--- /dev/null
+/*
+ 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. */
+
+/*
+ * 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->start = in->start;
+ out->stop = in->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->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' ) {
+ // NOTE: out->size remains unchanged
+ hb_buffer_realloc( out, out->size + 1 );
+ out->data[out->size] = '\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
+};
OSDN Git Service
