diff options
| -rw-r--r-- | src/demuxers/demux_ts.c | 144 |
1 files changed, 43 insertions, 101 deletions
diff --git a/src/demuxers/demux_ts.c b/src/demuxers/demux_ts.c index 3766c8af1..ac65030fb 100644 --- a/src/demuxers/demux_ts.c +++ b/src/demuxers/demux_ts.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: demux_ts.c,v 1.12 2001/09/04 16:19:27 guenter Exp $ + * $Id: demux_ts.c,v 1.13 2001/09/10 00:55:48 jcdutton Exp $ * * Demultiplexer for MPEG2 Transport Streams. * @@ -34,6 +34,8 @@ * * Date Author * ---- ------ + * 10-Sep-2001 James Courtier-Dutton <jcdutton> + * Re-wrote sync code so that it now does not loose any data. * 27-Aug-2001 Hubert Matthews Reviewed by: n/a * Added in synchronisation code. * @@ -72,6 +74,9 @@ #define PKT_SIZE 188 #define BODY_SIZE (188 - 4) #define MAX_PIDS ((BODY_SIZE - 1 - 13) / 4) +#define SYNC_BYTE 0x47 +#define MIN_SYNCS 5 +#define BUF_SIZE ((MIN_SYNCS+1) * PKT_SIZE) #define NULL_PID 8191 #define INVALID_PID ((unsigned int)(-1)) @@ -617,114 +622,52 @@ static void demux_ts_parse_pmt(demux_ts *this, } } -/********************************************************************* - * - * 2001/08/26 Hubert Matthews - * - * Added input synchronisation code. This code ensures synchronisation - * where possible by checking that we have 5 sync bytes at 188 bytes apart. - * On startup, it finds the first packet with a sync byte in it and starts - * buffering after that. It starts to release packets to the demux when it - * has found five synchronised packets in a row. If sync is broken at any - * time (bit error or dropped multicast packet, for instance) it dumps all - * its buffers and attempts to acquire sync again. - * - * Returns NULL when it is in buffering mode, and the address of an aligned - * packet otherwise. NULL causes the calling function to go back around its - * loop, so its harmless and easier than doing the packet looping internally. - */ - -#define SYNC_BYTE 0x47 -#define MIN_SYNCS 5 -#define BUF_SIZE ((MIN_SYNCS+1) * PKT_SIZE) -#define WRAP_ADD(x, incr, limit) \ - (x) += (incr); \ - if ((x) >= (limit)) (x) -= (limit) -#define BUMP(x) WRAP_ADD((x), PKT_SIZE, (BUF_SIZE - PKT_SIZE)) - -/* When we've acquired sync, we need to set all of the continuity - * counters to an invalid value to disable the sequence checking */ +void correct_for_sync(demux_ts *this,uint8_t *buf) { + int32_t n, read_length; + if((buf[0] == SYNC_BYTE) && (buf[PKT_SIZE] == SYNC_BYTE) && + (buf[PKT_SIZE*2] == SYNC_BYTE) && (buf[PKT_SIZE*3] == SYNC_BYTE)) { + return; + } + for(n=1;n<PKT_SIZE;n++) { + if((buf[n] == SYNC_BYTE) && (buf[n+PKT_SIZE] == SYNC_BYTE) && + (buf[n+(PKT_SIZE*2)] == SYNC_BYTE) && (buf[n+(PKT_SIZE*3)] == SYNC_BYTE)) { + /* Found sync, fill in */ + memmove(&buf[0],&buf[n],((PKT_SIZE*MIN_SYNCS)-n)); + read_length = this->input->read(this->input, &buf[(PKT_SIZE*MIN_SYNCS)-n], n); + return; + } + } + printf("RE-Sync failed\n"); /* Sync up here */ + return; -static void resetAllCCs(demux_ts * this) { - int i; - for (i = 0; i != MAX_PIDS; ++i) - this->media[i].counter = INVALID_CC; -} - -/* Find the first sync byte in the packet pointed to by p */ - -static int searchForSyncByte(const unsigned char * p) { - const unsigned char * start = p, * end = p + PKT_SIZE; - - while (p != end && *p != SYNC_BYTE) - p++; - - if (p == end) - return -1; - else - return p - start; } + /* Main synchronisation routine. - * Returns NULL when it is in buffering mode, and the address of an aligned - * packet otherwise. NULL causes the calling function to go back around its - * loop, so its harmless and easier than doing the packet looping internally. */ static unsigned char * demux_synchronise(demux_ts * this) { - static int in, out, count; /* statics are zeroed */ - static unsigned char buf[BUF_SIZE]; - - int syncByte, syncBytePosn; - unsigned char * retPtr = NULL; - - if (this->input->read(this->input, &buf[in], PKT_SIZE) != PKT_SIZE) { - if (count > 0) { - int oldOut = out; /* drain pipeline on end of stream */ - BUMP(out); - count--; - retPtr = &buf[oldOut]; - } else { - this->status = DEMUX_FINISHED; - } - return retPtr; - } - - syncBytePosn = out; - WRAP_ADD(syncBytePosn, count * PKT_SIZE, BUF_SIZE - PKT_SIZE); - syncByte = buf[syncBytePosn]; - - if (syncByte != SYNC_BYTE) { /* new packet not in sync */ - int syncPosn = searchForSyncByte(&buf[in]); - if (syncPosn > 0) { - memmove(&buf[0], &buf[in + syncPosn], PKT_SIZE - syncPosn); - in = PKT_SIZE - syncPosn; - } else { - in = 0; /* no sync byte in packet, so start again */ - } - out = count = 0; - } else { /* this packet extends the sync run */ - BUMP(in); - count++; - if (count > MIN_SYNCS) { /* sync acquired */ - int oldOut = out; - resetAllCCs(this); - BUMP(out); - count--; - retPtr = &buf[oldOut]; + static int32_t packet_number=MIN_SYNCS; + static uint8_t buf[BUF_SIZE]; /* This should change to a malloc. */ + uint8_t *return_pointer = NULL; + int32_t n, read_length; + + if (packet_number == MIN_SYNCS) { + for(n=0;n<MIN_SYNCS;n++) { + read_length = this->input->read(this->input, &buf[n*PKT_SIZE], PKT_SIZE); + if(read_length != PKT_SIZE) { + this->status = DEMUX_FINISHED; + return NULL; + } } - } - - return retPtr; + packet_number=0; + correct_for_sync(this,&buf[0]); + } + return_pointer=&buf[PKT_SIZE*packet_number]; + packet_number++; + return return_pointer; } - -#undef BUMP -#undef WRAP_ADD -#undef MIN_SYNCS -#undef BUF_SIZE -#undef SYNC_BYTE - - + /* transport stream packet layer */ static void demux_ts_parse_packet (demux_ts *this) { @@ -757,7 +700,6 @@ static void demux_ts_parse_packet (demux_ts *this) { /* * Discard packets that are obviously bad. - * FIXME: maybe search for 0x47 is the first 188 bytes[packet size] of stream. */ if (sync_byte != 0x47) { fprintf (stderr, "demux error! invalid ts sync byte %02x\n",originalPkt[0]); |