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diff --git a/DOCS/OUTDATED-tech/libvo.txt b/DOCS/OUTDATED-tech/libvo.txt new file mode 100644 index 0000000000..245d29eade --- /dev/null +++ b/DOCS/OUTDATED-tech/libvo.txt @@ -0,0 +1,173 @@ +libvo --- the library to handle video output by A'rpi, 2002.04 +============================================ + +Note: before start on this, read colorspaces.txt ! + +The constants for different pixelformats are defined in img_format.h, +their usage is mandatory. + +WARNING: Please keep in mind that some of this information may be out-dated, +so if you are working on a new vo, consider submitting preliminary patches +very early on. Currently vo_gl is one of the more up-to-date VOs to use +as reference if you are unsure about something and do not want to ask on the +list. +vo_vdpau and vo_direct3d may be a good choice, too, they use different +approaches closer to the sometimes convoluted way DirectX works. + +Each vo driver _has_ to implement these: + + preinit(): + init the video system (to support querying for supported formats) + + uninit(): + Uninit the whole system, this is on the same "level" as preinit. + + control(): + Current controls (VOCTRL_QUERY_FORMAT must be implemented, + VOCTRL_DRAW_IMAGE, VOCTRL_FULLSCREEN, VOCTRL_UPDATE_SCREENINFO + should be implemented): + VOCTRL_QUERY_FORMAT - queries if a given pixelformat is supported. + It also returns various flags decsirbing the capabilities + of the driver with teh given mode. for the flags, see + file vfcaps.h ! + the most important flags, every driver must properly report + these: + 0x1 - supported (with or without conversion) + 0x2 - supported without conversion (define 0x1 too!) + 0x100 - driver/hardware handles timing (blocking) + also SET sw/hw scaling and osd support flags, and flip, + and accept_stride if you implement VOCTRL_DRAW_IMAGE (see bellow) + NOTE: VOCTRL_QUERY_FORMAT may be called _before_ first config() + but is always called between preinit() and uninit() + VOCTRL_GET_IMAGE + libmpcodecs Direct Rendering interface + You need to update mpi (mp_image.h) structure, for example, + look at vo_x11, vo_sdl, vo_xv or mga_common. + VOCTRL_DRAW_IMAGE + replacement for the current draw_slice/draw_frame way of + passing video frames. by implementing SET_IMAGE, you'll get + image in mp_image struct instead of by calling draw_*. + unless you return VO_TRUE for VOCTRL_DRAW_IMAGE call, the + old-style draw_* functils will be called! + Note: draw_slice is still mandatory, for per-slice rendering! + VOCTRL_RESET - reset the video device + This is sent on seeking and similar and is useful if you are + using a device which prebuffers frames that need to flush them + before refilling audio/video buffers. + VOCTRL_PAUSE + VOCTRL_RESUME + VOCTRL_GUISUPPORT + return true only if driver supports co-operation with + MPlayer's GUI (not yet used by GUI) + VOCTRL_SET_EQUALIZER + set the video equalizer to the given values + two arguments are provided: item and value + item is a string, the possible values are (currently): + brightness, contrast, saturation, hue + VOCTRL_GET_EQUALIZER + get the current video equalizer values + two arguments are provided: item and value + item is a string, the possible values are (currently): + brightness, contrast, saturation, hue + VOCTRL_ONTOP + Makes the player window stay-on-top. Only supported (currently) + by drivers which use X11, except SDL, as well as directx and + gl2 under Windows. + VOCTRL_BORDER + Makes the player window borderless. + VOCTRL_FULLSCREEN + Switch from and to fullscreen mode + VOCTRL_GET_PANSCAN + VOCTRL_SET_PANSCAN + Needed to implement pan-scan support ('w' and 'e' keys during + playback in fullscreen mode) + VOCTRL_START_SLICE + Called before the first draw_slice of each frame, useful if + you need to do some set-up work. + VOCTRL_DRAW_EOSD + Required for EOSD (ASS subtitle) support. Provides all + information necessary to draw the EOSD for the current video + frame. + VOCTRL_GET_EOSD_RES + Required for EOSD (ASS subtitle) support. Informs the ASS + renderer about the properties of the drawing area (size, + borders). + VOCTRL_SET_DEINTERLACE + VOCTRL_GET_DEINTERLACE + Get or set deinterlacing status for VOs that support some kind + of deinterlacing. + VOCTRL_UPDATE_SCREENINFO + Should set the xinerama_x, xinerama_y, vo_screenwidth and + vo_screenheight appropriately for the currently used + monitor and -xineramascreen option. + Usually should simply call the w32_update_xinerama_info or + update_xinerama_info function. + By supporting this, the VO also requests the newer API + that sets vo_dx, vo_dy etc. appropriately before config() + is called. + + config(): + Set up the video system. You get the dimensions and flags. + width, height: size of the source image + d_width, d_height: wanted scaled/display size (it's a hint) + Flags: + 0x01 - force fullscreen (-fs) + 0x02 - allow mode switching (-vm) + 0x04 - allow software scaling (-zoom) + 0x08 - flipping (-flip) + They're defined as VOFLAG_* (see libvo/video_out.h) + + IMPORTANT NOTE: config() may be called 0 (zero), 1 or more (2,3...) + times between preinit() and uninit() calls. You MUST handle it, and + you shouldn't crash at second config() call or at uninit() without + any config() call! To make your life easier, vo_config_count is + set to the number of previous config() call, counted from preinit(). + It's set by the caller (vf_vo.c), you don't have to increase it! + So, you can check for vo_config_count>0 in uninit() when freeing + resources allocated in config() to avoid crash! + + You should implement VOCTRL_UPDATE_SCREENINFO so that vo_dx, vo_dy, + vo_dwidth and vo_dheight are already pre-set to values that take + aspect and -geometry into account. It is also necessary to properly + support multi-monitor setups (if based on x11_common, w32_common). + + draw_slice(): this displays YV12 pictures (3 planes, one full sized that + contains brightness (Y), and 2 quarter-sized which the colour-info + (U,V). MPEG codecs (libmpeg2, opendivx) use this. This doesn't have + to display the whole frame, only update small parts of it. + If this is not supported, it must be signaled in QUERY_FORMAT with + VOCAP_NOSLICES. + + draw_frame(): this is the older interface, this displays only complete + frames, and can do only packed format (YUY2, RGB/BGR). + Win32 codecs use this (DivX, Indeo, etc). + If you implement VOCTRL_DRAW_IMAGE, you do not need to implement draw_frame. + + draw_osd(): this displays subtitles and OSD. + It's a bit tricky to use it, since it's a callback-style stuff. + It should call vo_draw_text() with screen dimension and your + draw_alpha implementation for the pixelformat (function pointer). + The vo_draw_text() checks the characters to draw, and calls + draw_alpha() for each. As a help, osd.c contains draw_alpha for + each pixelformats, use this if possible! + Note that if you do not draw directly onto the video you should + use vo_draw_text_ext() which allows you to specify the border + values etc. needed to draw DVD menu highlights at the correct place. + If you do not want to implement this, you can still use -vf + expand=osd=1 to draw the OSD, or even implement code to insert + this filter automatically. + Make sure you set VFCAP_OSD depending on whether you implemented it + or not. + + NOTE: This one will be obsolete soon! But it's still useful when + you want to do tricks, like rendering osd _after_ hardware scaling + (tdfxfb) or render subtitles under of the image (vo_mpegpes, sdl) + + NOTE2: above NOTE is probably wrong, there are currently no plans to + obsolete draw_osd, though there is the more advanced EOSD support for + ASS subtitles. + + flip_page(): this is called after each frame, this displays the buffer for + real. This is 'swapbuffers' when doublebuffering. + Try to do as little work here as possible, since that affect jitter/ + A-V sync. |