mirror of https://github.com/mpv-player/mpv
53 lines
2.0 KiB
Plaintext
53 lines
2.0 KiB
Plaintext
First draft on video filter layer by A'rpi
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=================================
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Main goals:
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- it should be in libmpcodecs
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- it should reduce number of memcpys and memoru allocation to minimum
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- it should do postprocessing, colorspace convert, scale and crop/expand/flip
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[is there any other type of filters? maybe we could generalize these]
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- maybe: sub/osd
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Implementation:
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The video filter plugin should implement the get_image() call (called from
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the video decoder) and call get_image() for the destination image.
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so, it would have:
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optional:
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int get_image(mp_image_t* mpi) // called through control()
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if the filter doesn't implement this call, the core (vd.c) will alloc
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buffer using memalign() as for disabled direct rendering.
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mandatory:
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mp_vfilter_data* init()
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void uninit(mp_vfilter_data* vfd)
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int control(mp_vfilter_data* vfd, ...)
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mp_image_t* process(mp_vfilter_data* vfd, mp_image_t* mpi,(*get_image)())
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this function will receive an mpi (maybe previously returned by get_image())
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and should return the filtered mpi. it should use mpcodecs_get_image() to
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allocate a new mpi.
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the returned mpi may be EXPORT type, so just doing some pointer/stride
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tricks (usually enough for crop/expand/flip) without duplicating the
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image buffer or doing the modifications in the incoming buffer (if its
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type allows it - so no flags PRESERVE/READABLE set)
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mp_vfilter_data would be a transparent (to caller) pointer, used by the
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filter instance to store its internal data, tables, parameters etc.
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it would allow a fliter to be used more than one times in the queue.
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for example: resize in 2 step, postproc+resize+postproc, expand+scale+crop etc
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the tricky part of these filters is finding and implementing Direct
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Filtering(C) using get_image().
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anyway, as first step you can skip get_image() implementation, and just
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leave it to vd.c core. in most cases it will be enough, direct filtering
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only helps with simple filters (crop/expand/flip) in most cases.
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