#include "hb.h"
#include "a52dec/a52.h"
+#include "libavutil/crc.h"
struct hb_work_private_s
{
int flags_out;
int rate;
int bitrate;
+ int out_discrete_channels;
+ int error;
+ int frames; // number of good frames decoded
+ int crc_errors; // number of frames with crc errors
+ int bytes_dropped; // total bytes dropped while resyncing
float level;
float dynamic_range_compression;
-
- int error;
- int sync;
- int size;
-
- int64_t next_expected_pts;
-
- int64_t sequence;
-
+ double next_expected_pts;
+ int64_t last_buf_pts;
+ hb_list_t *list;
+ const AVCRC *crc_table;
uint8_t frame[3840];
-
- hb_list_t * list;
-
- int out_discrete_channels;
-
};
static int deca52Init( hb_work_object_t *, hb_job_t * );
pv->job = job;
+ pv->crc_table = av_crc_get_table( AV_CRC_16_ANSI );
pv->list = hb_list_init();
pv->state = a52_init( 0 );
pv->level = 32768.0;
pv->dynamic_range_compression = audio->config.out.dynamic_range_compression;
- pv->next_expected_pts = 0;
- pv->sequence = 0;
-
return 0;
}
static void deca52Close( hb_work_object_t * w )
{
hb_work_private_t * pv = w->private_data;
+
+ if ( pv->crc_errors )
+ {
+ hb_log( "deca52: %d frames decoded, %d crc errors, %d bytes dropped",
+ pv->frames, pv->crc_errors, pv->bytes_dropped );
+ }
a52_free( pv->state );
hb_list_empty( &pv->list );
free( pv );
return HB_WORK_DONE;
}
- pv->sequence = (*buf_in)->sequence;
+ if ( (*buf_in)->start < -1 && pv->next_expected_pts == 0 )
+ {
+ // discard buffers that start before video time 0
+ *buf_out = NULL;
+ return HB_WORK_OK;
+ }
hb_list_add( pv->list, *buf_in );
*buf_in = NULL;
*buf_out = buf = Decode( w );
while( buf )
{
- buf->sequence = pv->sequence;
buf->next = Decode( w );
buf = buf->next;
}
hb_buffer_t * buf;
hb_audio_t * audio = w->audio;
int i, j, k;
- uint64_t pts, pos;
+ int size = 0;
- /* Get a frame header if don't have one yet */
- if( !pv->sync )
+ // check that we're at the start of a valid frame and align to the
+ // start of a valid frame if we're not.
+ // we have to check the header & crc so we need at least
+ // 7 (the header size) + 128 (the minimum frame size) bytes
+ while( hb_list_bytes( pv->list ) >= 7+128 )
{
- while( hb_list_bytes( pv->list ) >= 7 )
+ /* check if this is a valid header */
+ hb_list_seebytes( pv->list, pv->frame, 7 );
+ size = a52_syncinfo( pv->frame, &pv->flags_in, &pv->rate, &pv->bitrate );
+ if ( size > 0 )
{
- /* We have 7 bytes, check if this is a correct header */
- hb_list_seebytes( pv->list, pv->frame, 7 );
- pv->size = a52_syncinfo( pv->frame, &pv->flags_in, &pv->rate,
- &pv->bitrate );
- if( pv->size )
+ // header looks valid - check the crc1
+ if( size > hb_list_bytes( pv->list ) )
+ {
+ // don't have all the frame's data yet
+ return NULL;
+ }
+ int crc1size = (size >> 1) + (size >> 3);
+ hb_list_seebytes( pv->list, pv->frame, crc1size );
+ if ( av_crc( pv->crc_table, 0, pv->frame + 2, crc1size - 2 ) == 0 )
{
- /* It is. W00t. */
+ // crc1 is ok - say we have valid frame sync
if( pv->error )
{
- hb_log( "a52_syncinfo ok" );
+ hb_log( "output track %d: ac3 in sync after skipping %d bytes",
+ audio->config.out.track, pv->error );
+ pv->bytes_dropped += pv->error;
+ pv->error = 0;
}
- pv->error = 0;
- pv->sync = 1;
break;
}
-
- /* It is not */
- if( !pv->error )
- {
- hb_log( "a52_syncinfo failed" );
- pv->error = 1;
- }
-
- /* Try one byte later */
- hb_list_getbytes( pv->list, pv->frame, 1, NULL, NULL );
}
+ // no sync - discard one byte then try again
+ hb_list_getbytes( pv->list, pv->frame, 1, NULL, NULL );
+ ++pv->error;
}
- if( !pv->sync ||
- hb_list_bytes( pv->list ) < pv->size )
+ // we exit the above loop either in error state (we didn't find sync
+ // or don't have enough data yet to validate sync) or in sync. If we're
+ // not in sync we need more data so just return.
+ if( pv->error || size <= 0 || hb_list_bytes( pv->list ) < size )
{
/* Need more data */
return NULL;
}
- /* Get the whole frame */
- hb_list_getbytes( pv->list, pv->frame, pv->size, &pts, &pos );
- if (pts == -1)
+ // Get the whole frame and check its CRC. If the CRC is wrong
+ // discard the frame - we'll resync on the next call.
+
+ uint64_t ipts;
+ hb_list_getbytes( pv->list, pv->frame, size, &ipts, NULL );
+ if ( av_crc( pv->crc_table, 0, pv->frame + 2, size - 2 ) != 0 )
+ {
+ ++pv->crc_errors;
+ return NULL;
+ }
+ ++pv->frames;
+ if ( ipts != pv->last_buf_pts )
+ {
+ pv->last_buf_pts = ipts;
+ }
+ else
{
- pts = pv->next_expected_pts;
+ // spec says that the PTS is the start time of the first frame
+ // that starts in the PES frame so we only use the PTS once then
+ // get the following frames' PTS from the frame length.
+ ipts = -1;
}
+ double pts = ( ipts != -1 ) ? ipts : pv->next_expected_pts;
+ double frame_dur = (6. * 256. * 90000.) / pv->rate;
+
/* AC3 passthrough: don't decode the AC3 frame */
if( audio->config.out.codec == HB_ACODEC_AC3 )
{
- buf = hb_buffer_init( pv->size );
- memcpy( buf->data, pv->frame, pv->size );
- buf->start = pts + ( pos / pv->size ) * 6 * 256 * 90000 / pv->rate;
- buf->stop = buf->start + 6 * 256 * 90000 / pv->rate;
- pv->next_expected_pts = buf->stop;
- pv->sync = 0;
+ buf = hb_buffer_init( size );
+ memcpy( buf->data, pv->frame, size );
+ buf->start = pts;
+ pts += frame_dur;
+ buf->stop = pts;
+ pv->next_expected_pts = pts;
return buf;
}
/* Feed liba52 */
a52_frame( pv->state, pv->frame, &pv->flags_out, &pv->level, 0 );
- if ( pv->dynamic_range_compression > 1.0 )
+ /* If a user specifies strong dynamic range compression (>1), adjust it.
+ If a user specifies default dynamic range compression (1), leave it alone.
+ If a user specifies no dynamic range compression (0), call a null function. */
+ if( pv->dynamic_range_compression > 1.0 )
{
- a52_dynrng( pv->state, dynrng_call, &pv->dynamic_range_compression);
+ a52_dynrng( pv->state, dynrng_call, &pv->dynamic_range_compression );
+ }
+ else if( !pv->dynamic_range_compression )
+ {
+ a52_dynrng( pv->state, NULL, NULL );
}
/* 6 blocks per frame, 256 samples per block, channelsused channels */
buf = hb_buffer_init( 6 * 256 * pv->out_discrete_channels * sizeof( float ) );
- buf->start = pts + ( pos / pv->size ) * 6 * 256 * 90000 / pv->rate;
- buf->stop = buf->start + 6 * 256 * 90000 / pv->rate;
-
- /*
- * To track AC3 PTS add this back in again.
- *hb_log("AC3: pts is %lld, buf->start %lld buf->stop %lld", pts, buf->start, buf->stop);
- */
-
- pv->next_expected_pts = buf->stop;
+ buf->start = pts;
+ pts += frame_dur;
+ buf->stop = pts;
+ pv->next_expected_pts = pts;
for( i = 0; i < 6; i++ )
{
}
}
-
- pv->sync = 0;
return buf;
}
-static int deca52BSInfo( hb_work_object_t *w, const hb_buffer_t *b,
- hb_work_info_t *info )
+static int find_sync( const uint8_t *buf, int len )
{
int i;
- int rate = 0, bitrate = 0, flags = 0;
- int old_rate = 0, old_bitrate = 0;
- uint8_t raw;
+ // since AC3 frames don't line up with MPEG ES frames scan the
+ // frame for an AC3 sync pattern.
+ for ( i = 0; i < len - 16; ++i )
+ {
+ int rate, bitrate, flags;
+ int size = a52_syncinfo( (uint8_t *)buf + i, &flags, &rate, &bitrate );
+ if( size > 0 )
+ {
+ // we have a plausible sync header - see if crc1 checks
+ int crc1size = (size >> 1) + (size >> 3);
+ if ( i + crc1size > len )
+ {
+ // don't have enough data to check crc1
+ break;
+ }
+ if ( av_crc( av_crc_get_table( AV_CRC_16_ANSI ), 0,
+ buf + i + 2, crc1size - 2 ) == 0 )
+ {
+ // crc checks - we've got sync
+ return i;
+ }
+ }
+ }
+ return -1;
+}
+
+static int deca52BSInfo( hb_work_object_t *w, const hb_buffer_t *b,
+ hb_work_info_t *info )
+{
memset( info, 0, sizeof(*info) );
- /* since AC3 frames don't line up with MPEG ES frames scan the
- * entire frame for an AC3 sync pattern. */
- for ( i = 0; i < b->size - 7; ++i )
+ // We don't know if the way that AC3 frames are fragmented into whatever
+ // packetization the container uses will give us enough bytes per fragment
+ // to check the CRC (we need at least 5/8 of the the frame). So we
+ // copy the fragment we got into an accumulation buffer in the audio object
+ // then look for sync over all the frags we've accumulated so far.
+ uint8_t *buf = w->audio->priv.config.a52.buf;
+ int len = w->audio->priv.config.a52.len, blen = b->size;
+ if ( len + blen > sizeof(w->audio->priv.config.a52.buf) )
{
- if( a52_syncinfo( &b->data[i], &flags, &rate, &bitrate ) != 0 )
+ // we don't have enough empty space in the accumulation buffer to
+ // hold the new frag - make room for it by discarding the oldest data.
+ if ( blen >= sizeof(w->audio->priv.config.a52.buf) )
{
- /*
- * Got sync apparently, save these values and check that they
- * also match when we get sync again.
- */
- if( old_rate )
- {
- if( rate == old_rate && bitrate == old_bitrate )
- {
- break;
- }
- }
-
- old_rate = rate;
- old_bitrate = bitrate;
- raw = b->data[i+5];
+ // the frag is bigger than our accumulation buffer - copy all
+ // that will fit (the excess doesn't matter since the buffer
+ // is many times the size of a max length ac3 frame).
+ blen = sizeof(w->audio->priv.config.a52.buf);
+ len = 0;
+ }
+ else
+ {
+ // discard enough bytes from the front of the buffer to make
+ // room for the new stuff
+ int newlen = sizeof(w->audio->priv.config.a52.buf) - blen;
+ memcpy( buf, buf + len - newlen, newlen );
+ len = newlen;
}
}
- if ( rate == 0 || bitrate == 0 )
+ // add the new frag to the buffer
+ memcpy( buf+len, b->data, blen );
+ len += blen;
+
+ int i;
+ if ( ( i = find_sync( buf, len ) ) < 0 )
{
- /* didn't find AC3 sync */
+ // didn't find sync - wait for more data
+ w->audio->priv.config.a52.len = len;
return 0;
}
- /*
- * bsid | bsmod | acmod | cmixlev | surmixlev | dsurmod | lfeon | dialnorm | compre
- * 5 3 3 2 2 2 1 5 1
- * [ byte1 ][ byte2 ][ byte3 ]
- */
+ // got sync - extract and canoncalize the bitstream parameters
+ int rate = 0, bitrate = 0, flags = 0;
+ uint8_t raw = buf[i + 5];
+ a52_syncinfo( buf + i, &flags, &rate, &bitrate );
+
+ if ( rate == 0 || bitrate == 0 )
+ {
+ // invalid AC-3 parameters - toss what we have so we'll start over
+ // with the next buf otherwise we'll keep syncing on this junk.
+ w->audio->priv.config.a52.len = 0;
+ return 0;
+ }
+ // bsid | bsmod | acmod | cmixlv | surmixlv | dsurmod | lfeon | dialnorm | compre
+ // 5 3 3 2 2 2 1 5 1
+ // byte1 | byte2 | byte3
info->name = "AC-3";
info->rate = rate;
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