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https://gitlab.freedesktop.org/gstreamer/gstreamer.git
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531 lines
15 KiB
C
531 lines
15 KiB
C
/* GStreamer
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* Copyright (C) <2007> Wim Taymans <wim.taymans@gmail.com>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
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* Boston, MA 02110-1301, USA.
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*/
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#include <string.h>
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#include <stdlib.h>
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#include "rdtjitterbuffer.h"
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#include "gstrdtbuffer.h"
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GST_DEBUG_CATEGORY_STATIC (rdt_jitter_buffer_debug);
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#define GST_CAT_DEFAULT rdt_jitter_buffer_debug
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#define MAX_WINDOW RDT_JITTER_BUFFER_MAX_WINDOW
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#define MAX_TIME (2 * GST_SECOND)
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/* signals and args */
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enum
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{
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LAST_SIGNAL
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};
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enum
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{
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PROP_0
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};
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/* GObject vmethods */
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static void rdt_jitter_buffer_finalize (GObject * object);
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/* static guint rdt_jitter_buffer_signals[LAST_SIGNAL] = { 0 }; */
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G_DEFINE_TYPE (RDTJitterBuffer, rdt_jitter_buffer, G_TYPE_OBJECT);
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static void
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rdt_jitter_buffer_class_init (RDTJitterBufferClass * klass)
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{
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GObjectClass *gobject_class;
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gobject_class = (GObjectClass *) klass;
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gobject_class->finalize = rdt_jitter_buffer_finalize;
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GST_DEBUG_CATEGORY_INIT (rdt_jitter_buffer_debug, "rdtjitterbuffer", 0,
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"RDT Jitter Buffer");
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}
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static void
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rdt_jitter_buffer_init (RDTJitterBuffer * jbuf)
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{
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jbuf->packets = g_queue_new ();
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rdt_jitter_buffer_reset_skew (jbuf);
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}
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static void
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rdt_jitter_buffer_finalize (GObject * object)
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{
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RDTJitterBuffer *jbuf;
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jbuf = RDT_JITTER_BUFFER_CAST (object);
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rdt_jitter_buffer_flush (jbuf);
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g_queue_free (jbuf->packets);
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G_OBJECT_CLASS (rdt_jitter_buffer_parent_class)->finalize (object);
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}
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/**
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* rdt_jitter_buffer_new:
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*
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* Create an #RDTJitterBuffer.
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*
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* Returns: a new #RDTJitterBuffer. Use g_object_unref() after usage.
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*/
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RDTJitterBuffer *
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rdt_jitter_buffer_new (void)
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{
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RDTJitterBuffer *jbuf;
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jbuf = g_object_new (RDT_TYPE_JITTER_BUFFER, NULL);
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return jbuf;
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}
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void
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rdt_jitter_buffer_reset_skew (RDTJitterBuffer * jbuf)
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{
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jbuf->base_time = -1;
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jbuf->base_rtptime = -1;
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jbuf->ext_rtptime = -1;
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jbuf->window_pos = 0;
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jbuf->window_filling = TRUE;
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jbuf->window_min = 0;
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jbuf->skew = 0;
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jbuf->prev_send_diff = -1;
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}
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/* For the clock skew we use a windowed low point averaging algorithm as can be
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* found in http://www.grame.fr/pub/TR-050601.pdf. The idea is that the jitter is
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* composed of:
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*
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* J = N + n
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*
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* N : a constant network delay.
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* n : random added noise. The noise is concentrated around 0
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*
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* In the receiver we can track the elapsed time at the sender with:
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*
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* send_diff(i) = (Tsi - Ts0);
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*
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* Tsi : The time at the sender at packet i
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* Ts0 : The time at the sender at the first packet
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*
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* This is the difference between the RDT timestamp in the first received packet
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* and the current packet.
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*
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* At the receiver we have to deal with the jitter introduced by the network.
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*
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* recv_diff(i) = (Tri - Tr0)
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*
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* Tri : The time at the receiver at packet i
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* Tr0 : The time at the receiver at the first packet
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*
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* Both of these values contain a jitter Ji, a jitter for packet i, so we can
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* write:
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*
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* recv_diff(i) = (Cri + D + ni) - (Cr0 + D + n0))
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*
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* Cri : The time of the clock at the receiver for packet i
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* D + ni : The jitter when receiving packet i
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*
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* We see that the network delay is irrelevant here as we can eliminate D:
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*
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* recv_diff(i) = (Cri + ni) - (Cr0 + n0))
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*
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* The drift is now expressed as:
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*
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* Drift(i) = recv_diff(i) - send_diff(i);
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*
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* We now keep the W latest values of Drift and find the minimum (this is the
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* one with the lowest network jitter and thus the one which is least affected
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* by it). We average this lowest value to smooth out the resulting network skew.
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*
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* Both the window and the weighting used for averaging influence the accuracy
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* of the drift estimation. Finding the correct parameters turns out to be a
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* compromise between accuracy and inertia.
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*
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* We use a 2 second window or up to 512 data points, which is statistically big
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* enough to catch spikes (FIXME, detect spikes).
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* We also use a rather large weighting factor (125) to smoothly adapt. During
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* startup, when filling the window, we use a parabolic weighting factor, the
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* more the window is filled, the faster we move to the detected possible skew.
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*
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* Returns: @time adjusted with the clock skew.
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*/
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static GstClockTime
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calculate_skew (RDTJitterBuffer * jbuf, guint32 rtptime, GstClockTime time,
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guint32 clock_rate)
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{
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guint64 ext_rtptime;
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guint64 send_diff, recv_diff;
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gint64 delta;
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gint64 old;
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gint pos, i;
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GstClockTime gstrtptime, out_time;
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//ext_rtptime = gst_rtp_buffer_ext_timestamp (&jbuf->ext_rtptime, rtptime);
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ext_rtptime = rtptime;
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gstrtptime = gst_util_uint64_scale_int (ext_rtptime, GST_SECOND, clock_rate);
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again:
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/* first time, lock on to time and gstrtptime */
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if (jbuf->base_time == -1)
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jbuf->base_time = time;
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if (jbuf->base_rtptime == -1)
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jbuf->base_rtptime = gstrtptime;
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if (gstrtptime >= jbuf->base_rtptime)
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send_diff = gstrtptime - jbuf->base_rtptime;
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else {
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/* elapsed time at sender, timestamps can go backwards and thus be smaller
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* than our base time, take a new base time in that case. */
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GST_DEBUG ("backward timestamps at server, taking new base time");
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jbuf->base_rtptime = gstrtptime;
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jbuf->base_time = time;
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send_diff = 0;
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}
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GST_DEBUG ("extrtp %" G_GUINT64_FORMAT ", gstrtp %" GST_TIME_FORMAT ", base %"
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GST_TIME_FORMAT ", send_diff %" GST_TIME_FORMAT, ext_rtptime,
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GST_TIME_ARGS (gstrtptime), GST_TIME_ARGS (jbuf->base_rtptime),
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GST_TIME_ARGS (send_diff));
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if (jbuf->prev_send_diff != -1 && time != -1) {
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gint64 delta_diff;
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if (send_diff > jbuf->prev_send_diff)
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delta_diff = send_diff - jbuf->prev_send_diff;
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else
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delta_diff = jbuf->prev_send_diff - send_diff;
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/* server changed rtp timestamps too quickly, reset skew detection and start
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* again. This value is sortof arbitrary and can be a bad measurement up if
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* there are many packets missing because then we get a big gap that is
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* unrelated to a timestamp switch. */
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if (delta_diff > GST_SECOND) {
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GST_DEBUG ("delta changed too quickly %" GST_TIME_FORMAT " reset skew",
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GST_TIME_ARGS (delta_diff));
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rdt_jitter_buffer_reset_skew (jbuf);
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goto again;
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}
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}
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jbuf->prev_send_diff = send_diff;
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/* we don't have an arrival timestamp so we can't do skew detection. we
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* should still apply a timestamp based on RDT timestamp and base_time */
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if (time == -1)
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goto no_skew;
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/* elapsed time at receiver, includes the jitter */
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recv_diff = time - jbuf->base_time;
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GST_DEBUG ("time %" GST_TIME_FORMAT ", base %" GST_TIME_FORMAT ", recv_diff %"
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GST_TIME_FORMAT, GST_TIME_ARGS (time), GST_TIME_ARGS (jbuf->base_time),
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GST_TIME_ARGS (recv_diff));
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/* measure the diff */
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delta = ((gint64) recv_diff) - ((gint64) send_diff);
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pos = jbuf->window_pos;
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if (jbuf->window_filling) {
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/* we are filling the window */
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GST_DEBUG ("filling %d, delta %" G_GINT64_FORMAT, pos, delta);
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jbuf->window[pos++] = delta;
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/* calc the min delta we observed */
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if (pos == 1 || delta < jbuf->window_min)
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jbuf->window_min = delta;
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if (send_diff >= MAX_TIME || pos >= MAX_WINDOW) {
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jbuf->window_size = pos;
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/* window filled */
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GST_DEBUG ("min %" G_GINT64_FORMAT, jbuf->window_min);
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/* the skew is now the min */
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jbuf->skew = jbuf->window_min;
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jbuf->window_filling = FALSE;
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} else {
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gint perc_time, perc_window, perc;
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/* figure out how much we filled the window, this depends on the amount of
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* time we have or the max number of points we keep. */
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perc_time = send_diff * 100 / MAX_TIME;
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perc_window = pos * 100 / MAX_WINDOW;
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perc = MAX (perc_time, perc_window);
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/* make a parabolic function, the closer we get to the MAX, the more value
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* we give to the scaling factor of the new value */
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perc = perc * perc;
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/* quickly go to the min value when we are filling up, slowly when we are
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* just starting because we're not sure it's a good value yet. */
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jbuf->skew =
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(perc * jbuf->window_min + ((10000 - perc) * jbuf->skew)) / 10000;
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jbuf->window_size = pos + 1;
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}
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} else {
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/* pick old value and store new value. We keep the previous value in order
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* to quickly check if the min of the window changed */
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old = jbuf->window[pos];
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jbuf->window[pos++] = delta;
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if (delta <= jbuf->window_min) {
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/* if the new value we inserted is smaller or equal to the current min,
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* it becomes the new min */
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jbuf->window_min = delta;
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} else if (old == jbuf->window_min) {
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gint64 min = G_MAXINT64;
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/* if we removed the old min, we have to find a new min */
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for (i = 0; i < jbuf->window_size; i++) {
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/* we found another value equal to the old min, we can stop searching now */
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if (jbuf->window[i] == old) {
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min = old;
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break;
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}
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if (jbuf->window[i] < min)
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min = jbuf->window[i];
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}
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jbuf->window_min = min;
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}
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/* average the min values */
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jbuf->skew = (jbuf->window_min + (124 * jbuf->skew)) / 125;
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GST_DEBUG ("delta %" G_GINT64_FORMAT ", new min: %" G_GINT64_FORMAT,
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delta, jbuf->window_min);
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}
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/* wrap around in the window */
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if (pos >= jbuf->window_size)
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pos = 0;
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jbuf->window_pos = pos;
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no_skew:
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/* the output time is defined as the base timestamp plus the RDT time
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* adjusted for the clock skew .*/
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out_time = jbuf->base_time + send_diff + jbuf->skew;
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GST_DEBUG ("skew %" G_GINT64_FORMAT ", out %" GST_TIME_FORMAT,
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jbuf->skew, GST_TIME_ARGS (out_time));
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return out_time;
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}
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/**
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* rdt_jitter_buffer_insert:
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* @jbuf: an #RDTJitterBuffer
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* @buf: a buffer
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* @time: a running_time when this buffer was received in nanoseconds
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* @clock_rate: the clock-rate of the payload of @buf
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* @tail: TRUE when the tail element changed.
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*
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* Inserts @buf into the packet queue of @jbuf. The sequence number of the
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* packet will be used to sort the packets. This function takes ownerhip of
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* @buf when the function returns %TRUE.
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* @buf should have writable metadata when calling this function.
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*
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* Returns: %FALSE if a packet with the same number already existed.
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*/
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gboolean
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rdt_jitter_buffer_insert (RDTJitterBuffer * jbuf, GstBuffer * buf,
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GstClockTime time, guint32 clock_rate, gboolean * tail)
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{
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GList *list;
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guint32 rtptime;
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guint16 seqnum;
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GstRDTPacket packet;
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gboolean more;
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g_return_val_if_fail (jbuf != NULL, FALSE);
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g_return_val_if_fail (buf != NULL, FALSE);
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more = gst_rdt_buffer_get_first_packet (buf, &packet);
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/* programmer error */
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g_return_val_if_fail (more == TRUE, FALSE);
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seqnum = gst_rdt_packet_data_get_seq (&packet);
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/* do skew calculation by measuring the difference between rtptime and the
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* receive time, this function will retimestamp @buf with the skew corrected
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* running time. */
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rtptime = gst_rdt_packet_data_get_timestamp (&packet);
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/* loop the list to skip strictly smaller seqnum buffers */
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for (list = jbuf->packets->head; list; list = g_list_next (list)) {
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guint16 qseq;
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gint gap;
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more =
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gst_rdt_buffer_get_first_packet (GST_BUFFER_CAST (list->data), &packet);
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/* programmer error */
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g_return_val_if_fail (more == TRUE, FALSE);
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qseq = gst_rdt_packet_data_get_seq (&packet);
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/* compare the new seqnum to the one in the buffer */
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gap = gst_rdt_buffer_compare_seqnum (seqnum, qseq);
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/* we hit a packet with the same seqnum, notify a duplicate */
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if (G_UNLIKELY (gap == 0))
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goto duplicate;
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/* seqnum > qseq, we can stop looking */
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if (G_LIKELY (gap < 0))
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break;
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}
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if (clock_rate) {
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time = calculate_skew (jbuf, rtptime, time, clock_rate);
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GST_BUFFER_TIMESTAMP (buf) = time;
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}
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if (list)
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g_queue_insert_before (jbuf->packets, list, buf);
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else
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g_queue_push_tail (jbuf->packets, buf);
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/* tail was changed when we did not find a previous packet, we set the return
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* flag when requested. */
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if (tail)
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*tail = (list == NULL);
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return TRUE;
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/* ERRORS */
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duplicate:
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{
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GST_WARNING ("duplicate packet %d found", (gint) seqnum);
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return FALSE;
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}
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}
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/**
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* rdt_jitter_buffer_pop:
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* @jbuf: an #RDTJitterBuffer
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*
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* Pops the oldest buffer from the packet queue of @jbuf. The popped buffer will
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* have its timestamp adjusted with the incoming running_time and the detected
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* clock skew.
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*
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* Returns: a #GstBuffer or %NULL when there was no packet in the queue.
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*/
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GstBuffer *
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rdt_jitter_buffer_pop (RDTJitterBuffer * jbuf)
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{
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GstBuffer *buf;
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g_return_val_if_fail (jbuf != NULL, FALSE);
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buf = g_queue_pop_tail (jbuf->packets);
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return buf;
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}
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/**
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* rdt_jitter_buffer_peek:
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* @jbuf: an #RDTJitterBuffer
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*
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* Peek the oldest buffer from the packet queue of @jbuf. Register a callback
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* with rdt_jitter_buffer_set_tail_changed() to be notified when an older packet
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* was inserted in the queue.
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*
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* Returns: a #GstBuffer or %NULL when there was no packet in the queue.
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*/
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GstBuffer *
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rdt_jitter_buffer_peek (RDTJitterBuffer * jbuf)
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{
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GstBuffer *buf;
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g_return_val_if_fail (jbuf != NULL, FALSE);
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buf = g_queue_peek_tail (jbuf->packets);
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|
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return buf;
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}
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|
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/**
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* rdt_jitter_buffer_flush:
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* @jbuf: an #RDTJitterBuffer
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*
|
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* Flush all packets from the jitterbuffer.
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*/
|
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void
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rdt_jitter_buffer_flush (RDTJitterBuffer * jbuf)
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{
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GstBuffer *buffer;
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g_return_if_fail (jbuf != NULL);
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|
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while ((buffer = g_queue_pop_head (jbuf->packets)))
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gst_buffer_unref (buffer);
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}
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|
|
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/**
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* rdt_jitter_buffer_num_packets:
|
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* @jbuf: an #RDTJitterBuffer
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*
|
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* Get the number of packets currently in "jbuf.
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*
|
|
* Returns: The number of packets in @jbuf.
|
|
*/
|
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guint
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rdt_jitter_buffer_num_packets (RDTJitterBuffer * jbuf)
|
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{
|
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g_return_val_if_fail (jbuf != NULL, 0);
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|
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return jbuf->packets->length;
|
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}
|
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|
|
/**
|
|
* rdt_jitter_buffer_get_ts_diff:
|
|
* @jbuf: an #RDTJitterBuffer
|
|
*
|
|
* Get the difference between the timestamps of first and last packet in the
|
|
* jitterbuffer.
|
|
*
|
|
* Returns: The difference expressed in the timestamp units of the packets.
|
|
*/
|
|
guint32
|
|
rdt_jitter_buffer_get_ts_diff (RDTJitterBuffer * jbuf)
|
|
{
|
|
guint64 high_ts, low_ts;
|
|
GstBuffer *high_buf, *low_buf;
|
|
guint32 result;
|
|
|
|
g_return_val_if_fail (jbuf != NULL, 0);
|
|
|
|
high_buf = g_queue_peek_head (jbuf->packets);
|
|
low_buf = g_queue_peek_tail (jbuf->packets);
|
|
|
|
if (!high_buf || !low_buf || high_buf == low_buf)
|
|
return 0;
|
|
|
|
//high_ts = gst_rtp_buffer_get_timestamp (high_buf);
|
|
//low_ts = gst_rtp_buffer_get_timestamp (low_buf);
|
|
high_ts = 0;
|
|
low_ts = 0;
|
|
|
|
/* it needs to work if ts wraps */
|
|
if (high_ts >= low_ts) {
|
|
result = (guint32) (high_ts - low_ts);
|
|
} else {
|
|
result = (guint32) (high_ts + G_MAXUINT32 + 1 - low_ts);
|
|
}
|
|
return result;
|
|
}
|