AVFoundation: improve changing the capture device format.

Make sure the device format is always set in the same way.
We don't actually set the format anymore when it's the same as
the current one. We also make sure the frame rate is preserved.

Change-Id: I1c68239bc99d9c3cef920effcf47fc253220c26f
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@theqtcompany.com>

1 files changed, 19 insertions, 25 deletions

diff --git a/src/plugins/avfoundation/camera/avfvideoencodersettingscontrol.mm b/src/plugins/avfoundation/camera/avfvideoencodersettingscontrol.mm
index 87bc91129..248997d57 100644
--- a/src/plugins/avfoundation/camera/avfvideoencodersettingscontrol.mm
+++ b/src/plugins/avfoundation/camera/avfvideoencodersettingscontrol.mm
@@ -215,6 +215,10 @@ NSDictionary *AVFVideoEncoderSettingsControl::applySettings(AVCaptureConnection
     if (!device)
         return nil;
 
+    AVFPSRange currentFps = qt_current_framerates(device, connection);
+    const bool needFpsChange = m_requestedSettings.frameRate() > 0
+                               && m_requestedSettings.frameRate() != currentFps.second;
+
     NSMutableDictionary *videoSettings = [NSMutableDictionary dictionary];
 
     // -- Codec
@@ -234,8 +238,8 @@ NSDictionary *AVFVideoEncoderSettingsControl::applySettings(AVCaptureConnection
     int h = m_requestedSettings.resolution().height();
 
 #if QT_MAC_PLATFORM_SDK_EQUAL_OR_ABOVE(__MAC_10_7, __IPHONE_7_0)
-    if (device.activeFormat) {
-        CMFormatDescriptionRef formatDesc = device.activeFormat.formatDescription;
+    if (AVCaptureDeviceFormat *currentFormat = device.activeFormat) {
+        CMFormatDescriptionRef formatDesc = currentFormat.formatDescription;
         CMVideoDimensions dim = CMVideoFormatDescriptionGetDimensions(formatDesc);
 
         // We have to change the device's activeFormat in 3 cases:
@@ -245,7 +249,7 @@ NSDictionary *AVFVideoEncoderSettingsControl::applySettings(AVCaptureConnection
         AVCaptureDeviceFormat *newFormat = nil;
         if ((w <= 0 || h <= 0)
                 && m_requestedSettings.frameRate() > 0
-                && !format_supports_framerate(device.activeFormat, m_requestedSettings.frameRate())) {
+                && !format_supports_framerate(currentFormat, m_requestedSettings.frameRate())) {
 
             newFormat = qt_find_best_framerate_match(device,
                                                      m_service->session()->defaultCodec(),
@@ -267,17 +271,10 @@ NSDictionary *AVFVideoEncoderSettingsControl::applySettings(AVCaptureConnection
             }
         }
 
-        if (newFormat && newFormat != device.activeFormat) {
-            const AVFConfigurationLock lock(device);
-            if (lock) {
-                m_restoreFormat = [device.activeFormat retain];
-                m_restoreFps = qt_current_framerates(device, connection);
-
-                device.activeFormat = newFormat;
-
-                formatDesc = newFormat.formatDescription;
-                dim = CMVideoFormatDescriptionGetDimensions(formatDesc);
-            }
+        if (qt_set_active_format(device, newFormat, !needFpsChange)) {
+            m_restoreFormat = [currentFormat retain];
+            formatDesc = newFormat.formatDescription;
+            dim = CMVideoFormatDescriptionGetDimensions(formatDesc);
         }
 
         if (w > 0 && h > 0) {
@@ -313,14 +310,12 @@ NSDictionary *AVFVideoEncoderSettingsControl::applySettings(AVCaptureConnection
 
     // -- FPS
 
-    const qreal fps = m_requestedSettings.frameRate();
-    if (fps > qreal(0)) {
-        if (!m_restoreFps.first && !m_restoreFps.second)
-            m_restoreFps = qt_current_framerates(device, connection);
+    if (needFpsChange) {
+        m_restoreFps = currentFps;
+        const qreal fps = m_requestedSettings.frameRate();
         qt_set_framerate_limits(device, connection, fps, fps);
     }
-    AVFPSRange currentFps = qt_current_framerates(device, connection);
-    m_actualSettings.setFrameRate(currentFps.second);
+    m_actualSettings.setFrameRate(qt_current_framerates(device, connection).second);
 
     // -- Codec Settings
 
@@ -379,18 +374,17 @@ void AVFVideoEncoderSettingsControl::unapplySettings(AVCaptureConnection *connec
     if (!device)
         return;
 
+    const bool needFpsChanged = m_restoreFps.first || m_restoreFps.second;
+
 #if QT_MAC_PLATFORM_SDK_EQUAL_OR_ABOVE(__MAC_10_7, __IPHONE_7_0)
     if (m_restoreFormat) {
-        const AVFConfigurationLock lock(device);
-        if (lock)
-            device.activeFormat = m_restoreFormat;
-
+        qt_set_active_format(device, m_restoreFormat, !needFpsChanged);
         [m_restoreFormat release];
         m_restoreFormat = nil;
     }
 #endif
 
-    if (m_restoreFps.first || m_restoreFps.second) {
+    if (needFpsChanged) {
         qt_set_framerate_limits(device, connection, m_restoreFps.first, m_restoreFps.second);
         m_restoreFps = AVFPSRange();
     }