Universal Text Subtitle Support Initial Implementation

- Patch by davidfstr ... Thanks!
- Adds support for reading TEXT subtitle tracks from file inputs
- Tested combinations:
-- MKV UTF-8 -> MKV UTF-8 (passthru)
-- MKV UTF-8 -> MP4 TX3G (upconvert)
-- MP4 TX3G -> MKV UTF-8 (downconvert)
-- MP4 TX3G -> MP4 TX3G (downconvert to UTF-8 then upconvert)
- Further explained here http://forum.handbrake.fr/viewtopic.php?f=4&t=16099 

git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@3283 b64f7644-9d1e-0410-96f1-a4d463321fa5

1 files changed, 240 insertions, 0 deletions

diff --git a/libhb/dectx3gsub.c b/libhb/dectx3gsub.c
new file mode 100644
index 000000000..fe413ad98
--- /dev/null
+++ b/libhb/dectx3gsub.c
@@ -0,0 +1,240 @@
+/* 
+   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 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" );
+                READ_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.
+            READ_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 );
+    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;
+    
+    free( startStyle );
+    free( endStyle );
+    
+    return out;
+}
+
+#undef READ_U8
+#undef READ_U16
+#undef READ_U32
+#undef READ_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 );
+    }
+    
+    // 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
+};