GPP Timed Text (26.245)
* A full reference to the format can be found here:
* http://www.3gpp.org/ftp/Specs/html-info/26245.htm
*
* @author David Foster (davidfstr)
*/
#include <stdlib.h>
#include <stdio.h>
#include "hb.h"
typedef enum {
BOLD = 0x1,
ITALIC = 0x2,
UNDERLINE = 0x4
} FaceStyleFlag;
#define NUM_FACE_STYLE_FLAGS 3
#define MAX_OPEN_TAG_SIZE 3 // "<b>"
#define MAX_CLOSE_TAG_SIZE 4 // "</b>"
typedef struct {
uint16_t startChar; // NOTE: indices in terms of *character* (not: byte) positions
uint16_t endChar;
uint16_t fontID;
uint8_t faceStyleFlags; // FaceStyleFlag
uint8_t fontSize;
uint32_t textColorRGBA;
} StyleRecord;
// NOTE: None of these macros check for buffer overflow
#define READ_U8() *pos; pos += 1;
#define READ_U16() (pos[0] << 8) | pos[1]; pos += 2;
#define READ_U32() (pos[0] << 24) | (pos[1] << 16) | (pos[2] << 8) | pos[3]; pos += 4;
#define READ_ARRAY(n) pos; pos += n;
#define SKIP_ARRAY(n) pos += n;
#define WRITE_CHAR(c) {dst[0]=c; dst += 1;}
#define WRITE_START_TAG(c) {dst[0]='<'; dst[1]=c; dst[2]='>'; dst += 3;}
#define WRITE_END_TAG(c) {dst[0]='<'; dst[1]='/'; dst[2]=c; dst[3]='>'; dst += 4;}
#define FOURCC(str) ((((uint32_t) str[0]) << 24) | \
(((uint32_t) str[1]) << 16) | \
(((uint32_t) str[2]) << 8) | \
(((uint32_t) str[3]) << 0))
#define IS_10xxxxxx(c) ((c & 0xC0) == 0x80)
static hb_buffer_t *tx3g_decode_to_utf8( hb_buffer_t *in )
{
uint8_t *pos = in->data;
uint8_t *end = in->data + in->size;
uint16_t numStyleRecords = 0;
uint8_t *startStyle;
uint8_t *endStyle;
/*
* Parse the packet as a TX3G TextSample.
*
* Look for a single StyleBox ('styl') and read all contained StyleRecords.
* Ignore all other box types.
*
* NOTE: Buffer overflows on read are not checked.
*/
uint16_t textLength = READ_U16();
uint8_t *text = READ_ARRAY(textLength);
startStyle = calloc( textLength, 1 );
endStyle = calloc( textLength, 1 );
while ( pos < end ) {
/*
* Read TextSampleModifierBox
*/
uint32_t size = READ_U32();
if ( size == 0 ) {
size = pos - end; // extends to end of packet
}
if ( size == 1 ) {
hb_log( "dectx3gsub: TextSampleModifierBox has unsupported large size" );
break;
}
uint32_t type = READ_U32();
if ( type == FOURCC("uuid") ) {
hb_log( "dectx3gsub: TextSampleModifierBox has unsupported extended type" );
break;
}
if ( type == FOURCC("styl") ) {
// Found a StyleBox. Parse the contained StyleRecords
if ( numStyleRecords != 0 ) {
hb_log( "dectx3gsub: found additional StyleBoxes on subtitle; skipping" );
SKIP_ARRAY(size);
continue;
}
numStyleRecords = READ_U16();
int i;
for (i=0; i<numStyleRecords; i++) {
StyleRecord curRecord;
curRecord.startChar = READ_U16();
curRecord.endChar = READ_U16();
curRecord.fontID = READ_U16();
curRecord.faceStyleFlags = READ_U8();
curRecord.fontSize = READ_U8();
curRecord.textColorRGBA = READ_U32();
startStyle[curRecord.startChar] |= curRecord.faceStyleFlags;
endStyle[curRecord.endChar] |= curRecord.faceStyleFlags;
}
} else {
// Found some other kind of TextSampleModifierBox. Skip it.
SKIP_ARRAY(size);
}
}
/*
* Copy text to output buffer, and add HTML markup for the style records
*/
int maxOutputSize = textLength + (numStyleRecords * NUM_FACE_STYLE_FLAGS * (MAX_OPEN_TAG_SIZE + MAX_CLOSE_TAG_SIZE));
hb_buffer_t *out = hb_buffer_init( maxOutputSize );
if ( out == NULL )
goto fail;
uint8_t *dst = out->data;
int charIndex = 0;
for ( pos = text, end = text + textLength; pos < end; pos++ ) {
if (IS_10xxxxxx(*pos)) {
// Is a non-first byte of a multi-byte UTF-8 character
WRITE_CHAR(*pos);
continue; // ...without incrementing 'charIndex'
}
uint8_t plusStyles = startStyle[charIndex];
uint8_t minusStyles = endStyle[charIndex];
if (minusStyles & UNDERLINE)
WRITE_END_TAG('u');
if (minusStyles & ITALIC)
WRITE_END_TAG('i');
if (minusStyles & BOLD)
WRITE_END_TAG('b');
if (plusStyles & BOLD)
WRITE_START_TAG('b');
if (plusStyles & ITALIC)
WRITE_START_TAG('i');
if (plusStyles & UNDERLINE)
WRITE_START_TAG('u');
WRITE_CHAR(*pos);
charIndex++;
}
// Trim output buffer to the actual amount of data written
out->size = dst - out->data;
// Copy metadata from the input packet to the output packet
out->s.frametype = HB_FRAME_SUBTITLE;
out->s.start = in->s.start;
out->s.stop = in->s.stop;
fail:
free( startStyle );
free( endStyle );
return out;
}
#undef READ_U8
#undef READ_U16
#undef READ_U32
#undef READ_ARRAY
#undef SKIP_ARRAY
#undef WRITE_CHAR
#undef WRITE_START_TAG
#undef WRITE_END_TAG
static int dectx3gInit( hb_work_object_t * w, hb_job_t * job )
{
return 0;
}
static int dectx3gWork( hb_work_object_t * w, hb_buffer_t ** buf_in,
hb_buffer_t ** buf_out )
{
hb_buffer_t * in = *buf_in;
hb_buffer_t * out = NULL;
// Warn if the subtitle's duration has not been passed through by the demuxer,
// which will prevent the subtitle from displaying at all
if ( in->s.stop == 0 ) {
hb_log( "dectx3gsub: subtitle packet lacks duration" );
}
if ( in->size > 0 ) {
out = tx3g_decode_to_utf8(in);
} else {
out = hb_buffer_init( 0 );
}
if ( out != NULL ) {
// We shouldn't be storing the extra NULL character,
// but the MP4 muxer expects this, unfortunately.
if (out->size > 0 && out->data[out->size - 1] != '\0')
{
hb_buffer_realloc(out, ++out->size);
out->data[out->size - 1] = '\0';
}
// If the input packet was non-empty, do not pass through
// an empty output packet (even if the subtitle was empty),
// as this would be interpreted as an end-of-stream
if ( in->size > 0 && out->size == 0 ) {
hb_buffer_close(&out);
}
}
// Dispose the input packet, as it is no longer needed
hb_buffer_close(&in);
*buf_in = NULL;
*buf_out = out;
return HB_WORK_OK;
}
static void dectx3gClose( hb_work_object_t * w )
{
// nothing
}
hb_work_object_t hb_dectx3gsub =
{
WORK_DECTX3GSUB,
"TX3G Subtitle Decoder",
dectx3gInit,
dectx3gWork,
dectx3gClose
};
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