C#写一段ffmpeg解码h264的代码

以下是使用FFmpeg解码H.264视频的示例代码，需要安装FFmpeg库并将其添加到项目引用中：

using System;
using System.Diagnostics;
using System.Drawing;
using System.Drawing.Imaging;
using System.Runtime.InteropServices;

using FFmpeg.AutoGen;

namespace FFmpegDecodeH264
{
    class Program
    {
        static void Main(string[] args)
        {
            // 设置FFmpeg的路径
            string ffmpegPath = @"C:\ffmpeg\bin\ffmpeg.exe";
            ffmpeg.av_register_all();

            // 打开输入文件
            AVFormatContext* pFormatContext = null;
            int result = ffmpeg.avformat_open_input(&pFormatContext, "input.h264", null, null);
            if (result < 0)
            {
                Console.WriteLine("无法打开输入文件");
                return;
            }

            // 获取流信息
            result = ffmpeg.avformat_find_stream_info(pFormatContext, null);
            if (result < 0)
            {
                Console.WriteLine("无法获取流信息");
                return;
            }

            // 查找视频流
            int videoStreamIndex = -1;
            for (int i = 0; i < pFormatContext->nb_streams; i++)
            {
                if (pFormatContext->streams[i]->codec->codec_type == AVMediaType.AVMEDIA_TYPE_VIDEO)
                {
                    videoStreamIndex = i;
                    break;
                }
            }

            if (videoStreamIndex == -1)
            {
                Console.WriteLine("找不到视频流");
                return;
            }

            // 获取视频流解码器
            AVCodecContext* pCodecContext = pFormatContext->streams[videoStreamIndex]->codec;
            AVCodec* pCodec = ffmpeg.avcodec_find_decoder(pCodecContext->codec_id);
            if (pCodec == null)
            {
                Console.WriteLine("无法获取解码器");
                return;
            }

            // 打开解码器
            result = ffmpeg.avcodec_open2(pCodecContext, pCodec, null);
            if (result < 0)
            {
                Console.WriteLine("无法打开解码器");
                return;
            }

            // 循环读取帧并解码
            AVPacket packet = new AVPacket();
            AVFrame* pFrame = ffmpeg.av_frame_alloc();
            AVFrame* pFrameRGB = ffmpeg.av_frame_alloc();
            SwsContext* pSwsContext = null;

            while (ffmpeg.av_read_frame(pFormatContext, &packet) >= 0)
            {
                if (packet.stream_index == videoStreamIndex)
                {
                    // 解码一帧
                    int frameFinished = 0;
                    result = ffmpeg.avcodec_decode_video2(pCodecContext, pFrame, &frameFinished, &packet);
                    if (result < 0)
                    {
                        Console.WriteLine("解码错误");
                        return;
                    }

                    // 如果解码成功，将帧转换为RGB格式
                    if (frameFinished != 0)
                    {
                        // 初始化转换器
                        if (pSwsContext == null)
                        {
                            pSwsContext = ffmpeg.sws_getContext(
                                pCodecContext->width, pCodecContext->height, pCodecContext->pix_fmt,
                                pCodecContext->width, pCodecContext->height, AVPixelFormat.AV_PIX_FMT_RGB24,
                                ffmpeg.SWS_BILINEAR, null, null, null);
                        }

                        // 分配RGB帧
                        int numBytes = ffmpeg.av_image_get_buffer_size(AVPixelFormat.AV_PIX_FMT_RGB24, pCodecContext->width, pCodecContext->height, 1);
                        byte* buffer = (byte*)ffmpeg.av_malloc((ulong)numBytes);
                        ffmpeg.av_image_fill_arrays(pFrameRGB->data, pFrameRGB->linesize, buffer, AVPixelFormat.AV_PIX_FMT_RGB24, pCodecContext->width, pCodecContext->height, 1);

                        // 转换帧
                        ffmpeg.sws_scale(pSwsContext, pFrame->data, pFrame->linesize, 0, pCodecContext->height, pFrameRGB->data, pFrameRGB->linesize);

                        // 显示帧
                        Bitmap bitmap = new Bitmap(pCodecContext->width, pCodecContext->height, pCodecContext->width * 3, PixelFormat.Format24bppRgb, new IntPtr(pFrameRGB->data[0]));
                        bitmap.Save("output.bmp", ImageFormat.Bmp);

                        // 释放RGB帧内存
                        ffmpeg.av_free(buffer);
                    }
                }

                // 释放数据包
                ffmpeg.av_packet_unref(&packet);
            }

            // 释放资源
            ffmpeg.av_frame_free(&pFrame);
            ffmpeg.av_frame_free(&pFrameRGB);
            ffmpeg.sws_freeContext(pSwsContext);
            ffmpeg.avcodec_close(pCodecContext);
            ffmpeg.avformat_close_input(&pFormatContext);
        }
    }
}