diff options
| -rw-r--r-- | libhb/decssasub.c | 269 |
1 files changed, 269 insertions, 0 deletions
diff --git a/libhb/decssasub.c b/libhb/decssasub.c new file mode 100644 index 000000000..e4ff0dc59 --- /dev/null +++ b/libhb/decssasub.c @@ -0,0 +1,269 @@ +/* + 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 SSA subtitles to UTF-8 subtitles with limited HTML-style markup (<b>, <i>, <u>). + * + * SSA format references: + * http://www.matroska.org/technical/specs/subtitles/ssa.html + * http://moodub.free.fr/video/ass-specs.doc + * vlc-1.0.4/modules/codec/subtitles/subsass.c:ParseSSAString + * + * @author David Foster (davidfstr) + */ + +#include <stdlib.h> +#include <stdio.h> +#include "hb.h" + +typedef enum { + BOLD = 0x01, + ITALIC = 0x02, + UNDERLINE = 0x04 +} StyleSet; + +// "<b></b>".len + "<i></i>".len + "<u></u>".len +#define MAX_OVERHEAD_PER_OVERRIDE (7 * 3) + +#define SSA_2_HB_TIME(hr,min,sec,centi) \ + ( 90L * ( hr * 1000L * 60 * 60 +\ + min * 1000L * 60 +\ + sec * 1000L +\ + centi * 10L ) ) + +static StyleSet ssa_parse_style_override( char *pos, StyleSet prevStyles ) +{ + StyleSet nextStyles = prevStyles; + for (;;) + { + // Skip over leading '{' or last '\\' + pos++; + + // Scan for next \code + while ( *pos != '\\' && *pos != '}' && *pos != '\0' ) pos++; + if ( *pos != '\\' ) + { + // End of style override block + break; + } + + // If next chars are \[biu][01], interpret it + if ( strchr("biu", pos[1]) && strchr("01", pos[2]) ) + { + StyleSet styleID = + pos[1] == 'b' ? BOLD : + pos[1] == 'i' ? ITALIC : + pos[1] == 'u' ? UNDERLINE : 0; + int enabled = (pos[2] == '1'); + + if (enabled) + { + nextStyles |= styleID; + } + else + { + nextStyles &= ~styleID; + } + } + } + return nextStyles; +} + +static void ssa_append_html_tags_for_style_change( + char **dst, StyleSet prevStyles, StyleSet nextStyles ) +{ + #define APPEND(str) { \ + char *src = str; \ + while (*src) { *(*dst)++ = *src++; } \ + } + + // Reverse-order close all previous styles + if (prevStyles & UNDERLINE) APPEND("</u>"); + if (prevStyles & ITALIC) APPEND("</i>"); + if (prevStyles & BOLD) APPEND("</b>"); + + // Forward-order open all next styles + if (nextStyles & BOLD) APPEND("<b>"); + if (nextStyles & ITALIC) APPEND("<i>"); + if (nextStyles & UNDERLINE) APPEND("<u>"); + + #undef APPEND +} + +/* + * SSA packet format: + * Dialogue: Marked,Start,End,Style,Name,MarginL,MarginR,MarginV,Effect,Text + * 1 2 3 4 5 6 7 8 9 10 + */ +static hb_buffer_t *ssa_decode_to_utf8( hb_buffer_t *in ) +{ + uint8_t *pos = in->data; + uint8_t *end = in->data + in->size; + + // Store NULL after the end of the buffer to make using sscanf safe + hb_buffer_realloc( in, in->size + 1 ); + in->data[in->size] = '\0'; + + /* + * Parse Start and End fields for timing information + */ + int start_hr, start_min, start_sec, start_centi; + int end_hr, end_min, end_sec, end_centi; + int numPartsRead = sscanf( (char *) in->data, "%*128[^,]," + "%d:%d:%d.%d," // Start + "%d:%d:%d.%d,", // End + &start_hr, &start_min, &start_sec, &start_centi, + &end_hr, &end_min, &end_sec, &end_centi ); + if ( numPartsRead != 8 ) + goto fail; + + in->start = SSA_2_HB_TIME(start_hr, start_min, start_sec, start_centi); + in->stop = SSA_2_HB_TIME( end_hr, end_min, end_sec, end_centi); + + /* + * Advance 'pos' to the beginning of the Text field + */ + int curFieldID = 1; + while (pos < end) + { + if ( *pos++ == ',' ) + { + curFieldID++; + if ( curFieldID == 10 ) // Text + break; + } + } + if ( curFieldID != 10 ) + goto fail; + uint8_t *textFieldPos = pos; + + // Count the number of style overrides in the Text field + int numStyleOverrides = 0; + while ( pos < end ) + { + if (*pos++ == '{') + { + numStyleOverrides++; + } + } + + int maxOutputSize = (end - pos) + ((numStyleOverrides + 1) * MAX_OVERHEAD_PER_OVERRIDE); + hb_buffer_t *out = hb_buffer_init( maxOutputSize ); + if ( out == NULL ) + return NULL; + + /* + * The Text field contains plain text marked up with: + * (1) '\n' -> space + * (2) '\N' -> newline + * (3) curly-brace control codes like '{\k44}' -> empty (strip them) + * + * Perform the above conversions and copy it to the output packet + */ + StyleSet prevStyles = 0; + uint8_t *dst = out->data; + pos = textFieldPos; + while ( pos < end ) + { + if ( pos[0] == '\\' && pos[1] == 'n' ) + { + *dst++ = ' '; + pos += 2; + } + else if ( pos[0] == '\\' && pos[1] == 'N' ) + { + *dst++ = '\n'; + pos += 2; + } + else if ( pos[0] == '{' ) + { + // Parse SSA style overrides and append appropriate HTML style tags + StyleSet nextStyles = ssa_parse_style_override( pos, prevStyles ); + ssa_append_html_tags_for_style_change( &dst, prevStyles, nextStyles ); + prevStyles = nextStyles; + + // Skip past SSA control code + while ( pos < end && *pos != '}' ) pos++; + if ( pos < end && *pos == '}' ) pos++; + } + else + { + // Copy raw character + *dst++ = *pos++; + } + } + + // Append closing HTML style tags + ssa_append_html_tags_for_style_change( &dst, prevStyles, 0 ); + + // 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; + + return out; + +fail: + hb_log( "decssasub: malformed SSA subtitle packet: %.*s\n", in->size, in->data ); + return NULL; +} + +static int decssaInit( hb_work_object_t * w, hb_job_t * job ) +{ + return 0; +} + +static int decssaWork( 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; + + if ( in->size > 0 ) { + out = ssa_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 decssaClose( hb_work_object_t * w ) +{ + // nothing +} + +hb_work_object_t hb_decssasub = +{ + WORK_DECSSASUB, + "SSA Subtitle Decoder", + decssaInit, + decssaWork, + decssaClose +}; |