网上关于filter的使用应该不少，参照下，然后根据ffmpeg官方的文档，应该很容易实现需求，所以这里仅介绍用代码怎么调用filter来达到想要的效果。
下面是ffmpeg中blend这个filter声明的相关代码（基于ffmpeg 2.8最新版本）：
1 AVFilter ff_vf_blend = {
2 .name = "blend",
3 .description = NULL_IF_CONFIG_SMALL("Blend two video frames into each other."),
4 .init = init,
5 .uninit = uninit,
6 .priv_size = sizeof(BlendContext),
7 .query_formats = query_formats,
8 .inputs = blend_inputs,
9 .outputs = blend_outputs,
10 .priv_class = &blend_class,
11 .flags = AVFILTER_FLAG_SUPPORT_TIMELINE_INTERNAL | AVFILTER_FLAG_SLICE_THREADS,
12 };
ffmpeg中所有的filter基本都和上面的结构一样，比较关键的是：
name：你可以根据name来获取此filter
inputs：定义了此filter输入的参数信息，每个输入通道的格式一般都有name（唯一标识符）、type（类型：视频|音频）、filter_frame（对应的输入函数，如果需要输入AVFrame一般都会调用ff_dualinput_filter_frame）
outputs：定义了此filter输出的，根据request_frame指定函数（request_frame）来处理。
所以在使用blend filter，按照下面思路即可：
1.blend需要二个输入，我们可以申请二个buffer filter，然后通过系统的avfilter_link函数来给blend填充数据；
2.blend有一个输出，我们可以申请一个buffersink filter，同理来获取数据；
转为代码：
1 #include <stdio.h>
2
3 #define __STDC_CONSTANT_MACROS
4
5 #ifdef _WIN32
6 #define snprintf _snprintf
7 //Windows
8 extern "C"
9 {
10 #include "libavfilter/avfiltergraph.h"
11 #include "libavfilter/buffersink.h"
12 #include "libavfilter/buffersrc.h"
13 #include "libavutil/avutil.h"
14 #include "libavutil/imgutils.h"
15 #include "libavformat/avformat.h"
16 };
17 #else
18 //Linux...
19 #ifdef __cplusplus
20 extern "C"
21 {
22 #endif
23 #include <libavfilter/avfiltergraph.h>
24 #include <libavfilter/buffersink.h>
25 #include <libavfilter/buffersrc.h>
26 #include <libavutil/avutil.h>
27 #include <libavutil/imgutils.h>
28 #ifdef __cplusplus
29 };
30 #endif
31 #endif
32
33
34 static AVFormatContext *pFormatCtx;
35 static AVCodecContext *pCodecCtx;
36 static int video_stream_index = -1;
37
38 AVFilterContext *inputContexts1, *inputContexts2;
39 AVFilterContext *outputContext;
40 AVFilterGraph *graph;
41
42 static int init_filter_graph(AVFilterGraph **pGraph, AVFilterContext **pInput1, AVFilterContext **pInput2, AVFilterContext **pOutput)
43 {
44 AVFilterGraph* tFilterGraph;
45 AVFilterContext* tBufferContext1;
46 AVFilter* tBuffer1;
47 AVFilterContext* tBufferContext2;
48 AVFilter* tBuffer2;
49 AVFilterContext* tOverlayContext;
50 AVFilter* tOverlay;
51 AVFilterContext* tBufferSinkContext;
52 AVFilter* tBufferSink;
53 AVFilter* tFormat;
54 AVFilterContext* tFormatContext;
55
56 int tError;
57
58 /* Create a new filtergraph, which will contain all the filters. */
59 tFilterGraph = avfilter_graph_alloc();
60 const char *args = "video_size=512x288:pix_fmt=0:time_base=1/30:pixel_aspect=1/1";//这里的参数根据实际视频参数来设置
61
62 if (!tFilterGraph) {
63 return -1;
64 }
65
66 { // BUFFER FILTER 1
67 tBuffer1 = avfilter_get_by_name("buffer");
68 if (!tBuffer1) {
69 return -1;
70 }
71 int ret = avfilter_graph_create_filter(&tBufferContext1, tBuffer1, "top",
72 args, NULL, tFilterGraph);
73 if (ret < 0) {
74 printf("Cannot create buffer source\n");
75 return ret;
76 }
77 }
78
79 { // BUFFER FILTER 2
80 tBuffer2 = avfilter_get_by_name("buffer");
81 if (!tBuffer2) {
82 return -1;
83 }
84 if (1) {
85
86 int ret = avfilter_graph_create_filter(&tBufferContext2, tBuffer2, "bottom",
87 args, NULL, tFilterGraph);
88 if (ret < 0) {
89 printf("Cannot create buffer source\n");
90 return ret;
91 }
92 }
93 }
94
95 { // BLEND FILTER
96 tOverlay = avfilter_get_by_name("blend");
97 if (!tOverlay) {
98 return -1;
99 }
100 tOverlayContext = avfilter_graph_alloc_filter(tFilterGraph, tOverlay, "blend");
101 if (!tOverlayContext) {
102 return -1;
103 }
104 AVDictionary *tOptionsDict = NULL;
105 av_dict_set(&tOptionsDict, "all_mode", "normal", 0);
106 av_dict_set(&tOptionsDict, "all_opacity", "1", 0);
107 av_dict_set(&tOptionsDict, "all_expr", "A*(if(gte(T,10),1,T/10))+B*(1-(if(gte(T,10),1,T/10)))", 0);//详情参见ffmpeg官方文档
108 tError = avfilter_init_dict(tOverlayContext, &tOptionsDict);
109 av_dict_free(&tOptionsDict);
110 if (tError < 0) {
111 return tError;
112 }
113 }
114
115 { // FORMAT FILTER
116 tFormat = avfilter_get_by_name("format");
117 if (!tFormat) {
118 // Could not find the tFormat filter.
119 return -1;
120 }
121
122 tFormatContext = avfilter_graph_alloc_filter(tFilterGraph, tFormat, "format");
123 if (!tFormatContext) {
124 // Could not allocate the tFormat instance.
125 return -1;
126 }
127 AVDictionary *tOptionsDict = NULL;
128 av_dict_set(&tOptionsDict, "pix_fmts", "yuv420p", 0);
129 tError = avfilter_init_dict(tFormatContext, &tOptionsDict);
130 av_dict_free(&tOptionsDict);
131 if (tError < 0) {
132 // Could not initialize the tFormat filter.
133 return tError;
134 }
135 }
136
137 { // BUFFERSINK FILTER
138 tBufferSink = avfilter_get_by_name("buffersink");
139 if (!tBufferSink) {
140 return -1;
141 }
142
143 tBufferSinkContext = avfilter_graph_alloc_filter(tFilterGraph, tBufferSink, "sink");
144 if (!tBufferSinkContext) {
145 return -1;
146 }
147
148 tError = avfilter_init_str(tBufferSinkContext, NULL);
149 if (tError < 0) {
150 return tError;
151 }
152 }
153
154 // Linking graph
155 tError = avfilter_link(tBufferContext1, 0, tOverlayContext, 0);
156 if (tError >= 0)
157 {
158 tError = avfilter_link(tBufferContext2, 0, tOverlayContext, 1);
159 }
160 if (tError >= 0)
161 {
162 tError = avfilter_link(tOverlayContext, 0, tFormatContext, 0);
163 }
164 if (tError >= 0)
165 {
166 tError = avfilter_link(tFormatContext, 0, tBufferSinkContext, 0);
167 }
168 if (tError < 0) { // Error connecting filters.
169 return tError;
170 }
171
172 tError = avfilter_graph_config(tFilterGraph, NULL);
173 if (tError < 0) {
174 return tError;
175 }
176
177 *pGraph = tFilterGraph;
178 *pInput1 = tBufferContext1;
179 *pInput2 = tBufferContext2;
180 *pOutput = tBufferSinkContext;
181
182 return 0;
183 }
184
185 static int open_input_file(const char *filename)
186 {
187 int ret;
188 AVCodec *dec;
189
190 if ((ret = avformat_open_input(&pFormatCtx, filename, NULL, NULL)) < 0) {
191 printf("Cannot open input file\n");
192 return ret;
193 }
194
195 if ((ret = avformat_find_stream_info(pFormatCtx, NULL)) < 0) {
196 printf("Cannot find stream information\n");
197 return ret;
198 }
199
200 /* select the video stream */
201 ret = av_find_best_stream(pFormatCtx, AVMEDIA_TYPE_VIDEO, -1, -1, &dec, 0);
202 if (ret < 0) {
203 printf("Cannot find a video stream in the input file\n");
204 return ret;
205 }
206 video_stream_index = ret;
207 pCodecCtx = pFormatCtx->streams[video_stream_index]->codec;
208
209 /* init the video decoder */
210 if ((ret = avcodec_open2(pCodecCtx, dec, NULL)) < 0) {
211 printf("Cannot open video decoder\n");
212 return ret;
213 }
214
215 return 0;
216 }
217
218
219 int main(int argc, char* argv[])
220 {
221 av_register_all();
222 avfilter_register_all();
223
224 if ((open_input_file("cuc_ieschool.flv")) < 0)
225 return 1;
226
227 init_filter_graph(&graph,&inputContexts1,&inputContexts2,&outputContext);
228
229 int ret;
230 AVFrame *frame_in;
231 AVFrame *frame_out;
232 unsigned char *frame_buffer_in;
233 unsigned char *frame_buffer_out;
234
235 //Input YUV
236 FILE *fp_in=fopen("512x288.yuv","rb+");
237 if(fp_in==NULL){
238 printf("Error open input file.\n");
239 return -1;
240 }
241 //Ouput YUV
242 FILE *fp_yuv = fopen("test.yuv", "wb+");
243 int in_width= 512;
244 int in_height= 288;
245
246
247 frame_in=av_frame_alloc();
248 frame_buffer_in=(unsigned char *)av_malloc(av_image_get_buffer_size(AV_PIX_FMT_YUV420P, in_width,in_height,1));
249 av_image_fill_arrays(frame_in->data, frame_in->linesize,frame_buffer_in,
250 AV_PIX_FMT_YUV420P,in_width, in_height,1);
251
252 frame_in->width=in_width;
253 frame_in->height=in_height;
254 frame_in->format=AV_PIX_FMT_YUV420P;
255
256 AVPacket packet;
257 AVFrame *pFrame = av_frame_alloc();
258 AVFrame *pFrame_out = av_frame_alloc();
259 int count = 5;//保存的yuv数
260 int readonce = 10;//便于观察，取yuv文件第10副来混合，如果你想混合2个视频，可自行修改，另外注意，blend需要2个Frame意味着如果你需要混合请确保输入满足此要求
261 if (readonce-- > 0) {
262 //get one buffer from yuv.
263 if (fread(frame_buffer_in, 1, in_width*in_height * 3 / 2, fp_in) != in_width*in_height * 3 / 2) {
264 return 1;
265 }
266 //input Y,U,V
267 frame_in->data[0] = frame_buffer_in;
268 frame_in->data[1] = frame_buffer_in + in_width*in_height;
269 frame_in->data[2] = frame_buffer_in + in_width*in_height * 5 / 4;
270 }
271
272 while (1) {
273 //read one packet.
274 ret = av_read_frame(pFormatCtx, &packet);
275 if (ret< 0)
276 break;
277 if (packet.stream_index == 0) {
278 int got_frame = 0;
279 //decode
280 ret = avcodec_decode_video2(pCodecCtx, pFrame, &got_frame, &packet);
281 if (ret < 0) {
282 printf("Error decoding video\n");
283 break;
284 }
285 //success
286 if (got_frame) {
287 pFrame->pts = av_frame_get_best_effort_timestamp(pFrame);
288 /* push the decoded frame into the filtergraph */
289 if (av_buffersrc_add_frame(inputContexts1, pFrame) < 0) {
290 printf("Error while feeding the filtergraph\n");
291 break;
292 }
293
294 frame_in->pts = pFrame->pts;
295 if (av_buffersrc_add_frame(inputContexts2, frame_in) < 0) {
296 printf("Error while add frame.\n");
297 break;
298 }
299 /* pull filtered pictures from the filtergraph */
300 while (1) {
301 ret = av_buffersink_get_frame(outputContext, pFrame_out);
302 if (ret < 0)
303 break;
304 if (pFrame_out->format == AV_PIX_FMT_YUV420P && count-- > 0) {
305 //Y, U, V
306 for (int i = 0; i < pFrame_out->height; i++) {
307 fwrite(pFrame_out->data[0] + pFrame_out->linesize[0] * i, 1, pFrame_out->width, fp_yuv);
308 }
309 for (int i = 0; i < pFrame_out->height / 2; i++) {
310 fwrite(pFrame_out->data[1] + pFrame_out->linesize[1] * i, 1, pFrame_out->width / 2, fp_yuv);
311 }
312 for (int i = 0; i < pFrame_out->height / 2; i++) {
313 fwrite(pFrame_out->data[2] + pFrame_out->linesize[2] * i, 1, pFrame_out->width / 2, fp_yuv);
314 }
315 printf("Process 1 frame!\n");
316 }
317 av_frame_unref(pFrame_out);
318 }
319 }
320 av_frame_unref(pFrame);
321 }
322 av_free_packet(&packet);
323 }
324
325 fclose(fp_in);
326 fclose(fp_yuv);
327
328 av_frame_free(&pFrame);
329 av_frame_free(&pFrame_out);
330 av_frame_free(&frame_in);
331 avfilter_graph_free(&graph);
332
333 return 0;
334 }
文件的网盘地址：https://pan.baidu.com/s/1pLi6px5
另外一个变种，关于动态文字水印：https://pan.baidu.com/s/1eSJw9we
时间： 2024-10-20 14:31:53