From bd1e80cba6360af5c6f8e4d9eeba28ae8fa1f998 Mon Sep 17 00:00:00 2001
From: Benjamin Chen <bechen@mozilla.com>
Date: Tue, 5 May 2015 16:00:14 +0800
Subject: [PATCH] Bug 1104643 - Interpolate the audio clock by system clock if
 the qudio clock is not going forward. r=padenot

---
 media/libcubeb/src/cubeb_opensl.c | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/media/libcubeb/src/cubeb_opensl.c b/media/libcubeb/src/cubeb_opensl.c
index 7f166149997..c90e68f30a6 100644
--- a/media/libcubeb/src/cubeb_opensl.c
+++ b/media/libcubeb/src/cubeb_opensl.c
@@ -11,6 +11,7 @@
 #include <pthread.h>
 #include <SLES/OpenSLES.h>
 #include <math.h>
+#include <time.h>
 #if defined(__ANDROID__)
 #include <sys/system_properties.h>
 #include "android/sles_definitions.h"
@@ -70,6 +71,9 @@ struct cubeb_stream {
   unsigned int inputrate;
   unsigned int outputrate;
   unsigned int latency;
+  int64_t lastPosition;
+  int64_t lastPositionTimeStamp;
+  int64_t lastCompensativePosition;
 };
 
 static void
@@ -511,6 +515,9 @@ opensl_stream_init(cubeb * ctx, cubeb_stream ** stream, char const * stream_name
   stm->latency = latency;
   stm->stream_type = stream_params.stream_type;
   stm->framesize = stream_params.channels * sizeof(int16_t);
+  stm->lastPosition = -1;
+  stm->lastPositionTimeStamp = 0;
+  stm->lastCompensativePosition = -1;
 
   int r = pthread_mutex_init(&stm->mutex, NULL);
   assert(r == 0);
@@ -697,11 +704,22 @@ opensl_stream_get_position(cubeb_stream * stm, uint64_t * position)
   SLresult res;
   int r;
   uint32_t mixer_latency;
+  uint32_t compensation_msec = 0;
 
   res = (*stm->play)->GetPosition(stm->play, &msec);
   if (res != SL_RESULT_SUCCESS)
     return CUBEB_ERROR;
 
+  struct timespec t;
+  clock_gettime(CLOCK_MONOTONIC, &t);
+  if(stm->lastPosition == msec || msec < stm->lastCompensativePosition) {
+    compensation_msec =
+      (t.tv_sec*1000000000LL + t.tv_nsec - stm->lastPositionTimeStamp) / 1000000;
+  } else {
+    stm->lastPositionTimeStamp = t.tv_sec*1000000000LL + t.tv_nsec;
+    stm->lastPosition = msec;
+  }
+
   samplerate = stm->inputrate;
 
   r = stm->context->get_output_latency(&mixer_latency, stm->stream_type);
@@ -715,12 +733,14 @@ opensl_stream_get_position(cubeb_stream * stm, uint64_t * position)
   assert(maximum_position >= 0);
 
   if (msec > mixer_latency) {
-    int64_t unadjusted_position = samplerate * (msec - mixer_latency) / 1000;
+    int64_t unadjusted_position =
+      samplerate * (msec - mixer_latency + compensation_msec) / 1000;
     *position = unadjusted_position < maximum_position ?
       unadjusted_position : maximum_position;
   } else {
     *position = 0;
   }
+  stm->lastCompensativePosition = *position;
   return CUBEB_OK;
 }