/** State for an RTP source */
struct rtp_source_t
{
- mtime_t expiry; /* inactivation date */
uint32_t ssrc;
+ uint32_t jitter; /* interarrival delay jitter estimate */
+ mtime_t last_rx; /* last received packet local timestamp */
+ uint32_t last_ts; /* last received packet RTP timestamp */
+
uint16_t bad_seq; /* tentatively next expected sequence for resync */
uint16_t max_seq; /* next expected sequence */
- uint32_t jitter; /* interarrival delay jitter estimate */
uint16_t last_seq; /* sequence of the last dequeued packet */
block_t *blocks; /* re-ordered blocks queue */
return NULL;
source->ssrc = ssrc;
+ source->jitter = 0;
source->max_seq = source->bad_seq = init_seq;
source->last_seq = init_seq - 1;
source->blocks = NULL;
return GetWBE (block->p_buffer + 2);
}
+static inline uint32_t rtp_timestamp (const block_t *block)
+{
+ assert (block->i_buffer >= 12);
+ return GetDWBE (block->p_buffer + 4);
+}
+
/**
* Receives an RTP packet and queues it.
* @param demux VLC demux object
}
/* RTP source garbage collection */
- if (tmp->expiry < now)
+ if ((tmp->last_rx + (p_sys->timeout * CLOCK_FREQ)) < now)
{
rtp_source_destroy (demux, session, tmp);
if (--session->srcc > 0)
goto drop;
tab[session->srcc++] = src;
+ /* Cannot compute jitter yet */
+ }
+ else if (session->ptc > 0)
+ {
+ /* Recompute jitter estimate. That is computed from the RTP timestamps
+ * and the system clock. It is independent of RTP sequence. */
+ /* FIXME: payload types have the same frequency? */
+ uint32_t freq = session->ptv[0].frequency;
+ uint32_t ts = rtp_timestamp (block);
+ int64_t d = ((now - src->last_rx) * freq) / CLOCK_FREQ;
+ d -= ts - src->last_ts;
+ if (d < 0) d = -d;
+ src->jitter += ((d - src->jitter) + 8) >> 4;
}
+ src->last_rx = now;
+ src->last_ts = rtp_timestamp (block);
/* Be optimistic for the first packet. Certain codec, such as Vorbis
* do not like loosing the first packet(s), so we cannot just wait
* Otherwise it would be impossible to compute consistent timestamps. */
/* FIXME: handle timestamp wrap properly */
/* TODO: sync multiple sources sanely... */
- const uint32_t timestamp = GetDWBE (block->p_buffer + 4);
+ const uint32_t timestamp = rtp_timestamp (block);
block->i_pts = UINT64_C(1) * CLOCK_FREQ * timestamp / pt->frequency;
/* CSRC count */