[vlc-commits] demux: add moving average helper

[Francois Cartegnie]

vlc/vlc-3.0 | branch: master | Francois Cartegnie <fcvlcdev at free.fr> | Wed Aug  1 11:44:38 2018 +0200| [1cb156b662a8369c3e32612c85aa672bf00b37dd] | committer: Francois Cartegnie

demux: add moving average helper

> http://git.videolan.org/gitweb.cgi/vlc/vlc-3.0.git/?a=commit;h=1cb156b662a8369c3e32612c85aa672bf00b37dd
---

 modules/demux/moving_avg.h | 100 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 100 insertions(+)

diff --git a/modules/demux/moving_avg.h b/modules/demux/moving_avg.h
new file mode 100644
index 0000000000..fcd2de2de9
--- /dev/null
+++ b/modules/demux/moving_avg.h
@@ -0,0 +1,100 @@
+/*****************************************************************************
+ * moving_avg.h: Moving average helper
+ *****************************************************************************
+ * Copyright © 2018 VideoLabs, VideoLAN, VLC authors
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
+ *****************************************************************************/
+#ifndef VLC_MOVING_AVG_H
+#define VLC_MOVING_AVG_H
+
+#ifndef MVA_PACKETS
+ #define MVA_PACKETS 6
+#endif
+
+struct mva_packet_s
+{
+    mtime_t duration;
+    mtime_t dts;
+    mtime_t diff;
+};
+
+struct moving_average_s
+{
+    struct mva_packet_s packets[MVA_PACKETS];
+    unsigned i_packet;
+};
+
+static void mva_init(struct moving_average_s *m)
+{
+    m->i_packet = 0;
+}
+
+static mtime_t mva_get(const struct moving_average_s *m);
+
+static void mva_add(struct moving_average_s *m,
+                     mtime_t dts, mtime_t duration)
+{
+    m->packets[m->i_packet % MVA_PACKETS].dts = dts;
+    m->packets[m->i_packet % MVA_PACKETS].duration = duration;
+    m->packets[m->i_packet % MVA_PACKETS].diff = duration; /* will erase, last one */
+    m->i_packet++;
+}
+
+static mtime_t mva_get(const struct moving_average_s *m)
+{
+    unsigned start;
+    const struct mva_packet_s *min = NULL, *max = NULL;
+
+    if(likely(m->i_packet >= MVA_PACKETS))
+    {
+        start = m->i_packet - MVA_PACKETS;
+        for(unsigned i = start; i < m->i_packet; i++)
+        {
+            if(!min || m->packets[i % MVA_PACKETS].diff < min->diff)
+                min = &m->packets[i % MVA_PACKETS];
+
+            if(!max || m->packets[i % MVA_PACKETS].diff > max->diff)
+                max = &m->packets[i % MVA_PACKETS];
+        }
+    }
+    else start = 0;
+
+    unsigned count = 0;
+    mtime_t avgdiff = 0;
+    for(unsigned i = start; i < m->i_packet; i++)
+    {
+        if(&m->packets[i % MVA_PACKETS] == min ||
+            &m->packets[i % MVA_PACKETS] == max)
+            continue;
+        avgdiff += m->packets[i % MVA_PACKETS].diff;
+        count++;
+    }
+
+    return count ? avgdiff / count : 0;
+}
+
+static struct mva_packet_s * mva_getLastPacket(struct moving_average_s *m)
+{
+    return m->i_packet > 0 ? &m->packets[(m->i_packet - 1) % MVA_PACKETS] : NULL;
+}
+
+static mtime_t mva_getLastDTS(struct moving_average_s *m)
+{
+    struct mva_packet_s *p = mva_getLastPacket(m);
+    return p ? p->dts : 0;
+}
+
+#endif