From 2953801a5f49d80b0deaaafb06aa6fb8f9891f80 Mon Sep 17 00:00:00 2001
From: Mark Nauwelaerts <mark.nauwelaerts@collabora.co.uk>
Date: Wed, 18 Aug 2010 14:40:48 +0200
Subject: [PATCH] rtpamrpay: properly support perfect-rtptime

---
 gst/rtp/gstrtpamrpay.c | 83 +++++++++++++++++++++++++++++++++++++++++-
 gst/rtp/gstrtpamrpay.h |  3 ++
 2 files changed, 85 insertions(+), 1 deletion(-)

diff --git a/gst/rtp/gstrtpamrpay.c b/gst/rtp/gstrtpamrpay.c
index 2ade6a757..ded5cfe98 100644
--- a/gst/rtp/gstrtpamrpay.c
+++ b/gst/rtp/gstrtpamrpay.c
@@ -90,6 +90,9 @@ static gboolean gst_rtp_amr_pay_setcaps (GstBaseRTPPayload * basepayload,
 static GstFlowReturn gst_rtp_amr_pay_handle_buffer (GstBaseRTPPayload * pad,
     GstBuffer * buffer);
 
+static GstStateChangeReturn
+gst_rtp_amr_pay_change_state (GstElement * element, GstStateChange transition);
+
 GST_BOILERPLATE (GstRtpAMRPay, gst_rtp_amr_pay, GstBaseRTPPayload,
     GST_TYPE_BASE_RTP_PAYLOAD);
 
@@ -113,6 +116,10 @@ static void
 gst_rtp_amr_pay_class_init (GstRtpAMRPayClass * klass)
 {
   GstBaseRTPPayloadClass *gstbasertppayload_class;
+  GstElementClass *gstelement_class;
+
+  gstelement_class = (GstElementClass *) klass;
+  gstelement_class->change_state = gst_rtp_amr_pay_change_state;
 
   gstbasertppayload_class = (GstBaseRTPPayloadClass *) klass;
 
@@ -129,6 +136,14 @@ gst_rtp_amr_pay_init (GstRtpAMRPay * rtpamrpay, GstRtpAMRPayClass * klass)
   /* needed because of GST_BOILERPLATE */
 }
 
+static void
+gst_rtp_amr_pay_reset (GstRtpAMRPay * pay)
+{
+  pay->next_rtp_time = 0;
+  pay->first_ts = GST_CLOCK_TIME_NONE;
+  pay->first_rtp_time = 0;
+}
+
 static gboolean
 gst_rtp_amr_pay_setcaps (GstBaseRTPPayload * basepayload, GstCaps * caps)
 {
@@ -178,6 +193,29 @@ wrong_type:
   }
 }
 
+static void
+gst_rtp_amr_pay_recalc_rtp_time (GstRtpAMRPay * rtpamrpay,
+    GstClockTime timestamp)
+{
+  /* re-sync rtp time */
+  if (GST_CLOCK_TIME_IS_VALID (rtpamrpay->first_ts) &&
+      GST_CLOCK_TIME_IS_VALID (timestamp) && timestamp >= rtpamrpay->first_ts) {
+    GstClockTime diff;
+    guint32 rtpdiff;
+
+    /* interpolate to reproduce gap from start, rather than intermediate
+     * intervals to avoid roundup accumulation errors */
+    diff = timestamp - rtpamrpay->first_ts;
+    rtpdiff = ((diff / GST_MSECOND) * 8) <<
+        (rtpamrpay->mode == GST_RTP_AMR_P_MODE_WB);
+    rtpamrpay->next_rtp_time = rtpamrpay->first_rtp_time + rtpdiff;
+    GST_DEBUG_OBJECT (rtpamrpay,
+        "elapsed time %" GST_TIME_FORMAT ", rtp %d, "
+        "new offset %" G_GUINT64_FORMAT, GST_TIME_ARGS (diff), rtpdiff,
+        rtpamrpay->next_rtp_time);
+  }
+}
+
 /* -1 is invalid */
 static gint nb_frame_size[16] = {
   12, 13, 15, 17, 19, 20, 26, 31,
@@ -203,6 +241,7 @@ gst_rtp_amr_pay_handle_buffer (GstBaseRTPPayload * basepayload,
   gint i, num_packets, num_nonempty_packets;
   gint amr_len;
   gint *frame_size;
+  gboolean sid = FALSE;
 
   rtpamrpay = GST_RTP_AMR_PAY (basepayload);
   mtu = GST_BASE_RTP_PAYLOAD_MTU (rtpamrpay);
@@ -234,11 +273,14 @@ gst_rtp_amr_pay_handle_buffer (GstBaseRTPPayload * basepayload,
     FT = (data[i] & 0x78) >> 3;
 
     fr_size = frame_size[FT];
-    GST_DEBUG_OBJECT (basepayload, "frame size %d", fr_size);
+    GST_DEBUG_OBJECT (basepayload, "frame type %d, frame size %d", FT, fr_size);
     /* FIXME, we don't handle this yet.. */
     if (fr_size <= 0)
       goto wrong_size;
 
+    if (fr_size == 5)
+      sid = TRUE;
+
     amr_len += fr_size;
     num_nonempty_packets++;
     num_packets++;
@@ -272,7 +314,21 @@ gst_rtp_amr_pay_handle_buffer (GstBaseRTPPayload * basepayload,
     GST_DEBUG_OBJECT (basepayload, "discont, setting marker bit");
     GST_BUFFER_FLAG_SET (outbuf, GST_BUFFER_FLAG_DISCONT);
     gst_rtp_buffer_set_marker (outbuf, TRUE);
+    gst_rtp_amr_pay_recalc_rtp_time (rtpamrpay, timestamp);
+  }
+
+  if (G_UNLIKELY (sid)) {
+    gst_rtp_amr_pay_recalc_rtp_time (rtpamrpay, timestamp);
+  }
+
+  /* perfect rtptime */
+  if (G_UNLIKELY (!GST_CLOCK_TIME_IS_VALID (rtpamrpay->first_ts))) {
+    rtpamrpay->first_ts = timestamp;
+    rtpamrpay->first_rtp_time = rtpamrpay->next_rtp_time;
   }
+  GST_BUFFER_OFFSET (outbuf) = rtpamrpay->next_rtp_time;
+  rtpamrpay->next_rtp_time +=
+      (num_packets * 160) << (rtpamrpay->mode == GST_RTP_AMR_P_MODE_WB);
 
   /* get payload, this is now writable */
   payload = gst_rtp_buffer_get_payload (outbuf);
@@ -350,6 +406,31 @@ too_big:
   }
 }
 
+static GstStateChangeReturn
+gst_rtp_amr_pay_change_state (GstElement * element, GstStateChange transition)
+{
+  GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
+
+  /* handle upwards state changes here */
+  switch (transition) {
+    default:
+      break;
+  }
+
+  ret = GST_ELEMENT_CLASS (parent_class)->change_state (element, transition);
+
+  /* handle downwards state changes */
+  switch (transition) {
+    case GST_STATE_CHANGE_PAUSED_TO_READY:
+      gst_rtp_amr_pay_reset (GST_RTP_AMR_PAY (element));
+      break;
+    default:
+      break;
+  }
+
+  return ret;
+}
+
 gboolean
 gst_rtp_amr_pay_plugin_init (GstPlugin * plugin)
 {
diff --git a/gst/rtp/gstrtpamrpay.h b/gst/rtp/gstrtpamrpay.h
index ce86d0d9c..36e32fc17 100644
--- a/gst/rtp/gstrtpamrpay.h
+++ b/gst/rtp/gstrtpamrpay.h
@@ -51,6 +51,9 @@ struct _GstRtpAMRPay
   GstBaseRTPPayload payload;
 
   GstRtpAMRPayMode mode;
+  GstClockTime first_ts;
+  guint32 first_rtp_time;
+  guint32 next_rtp_time;
 };
 
 struct _GstRtpAMRPayClass
-- 
2.34.1