wxMediaCtrl is a class for displaying types of media, such as videos, audio files, natively through native codecs.
wxMediaCtrl uses native backends to render media, for example on Windows there is a ActiveMovie/DirectShow backend, and on Macintosh there is a QuickTime backend.
See also
Derived from
Include files
<wx/mediactrl.h>
Members
Rendering media
Operation
Video size
Player controls
Choosing a backend
Creating a backend
wxMediaCtrl::wxMediaCtrl
wxMediaCtrl::Create
wxMediaCtrl::GetBestSize
wxMediaCtrl::GetPlaybackRate
wxMediaCtrl::GetVolume
wxMediaCtrl::GetState
wxMediaCtrl::Length
wxMediaCtrl::Load
wxMediaCtrl::Load
wxMediaCtrl::Load
wxMediaCtrl::LoadURI
wxMediaCtrl::LoadURIWithProxy
wxMediaCtrl::Pause
wxMediaCtrl::Play
wxMediaCtrl::Seek
wxMediaCtrl::SetPlaybackRate
wxMediaCtrl::SetVolume
wxMediaCtrl::ShowPlayerControls
wxMediaCtrl::Stop
wxMediaCtrl::Tell
Depending upon the backend, wxMediaCtrl can render and display pretty much any kind of media that the native system can - such as an image, mpeg video, or mp3 (without license restrictions - since it relies on native system calls that may not technically have mp3 decoding available, for example, it falls outside the realm of licensing restrictions).
For general operation, all you need to do is call wxMediaCtrl::Load to load the file you want to render, catch the EVT_MEDIA_LOADED event, and then call wxMediaCtrl::Play to show the video/audio of the media in that event.
More complex operations are generally more heavily dependant on the capabilities of the backend. For example, QuickTime cannot set the playback rate of certain streaming media - while DirectShow is slightly more flexible in that regard.
When wxMediaCtrl plays a file, it plays until the stop position is reached (currently the end of the file/stream). Right before it hits the end of the stream, it fires off a EVT_MEDIA_STOP event to its parent window, at which point the event handler can choose to veto the event, preventing the stream from actually stopping.
Example:
//connect to the media event
this->Connect(wxMY_ID, wxEVT_MEDIA_STOP, (wxObjectEventFunction)
(wxEventFunction)(wxMediaEventFunction) &MyFrame::OnMediaStop);
//...
void MyFrame::OnMediaStop(const wxMediaEvent& evt)
{
if(bUserWantsToSeek)
{
m_mediactrl->SetPosition(
m_mediactrl->GetDuration() << 1
);
evt.Veto();
}
}
When wxMediaCtrl stops, either by the EVT_MEDIA_STOP not being
vetoed, or by manually calling
wxMediaCtrl::Stop, where it actually
stops is not at the beginning, rather, but at the beginning of
the stream. That is, when it stops and play is called, playback
is gauranteed to start at the beginning of the media. This is
because some streams are not seekable, and when stop is called
on them they return to the beginning, thus wxMediaCtrl tries
to keep consistant for all types of media.Note that when changing the state of the media through Play() and other methods, the media may not actually be in the wxMEDIASTATE_PLAYING, for example. If you are relying on the media being in certain state catch the event relevant to the state. See wxMediaEvent for the kinds of events that you can catch.
By default, wxMediaCtrl will scale the size of the video to the requested amount passed to either it's constructor or Create(). After calling Load or performing an equivilant operation, you can subsequently obtain the "real" size of the video (if there is any) by calling GetBestSize(). Note that the actual result on the display will be slightly different when ShowPlayerControls is activated and the actual video size will be less then specified due to the extra controls provided by the native toolkit. In addition, the backend may modify GetBestSize() to include the size of the extra controls - so if you want the real size of the video just disable ShowPlayerControls().
The idea with setting GetBestSize to the size of the video is that GetBestSize is a wxWindow-derived function that is called when sizers on a window recalculate. What this means is that if you use sizers by default the video will show in it's original size without any extra assistance needed from the user.
Normally, when you use wxMediaCtrl it is just a window for the video to play in. However, some toolkits have their own media player interface. For example, QuickTime generally has a bar below the video with a slider. A special feature available to wxMediaCtrl, you can use the toolkit's interface instead of making your own by using the ShowPlayerControls() function. There are several options for the flags parameter, with the two general flags being wxMEDIACTRLPLAYERCONTROLS_NONE which turns off the native interface, and wxMEDIACTRLPLAYERCONTROLS_DEFAULT which lets wxMediaCtrl decide what native controls on the interface. Be sure to review the caveats outlined in Video size before doing so.
Generally, you should almost certainly leave this part up to wxMediaCtrl - but if you need a certain backend for a particular reason, such as QuickTime for playing .mov files, all you need to do to choose a specific backend is to pass the name of the backend class to wxMediaCtrl::Create.
The following are valid backend identifiers -
| wxMEDIABACKEND_DIRECTSHOW | Use ActiveMovie/DirectShow. Uses the native ActiveMovie (I.E. DirectShow) control. Default backend on Windows and supported by nearly all Windows versions, even some Windows CE versions. May display a windows media player logo while inactive. |
| wxMEDIABACKEND_QUICKTIME | Use QuickTime. Mac Only. WARNING: May not working correctly embedded in a wxNotebook. |
| wxMEDIABACKEND_GSTREAMER | Use GStreamer. Unix Only. Requires GStreamer 0.8 along with at the very least the xvimagesink, xoverlay, and gst-play modules of gstreamer to function. You need the correct modules to play the relavant files, for example the mad module to play mp3s, etc. |
| wxMEDIABACKEND_WMP10 | Uses Windows Media Player 10 (Windows only) - works on mobile machines with Windows Media Player 10 and desktop machines with either Windows Media Player 9 or 10 |
Note that other backends such as wxMEDIABACKEND_MCI can now be found at wxCode.
Creating a backend for wxMediaCtrl is a rather simple process. Simply derive from wxMediaBackendCommonBase and implement the methods you want. The methods in wxMediaBackend correspond to those in wxMediaCtrl except for CreateControl which does the actual creation of the control, in cases where a custom control is not needed you may simply call wxControl::Create.
You need to make sure to use the DECLARE_CLASS and IMPLEMENT_CLASS macros.
The only real tricky part is that you need to make sure the file in compiled in, which if there are just backends in there will not happen and you may need to use a force link hack (see http://www.wxwidgets.org/wiki/index.php/RTTI).
This is a rather simple example of how to create a backend in the wxActiveXContainer documentation.
wxMediaCtrl()
Default constructor - you must call Create before calling any other methods of wxMediaCtrl.
wxMediaCtrl( wxWindow* parent, wxWindowID id, const wxString& fileName = wxT(""), const wxPoint& pos = wxDefaultPosition, const wxSize& size = wxDefaultSize, long style = 0, const wxString& szBackend = wxT(""), const wxValidatorvalidator = wxDefaultValidator, const wxString& name = wxPanelNameStr )
Constructor that calls Create. You may prefer to call Create directly to check to see if wxMediaCtrl is available on the system.
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bool Create( wxWindow* parent, wxWindowID id, const wxString& fileName = wxT(""), const wxPoint& pos = wxDefaultPosition, const wxSize& size = wxDefaultSize, long style = 0, const wxString& szBackend = wxT(""), const wxValidatorvalidator = wxDefaultValidator, const wxString& name = wxPanelNameStr )
Creates this control. Returns false if it can't load the movie located at fileName or it cannot load one of its native backends.
If you specify a file to open via fileName and you don't specify a backend to use, wxMediaCtrl tries each of its backends until one that can render the path referred to by fileName can be found.
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wxSize GetBestSize()
Obtains the best size relative to the original/natural size of the video, if there is any. See Video size for more information.
double GetPlaybackrate()
Obtains the playback rate, or speed of the media. 1.0 represents normal speed, while 2.0 represents twice the normal speed of the media, for example. Not supported on the GStreamer (Unix) backend. Returns 0 on failure.
double GetVolume()
Gets the volume of the media from a 0.0 to 1.0 range. Note that due to rounding and other errors this may not be the exact value sent to SetVolume.
wxMediaCtrlState GetState()
Obtains the state the playback of the media is in -
| wxMEDIASTATE_STOPPED | The movie has stopped. |
| wxMEDIASTATE_PAUSED | The movie is paused. |
| wxMEDIASTATE_PLAYING | The movie is currently playing. |
wxFileOffset Length()
Obtains the length - the total amount of time the movie has in milliseconds.
bool Load(const wxString& fileName)
Loads the file that fileName refers to. Returns false if loading fails.
bool Load(const wxURI& uri)
Loads the location that uri refers to. Note that this is very implementation-dependant, although HTTP URI/URLs are generally supported, for example. Returns false if loading fails.
bool Load(const wxURI& uri, const wxURI& proxy)
Loads the location that uri refers to with the proxy proxy. Not implemented on most backends so it should be called with caution. Returns false if loading fails.
bool LoadURI(const wxURI& uri)
Same as Load. Kept for wxPython compatability.
bool LoadURIWithProxy(const wxURI& uri, const wxURI& proxy)
Same as Load. Kept for wxPython compatability.
bool Pause()
Pauses playback of the movie.
bool Play()
Resumes playback of the movie.
wxFileOffset Seek(wxFileOffset where, wxSeekMode mode)
Seeks to a position within the movie.
bool SetPlaybackRate(double dRate)
Sets the playback rate, or speed of the media, to that referred by dRate. 1.0 represents normal speed, while 2.0 represents twice the normal speed of the media, for example. Not supported on the GStreamer (Unix) backend. Returns true if successful.
bool SetVolume(double dVolume)
Sets the volume of the media from a 0.0 to 1.0 range to that referred by dVolume. 1.0 represents full volume, while 0.5 represents half (50 percent) volume, for example. Note that this may not be exact due to conversion and rounding errors, although setting the volume to full or none is always exact. Returns true if successful.
bool ShowPlayerControls(wxMediaCtrlPlayerControls flags = wxMEDIACTRLPLAYERCONTROLS_DEFAULT)
A special feature to wxMediaCtrl. Applications using native toolkits such as QuickTime usually have a scrollbar, play button, and more provided to them by the toolkit. By default wxMediaCtrl does not do this. However, on the directshow and quicktime backends you can show or hide the native controls provided by the underlying toolkit at will using ShowPlayerControls. Simply calling the function with default parameters tells wxMediaCtrl to use the default controls provided by the toolkit. The function takes a wxMediaCtrlPlayerControls enumeration as follows:
| wxMEDIACTRLPLAYERCONTROLS_NONE | No controls. return wxMediaCtrl to it's default state. |
| wxMEDIACTRLPLAYERCONTROLS_STEP | Step controls like fastfoward, step one frame etc. |
| wxMEDIACTRLPLAYERCONTROLS_VOLUME | Volume controls like the speaker icon, volume slider, etc. |
| wxMEDIACTRLPLAYERCONTROLS_DEFAULT | Default controls for the toolkit. Currently a typedef for wxMEDIACTRLPLAYERCONTROLS_STEP and wxMEDIACTRLPLAYERCONTROLS_VOLUME. |
For more see Player controls. Currently only implemented on the QuickTime and DirectShow backends. The function returns true on success.
bool Stop()
Stops the media.
See Operation for an overview of how stopping works.
wxFileOffset Tell()
Obtains the current position in time within the movie in milliseconds.