C++实现ffmpeg将图片推成rtsp视频流

要将图片推送为RTSP视频流，需要使用FFmpeg和libx264编码器。以下是一个C语言示例程序，说明如何将单个图片推送为RTSP视频流。

首先，需要包含必要的头文件：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <libavutil/opt.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>

然后，需要定义一些常量和变量：

#define WIDTH 640
#define HEIGHT 480
#define FPS 30
#define BITRATE 500000

AVFormatContext *fmt_ctx = NULL;
AVStream *video_stream = NULL;
AVCodecContext *codec_ctx = NULL;
AVCodec *codec = NULL;
AVPacket pkt;
AVFrame *frame = NULL;
uint8_t *frame_buffer = NULL;
struct SwsContext *sws_ctx = NULL;
int sockfd = -1;
struct sockaddr_in server_addr;

接下来，需要初始化FFmpeg库和网络套接字：

av_register_all();
avformat_network_init();

if (avformat_alloc_output_context2(&fmt_ctx, NULL, "rtsp", "rtsp://127.0.0.1:8554/live") < 0) {
    fprintf(stderr, "Error allocating output context.\n");
    exit(1);
}

codec = avcodec_find_encoder(AV_CODEC_ID_H264);
if (!codec) {
    fprintf(stderr, "Codec not found.\n");
    exit(1);
}

video_stream = avformat_new_stream(fmt_ctx, codec);
if (!video_stream) {
    fprintf(stderr, "Failed to create new stream.\n");
    exit(1);
}

codec_ctx = video_stream->codec;
codec_ctx->codec_id = AV_CODEC_ID_H264;
codec_ctx->codec_type = AVMEDIA_TYPE_VIDEO;
codec_ctx->pix_fmt = AV_PIX_FMT_YUV420P;
codec_ctx->width = WIDTH;
codec_ctx->height = HEIGHT;
codec_ctx->time_base = (AVRational){1, FPS};
codec_ctx->bit_rate = BITRATE;
codec_ctx->gop_size = FPS;
codec_ctx->max_b_frames = 0;
codec_ctx->qmin = 10;
codec_ctx->qmax = 51;
codec_ctx->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;

if (avcodec_open2(codec_ctx, codec, NULL) < 0) {
    fprintf(stderr, "Failed to open codec.\n");
    exit(1);
}

frame = av_frame_alloc();
frame->format = codec_ctx->pix_fmt;
frame->width = codec_ctx->width;
frame->height = codec_ctx->height;
av_frame_get_buffer(frame, 0);

frame_buffer = (uint8_t *)malloc(avpicture_get_size(codec_ctx->pix_fmt, codec_ctx->width, codec_ctx->height));
avpicture_fill((AVPicture *)frame, frame_buffer, codec_ctx->pix_fmt, codec_ctx->width, codec_ctx->height);

sws_ctx = sws_getContext(WIDTH, HEIGHT, AV_PIX_FMT_RGB24, codec_ctx->width, codec_ctx->height, codec_ctx->pix_fmt, SWS_BICUBIC, NULL, NULL, NULL);

sockfd = socket(AF_INET, SOCK_DGRAM, 0);
if (sockfd < 0) {
    fprintf(stderr, "Failed to create socket.\n");
    exit(1);
}

memset(&server_addr, 0, sizeof(server_addr));
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(8554);
server_addr.sin_addr.s_addr = inet_addr("127.0.0.1");

接下来，需要循环读取图片并将其编码为H.264流：

while (1) {
    AVFrame *rgb_frame = av_frame_alloc();
    uint8_t *rgb_frame_buffer = (uint8_t *)malloc(WIDTH * HEIGHT * 3);
    FILE *fp = fopen("image.jpg", "rb");
    fread(rgb_frame_buffer, 1, WIDTH * HEIGHT * 3, fp);
    fclose(fp);
    avpicture_fill((AVPicture *)rgb_frame, rgb_frame_buffer, AV_PIX_FMT_RGB24, WIDTH, HEIGHT);
    sws_scale(sws_ctx, rgb_frame->data, rgb_frame->linesize, 0, HEIGHT, frame->data, frame->linesize);
    av_frame_free(&rgb_frame);
    free(rgb_frame_buffer);

    int ret = avcodec_send_frame(codec_ctx, frame);
    if (ret < 0) {
        fprintf(stderr, "Error sending frame to encoder.\n");
        exit(1);
    }

    while (ret >= 0) {
        ret = avcodec_receive_packet(codec_ctx, &pkt);
        if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
            break;
        } else if (ret < 0) {
            fprintf(stderr, "Error receiving packet from encoder.\n");
            exit(1);
        }

        pkt.stream_index = video_stream->index;
        av_packet_rescale_ts(&pkt, codec_ctx->time_base, video_stream->time_base);
        av_interleaved_write_frame(fmt_ctx, &pkt);

        sendto(sockfd, pkt.data, pkt.size, 0, (struct sockaddr *)&server_addr, sizeof(server_addr));

        av_packet_unref(&pkt);
    }

    usleep(1000000 / FPS);
}

最后，需要释放资源并关闭套接字：

av_write_trailer(fmt_ctx);

avcodec_free_context(&codec_ctx);
av_frame_free(&frame);
sws_freeContext(sws_ctx);
free(frame_buffer);

close(sockfd);

avformat_free_context(fmt_ctx);

avformat_network_deinit();

完整的示例程序可以在以下链接中找到：https://github.com/FFmpeg/FFmpeg/blob/master/doc/examples/encode_video.c