diff options
Diffstat (limited to 'src/liba52')
| -rw-r--r-- | src/liba52/xine_decoder.c | 29 |
1 files changed, 28 insertions, 1 deletions
diff --git a/src/liba52/xine_decoder.c b/src/liba52/xine_decoder.c index 25e8eb9a3..061e76414 100644 --- a/src/liba52/xine_decoder.c +++ b/src/liba52/xine_decoder.c @@ -17,7 +17,7 @@ * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA * - * $Id: xine_decoder.c,v 1.59 2003/11/02 13:50:09 miguelfreitas Exp $ + * $Id: xine_decoder.c,v 1.60 2003/11/04 00:45:24 jcdutton Exp $ * * stuff needed to turn liba52 into a xine decoder plugin */ @@ -429,6 +429,33 @@ static void a52dec_decode_data (audio_decoder_t *this_gen, buf_element_t *buf) { end = buf->content + buf->size; } + /* A52 packs come from the DVD in blocks of about 2048 bytes. + * Only 1 PTS values can be assigned to each block. + * An A52 frame is about 1700 bytes long. + * So, a single A52 packs can contain 2 A52 frames (or the beginning of an A52 frame at least). + * If we have a PTS value, which A52 frame does it apply to? The A52 pack tells us that. + * So, the info about which A52 frame the PTS applies to is contained in decoder_info sent from the demuxer. + * + * The PTS value from the A52 pack (DVD sector) can only be applied at the start of an A52 frame. + * We call the start of an A52 frame a frame header. + * So, if a A52 pack has 2 "Number of frame headers" is means that the A52 pack contains 2 A52 frame headers. + * The "First access unit" then tells us which A52 frame the PTS value applies to. + * + * Take the following example: - + * PACK1: PTS = 10. Contains the entire A52 frame1, followed by the beginning of the frame2. PTS applies to frame1. + * PACK2: PTS = 1000, Contains the rest of frame2, and the whole of frame3. and the start of frame4. PTS applies to frame4. + * PACK3: PTS = 0 (none), Contains the rest of frame4. + * + * Output should be: - + * frame1, PTS=10 + * frame2, PTS=0 + * frame3, PTS=0 + * frame4, PTS=1000 + * + * So, we have to keep track of PTS values from previous A52 packs here, otherwise they get put on the wrong frame. + */ + + if (buf->pts) { int32_t info; info = buf->decoder_info[1]; |