使用ffmepg实现多路视频流合并

本文主要是介绍使用ffmepg实现多路视频流合并，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

做视频会议系统的时候，有时需要实现多路视频画面合并后推流功能，要直接底层实现这样的功能还是不太容易的，如果借助ffmpeg就方便多了，使用ffmpeg的滤镜功能就能实现多路合并的效果。

首先说明需要用到的ffmpeg对象，以及一些必要的字段。

ffmpeg版本：

version 4.3

所用到的头文件：

#include <libavutil/avassert.h>
#include <libavutil/opt.h>
#include <libavfilter/avfilter.h>

需要的数据结构如下：

每一条输入流需要如下的字段

typedef struct Stream{int x;int y;int width;int height;int format;//参考AVPixelFormatAVFilterContext* buffersrc_ctx;AVFilter* buffersrc;AVFilterInOut* output;AVFrame* inputFrame;
} Stream;

输出流需要如下字段

typedef struct Merge {AVFilterGraph* filter_graph;AVFilterContext* buffersink_ctx;AVFilter* buffersink;AVFilterInOut* input;const char* filters_descr;AVFrame* outputFrame;unsigned char* outputBuffer;int outputWidth;int outputHeight;int outputFormat;//参考AVPixelFormatStream *streams[128];int streamCount;
} Merge;

主要流程如下：

1、构造输出流及输入流

构造输出流，输出流需要设置分辨率以及输出的像素格式

Merge* Merge_Create(int outputWidth, int outputHeight, int outputFormat) {Merge* merge = malloc(sizeof(Merge));memset(merge, 0, sizeof(Merge));merge->outputWidth = outputWidth;merge->outputHeight = outputHeight;merge->outputFormat = outputFormat;return merge;
}

添加输入流，输入流需要设置在输出流中的位置和大小，以及输入流像素格式

Stream* Merge_AddStream(Merge* merge, int x, int y, int width, int height, int format) {Stream* stream = malloc(sizeof(Stream));memset(merge, 0, sizeof(Stream));stream->x = x;stream->y = y;stream->width = width;stream->height = height;stream->format = format;merge->streams[merge->streamCount++] = stream;return stream;
}

2、初始化滤镜

主要用到的滤镜是filters_descr = "[in0]pad=1280:640:0:0:black[x0];[x0][in1]overlay=640:0[x1];[x1][in2]overlay=600:0[x2];[x2]null[out]";

//初始化Merge
int Merge_Init(Merge* merge) {char args[512];char name[8];char* filters_descr = NULL;int ret;//avfilter_register_all();//旧版可能用到此行merge->buffersink = avfilter_get_by_name("buffersink");av_assert0(merge->buffersink);merge->input = avfilter_inout_alloc();if (merge->input == NULL){printf("alloc inout  fail\n");goto fail;}merge->filter_graph = avfilter_graph_alloc();if (merge->input == NULL){printf("alloc graph  fail\n");goto fail;}ret = avfilter_graph_create_filter(&merge->buffersink_ctx, merge->buffersink, "out", NULL, NULL, merge->filter_graph);if (ret < 0){printf("graph create  fail\n");goto fail;}merge->input->name = av_strdup("out");merge->input->filter_ctx = merge->buffersink_ctx;merge->input->pad_idx = 0;merge->input->next = NULL;merge->outputFrame = av_frame_alloc();if (merge->outputFrame == NULL){printf("alloc frame  fail\n");goto fail;}merge->outputBuffer = (unsigned char*)av_malloc(av_image_get_buffer_size(merge->outputFormat, merge->outputWidth, merge->outputHeight, 1));if (merge->outputBuffer == NULL){printf("alloc buffer  fail\n");goto fail;}enum AVPixelFormat pix_fmts[2] = { 0, AV_PIX_FMT_NONE };pix_fmts[0] = merge->outputFormat;ret = av_opt_set_int_list(merge->buffersink_ctx, "pix_fmts", pix_fmts, AV_PIX_FMT_NONE, AV_OPT_SEARCH_CHILDREN);if (ret < 0) {printf("set opt fail\n");goto fail;}Stream** streams = merge->streams;for (int i = 0; i < merge->streamCount; i++){streams[i]->buffersrc = avfilter_get_by_name("buffer");av_assert0(streams[i]->buffersrc);snprintf(args, sizeof(args), "video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d", streams[i]->width, streams[i]->height, streams[i]->format, 1, 90000, 1, 1);snprintf(name, sizeof(name), "in%d", i);ret = avfilter_graph_create_filter(&streams[i]->buffersrc_ctx, streams[i]->buffersrc, name, args, NULL, merge->filter_graph);if (ret < 0){printf("stream graph create fail\n");goto fail;}streams[i]->output = avfilter_inout_alloc();streams[i]->output->name = av_strdup(name);streams[i]->output->filter_ctx = streams[i]->buffersrc_ctx;streams[i]->output->pad_idx = 0;streams[i]->output->next = NULL;streams[i]->inputFrame = av_frame_alloc();if (streams[i]->inputFrame == NULL){printf("alloc frame  fail\n");goto fail;}streams[i]->inputFrame->format = streams[i]->format;streams[i]->inputFrame->width = streams[i]->width;streams[i]->inputFrame->height = streams[i]->height;if (i > 0){streams[i - 1]->output->next = streams[i]->output;}}/*filters_descr = "[in0]pad=1280:640:0:0:black[x0];[x0][in1]overlay=640:0[x1];[x1][in2]overlay=600:0[x2];[x2]null[out]";*/filters_descr = malloc(sizeof(char) * merge->streamCount * 128);if (filters_descr == NULL){printf("alloc string  fail\n");goto fail;}char sigle_descr[128];snprintf(sigle_descr, sizeof(sigle_descr), "[in0]pad=%d:%d:%d:%d:black[x0];", merge->outputWidth, merge->outputHeight, streams[0]->x, streams[0]->y);strcpy(filters_descr, sigle_descr);int i = 1;for (; i < merge->streamCount; i++){snprintf(sigle_descr, sizeof(sigle_descr), "[x%d][in%d]overlay=%d:%d[x%d];", i - 1, i, streams[i]->x, streams[i]->y, i);strcat(filters_descr, sigle_descr);}snprintf(sigle_descr, sizeof(sigle_descr), "[x%d]null[out]", i - 1);strcat(filters_descr, sigle_descr);ret = avfilter_graph_parse_ptr(merge->filter_graph, filters_descr, &merge->input, &streams[0]->output, NULL);if (ret < 0){printf("graph parse fail\n");goto fail;}// 过滤配置初始化ret = avfilter_graph_config(merge->filter_graph, NULL);if (ret < 0){printf("graph config fail\n");goto fail;}if (filters_descr != NULL)free(filters_descr);return 0;
fail:if (filters_descr != NULL)free(filters_descr);Merge_Deinit(merge); //执行反初始化return -1;
}

3、写输入流

void Merge_WriteStream(Merge* merge, Stream* stream, const unsigned char* buffer, int timestamp) {av_image_fill_arrays(stream->inputFrame->data, stream->inputFrame->linesize, buffer, stream->format, stream->width, stream->height, 1);stream->inputFrame->pts = timestamp;if (av_buffersrc_write_frame(stream->buffersrc_ctx, stream->inputFrame) < 0) {printf("Error while add frame.\n");}
}

4、合并流

调用下列方法，即可得到合并后的一帧的数据。可以按照一定帧率调用3、4方法。

const unsigned char* Merge_Merge(Merge* merge) {int	ret = av_buffersink_get_frame(merge->buffersink_ctx, merge->outputFrame);if (ret < 0) {printf("Error while get frame.\n");return NULL;}av_image_copy_to_buffer(merge->outputBuffer,av_image_get_buffer_size(merge->outputFormat, merge->outputWidth, merge->outputHeight, 1),merge->outputFrame->data, merge->outputFrame->linesize, merge->outputFrame->format, merge->outputFrame->width, merge->outputFrame->height, 1);av_frame_unref(merge->outputFrame);return  merge->outputBuffer;
}

5、结束，反初始化，销毁对象

static void Merge_Deinit(Merge* merge)
{if (merge->input != NULL)avfilter_inout_free(&merge->input);if (merge->filter_graph != NULL)avfilter_graph_free(&merge->filter_graph);if (merge->outputFrame != NULL)av_frame_free(&merge->outputFrame);if (merge->outputBuffer != NULL)av_free(merge->outputBuffer);for (int i = 0; i < merge->streamCount; i++){Stream* stream = merge->streams[i]; if (stream->inputFrame != NULL)av_frame_free(&stream->inputFrame);free(stream);}merge->streamCount = 0;
}

void Merge_Destroy(Merge* merge) {Merge_Deinit(merge);free(merge);
}

调用流程示例：

int main() {int flag = 1;Merge* merge = Merge_Create(1920, 1080, 0);Stream* stream1 = Merge_AddStream(merge, 0, 0, 960, 540, 0);Stream* stream2 = Merge_AddStream(merge, 960, 540, 960, 540, 0);Stream* stream3 = Merge_AddStream(merge, 0, 540, 960, 540, 0);if (Merge_Init(merge) != 0){Merge_Destroy(merge);return -1;}while (flag){clock_t time = clock();unsigned char* buffer1;unsigned char* buffer2;unsigned char* buffer3;//获取每路流的数据...//获取每路流的数据-endMerge_WriteStream(merge, stream1, buffer1, time);Merge_WriteStream(merge, stream2, buffer2, time);Merge_WriteStream(merge, stream3, buffer3, time);unsigned char* mergedBuffer = Merge_Merge(merge);//显示或编码推流...//显示或编码推流-end}Merge_Destroy(merge);
}

需要注意的是上述方法最好在单线程中使用，多线程使用可能需要另外做修改，或者参考：

https://download.csdn.net/download/u013113678/32899063

效果如下