Add QT_GSTREAMER_CAMERABIN_VIDEOSRC environment variable.

It can be used to set which video source element should be used by
the camerabin.

Change-Id: I8d1cd8c4ba6fe5a89817699f645b0997e713aaca
Reviewed-by: Samuli Piippo <samuli.piippo@digia.com>
Reviewed-by: Christian Stromme <christian.stromme@digia.com>

src/gsttools/qgstutils.cpp

@@ -430,13 +430,15 @@ QVector<QGstUtils::CameraInfo> QGstUtils::enumerateCameras(GstElementFactory *fa
                     QStringLiteral("primary"),
                     QGstreamerVideoInputDeviceControl::primaryCamera(),
                     0,
-                    QCamera::BackFace
+                    QCamera::BackFace,
+                    QByteArray()
                 };
                 const CameraInfo secondary = {
                     QStringLiteral("secondary"),
                     QGstreamerVideoInputDeviceControl::secondaryCamera(),
                     0,
-                    QCamera::FrontFace
+                    QCamera::FrontFace,
+                    QByteArray()
                 };
 
                 devices.append(primary);
@@ -498,14 +500,17 @@ QVector<QGstUtils::CameraInfo> QGstUtils::enumerateCameras(GstElementFactory *fa
 
         if (isCamera) {
             // find out its driver "name"
+            QByteArray driver;
             QString name;
             struct v4l2_capability vcap;
             memset(&vcap, 0, sizeof(struct v4l2_capability));
 
-            if (ioctl(fd, VIDIOC_QUERYCAP, &vcap) != 0)
+            if (ioctl(fd, VIDIOC_QUERYCAP, &vcap) != 0) {
                 name = entryInfo.fileName();
-            else
+            } else {
+                driver = QByteArray((const char*)vcap.driver);
                 name = QString::fromUtf8((const char*)vcap.card);
+            }
             //qDebug() << "found camera: " << name;
 
 
@@ -513,7 +518,8 @@ QVector<QGstUtils::CameraInfo> QGstUtils::enumerateCameras(GstElementFactory *fa
                 entryInfo.absoluteFilePath(),
                 name,
                 0,
-                QCamera::UnspecifiedPosition
+                QCamera::UnspecifiedPosition,
+                driver
             };
             devices.append(device);
         }
@@ -561,6 +567,15 @@ int QGstUtils::cameraOrientation(const QString &device, GstElementFactory * fact
     return 0;
 }
 
+QByteArray QGstUtils::cameraDriver(const QString &device, GstElementFactory *factory)
+{
+    foreach (const CameraInfo &camera, enumerateCameras(factory)) {
+        if (camera.name == device)
+            return camera.driver;
+    }
+    return QByteArray();
+}
+
 
 void qt_gst_object_ref_sink(gpointer object)
 {

src/multimedia/gsttools_headers/qgstutils_p.h

@@ -65,6 +65,7 @@ namespace QGstUtils {
         QString description;
         int orientation;
         QCamera::Position position;
+        QByteArray driver;
     };
 
     QMap<QByteArray, QVariant> gstTagListToMap(const GstTagList *list);
@@ -84,6 +85,7 @@ namespace QGstUtils {
     QString cameraDescription(const QString &device, GstElementFactory * factory = 0);
     QCamera::Position cameraPosition(const QString &device, GstElementFactory * factory = 0);
     int cameraOrientation(const QString &device, GstElementFactory * factory = 0);
+    QByteArray cameraDriver(const QString &device, GstElementFactory * factory = 0);
 }
 
 void qt_gst_object_ref_sink(gpointer object);

src/plugins/gstreamer/camerabin/camerabinsession.cpp

@@ -412,9 +412,41 @@ GstElement *CameraBinSession::buildCameraSource()
         if (g_object_class_find_property(G_OBJECT_GET_CLASS(m_videoSrc), "video-source")) {
             GstElement *src = 0;
 
-            if (m_videoInputFactory)
+            /* QT_GSTREAMER_CAMERABIN_VIDEOSRC can be used to set the video source element.
+
+               --- Usage
+
+                 QT_GSTREAMER_CAMERABIN_VIDEOSRC=[drivername=elementname[,drivername2=elementname2 ...],][elementname]
+
+               --- Examples
+
+                 Always use 'somevideosrc':
+                 QT_GSTREAMER_CAMERABIN_VIDEOSRC="somevideosrc"
+
+                 Use 'somevideosrc' when the device driver is 'somedriver', otherwise use default:
+                 QT_GSTREAMER_CAMERABIN_VIDEOSRC="somedriver=somevideosrc"
+
+                 Use 'somevideosrc' when the device driver is 'somedriver', otherwise use 'somevideosrc2'
+                 QT_GSTREAMER_CAMERABIN_VIDEOSRC="somedriver=somevideosrc,somevideosrc2"
+            */
+            const QByteArray envVideoSource = qgetenv("QT_GSTREAMER_CAMERABIN_VIDEOSRC");
+            if (!envVideoSource.isEmpty()) {
+                QList<QByteArray> sources = envVideoSource.split(',');
+                foreach (const QByteArray &source, sources) {
+                    QList<QByteArray> keyValue = source.split('=');
+                    if (keyValue.count() == 1) {
+                        src = gst_element_factory_make(keyValue.at(0), "camera_source");
+                        break;
+                    } else if (keyValue.at(0) == QGstUtils::cameraDriver(m_inputDevice, m_sourceFactory)) {
+                        src = gst_element_factory_make(keyValue.at(1), "camera_source");
+                        break;
+                    }
+                }
+            } else if (m_videoInputFactory) {
                 src = m_videoInputFactory->buildElement();
-            else
+            }
+
+            if (!src)
                 src = gst_element_factory_make("v4l2src", "camera_source");
 
             if (src) {