ffmpeg api判断输入流是什么编码格式（H264？HEVC？）

#include <libavformat/avformat.h>
#include <libavcodec/avcodec.h>
#include <libswscale/swscale.h>
#include <libavutil/mathematics.h>
#include <libavutil/time.h>
#include <libavutil/opt.h>

int is_h264_file(char *filename)
{
	AVFormatContext *ifmt_ctx = NULL;
	AVDictionary *input_options = NULL;
	int ret = 0;
 
	av_register_all();
	avformat_network_init(); 

	if ((ret = av_dict_set(&input_options, "rtmp_live", "live", 0)) < 0) {
		printf("Failed to set rtmp_live mode for server\n");
	}

	if ((ret = av_dict_set(&input_options, "rw_timeout", "10000", 0)) < 0) {
		printf("failed to set rw_timeout value(10 seconds) for server\n");
	}	

	if ((ret = avformat_open_input(&ifmt_ctx, filename, NULL, &input_options)) < 0) {
			printf( "Could not open input file.");
			return 0;
		}

	printf("ifmt_ctx->video_codec_id:%d\n",ifmt_ctx->video_codec_id);
	if ((ret = avformat_find_stream_info(ifmt_ctx, 0)) < 0) {
	
			printf( "Failed to retrieve input stream information");
 
			avformat_close_input(&ifmt_ctx);
			return 0;
	
		}
 
	//ifmt_ctx->streams[0]->codecpar->codec_id;
 
	av_dump_format(ifmt_ctx, 0, filename, 0);

	int videoStream = -1;
	for (int i = 0; i < ifmt_ctx->nb_streams; i++)
	{
		if (ifmt_ctx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO)
		{
			videoStream = i;
			break;
		}
	}

	if (videoStream == -1)
		return -1; // 没有查找到视频流video stream

	printf("3ifmt_ctx->video_codec_id:%d\n",ifmt_ctx->streams[videoStream]->codecpar->codec_id);
 
	
	if(ifmt_ctx->streams[videoStream]->codecpar->codec_id==AV_CODEC_ID_H264)
	{
		printf("is h264 file\n");
		avformat_close_input(&ifmt_ctx);
		return 1;
	} 
	else if (ifmt_ctx->streams[videoStream]->codecpar->codec_id==AV_CODEC_ID_HEVC)
	{
		printf("is hevc file\n");
        avformat_close_input(&ifmt_ctx);
        return 1;
	}
	else 
	{
		printf("is not h264/hevc file\n");
		avformat_close_input(&ifmt_ctx);
		return 0;
	}
 
}

int main(int argc,char *argv[])
{
	int ret = is_h264_file(argv[1]);
	printf("ret : %d", ret);
	
	return 0;
}

linux下编译：gcc -g isH264.c -o isH264 -I ./include -L ./lib -lavformat -lavcodec -lavutil -lswscale
测试使用：./isH264 rtmp://127.0.0.1:1935/live/rtmp