]> git.saurik.com Git - wxWidgets.git/blobdiff - src/unix/mediactrl.cpp
define WM_CONTEXTMENU if the standard headers don't
[wxWidgets.git] / src / unix / mediactrl.cpp
index 838775b45c2c3d8b6733a9c035d3c3c9092ff5a9..cf20c15e2e63faca32faf2043d48fc4323c02ee5 100644 (file)
@@ -1,6 +1,6 @@
 /////////////////////////////////////////////////////////////////////////////
-// Name:        mac/carbon/mediactrl.cpp
-// Purpose:     Built-in Media Backends for Unix (stub)
+// Name:        unix/mediactrl.cpp
+// Purpose:     Built-in Media Backends for Unix
 // Author:      Ryan Norton <wxprojects@comcast.net>
 // Modified by:
 // Created:     02/04/05
 //---------------------------------------------------------------------------
 #if wxUSE_MEDIACTRL
 
+//===========================================================================
+//  BACKEND DECLARATIONS
+//===========================================================================
+
+//---------------------------------------------------------------------------
+//
+//  wxGStreamerMediaBackend
+//
+//TODO:
+//TODO:  This is really not the best way to play-stop -
+//TODO:  it should just have one playbin and stick with it the whole
+//TODO:  instance of wxGStreamerMediaBackend - but stopping appears
+//TODO:  to invalidate the playbin object...
+//TODO:
+//
+//---------------------------------------------------------------------------
+#if wxUSE_GSTREAMER
+
+//---------------------------------------------------------------------------
+//  GStreamer Includes
+//---------------------------------------------------------------------------
+#include <gst/gst.h>
+#include <gst/xoverlay/xoverlay.h>
+
+#include <string.h> //strstr
+
+#include "wx/log.h"
+
+#ifdef __WXGTK__
+    //for <gdk/gdkx.h>/related for GDK_WINDOW_XWINDOW
+#    include "wx/gtk/win_gtk.h"
+#    include <gtk/gtksignal.h>
+#    if wxUSE_DYNLIB_CLASS
+#        include "wx/dynlib.h"
+#    endif
+//#    include <gst/gconf/gconf.h> //gstreamer gnome interface - needs deps
+#endif
+
+
+class WXDLLIMPEXP_MEDIA wxGStreamerMediaBackend : public wxMediaBackend
+{
+public:
+
+    wxGStreamerMediaBackend();
+    ~wxGStreamerMediaBackend();
+
+    virtual bool CreateControl(wxControl* ctrl, wxWindow* parent,
+                                     wxWindowID id,
+                                     const wxPoint& pos,
+                                     const wxSize& size,
+                                     long style,
+                                     const wxValidator& validator,
+                                     const wxString& name);
+
+    virtual bool Play();
+    virtual bool Pause();
+    virtual bool Stop();
+
+    virtual bool Load(const wxString& fileName);
+    virtual bool Load(const wxURI& location);
+
+    virtual wxMediaState GetState();
+
+    virtual bool SetPosition(wxLongLong where);
+    virtual wxLongLong GetPosition();
+    virtual wxLongLong GetDuration();
+
+    virtual void Move(int x, int y, int w, int h);
+    wxSize GetVideoSize() const;
+
+    virtual double GetPlaybackRate();
+    virtual bool SetPlaybackRate(double dRate);
+
+    void Cleanup();
+
+    static void OnFinish(GstElement *play,  gpointer data);
+    static void OnError (GstElement *play,  GstElement *src,
+                         GError     *err,   gchar      *debug,
+                         gpointer    data);
+    static void OnVideoCapsReady(GstPad* pad,  GParamSpec* pspec, gpointer data);
+    
+    static bool TransCapsToVideoSize(wxGStreamerMediaBackend* be, GstPad* caps);
+    void PostRecalcSize();
+    
+#ifdef __WXGTK__
+    static gint OnGTKRealize(GtkWidget* theWidget, wxGStreamerMediaBackend* be);
+#endif
+
+    GstElement* m_player;       //GStreamer media element
+    
+    wxSize      m_videoSize;
+    wxControl*  m_ctrl;
+    
+    wxLongLong m_nPausedPos;
+
+    DECLARE_DYNAMIC_CLASS(wxGStreamerMediaBackend);
+};
+
+
+//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+//
+// wxGStreamerMediaBackend
+//
+//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+
+IMPLEMENT_DYNAMIC_CLASS(wxGStreamerMediaBackend, wxMediaBackend);
+
+//---------------------------------------------------------------------------
+// wxGStreamerMediaBackend Constructor
+//
+// Sets m_player to NULL signifying we havn't loaded anything yet
+//---------------------------------------------------------------------------
+wxGStreamerMediaBackend::wxGStreamerMediaBackend() : m_player(NULL), m_videoSize(0,0)
+{
+}
+
+//---------------------------------------------------------------------------
+// wxGStreamerMediaBackend Destructor
+//
+// Stops/cleans up memory  
+//---------------------------------------------------------------------------
+wxGStreamerMediaBackend::~wxGStreamerMediaBackend()
+{
+    Cleanup();
+}
+
+//---------------------------------------------------------------------------
+// wxGStreamerMediaBackend::OnGTKRealize
+//
+// If the window wasn't realized when Load was called, this is the
+// callback for when it is.
+//
+// 1) Installs GTK idle handler if it doesn't exist
+// 2) Yeilds to avoid an X11 bug (?)
+// 3) Tells GStreamer to play the video in our control
+//---------------------------------------------------------------------------
+#ifdef __WXGTK__
+
+#ifdef __WXDEBUG__
+
+#if wxUSE_THREADS
+#   define DEBUG_MAIN_THREAD if (wxThread::IsMain() && g_mainThreadLocked) printf("gui reentrance");
+#else
+#   define DEBUG_MAIN_THREAD
+#endif
+#else
+#define DEBUG_MAIN_THREAD
+#endif // Debug
+
+extern void wxapp_install_idle_handler();
+extern bool g_isIdle;
+extern bool g_mainThreadLocked;
+
+gint wxGStreamerMediaBackend::OnGTKRealize(GtkWidget* theWidget, 
+                                           wxGStreamerMediaBackend* be)
+{
+    DEBUG_MAIN_THREAD
+    
+    if (g_isIdle)
+        wxapp_install_idle_handler();
+
+    wxYield();    //FIXME: X Server gets an error if I don't do this or a messagebox beforehand?!?!??
+    
+    GdkWindow *window = GTK_PIZZA(theWidget)->bin_window;
+    wxASSERT(window);
+    
+    GstElement* videosink;
+    g_object_get (G_OBJECT (be->m_player), "video-sink", &videosink, NULL);
+    
+    GstElement* overlay = gst_bin_get_by_interface (GST_BIN (videosink),
+                                    GST_TYPE_X_OVERLAY);
+    gst_x_overlay_set_xwindow_id( GST_X_OVERLAY(overlay),
+                                GDK_WINDOW_XWINDOW( window )
+                                );
+    
+    return 0;
+}
+
+
+#endif
+
+//---------------------------------------------------------------------------
+// wxGStreamerMediaBackend::Cleanup
+//
+// Frees the gstreamer interfaces if there were any created
+//---------------------------------------------------------------------------
+void wxGStreamerMediaBackend::Cleanup()
+{
+    if(m_player && GST_IS_OBJECT(m_player))
+    {
+        gst_element_set_state (m_player, GST_STATE_NULL);
+        gst_object_unref (GST_OBJECT (m_player));
+    }
+}
+
+//---------------------------------------------------------------------------
+// wxGStreamerMediaBackend::CreateControl
+//
+// Initializes GStreamer and creates the wx side of our media control
+//---------------------------------------------------------------------------
+bool wxGStreamerMediaBackend::CreateControl(wxControl* ctrl, wxWindow* parent,
+                                wxWindowID id,
+                                const wxPoint& pos,
+                                const wxSize& size,
+                                long style,
+                                const wxValidator& validator,
+                                const wxString& name)
+{
+    //init gstreamer
+    gst_init(NULL, NULL);
+    
+    m_ctrl = ctrl;
+
+    return m_ctrl->wxControl::Create(parent, id, pos, size,
+                            style,  //remove borders???
+                            validator, name);
+}
+
+//---------------------------------------------------------------------------
+// wxGStreamerMediaBackend::TransCapsToVideoSize
+//
+// Gets the size of our video (in wxSize) from a GstPad
+//---------------------------------------------------------------------------
+bool wxGStreamerMediaBackend::TransCapsToVideoSize(wxGStreamerMediaBackend* be, GstPad* pad)
+{
+    const GstCaps* caps = GST_PAD_CAPS (pad);
+    if(caps)
+    {
+
+        const GstStructure *s;
+        s = gst_caps_get_structure (caps, 0);
+        wxASSERT(s);
+
+        gst_structure_get_int (s, "width", &be->m_videoSize.x);
+        gst_structure_get_int (s, "height", &be->m_videoSize.y);
+
+        const GValue *par;
+        par = gst_structure_get_value (s, "pixel-aspect-ratio");
+
+        if (par)
+        {
+            int num = gst_value_get_fraction_numerator (par),
+                den = gst_value_get_fraction_denominator (par);
+
+            //TODO: maybe better fraction normalization...
+            if (num > den)
+                be->m_videoSize.x = (int) ((float) num * be->m_videoSize.x / den);
+            else
+                be->m_videoSize.y = (int) ((float) den * be->m_videoSize.y / num);
+        }
+
+        be->PostRecalcSize();        
+        return true;
+    }//end if caps
+    
+    return false;
+}
+
+//---------------------------------------------------------------------------
+// wxGStreamerMediaBackend::PostRecalcSize
+//
+// Forces parent to recalc its layout if it has sizers to update
+// to the new video size
+//---------------------------------------------------------------------------
+void wxGStreamerMediaBackend::PostRecalcSize()
+{
+        m_ctrl->InvalidateBestSize();
+        m_ctrl->GetParent()->Layout();
+        m_ctrl->GetParent()->Refresh();
+        m_ctrl->GetParent()->Update();
+}
+
+//---------------------------------------------------------------------------
+// wxGStreamerMediaBackend::OnFinish
+//
+// Called by gstreamer when the media is done playing
+//
+// 1) Send a wxEVT_MEDIA_STOP to the control
+// 2) If veteod, break out
+// 3) really stop the media
+// 4) Send a wxEVT_MEDIA_FINISHED to the control
+//---------------------------------------------------------------------------
+void wxGStreamerMediaBackend::OnFinish(GstElement *play, gpointer    data)
+{
+    wxGStreamerMediaBackend* m_parent = (wxGStreamerMediaBackend*) data;
+
+    wxMediaEvent theEvent(wxEVT_MEDIA_STOP,
+                        m_parent->m_ctrl->GetId());
+    m_parent->m_ctrl->ProcessEvent(theEvent);
+
+    if(theEvent.IsAllowed())
+    {
+        bool bOk = m_parent->Stop();
+        wxASSERT(bOk);
+
+        //send the event to our child
+        wxMediaEvent theEvent(wxEVT_MEDIA_FINISHED,
+                            m_parent->m_ctrl->GetId());
+        m_parent->m_ctrl->ProcessEvent(theEvent);
+    }
+}
+
+//---------------------------------------------------------------------------
+// wxGStreamerMediaBackend::OnError
+//
+// Called by gstreamer when an error is encountered playing the media
+//
+// TODO: Make this better - maybe some more intelligent wxLog stuff
+//---------------------------------------------------------------------------
+void wxGStreamerMediaBackend::OnError(GstElement *play,
+    GstElement *src,
+    GError     *err,
+    gchar      *debug,
+    gpointer    data)
+{
+    wxLogSysError(
+        wxString::Format(
+            wxT("Error in wxMediaCtrl!\nError Message:%s\nDebug:%s\n"), 
+            (const wxChar*)wxConvUTF8.cMB2WX(err->message),
+            (const wxChar*)wxConvUTF8.cMB2WX(debug)
+                        )
+                 );
+}
+
+
+//---------------------------------------------------------------------------
+// wxGStreamerMediaBackend::Load (File version)
+//
+// Just calls the URI version
+//---------------------------------------------------------------------------
+bool wxGStreamerMediaBackend::Load(const wxString& fileName)
+{
+    return Load( 
+                    wxURI( 
+                            wxString( wxT("file://") ) + fileName 
+                         ) 
+               );
+}
+
+//---------------------------------------------------------------------------
+// wxGStreamerMediaBackend::OnVideoCapsReady
+//
+// Called by gstreamer when the video caps for the media is ready
+//---------------------------------------------------------------------------
+void wxGStreamerMediaBackend::OnVideoCapsReady(GstPad* pad, GParamSpec* pspec, gpointer data)
+{
+    wxGStreamerMediaBackend::TransCapsToVideoSize((wxGStreamerMediaBackend*) data, pad);    
+}
+
+//---------------------------------------------------------------------------
+// wxGStreamerMediaBackend::Load (URI version)
+//
+// 1) Stops/Cleanups the previous instance if there is any
+// 2) Creates the gstreamer playbin
+// 3) If there is no playbin bail out
+// 4) Set up the error and end-of-stream callbacks for our player
+// 5) Make our video sink and make sure it supports the x overlay interface
+// 6) Make sure the passed URI is valid and tell playbin to load it
+// 7) Use the xoverlay extension to tell gstreamer to play in our window
+// 8) Get the video size - pause required to set the stream in action
+//---------------------------------------------------------------------------
+bool wxGStreamerMediaBackend::Load(const wxURI& location)
+{
+    //1
+    Cleanup();
+    
+    //2
+    m_player    = gst_element_factory_make ("playbin", "play");
+
+    //3
+    if (!m_player)
+        return false;
+        
+    //4
+    g_signal_connect (m_player, "eos", G_CALLBACK (OnFinish), this);
+    g_signal_connect (m_player, "error", G_CALLBACK (OnError), this);
+
+    //5
+    GstElement* overlay = NULL;
+    GstElement* videosink;
+
+#if defined(__WXGTK__) && wxUSE_DYNLIB_CLASS
+
+    //use gnome-specific gstreamer extensions
+    //if synthisis (?) file not found, it 
+    //spits out a warning and uses ximagesink
+    wxDynamicLibrary gstgconf;
+    if(gstgconf.Load(gstgconf.CanonicalizeName(wxT("gstgconf-0.8"))))
+    {
+        typedef GstElement* (*LPgst_gconf_get_default_video_sink) (void);
+        LPgst_gconf_get_default_video_sink pGst_gconf_get_default_video_sink = 
+        (LPgst_gconf_get_default_video_sink)
+            gstgconf.GetSymbol(wxT("gst_gconf_get_default_video_sink"));
+
+        if (pGst_gconf_get_default_video_sink)        
+        {
+            videosink = (*pGst_gconf_get_default_video_sink) ();
+            wxASSERT( GST_IS_BIN(videosink) );
+            overlay = gst_bin_get_by_interface (GST_BIN (videosink),
+                                            GST_TYPE_X_OVERLAY);
+        }
+        
+        gstgconf.Detach();
+    }
+        
+        if ( ! GST_IS_X_OVERLAY(overlay) )
+        {
+#endif
+            videosink = gst_element_factory_make ("xvimagesink", "videosink");
+            if ( !GST_IS_OBJECT(videosink) )
+                videosink = gst_element_factory_make ("ximagesink", "videosink");
+            
+            overlay = videosink;
+        
+            wxASSERT( GST_IS_X_OVERLAY(overlay) );
+            if ( ! GST_IS_X_OVERLAY(overlay) )
+                return false;
+#if defined(__WXGTK__) && wxUSE_DYNLIB_CLASS
+        }
+#endif
+
+    g_object_set (G_OBJECT (m_player),
+                    "video-sink", videosink,
+//                    "audio-sink", m_audiosink,
+                    NULL);    
+
+    //6
+    wxString locstring = location.BuildUnescapedURI();
+    wxASSERT(gst_uri_protocol_is_valid("file"));
+    wxASSERT(gst_uri_is_valid(locstring.mb_str()));
+
+    g_object_set (G_OBJECT (m_player), "uri", (const char*)locstring.mb_str(), NULL);
+        
+    //7    
+#ifdef __WXGTK__
+    if(!GTK_WIDGET_REALIZED(m_ctrl->m_wxwindow))
+    {
+        //Not realized yet - set to connect at realization time
+        gtk_signal_connect( GTK_OBJECT(m_ctrl->m_wxwindow), 
+                            "realize",
+                            GTK_SIGNAL_FUNC(wxGStreamerMediaBackend::OnGTKRealize),
+                            (gpointer) this );
+    }        
+    else
+    {
+        wxYield(); //see realize callback...
+        GdkWindow *window = GTK_PIZZA(m_ctrl->m_wxwindow)->bin_window;
+        wxASSERT(window);
+#endif
+
+    gst_x_overlay_set_xwindow_id( GST_X_OVERLAY(overlay),
+#ifdef __WXGTK__
+                        GDK_WINDOW_XWINDOW( window )
+#else
+                        ctrl->GetHandle()
+#endif
+                                  );
+
+#ifdef __WXGTK__                                  
+    } //end else block
+#endif 
+    
+    //8
+    
+    wxASSERT(gst_element_set_state (m_player,
+                GST_STATE_PAUSED)    == GST_STATE_SUCCESS);            
+
+    const GList *list = NULL;
+    g_object_get (G_OBJECT (m_player), "stream-info", &list, NULL);
+
+    for ( ; list != NULL; list = list->next)
+    {
+        GObject *info = (GObject *) list->data;
+        gint type;
+        GParamSpec *pspec;
+        GEnumValue *val;
+        GstPad *pad = NULL;
+
+        g_object_get (info, "type", &type, NULL);
+        pspec = g_object_class_find_property (
+                        G_OBJECT_GET_CLASS (info), "type");
+        val = g_enum_get_value (G_PARAM_SPEC_ENUM (pspec)->enum_class, type);
+
+        if (strstr (val->value_name, "VIDEO"))
+        {
+            //Newer gstreamer 0.8+ is SUPPOSED to have "object"...
+            //but a lot of old plugins still use "pad" :)
+            pspec = g_object_class_find_property (
+                        G_OBJECT_GET_CLASS (info), "object");
+                        
+            if (!pspec)
+                g_object_get (info, "pad", &pad, NULL);
+            else
+                g_object_get (info, "object", &pad, NULL);
+            
+            pad = (GstPad *) GST_PAD_REALIZE (pad);
+            wxASSERT(pad);
+
+            if(!wxGStreamerMediaBackend::TransCapsToVideoSize(this, pad));
+            {
+                //wait for those caps to get ready
+                g_signal_connect(
+                pad, 
+                "notify::caps", 
+                G_CALLBACK(wxGStreamerMediaBackend::OnVideoCapsReady),
+                this);
+            }
+        }//end if video
+        else
+        {
+            m_videoSize = wxSize(0,0);
+            PostRecalcSize();
+        }
+    }//end searching through info list    
+
+    m_nPausedPos = 0;
+    return true;
+}
+
+//---------------------------------------------------------------------------
+// wxGStreamerMediaBackend::Play
+//
+// Sets the stream to a playing state
+//---------------------------------------------------------------------------
+bool wxGStreamerMediaBackend::Play()
+{
+    if (gst_element_set_state (m_player, GST_STATE_PLAYING)
+            != GST_STATE_SUCCESS)
+        return false;
+    return true;
+}
+
+//---------------------------------------------------------------------------
+// wxGStreamerMediaBackend::Pause
+//
+// Marks where we paused and pauses the stream
+//---------------------------------------------------------------------------
+bool wxGStreamerMediaBackend::Pause()
+{
+    m_nPausedPos = GetPosition();
+    if (gst_element_set_state (m_player, GST_STATE_PAUSED)
+            != GST_STATE_SUCCESS)
+        return false;
+    return true;
+}
+
+//---------------------------------------------------------------------------
+// wxGStreamerMediaBackend::Stop
+//
+// Pauses the stream and sets the position to 0
+//---------------------------------------------------------------------------
+bool wxGStreamerMediaBackend::Stop()
+{
+    if (gst_element_set_state (m_player,
+                    GST_STATE_PAUSED)    != GST_STATE_SUCCESS)
+        return false;
+    return wxGStreamerMediaBackend::SetPosition(0);
+}
+
+//---------------------------------------------------------------------------
+// wxGStreamerMediaBackend::GetState
+//
+// Gets the state of the stream
+//---------------------------------------------------------------------------
+wxMediaState wxGStreamerMediaBackend::GetState()
+{
+    switch(GST_STATE(m_player))
+    {
+        case GST_STATE_PLAYING:
+            return wxMEDIASTATE_PLAYING;
+        case GST_STATE_PAUSED:
+            if (m_nPausedPos == 0)
+                return wxMEDIASTATE_STOPPED;
+            else
+                return wxMEDIASTATE_PAUSED;
+        default://case GST_STATE_READY:
+            return wxMEDIASTATE_STOPPED;
+    }
+}
+
+//---------------------------------------------------------------------------
+// wxGStreamerMediaBackend::GetPosition
+//
+// If paused, returns our marked position - otherwise it queries the 
+// GStreamer playbin for the position and returns that
+//
+//TODO:
+//TODO: In lue of the last big TODO, when you pause and seek gstreamer
+//TODO: doesn't update the position sometimes, so we need to keep track of whether    
+//TODO: we have paused or not and keep track of the time after the pause
+//TODO: and whenever the user seeks while paused
+//TODO:
+//---------------------------------------------------------------------------
+wxLongLong wxGStreamerMediaBackend::GetPosition()
+{
+    if(GetState() != wxMEDIASTATE_PLAYING)
+        return m_nPausedPos;
+    else
+    {
+        gint64 pos;
+        GstFormat fmtTime = GST_FORMAT_TIME;
+    
+        if (!gst_element_query (m_player, GST_QUERY_POSITION, &fmtTime, &pos))
+            return 0;
+        return pos / GST_MSECOND ;
+    }
+}
+
+//---------------------------------------------------------------------------
+// wxGStreamerMediaBackend::SetPosition
+//
+// Sets the position of the stream
+// Note that GST_MSECOND is 1000000 (GStreamer uses nanoseconds - so
+// there is 1000000 nanoseconds in a millisecond)
+//
+// If paused marks where we seeked to 
+//---------------------------------------------------------------------------
+bool wxGStreamerMediaBackend::SetPosition(wxLongLong where)
+{
+    if( gst_element_seek (m_player, (GstSeekType) (GST_SEEK_METHOD_SET |
+            GST_FORMAT_TIME | GST_SEEK_FLAG_FLUSH),
+            where.GetValue() * GST_MSECOND ) )
+    {
+        if (GetState() != wxMEDIASTATE_PLAYING)
+            m_nPausedPos = where;
+        
+        return true;
+    }        
+            
+    return false;
+}
+
+//---------------------------------------------------------------------------
+// wxGStreamerMediaBackend::GetDuration
+//
+// Obtains the total time of our stream
+//---------------------------------------------------------------------------
+wxLongLong wxGStreamerMediaBackend::GetDuration()
+{
+    gint64 length;
+    GstFormat fmtTime = GST_FORMAT_TIME;
+
+    if(!gst_element_query(m_player, GST_QUERY_TOTAL, &fmtTime, &length))
+        return 0;
+    return length / GST_MSECOND ;
+}
+
+//---------------------------------------------------------------------------
+// wxGStreamerMediaBackend::Move
+//
+// Called when the window is moved - GStreamer takes care of this
+// for us so nothing is needed
+//---------------------------------------------------------------------------
+void wxGStreamerMediaBackend::Move(int x, int y, int w, int h)
+{
+}
+
+//---------------------------------------------------------------------------
+// wxGStreamerMediaBackend::GetVideoSize
+//
+// Returns our cached video size from Load/OnVideoCapsReady
+//---------------------------------------------------------------------------
+wxSize wxGStreamerMediaBackend::GetVideoSize() const
+{    
+    return m_videoSize;
+}
+
+//---------------------------------------------------------------------------
+// wxGStreamerMediaBackend::GetPlaybackRate
+// wxGStreamerMediaBackend::SetPlaybackRate
+//
+// Obtains/Sets the playback rate of the stream
+//
+//TODO: PlaybackRate not currently supported via playbin directly -
+//TODO: Ronald S. Bultje noted on gstreamer-devel:
+//TODO:
+//TODO: Like "play at twice normal speed"? Or "play at 25 fps and 44,1 kHz"? As
+//TODO: for the first, yes, we have elements for that, btu they"re not part of
+//TODO: playbin. You can create a bin (with a ghost pad) containing the actual
+//TODO: video/audiosink and the speed-changing element for this, and set that
+//TODO: element as video-sink or audio-sink property in playbin. The
+//TODO: audio-element is called "speed", the video-element is called "videodrop"
+//TODO: (although that appears to be deprecated in favour of "videorate", which
+//TODO: again cannot do this, so this may not work at all in the end). For
+//TODO: forcing frame/samplerates, see audioscale and videorate. Audioscale is
+//TODO: part of playbin.
+//---------------------------------------------------------------------------
+double wxGStreamerMediaBackend::GetPlaybackRate()
+{
+    //not currently supported via playbin
+    return 1.0;
+}
+
+bool wxGStreamerMediaBackend::SetPlaybackRate(double dRate)
+{
+    //not currently supported via playbin
+    return false;
+}
+
+#endif //wxUSE_GSTREAMER
+
 //in source file that contains stuff you don't directly use
 #include <wx/html/forcelnk.h>
 FORCE_LINK_ME(basewxmediabackends);