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Thank you two great gods first!
You can refer to the source code of ffmpeg, doc\examples\filtering_video.c, an example of video filtering. For ffmpeg? \libavfilter\vf_eq.c, adjust brightness and contrast to enhance image quality.
Reference command line:
Ffmpeg.exe-I test.mp4-VF eq = contrast = 1: brightness = 0.1out.mp4.
Set brightness, contrast, saturation and approximate gamma adjustment.
The filter supports the following options:
contrast
Sets the contrast expression. The value must be a floating-point number between -2.0 and 2.0. The default value is 0.
clever
Sets the brightness expression. The value must be a floating-point number between-1.0- 1.0, and the default value is 0.
soak
Sets the saturation expression. The value must be a floating-point number between 0 and 3.0, and the default value is 1.
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Public unsafe video filtering {
# Region Class Member Variable
AVFilterGraph * m _ filter _ graph = null；
AVFilterContext * m _ buffer sink _ CTX = null；
AVFilterContext * m _ buffersrc _ CTX = null；
AVFrame * m _ filt _ frame = null
Object m _ lock _ record = new Object()； ?
#endregion？
public int Init(int width，int height，int contrast，int brightness) {
Lock (m_lock_record) {
//Key code snippet?
if (m_filter_graph！ = null)？
return- 1； ?
Contrast = contrast & lt 1? 1: comparison;
contrast = contrast & gt9 ? 9: comparison;
Brightness = brightness & lt 1? 1: brightness;
Brightness = Brightness & gt9? 9: brightness;
float contrast _ f = 1+((float)(contrast-5))/ 10；
float brightness _ f = 0+((float)(brightness-5))/ 10；
String Filter _ Description = String. format(" eq = contrast = "+contrast _ f . ToString()+":brightness = "+brightness _ f . ToString())；
Returns init_filters(width, height, filters _ descr);
}
}
Public int Reset(int width, int height, int contrast, int brightness) {
deinit()； ?
Returns Init (width, height, contrast, brightness); ?
}
public int Filter(av frame * frame _ src，AVFrame **frame_dst)？ {?
Lock (m_lock_record){
* frame _dst = frame _ src?
if (m_filter_graph == null) {
return- 1； ?
}
int ret？
//AV_BUFFERSRC_FLAG_KEEP_REF = 8，？
ret = ffmpeg . av _ buffersrc _ add _ frame _ flags(m _ buffersrc _ CTX，frame_src，8)；
if(ret & lt； 0)?
Return to ret?
ret = ffmpeg . av _ buffer sink _ get _ frame(m _ buffer sink _ CTX，m _ filt _ frame)； ?
if(ret & lt； 0)
Return to ret?
* frame _ dst = m _ filt _ frame; ?
Returns 0; ?
}?
}
public void UnrefFrame() {
Lock (m_lock_record) {
if (m_filter_graph == null)？
Return; ?
ffmpeg . av _ frame _ unref(m _ filt _ frame)； ?
}?
}?
public void Deinit()？ {?
if (m_filter_graph == null)？
Return; ?
if(m_filter_graph！ = null)？ {?
Fixed (avfiltergraph * * filter _ graph =&; m_filter_graph)？
ffmpeg . av filter _ graph _ free(filter _ graph)； ?
}?
if (m_filt_frame！ = null)？ {?
Fixed (avframe * * filter _ frame = & ampm _ filter _ frame)?
ffmpeg . av _ frame _ free(filt _ frame)； ?
}?
}?
private int init _ filters(int width，int height，string filters_descr) {
int ret = 0； ?
ffmpeg . av filter _ register _ all()； ?
//AVPixelFormat。 AV _ PIX _ FMT _ YUV 420 p = 0； ?
String parameter = string. Format("video_size=" + width。 ToString() + "x" + height。 ToString()+":pix _ fmt = 0:time _ base = 1/20 ")； ?
av filter * buffer src = ffmpeg . av filter _ get _ by _ name(" buffer ")； ?
av filter * buffer sink = ffmpeg . av filter _ get _ by _ name(" buffer sink ")； ?
AVFilterInOut * outputs = ffmpeg . av filter _ inout _ alloc()； ?
AVFilterInOut * inputs = ffmpeg . av filter _ inout _ alloc()； ?
//av rational time _ base； ?
int * pix _ fmts =(int *)ffmpeg . av _ malloc(8)； ?
pix_fmts[0] = (int)AVPixelFormat。 AV _ PIX _ FMT _ YUV 420 p； ?
pix _ fmts[ 1]=(int)AVPixelFormat。 AV _ PIX _ FMT _ none; ?
//AVPixelFormat pix _ fmts[]= { AVPixelFormat。 AV_PIX_FMT_YUV420P，AVPixelFormat。 AV _ PIX _ FMT _ none; ?
m _ filter _ graph = ffmpeg . av filter _ graph _ alloc()； ?
if(outputs = = null | | inputs = = null | | m _ filter _ graph = = null)？ {?
ret =- 1； ?
Go to the end; ?
}?
fixed(AVFilterContext * * buffersrc _ CTX = & amp； m_buffersrc_ctx) {？
ret = ffmpeg . av filter _ graph _ create _ filter(buffersrc _ CTX，buffer src，" in "，args，null，m _ filter _ graph)； ?
if(ret & lt； 0)? {?
Go to the end; ?
}?
}?
fixed(AVFilterContext * * buffer sink _ CTX = & amp； m_buffersink_ctx) {？
ret = ffmpeg . av filter _ graph _ create _ filter(buffersink _ CTX，buffer sink，" out "，null，null，m _ filter _ graph)； ?
if(ret & lt； 0){?
Go to the end; ?
}?
}
Int size = (int) ffmpeg.av _ int _ list _ length _ for _ size (1,(void*)pix_fmts, not checked ((ulong)AVPixelFormat. AV _ PIX _ FMT _ none); ?
ret = ffmpeg . av _ opt _ set _ bin(m _ buffer sink _ CTX，" pix_fmts "，(byte*)pix_fmts，size，ffmpeg。 AV _ OPT _ SEARCH _ CHILDREN)； ?
if(ret & lt； 0)?
Go to the end; ?
Output->; name = ffmpeg . av _ strdup(" in ")； ?
Output->; filter _ ctx = m _ buffersrc _ ctx？
Output->; pad _ idx = 0； ?
Output->; next = null？
Input->; name = ffmpeg . av _ strdup(" out ")； ?
Input->; filter _ ctx = m _ buffersink _ ctx？
Input->; pad _ idx = 0； ?
Input->; next = null？
Ret = ffmpeg. avfilter _ graph _ parse _ ptr (m _ filter _ graph, filters_descr, & input and output. Output, empty); ?
if(ret & lt； 0)?
Go to the end; ?
ret = ffmpeg . av filter _ graph _ config(m _ filter _ graph，null)； ?
if(ret & lt； 0)?
Go to the end; ?
m _ filt _ frame = ffmpeg . av _ frame _ alloc()； ?
end:？
ffmpeg . av filter _ inout _ free(& amp； Input); ?
ffmpeg . av filter _ inout _ free(& amp； Output); ?
ffmpeg . av _ free(pix _ fmts)； ?
if(ret & lt； 0)
deinit()；
Return to ret
}
}
After verification, the effect is obvious, and you can try to modify the parameters according to your own needs.