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git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@4436 b3059339-0415-0410-9bf9-f77b7e298cf2
154 lines
6.1 KiB
Plaintext
154 lines
6.1 KiB
Plaintext
VIDIX - VIDeo Interface for *niX
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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This interface was designed and introduced as interface to userspace drivers
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to provide DGA everywhere where it's possible (unline X11).
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I hope that these drivers will be portable same as X11 (not only on *nix).
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What is it:
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- It's portable successor of mga_vid technology which is located in user-space.
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- Unlikely X11 it's provides DGA everywhere where it's possible.
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- Unlikely v4l it provides interface for video playback
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- Unlikely linux's drivers it uses mathematics library.
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Why it was developed:
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As said Vladimir Dergachev
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(http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/gatos/km/km.rfc.txt):
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"0) Motivation
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v4l, v4l2 and Xv are all suffering from the same problem: attempt to fit
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existing multimedia devices into a fixed scheme."
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Well - I tried to implement something similar by motivation.
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How it works:
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~~~~~~~~~~~~~
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This interface is almost finished. But I guess it can be expanded by developer's
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requests.
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So any suggestions, reports, criticism are gladly accepted.
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1) APP calls vixGetVersion to check age of driver ;)
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2) APP calls vixProbe. Driver should return 0 if it can handle something in PC.
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3) APP calls vixGetCapability. Driver should return filled
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vidix_capability_t.type field at least.
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4) If above calls were succesful then APP calls vixInit function
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(Driver can have not exported this function in this case call will be
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skiped).
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5) After initializing of driver APP calls vixGetCapability again
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(In this case driver must fill every field of struct)
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6) APP calls vixQueryFourcc. Driver should answer - can it configure
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video memory for given fourcc or not.
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7) APP calls vixConfigPlayback. Driver should prepare BES on this call.
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APP pass to driver following info:
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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vidix_playback_t.fourcc - contains fourcc of movie
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vidix_playback_t.capability - currently contsinas copy of vidix_capability_t.flags
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vidix_playback_t.blend_factor- currently unused
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vidix_playback_t.src - x,y,w,h fields contain original movie size
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(in pixels) x and y often are nulls.
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vidix_playback_t.src.pitch.y These fields contain source pitches
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vidix_playback_t.src.pitch.u - for each Y,U,V plane in bytes.
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vidix_playback_t.src.pitch.v (For packed fourcc only Y value is used)
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They are hints for driver to use same destinition
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pitches as in source memory (to speed up
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memcpy process).
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Note: when source pitches are unknown or
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variable these field will be filled into 0.
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vidix_playback_t.dest - x,y,w,h fields contains destinition rectange
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on the screen in pixels.
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vidix_playback_t.num_frames - maximal # of frames which can be used by APP.
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(Currently 10).
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Driver should fill following fields:
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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vidix_playback_t.num_frames - real # of frames which will be used by driver.
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(Should be less or equal to app's num_frames).
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vidix_playback_t.dest.pitch.y These fields should contain alignment
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vidix_playback_t.dest.pitch.u - for each Y,U,V plane in bytes.
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vidix_playback_t.dest.pitch.v (For packed fourcc only Y value is used)
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vidix_playback_t.frame_size - Driver should tell to app which size of
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source frame (src.w and src.h) should
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use APP (according to pitches and offsets)
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vidix_playback_t.offsets - offsets from begin of BES memory for each frame
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vidix_playback_t.offset.y These field should contain offset
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vidix_playback_t.offset.u - for each Y,U,V plane within frame.
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vidix_playback_t.offset.v (For packed fourcc only Y value is used)
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vidix_playback_t.dga_addr - Address of BES memory.
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Also see this picture:
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VIDEO MEMORY layout:
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+----------- It's begin of video memory End of video memory--------------+
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v v
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[ RGB memory | YUV memory | UNDEF ]
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^
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+---- begin of BES memory
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BES MEMORY layout:
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+-------- begin of BES memory
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v
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[ | | | | |
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^ ^ ^ ^ ^
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| | | | + BEGIN of second frame
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| | | + BEGIN of V plane
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| | + BEGIN of U plane
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| +------- BEGIN of Y plane
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+--------- BEGIN of first frame
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This means that in general case:
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offset of frame != offset of BES
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offset of Y plane != offset of first frame
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But often: vidix_playback_t.offsets[0] = vidix_playback_t.offset.y = 0;
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Formula: (For Y plane) copy source to:
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vidix_playback_t.dga_addr +
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vidix_playback_t.offsets[i] +
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vidix_playback_t.offset.y
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8) APP calls vixPlaybackOn. Driver should activate BES on this call.
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9) PLAYBACK. Driver should sleep here ;)
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But during playback can be called:
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vixFrameSelect (if this function is exported)
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Driver should prepare and activate corresponded frame.
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This function is used only for double and trilpe buffering and
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never used for single buffering playback.
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vixGet(Set)GrKeys (if this function is exported)
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This interface should be tuned but intriduced for overlapped playback
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and video effects (TYPE_FX)
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vixPlaybackGet(Set)Eq (if this function is exported)
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For color correction.
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10) APP calls vixPlaybackOff. Driver should deactivate BES on this call.
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11) If vixDestroy is defined APP calls this function before unloading driver
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from memory.
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What functions are mandatory:
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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vixGetVersion
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vixProbe
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vixGetCapability
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vixQueryFourcc
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vixConfigPlayback
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vixPlaybackOn
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vixPlaybackOff
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All other functions are optionaly.
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Useful links:
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~~~~~~~~~~~~~
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Guide to DTV http://www.digitaltelevision.com/dtvbook/toc.shtml
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Fourcc http://www.webartz.com/fourcc/
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MPEG http://www.mpeg.org/MPEG/index.html
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Analog colors http://www.miranda.com/en/app_notes/TN/TN-05/TN-05.htm
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Please send your suggestions, reports, feedback to mplayer-dev-eng@mplayerhq.hu
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Best regards! Nick Kurshev.
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