From 691ecebe227d27914cd6efb1ff86d2d42679d3f3 Mon Sep 17 00:00:00 2001
From: Arun Raghavan <arun@centricular.com>
Date: Mon, 6 Apr 2015 16:22:34 +0530
Subject: [PATCH] osxaudio: Don't set the format on an initialized AudioUnit

We need to initialize the AudioUnit early to be able to probe the
underlying device, but according to the AudioUnitInitialize() and
AudioUnitUninitialize() documentation, format changes should be done
while the AudioUnit is uninitialized. So we explicitly uninitialize the
AudioUnit during a format change and reinitialize it when we're done.
---
 sys/osxaudio/gstosxcoreaudio.c         |  3 ++-
 sys/osxaudio/gstosxcoreaudiocommon.c   |  2 ++
 sys/osxaudio/gstosxcoreaudiohal.c      | 18 ++++++++++++++++++
 sys/osxaudio/gstosxcoreaudioremoteio.c | 27 +++++++++++++++++++++++++--
 4 files changed, 47 insertions(+), 3 deletions(-)

diff --git a/sys/osxaudio/gstosxcoreaudio.c b/sys/osxaudio/gstosxcoreaudio.c
index b425fb2..10fcd9c 100644
--- a/sys/osxaudio/gstosxcoreaudio.c
+++ b/sys/osxaudio/gstosxcoreaudio.c
@@ -168,7 +168,8 @@ gst_core_audio_open (GstCoreAudio * core_audio)
         "listener for AudioUnit: %d", (int) status);
   }
 
-  /* Initialize the AudioUnit */
+  /* Initialize the AudioUnit. We keep the audio unit initialized early so that
+   * we can probe the underlying device. */
   status = AudioUnitInitialize (core_audio->audiounit);
   if (status) {
     GST_ERROR_OBJECT (core_audio, "Failed to initialize AudioUnit: %d",
diff --git a/sys/osxaudio/gstosxcoreaudiocommon.c b/sys/osxaudio/gstosxcoreaudiocommon.c
index b81af9c..39d03ac 100644
--- a/sys/osxaudio/gstosxcoreaudiocommon.c
+++ b/sys/osxaudio/gstosxcoreaudiocommon.c
@@ -238,6 +238,7 @@ _core_audio_set_property (GstCoreAudio * core_audio, AudioUnitPropertyID inID,
   return TRUE;
 }
 
+/* The AudioUnit must be uninitialized before calling this */
 gboolean
 gst_core_audio_set_channel_layout (GstCoreAudio * core_audio,
     gint channels, GstCaps * caps)
@@ -297,6 +298,7 @@ gst_core_audio_set_channel_layout (GstCoreAudio * core_audio,
   return ret;
 }
 
+/* The AudioUnit must be uninitialized before calling this */
 gboolean
 gst_core_audio_set_format (GstCoreAudio * core_audio,
     AudioStreamBasicDescription format)
diff --git a/sys/osxaudio/gstosxcoreaudiohal.c b/sys/osxaudio/gstosxcoreaudiohal.c
index a05f384..c1fefcc 100644
--- a/sys/osxaudio/gstosxcoreaudiohal.c
+++ b/sys/osxaudio/gstosxcoreaudiohal.c
@@ -1123,6 +1123,15 @@ gst_core_audio_initialize_impl (GstCoreAudio * core_audio,
     gboolean is_passthrough, guint32 * frame_size)
 {
   gboolean ret = FALSE;
+  OSStatus status;
+
+  /* Uninitialize the AudioUnit before changing formats */
+  status = AudioUnitUninitialize (core_audio->audiounit);
+  if (status) {
+    GST_ERROR_OBJECT (core_audio, "Failed to uninitialize AudioUnit: %d",
+        (int) status);
+    return FALSE;
+  }
 
   core_audio->is_passthrough = is_passthrough;
   if (is_passthrough) {
@@ -1157,9 +1166,18 @@ gst_core_audio_initialize_impl (GstCoreAudio * core_audio,
   ret = TRUE;
 
 done:
+  /* Format changed, initialise the AudioUnit again */
+  status = AudioUnitInitialize (core_audio->audiounit);
+  if (status) {
+    GST_ERROR_OBJECT (core_audio, "Failed to initialize AudioUnit: %d",
+        (int) status);
+    ret = FALSE;
+  }
+
   if (ret) {
     GST_DEBUG_OBJECT (core_audio, "osxbuf ring buffer acquired");
   }
+
   return ret;
 }
 
diff --git a/sys/osxaudio/gstosxcoreaudioremoteio.c b/sys/osxaudio/gstosxcoreaudioremoteio.c
index d2f2f0b..76b0eba 100644
--- a/sys/osxaudio/gstosxcoreaudioremoteio.c
+++ b/sys/osxaudio/gstosxcoreaudioremoteio.c
@@ -84,10 +84,22 @@ gst_core_audio_initialize_impl (GstCoreAudio * core_audio,
     AudioStreamBasicDescription format, GstCaps * caps,
     gboolean is_passthrough, guint32 * frame_size)
 {
+  gboolean ret = FALSE;
+  OSStatus status;
+
+  /* Uninitialize the AudioUnit before changing formats */
+  status = AudioUnitUninitialize (core_audio->audiounit);
+  if (status) {
+    GST_ERROR_OBJECT (core_audio, "Failed to uninitialize AudioUnit: %d",
+        (int) status);
+    return FALSE;
+  }
+
   core_audio->is_passthrough = is_passthrough;
   core_audio->stream_idx = 0;
+
   if (!gst_core_audio_set_format (core_audio, format))
-    return FALSE;
+    goto done;
 
   /* FIXME: Use kAudioSessionProperty_CurrentHardwareSampleRate and
    * kAudioSessionProperty_CurrentHardwareIOBufferDuration with property
@@ -96,7 +108,18 @@ gst_core_audio_initialize_impl (GstCoreAudio * core_audio,
   *frame_size = 4196;
 
   GST_DEBUG_OBJECT (core_audio, "osxbuf ring buffer acquired");
-  return TRUE;
+  ret = TRUE;
+
+done:
+  /* Format changed, initialise the AudioUnit again */
+  status = AudioUnitInitialize (core_audio->audiounit);
+  if (status) {
+    GST_ERROR_OBJECT (core_audio, "Failed to initialize AudioUnit: %d",
+        (int) status);
+    ret = FALSE;
+  }
+
+  return ret;
 }
 
 static gboolean
-- 
2.7.4