mirror of
https://github.com/mpv-player/mpv
synced 2024-11-07 01:47:00 +01:00
some docs about video filter api
git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@8002 b3059339-0415-0410-9bf9-f77b7e298cf2
This commit is contained in:
arpi
parent
1e8c25f81e
commit
cb1ac8e282
@ -112,6 +112,206 @@ Short description of video path:
|
||||
Leaf filters are now: vf_vo.c (wrapper over libvo) and ve_XXX.c (video
|
||||
encoders used by mencoder).
|
||||
|
||||
The VIDEO FILTER API:
|
||||
=====================
|
||||
filename: vf_FILTERNAME.c
|
||||
|
||||
vf_info_t* info;
|
||||
pointer to the filter description structure:
|
||||
|
||||
const char *info; // description of the filter
|
||||
const char *name; // short name of the filter, must be FILTERNAME
|
||||
const char *author; // name and email/url of the author(s)
|
||||
const char *comment;// comment, url to papers describing algo etc.
|
||||
int (*open)(struct vf_instance_s* vf,char* args);
|
||||
// pointer to the open() function:
|
||||
|
||||
The open() function:
|
||||
|
||||
open() is called when the filter is appended/inserted to the filter chain.
|
||||
it'll receive the handler (vf) and the optional filter parameters as
|
||||
char* string. Note, that encoders (ve_*) and vo wrapper (vf_vo.c) have
|
||||
non-string arg, but it's specially handled by mplayer/mencoder.
|
||||
|
||||
The open() function should fill the vf_instance_t structure, with the
|
||||
implemented functions' pointers (see bellow).
|
||||
It can optinally allocate memory for its internal data (vf_priv_t) and
|
||||
store the pointer in vf->priv.
|
||||
|
||||
The open() func should parse (or at least check syntax) of parameters,
|
||||
and fail (return 0) if error.
|
||||
|
||||
Sample:
|
||||
|
||||
static int open(vf_instance_t *vf, char* args){
|
||||
vf->query_format=query_format;
|
||||
vf->config=config;
|
||||
vf->put_image=put_image;
|
||||
// allocate local storage:
|
||||
vf->priv=malloc(sizeof(struct vf_priv_s));
|
||||
vf->priv->w=
|
||||
vf->priv->h=-1;
|
||||
if(args) // parse args:
|
||||
if(sscanf(args, "%d:%d", &vf->priv->w, &vf->priv->h)!=2) return 0;
|
||||
return 1;
|
||||
}
|
||||
|
||||
Functions in vf_instance_s:
|
||||
|
||||
NOTE: All these are optional, their func pointer is either NULL or points to
|
||||
a default implementation. If you implement them, don't forget to set
|
||||
vf->FUNCNAME in your open() !
|
||||
|
||||
int (*query_format)(struct vf_instance_s* vf,
|
||||
unsigned int fmt);
|
||||
|
||||
The query_format() func. is called one or more times before the config(),
|
||||
to find out the capabilities and/or support status of a given colorspace (fmt).
|
||||
For the return values, see vfcap.h!
|
||||
Normally, a filter should return at least VFCAP_CSP_SUPPORTED for all supported
|
||||
colorspaces, and 0 for the unsupported ones. If your filter does linear
|
||||
conversion, it should query the next filter, and pass its capability flags.
|
||||
|
||||
Sample:
|
||||
|
||||
static int query_format(struct vf_instance_s* vf, unsigned int fmt){
|
||||
switch(fmt){
|
||||
case IMGFMT_YV12:
|
||||
case IMGFMT_I420:
|
||||
case IMGFMT_IYUV:
|
||||
case IMGFMT_422P:
|
||||
return vf_next_query_format(vf,IMGFMT_YUY2) & (~VFCAP_CSP_SUPPORTED_BY_HW);
|
||||
}
|
||||
return 0;
|
||||
}
|
||||
|
||||
|
||||
int (*config)(struct vf_instance_s* vf,
|
||||
int width, int height, int d_width, int d_height,
|
||||
unsigned int flags, unsigned int outfmt);
|
||||
|
||||
The config() is called to initialize/confugre the filter before using it.
|
||||
Its parameters are already well-known from libvo:
|
||||
width, height: size of the coded image
|
||||
d_width, d_height: wanted display size (usually aspect corrected w/h)
|
||||
flags: the "good" old flags set of libvo:
|
||||
0x01 - force fullscreen (-fs)
|
||||
0x02 - allow mode switching (-vm)
|
||||
0x04 - allow software scaling (-zoom)
|
||||
0x08 - flipping (-flip)
|
||||
(Usually you don't have to worry about flags, just pass it to next config.)
|
||||
outfmt: the selected colorspace/pixelformat. You'll receive images in this
|
||||
format.
|
||||
|
||||
Sample:
|
||||
|
||||
static int config(struct vf_instance_s* vf,
|
||||
int width, int height, int d_width, int d_height,
|
||||
unsigned int flags, unsigned int outfmt){
|
||||
// use d_width/d_height if not set by user:
|
||||
if(vf->priv->w==-1) vf->priv->w=d_width;
|
||||
if(vf->priv->h==-1) vf->priv->h=d_width;
|
||||
// initialize your filter code
|
||||
...
|
||||
// ok now config the rest of the filter chain, with our output parameters:
|
||||
return vf_next_config(vf,vf->priv->w,vf->priv->h,d_width,d_height,flags,outfmt);
|
||||
}
|
||||
|
||||
void (*uninit)(struct vf_instance_s* vf);
|
||||
|
||||
Okey, uninit() is the simplest, it's called at the end. You can free your
|
||||
private buffers etc here.
|
||||
|
||||
int (*put_image)(struct vf_instance_s* vf,
|
||||
mp_image_t *mpi);
|
||||
|
||||
Ah, put_image(). This is the main filter function it should convert/filter/
|
||||
transform the image data from one format/size/color/whatever to another.
|
||||
Its input parameter is an mpi (mplayer image) structure, see mp_image.h.
|
||||
Your filter has to request a new image buffer for the output, using the
|
||||
vf_get_image() function. NOTE: even if you don't want to modify the image,
|
||||
just pass it to the next filter, you have to either
|
||||
- do not implement put_image() at all - then it will be skipped
|
||||
- request a new image with type==EXPORT and copy the pointers
|
||||
NEVER pass the mpi as-is, it's local to filters and may cause trouble.
|
||||
|
||||
If you completely copy/transform the image, then you probably want this:
|
||||
|
||||
dmpi=vf_get_image(vf->next,mpi->imgfmt,
|
||||
MP_IMGTYPE_TEMP, MP_IMGFLAG_ACCEPT_STRIDE,
|
||||
vf->priv->w, vf->priv->h);
|
||||
|
||||
It will allocate a new image, and return an mp_image structure filled by
|
||||
buffer pointers and stride (bytes per line) values, in size of vf->priv->w
|
||||
times vf->priv->h. If your filter cannot handle stride, then left out
|
||||
MP_IMGFLAG_ACCEPT_STRIDE. Note, that you can do this, but it isn't recommended,
|
||||
the whole video path is designed to use strides to get optimal throughput.
|
||||
If your filter allocates output image buffers, then use MP_IMGTYPE_EXPORT,
|
||||
and fill the returned dmpi's planes[], stride[] with your buffer parameters.
|
||||
Note, it is not recommended (no direct rendering), so if you can, use
|
||||
vf_get_image() for buffer allocation!
|
||||
For other image types and flags see mp_image.h, it has comments.
|
||||
If you are unsure, feel free to ask on the -dev-eng maillist. Please
|
||||
describe the behaviour of your filter, an dits limitations, so we can
|
||||
suggest the optimal buffer type + flags for your code.
|
||||
|
||||
Now, that you have the input (mpi) and output (dmpi) buffers, you can do
|
||||
the conversion. If you didn't notice yet, mp_image has some useful info
|
||||
fields, may help you a lot creating if() or for() structures:
|
||||
flags: MP_IMGFLAG_PLANAR, MP_IMGFLAG_YUV, MP_IMGFLAG_SWAPPED
|
||||
helps you to handle various pixel formats in single code.
|
||||
bpp: bits per pixel
|
||||
WARNING! It's number of bits _allocated_ to store a pixel,
|
||||
it is not the number of bits actually used to keep colors!
|
||||
So, it's 16 for both 15 and 16bit color depth, and is 32 for
|
||||
32bpp (actually 24bit color depth) mode!
|
||||
It's 1 for 1bpp, 9 for YVU9, and is 12 for YV12 mode. Get it?
|
||||
For planar formats, you also have chroma_width, chroma_height and
|
||||
chroma_x_shift, chroma_y_shift too.
|
||||
|
||||
If you're done, call the rest of the filter chain to process your output
|
||||
image:
|
||||
return vf_next_put_image(vf,dmpi);
|
||||
|
||||
|
||||
Ok, the rest is for advanced functionality only:
|
||||
|
||||
int (*control)(struct vf_instance_s* vf,
|
||||
int request, void* data);
|
||||
|
||||
You can control the filter in runtime from mplayer/mencoder/dec_video:
|
||||
#define VFCTRL_QUERY_MAX_PP_LEVEL 4 /* test for postprocessing support (max level) */
|
||||
#define VFCTRL_SET_PP_LEVEL 5 /* set postprocessing level */
|
||||
#define VFCTRL_SET_EQUALIZER 6 /* set color options (brightness,contrast etc) */
|
||||
#define VFCTRL_GET_EQUALIZER 8 /* gset color options (brightness,contrast etc) */
|
||||
#define VFCTRL_DRAW_OSD 7
|
||||
#define VFCTRL_CHANGE_RECTANGLE 9 /* Change the rectangle boundaries */
|
||||
|
||||
void (*get_image)(struct vf_instance_s* vf,
|
||||
mp_image_t *mpi);
|
||||
|
||||
This is for direct rendering support, works the same way as in libvo drivers.
|
||||
It makes in-place pixel modifications possible.
|
||||
If you implement it (vf->get_image!=NULL) then it will be called to do the
|
||||
buffer allocation. You SHOULD check the buffer restrictions (stride, type,
|
||||
readability etc) and if all OK, then allocate the requested buffer using
|
||||
the vf_get_image() func and copying the buffer pointers.
|
||||
|
||||
void (*draw_slice)(struct vf_instance_s* vf,
|
||||
unsigned char** src, int* stride, int w,int h, int x, int y);
|
||||
|
||||
It's the good old draw_slice callback, already known from libvo.
|
||||
If you filter can operate on partial images, you can implement this one
|
||||
to improve performance (cache utilization).
|
||||
|
||||
Ah, and there is 2 set of capability/requirement flags (vfcap.h type)
|
||||
in vf_instance_t, used by default query_format() implementation, and by
|
||||
the automatic colorspace/stride matching code (vf_next_config()).
|
||||
|
||||
// caps:
|
||||
unsigned int default_caps; // used by default query_format()
|
||||
unsigned int default_reqs; // used by default config()
|
||||
|
||||
|
||||
The AUDIO path:
|
||||
===============
|
||||
|
||||
Loading…
Reference in New Issue
Block a user