FFmpeg添加滤镜调整视频对比度和亮度

Posted 2022-06-15 boonya

原文地址：https://blog.csdn.net/wer85121430/article/details/79642951

目的:调整视频的亮度和对比度。

可参考ffmpeg的源码：

\\examples\\filtering_video.c，视频滤波例子

\\libavfilter\\vf_eq.c，亮度对比度调整的具体实现

先使用ffmpeg.exe试试效果，女神的原始视频图片：

ffmpeg.exe -i record.mp4 -vf eq=contrast=1:brightness=-0.2 output.mp4 处理后图片

ffmpeg.exe -i record.mp4 -vf eq=contrast=1:brightness=0.2 output.mp4 处理后图片

效果还可以.

写好了，贴代码，主要是参考这个文件\\examples\\filtering_video.c，C代码改C#遇到了几个坑花了大半天时间

Init函数的contrast和brightness参数分别对应对比度和亮度，取值1-9，5为原始图像。

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1.   

[csharp]

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1. public unsafe class VideoFiltering  
2.   
3.     #region 类成员变量  
4.     AVFilterGraph* m_filter_graph = null;  
5.     AVFilterContext* m_buffersink_ctx = null;  
6.     AVFilterContext* m_buffersrc_ctx = null;  
7.     AVFrame* m_filt_frame = null;  
8.     Object m_lock_record = new Object();  
9.     #endregion  
10.   
11.     public int Init(int width, int height, int contrast, int brightness)  
12.       
13.         lock (m_lock_record)  
14.           
15.             // Critical code section  
16.             if (m_filter_graph != null)  
17.                 return -1;  
18.   
19.             contrast = contrast < 1 ? 1 : contrast;  
20.             contrast = contrast > 9 ? 9 : contrast;  
21.             brightness = brightness < 1 ? 1 : brightness;  
22.             brightness = brightness > 9 ? 9 : brightness;  
23.   
24.             float contrast_f = 1 + ((float)(contrast - 5)) / 10;  
25.             float brightness_f = 0 + ((float)(brightness - 5)) / 10;  
26.             string filters_descr = string.Format("eq=contrast=" + contrast_f.ToString() + ":brightness=" + brightness_f.ToString());  
27.   
28.             return init_filters(width, height, filters_descr);  
29.           
30.      
31.     public int Reset(int width, int height, int contrast, int brightness)  
32.       
33.         Deinit();  
34.         return Init(width, height, contrast, brightness);  
35.       
36.   
37.     public int Filter(AVFrame * frame_src, AVFrame **frame_dst)  
38.       
39.         lock (m_lock_record)  
40.           
41.             *frame_dst = frame_src;  
42.             if (m_filter_graph == null)  
43.               
44.                 return -1;  
45.               
46.   
47.             int ret;  
48.   
49.             //AV_BUFFERSRC_FLAG_KEEP_REF = 8,  
50.             ret = ffmpeg.av_buffersrc_add_frame_flags(m_buffersrc_ctx, frame_src, 8);  
51.             if (ret < 0)  
52.                 return ret;  
53.   
54.             ret = ffmpeg.av_buffersink_get_frame(m_buffersink_ctx, m_filt_frame);  
55.             if (ret < 0)  
56.                 return ret;  
57.   
58.             *frame_dst = m_filt_frame;  
59.   
60.             return 0;  
61.           
62.       
63.     public void UnrefFrame()  
64.       
65.         lock (m_lock_record)  
66.           
67.             if (m_filter_graph == null)  
68.                 return ;  
69.             ffmpeg.av_frame_unref(m_filt_frame);  
70.           
71.       
72.   
73.     public void Deinit()  
74.       
75.         if (m_filter_graph == null)  
76.             return ;  
77.   
78.         if(m_filter_graph != null)  
79.           
80.             fixed(AVFilterGraph** filter_graph = &m_filter_graph)  
81.                 ffmpeg.avfilter_graph_free(filter_graph);  
82.           
83.   
84.         if (m_filt_frame != null)  
85.           
86.             fixed (AVFrame** filt_frame = &m_filt_frame)  
87.                 ffmpeg.av_frame_free(filt_frame);  
88.           
89.   
90.       
91.   
92.     private int init_filters(int width, int height, string filters_descr)  
93.       
94.         int ret = 0;  
95.   
96.         ffmpeg.avfilter_register_all();  
97.   
98.         //AVPixelFormat.AV_PIX_FMT_YUV420P = 0;  
99.         string args = string.Format("video_size=" + width.ToString() + "x" + height.ToString() +  
100.                                     ":pix_fmt=0:time_base=1/20");  
101.               
102.         AVFilter* buffersrc = ffmpeg.avfilter_get_by_name("buffer");  
103.         AVFilter* buffersink = ffmpeg.avfilter_get_by_name("buffersink");  
104.         AVFilterInOut* outputs = ffmpeg.avfilter_inout_alloc();  
105.         AVFilterInOut* inputs = ffmpeg.avfilter_inout_alloc();  
106.         //AVRational time_base;  
107.   
108.         int* pix_fmts = (int*)ffmpeg.av_malloc(8);  
109.         pix_fmts[0] = (int)AVPixelFormat.AV_PIX_FMT_YUV420P;  
110.         pix_fmts[1] = (int)AVPixelFormat.AV_PIX_FMT_NONE;  
111.         //AVPixelFormat pix_fmts[] =  AVPixelFormat.AV_PIX_FMT_YUV420P, AVPixelFormat.AV_PIX_FMT_NONE ;  
112.   
113.         m_filter_graph = ffmpeg.avfilter_graph_alloc();  
114.         if(outputs == null || inputs == null || m_filter_graph == null)  
115.           
116.             ret = -1;  
117.             goto end;  
118.           
119.   
120.         fixed (AVFilterContext** buffersrc_ctx = &m_buffersrc_ctx)  
121.           
122.             ret = ffmpeg.avfilter_graph_create_filter(buffersrc_ctx, buffersrc, "in", args, null, m_filter_graph);  
123.             if (ret < 0)  
124.               
125.                 goto end;  
126.               
127.           
128.   
129.         fixed (AVFilterContext** buffersink_ctx = &m_buffersink_ctx)  
130.           
131.             ret = ffmpeg.avfilter_graph_create_filter(buffersink_ctx, buffersink, "out", null, null, m_filter_graph);  
132.             if (ret < 0)  
133.               
134.                 goto end;  
135.               
136.           
137.              
138.   
139.         int size = (int)ffmpeg.av_int_list_length_for_size(1, (void*)pix_fmts, unchecked((ulong)AVPixelFormat.AV_PIX_FMT_NONE));  
140.         ret = ffmpeg.av_opt_set_bin(m_buffersink_ctx, "pix_fmts", (byte*)pix_fmts, size, ffmpeg.AV_OPT_SEARCH_CHILDREN);  
141.         if(ret < 0)  
142.             goto end;  
143.   
144.         outputs->name = ffmpeg.av_strdup("in");  
145.         outputs->filter_ctx = m_buffersrc_ctx;  
146.         outputs->pad_idx = 0;  
147.         outputs->next = null;  
148.   
149.         inputs->name = ffmpeg.av_strdup("out");  
150.         inputs->filter_ctx = m_buffersink_ctx;  
151.         inputs->pad_idx = 0;  
152.         inputs->next = null;  
153.   
154.         ret = ffmpeg.avfilter_graph_parse_ptr(m_filter_graph, filters_descr, &inputs, &outputs, null);  
155.         if (ret < 0)  
156.             goto end;  
157.   
158.         ret = ffmpeg.avfilter_graph_config(m_filter_graph, null);  
159.         if (ret < 0)  
160.             goto end;  
161.   
162.         m_filt_frame = ffmpeg.av_frame_alloc();  
163.   
164.         end:  
165.         ffmpeg.avfilter_inout_free(&inputs);  
166.         ffmpeg.avfilter_inout_free(&outputs);  
167.   
168.         ffmpeg.av_free(pix_fmts);  
169.   
170.         if (ret < 0)  
171.             Deinit();  
172.   
173.         return ret;  
174.       
175.