* ogt.c : Overlay Graphics Text (SVCD subtitles) decoder thread
*****************************************************************************
* Copyright (C) 2003 VideoLAN
- * $Id: ogt.c,v 1.1 2003/12/07 22:14:26 rocky Exp $
+ * $Id: ogt.c,v 1.2 2003/12/08 06:01:11 rocky Exp $
*
* Authors: Rocky Bernstein
* based on code from:
static void Close ( vlc_object_t * );
vlc_module_begin();
- set_description( _("SVCD subtitle decoder") );
+ set_description( _("Philips OGT (SVCD subtitle) decoder") );
set_capability( "decoder", 50 );
set_callbacks( DecoderOpen, Close );
N_(DEBUG_LONGTEXT), VLC_TRUE );
add_submodule();
- set_description( _("SVCD subtitle packetizer") );
+ set_description( _("Phlips OGT (SVCD subtitle) packetizer") );
set_capability( "packetizer", 50 );
set_callbacks( PacketizerOpen, Close );
vlc_module_end();
return NULL;
}
-#define SPU_HEADER_LEN 5
-
-/*****************************************************************************
- Reassemble:
-
- The data for single screen subtitle may come in one of many
- non-contiguous packets of a stream. This routine is called when the
- next packet in the stream comes in. The job of this routine is to
- parse the header if this is the beginning) and combine the packets into one
- complete subtitle unit.
-
- If everything is complete, we will return a block. Otherwise return
- NULL.
-
+/*
The following information is mostly extracted from the SubMux package of
unknown author with additional experimentation.
The format is roughly as follows (everything is big-endian):
- byte subtitle channel 0-3
- byte subtitle packet number in this subtitle image 0-N,
- last is XOR'ed 0x80
- u_int16 subtitle image number
- u_int16 length in bytes of the rest
- byte option flags, unknown meaning except bit 3 (0x08) indicates
- presence of the duration field
- byte unknown meaning
- u_int32 duration in 1/90000ths of a second (optional), start time
- is as indicated by the PTS in the PES header
- u_int32 xpos
- u_int32 ypos
- u_int32 width (must be even)
- u_int32 height (must be even)
- byte[16] palette, 4 palette entries, each contains values for
- Y, U, V and transparency, 0 standing for transparent
- byte command,
- cmd>>6==1 indicates shift
- (cmd>>4)&3 is direction from, (0=top,1=left,2=right,3=bottom)
- u_int32 shift duration in 1/90000ths of a second
- u_int16 offset of odd field (subtitle image is presented interlaced)
- byte[] image
+ size description
+ -------------------------------------------
+ byte subtitle channel (0..7) in bits 0-3
+ byte subtitle packet number of this subtitle image 0-N,
+ if the subtitle packet is complete, the top bit of the byte is 1.
+ u_int16 subtitle image number
+ u_int16 length in bytes of the rest
+ byte option flags, unknown meaning except bit 3 (0x08) indicates
+ presence of the duration field
+ byte unknown
+ u_int32 duration in 1/90000ths of a second (optional), start time
+ is as indicated by the PTS in the PES header
+ u_int32 xpos
+ u_int32 ypos
+ u_int32 width (must be even)
+ u_int32 height (must be even)
+ byte[16] palette, 4 palette entries, each contains values for
+ Y, U, V and transparency, 0 standing for transparent
+ byte command,
+ cmd>>6==1 indicates shift
+ (cmd>>4)&3 is direction from, (0=top,1=left,2=right,3=bottom)
+ u_int32 shift duration in 1/90000ths of a second
+ u_int16 offset of odd field (subtitle image is presented interlaced)
+ byte[] bit image
The image is encoded using two bits per pixel that select a palette
entry except that value 00 starts a limited rle. When 00 is seen,
first field is padded to an even byte lenght and the complete subtitle
is padded to a 4-byte multiple that always include one zero byte at
the end.
+*/
+
+/* FIXME: do we really need p_buffer and p?
+ Can't all of thes _offset's and _lengths's get removed?
+*/
+static void
+ParseHeader( decoder_t *p_dec, uint8_t *p_buffer, block_t *p_block )
+{
+ decoder_sys_t *p_sys = p_dec->p_sys;
+ u_int8_t *p = p_buffer;
+ int i;
+
+ p_sys->i_pts = p_block->i_pts;
+
+ p_sys->i_spu_size = GETINT16(p);
+ p_sys->i_options = *p++;
+ p_sys->i_options2 = *p++;
+
+ if ( p_sys->i_options & 0x08 ) {
+ p_sys->i_duration = GETINT32(p);
+ } else {
+ /* 0 means display until next subtitle comes in. */
+ p_sys->i_duration = 0;
+ }
+ p_sys->i_x_start= GETINT16(p);
+ p_sys->i_y_start= GETINT16(p);
+ p_sys->i_width = GETINT16(p);
+ p_sys->i_height = GETINT16(p);
+
+ for (i=0; i<4; i++) {
+ p_sys->pi_palette[i].y = *p++;
+ p_sys->pi_palette[i].u = *p++;
+ p_sys->pi_palette[i].v = *p++;
+ /* We have just 4-bit resolution for alpha, but the value for SVCD
+ * has 8 bits so we scale down the values to the acceptable range */
+ p_sys->pi_palette[i].t = (*p++) >> 4;
+ }
+ p_sys->i_cmd = *p++;
+ /* We do not really know this, FIXME */
+ if ( p_sys->i_cmd ) {
+ p_sys->i_cmd_arg = GETINT32(p);
+ }
+ /* Image starts just after skipping next short */
+ p_sys->comp_image_offset = p + 2 - p_buffer;
+ /* There begins the first field, so no correction needed */
+ p_sys->first_field_offset = 0;
+ /* Actually, this is measured against a different origin, so we have to
+ adjust it */
+ p_sys->second_field_offset = GETINT16(p);
+ p_sys->comp_image_offset = p - p_buffer;
+ p_sys->comp_image_length =
+ p_sys->subtitle_data_length - p_sys->comp_image_offset;
+ p_sys->metadata_length = p_sys->comp_image_offset;
+
+ /*spuogt_init_subtitle_data(p_sys);*/
+
+ p_sys->subtitle_data_pos = 0;
+
+ dbg_print( (DECODE_DBG_PACKET),
+ "x-start: %d, y-start: %d, width: %d, height %d, "
+ "spu size: %d, duration: %u",
+ p_sys->i_x_start, p_sys->i_y_start,
+ p_sys->i_width, p_sys->i_height,
+ p_sys->i_spu_size, p_sys->i_duration );
+}
+
+
+#define SPU_HEADER_LEN 5
+
+/*****************************************************************************
+ Reassemble:
+
+ The data for single screen subtitle may come in one of many
+ non-contiguous packets of a stream. This routine is called when the
+ next packet in the stream comes in. The job of this routine is to
+ parse the header if this is the beginning) and combine the packets into one
+ complete subtitle unit.
+
+ If everything is complete, we will return a block. Otherwise return
+ NULL.
+
+ The format of the beginning of the subtitle packet that is used here.
+
+ size description
+ -------------------------------------------
+ byte subtitle channel (0..7) in bits 0-3
+ byte subtitle packet number of this subtitle image 0-N,
+ if the subtitle packet is complete, the top bit of the byte is 1.
+ u_int16 subtitle image number
*****************************************************************************/
static block_t *
if ( p_sys->i_packet == 0 ) {
/* First packet in the subtitle block */
- /* FIXME: Put all of this into a subroutine. */
- u_int8_t *p = p_buffer;
- p = p_buffer;
- int i;
-
- p_sys->i_pts = p_block->i_pts;
-
- p_sys->i_spu_size = GETINT16(p);
- p_sys->i_options = *p++;
- p_sys->i_options2 = *p++;
-
- if ( p_sys->i_options & 0x08 ) {
- p_sys->duration = GETINT32(p);
- } else {
- p_sys->duration = 0;
- }
- p_sys->i_x_start= GETINT16(p);
- p_sys->i_y_start= GETINT16(p);
- p_sys->i_width = GETINT16(p);
- p_sys->i_height = GETINT16(p);
-
- for (i=0; i<4; i++) {
- p_sys->pi_palette[i].y = *p++;
- p_sys->pi_palette[i].u = *p++;
- p_sys->pi_palette[i].v = *p++;
- /* We have just 4-bit resolution for alpha, but the value for SVCD
- * has 8 bits so we scale down the values to the acceptable range */
- p_sys->pi_palette[i].t = (*p++) >> 4;
- }
- p_sys->i_cmd = *p++;
- /* We do not really know this, FIXME */
- if ( p_sys->i_cmd ) {
- p_sys->i_cmd_arg = GETINT32(p);
- }
- /* Image starts just after skipping next short */
- p_sys->comp_image_offset = p + 2 - p_buffer;
- /* There begins the first field, so no correction needed */
- p_sys->first_field_offset = 0;
- /* Actually, this is measured against a different origin, so we have to
- adjust it */
- p_sys->second_field_offset = GETINT16(p);
- p_sys->comp_image_offset = p - p_buffer;
- p_sys->comp_image_length =
- p_sys->subtitle_data_length - p_sys->comp_image_offset;
- p_sys->metadata_length = p_sys->comp_image_offset;
-
- /*spuogt_init_subtitle_data(p_sys);*/
-
- p_sys->subtitle_data_pos = 0;
-
- dbg_print( (DECODE_DBG_PACKET),
- "x-start: %d, y-start: %d, width: %d, height %d, "
- "spu size: %d",
- p_sys->i_x_start, p_sys->i_y_start,
- p_sys->i_width, p_sys->i_height,
- p_sys->i_spu_size );
+ ParseHeader( p_dec, p_buffer, p_block );
}
-
+
block_ChainAppend( &p_sys->p_block, p_block );
p_sys->i_spu += p_block->i_buffer - SPU_HEADER_LEN;
projects / vlc / commitdiff