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diff --git a/PLUGINS.html b/PLUGINS.html index 2a66e88d..c9d6c542 100644 --- a/PLUGINS.html +++ b/PLUGINS.html @@ -1152,5 +1152,122 @@ of these functions, and VDR/osd.c to see how VDR opens the OSD and sets up its windows and color depths). <!--X1.1.5--></td></tr></table> +<!--X1.1.6--><table width=100%><tr><td bgcolor=#FF0000> </td><td width=100%> +<hr><h2>Devices</h2> + +<center><i><b>Expanding the possibilities</b></i></center><p> + +By default VDR is based on using DVB PCI cards that are supported by the +LinuxDVB driver. However, a plugin can implement additional devices that +can be used as sources of MPEG data for viewing or recording, and also +as output devices for replaying. Such a device can be a physical card +that is installed in the PC (like, for instance, an MPEG encoder card that +allows the analog signal of a proprietary set-top box to be integrated +into a VDR system; or an analog TV receiver card, which does the MPEG encoding +"on the fly" - assuming your machine is fast enough), or just a software program that takes an MPEG data +stream and displays it, for instance, on an existing graphics adapter. +<p> +To implement an additional device, a plugin must derive a class from cDevice: + +<p><table><tr><td bgcolor=#F0F0F0><pre><br> +#include <vdr/device.h> + +class cMyDevice : public cDevice { + ... + }; +</pre></td></tr></table><p> + +The derived class must implement several virtual functions, according to +the abilities this new class of devices can provide. See the comments in the +file <tt>VDR/device.h</tt> for more information on the various functions, +and also <tt>VDR/dvbdevice.[hc]</tt> for details on the implementation of +the <tt>cDvbDevice</tt>, which is used to access the DVB PCI cards. +<p> +<b>Channel selection</b> +<p> +If the new device can receive, it most likely needs to provide a way of +selecting which channel it shall tune to: + +<p><table><tr><td bgcolor=#F0F0F0><pre><br> +virtual bool SetChannelDevice(const cChannel *Channel); +</pre></td></tr></table><p> + +This function will be called with the desired channel and shall return whether +tuning to it was successful. +<p> +<b>Recording</b> +<p> +A device that can be used for recording must implement the functions + +<p><table><tr><td bgcolor=#F0F0F0><pre><br> +virtual bool SetPid(cPidHandle *Handle, int Type, bool On); +virtual bool OpenDvr(void); +virtual void CloseDvr(void); +virtual int GetTSPacket(uchar *Data); +</pre></td></tr></table><p> + +which allow VDR to set the PIDs that shall be recorded, set up the device fro +recording (and shut it down again), and receive the MPEG data stream. The data +must be delivered in the form of a Transport Stream (TS), which consists of +packets that are all 188 bytes in size. Each call to <tt>GetTSPacket()</tt> +must deliver exactly one such packet (if one is currently available). +<p> +If this device allows receiving several different data streams, it can +implement + +<p><table><tr><td bgcolor=#F0F0F0><pre><br> +virtual bool CanBeReUsed(int Frequency, int Vpid); +</pre></td></tr></table><p> + +to indicate this to VDR. +<p> +<b>Replaying</b> +<p> +The functions to implement replaying capabilites are + +<p><table><tr><td bgcolor=#F0F0F0><pre><br> +virtual bool HasDecoder(void) const; +virtual int SetPlayMode(bool On); +virtual void TrickSpeed(int Speed); +virtual void Clear(void); +virtual void Play(void); +virtual void Freeze(void); +virtual void Mute(void); +virtual void StillPicture(const uchar *Data, int Length); +virtual int PlayVideo(const uchar *Data, int Length); +</pre></td></tr></table><p> + +In addition, the following functions may be implemented to provide further +functionality: + +<p><table><tr><td bgcolor=#F0F0F0><pre><br> +virtual bool GrabImage(const char *FileName, bool Jpeg = true, int Quality = -1, int Si +virtual void SetVideoFormat(bool VideoFormat16_9); +virtual void SetVolumeDevice(int Volume); +</pre></td></tr></table><p> + +<b>Initializing new devices</b> +<p> +A derived cDevice class shall implement a static function + +<p><table><tr><td bgcolor=#F0F0F0><pre><br> +static bool Initialize(void); +</pre></td></tr></table><p> + +in which it determines whether the necessary hardware to run this sort of +device is actually present in this machine (or whatever other prerequisites +might be important), and then creates as many device objects as necessary. +See <tt>VDR/dvbdevice.c</tt> for the implementation of the <tt>cDvbDevice</tt> +initialize function. +<p> +A plugin that adds devices to a VDR instance shall call this initializing +function from its <a href="#Getting started"><tt>Start()</tt></a> function. +<p> +Nothing needs to be done to shut down the devices. VDR will automatically +shut down (delete) all devices when the program terminates. It is therefore +important that the devices are created on the heap, using the <tt>new</tt> +operator! +<!--X1.1.6--></td></tr></table> + </body> </html> |