diff options
Diffstat (limited to 'libhb/demuxmpeg.c')
| -rw-r--r-- | libhb/demuxmpeg.c | 56 |
1 files changed, 45 insertions, 11 deletions
diff --git a/libhb/demuxmpeg.c b/libhb/demuxmpeg.c index 424cce696..35d941ad0 100644 --- a/libhb/demuxmpeg.c +++ b/libhb/demuxmpeg.c @@ -8,11 +8,10 @@ /* Basic MPEG demuxer, only works with DVDs (2048 bytes packets) */ -int hb_demux_ps( hb_buffer_t * buf_ps, hb_list_t * list_es ) +int hb_demux_ps( hb_buffer_t * buf_ps, hb_list_t * list_es, hb_psdemux_t* state ) { hb_buffer_t * buf_es; int pos = 0; - int64_t scr; #define d (buf_ps->data) @@ -25,14 +24,49 @@ int hb_demux_ps( hb_buffer_t * buf_ps, hb_list_t * list_es ) return 0; } pos += 4; /* pack_start_code */ - /* extract the system clock reference (scr) */ - scr = ((uint64_t)(d[pos] & 0x38) << 27) | - ((uint64_t)(d[pos] & 0x03) << 28) | - ((uint64_t)(d[pos+1]) << 20) | - ((uint64_t)(d[pos+2] >> 3) << 15) | - ((uint64_t)(d[pos+2] & 3) << 13) | - ((uint64_t)(d[pos+3]) << 5) | - (d[pos+4] >> 3); + + if ( state ) + { + /* + * This section of code implements the timing model of + * the "Standard Target Decoder" (STD) of the MPEG2 standard + * (specified in ISO 13818-1 sections 2.4.2, 2.5.2 & Annex D). + * The STD removes and corrects for clock discontinuities so + * that the time stamps on the video, audio & other media + * streams can be used for cross-media synchronization. To do + * this the STD has its own timestamp value, the System Clock + * Reference or SCR, in the PACK header. Clock discontinuities + * are detected using the SCR & and the adjustment needed + * to correct post-discontinuity timestamps to be contiguous + * with pre-discontinuity timestamps is computed from pre- and + * post-discontinuity values of the SCR. Then this adjustment + * is applied to every media timestamp (PTS). + * + * ISO 13818-1 says there must be an SCR at least every 700ms + * (100ms for Transport Streams) so if the difference between + * this SCR & the previous is >700ms it's a discontinuity. + * If the difference is negative it's non-physical (time doesn't + * go backward) and must also be a discontinuity. When we find a + * discontinuity we adjust the scr_offset so that the SCR of the + * new packet lines up with that of the previous packet. + */ + /* extract the system clock reference (scr) */ + int64_t scr = ((uint64_t)(d[pos] & 0x38) << 27) | + ((uint64_t)(d[pos] & 0x03) << 28) | + ((uint64_t)(d[pos+1]) << 20) | + ((uint64_t)(d[pos+2] >> 3) << 15) | + ((uint64_t)(d[pos+2] & 3) << 13) | + ((uint64_t)(d[pos+3]) << 5) | + (d[pos+4] >> 3); + int64_t scr_delta = scr - state->last_scr; + if ( scr_delta > (90*700) || scr_delta < 0 ) + { + ++state->scr_changes; + state->scr_offset += scr_delta - 1; + } + state->last_scr = scr; + } + pos += 9; /* pack_header */ pos += 1 + ( d[pos] & 0x7 ); /* stuffing bytes */ @@ -119,7 +153,7 @@ int hb_demux_ps( hb_buffer_t * buf_ps, hb_list_t * list_es ) buf_es->id = id; buf_es->start = pts; - buf_es->stop = scr; + buf_es->stop = -1; if (id == 0xE0) { // Consume a chapter break, and apply it to the ES. buf_es->new_chap = buf_ps->new_chap; |