ffmpeg.auto 解码摄像头示例

以下是使用FFmpeg.AutoGen库在C#中解码摄像头视频流的示例代码：

using System;
using FFmpeg.AutoGen;

namespace FFmpegDecodingExample
{
    class Program
    {
        static void Main(string[] args)
        {
            // Initialize FFmpeg library
            ffmpeg.av_register_all();

            // Open video device
            AVFormatContext* videoInputContext = null;

            if (ffmpeg.avformat_open_input(&videoInputContext, "video_device_path", null, null) != 0)
            {
                Console.WriteLine("Failed to open video device");
                return;
            }

            // Find video stream
            if (ffmpeg.avformat_find_stream_info(videoInputContext, null) < 0)
            {
                Console.WriteLine("Failed to find stream information");
                return;
            }

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

            if (videoStreamIndex == -1)
            {
                Console.WriteLine("Failed to find video stream");
                return;
            }

            AVCodecContext* videoCodecContext = videoInputContext->streams[videoStreamIndex]->codec;

            // Find video decoder
            AVCodec* videoCodec = ffmpeg.avcodec_find_decoder(videoCodecContext->codec_id);
            if (videoCodec == null)
            {
                Console.WriteLine("Failed to find video decoder");
                return;
            }

            // Open video decoder
            if (ffmpeg.avcodec_open2(videoCodecContext, videoCodec, null) < 0)
            {
                Console.WriteLine("Failed to open video decoder");
                return;
            }

            // Read video frames
            AVPacket* packet = ffmpeg.av_packet_alloc();
            AVFrame* frame = ffmpeg.av_frame_alloc();

            while (ffmpeg.av_read_frame(videoInputContext, packet) >= 0)
            {
                if (packet->stream_index == videoStreamIndex)
                {
                    // Decode video packet
                    int ret = ffmpeg.avcodec_send_packet(videoCodecContext, packet);
                    if (ret < 0 || ret == ffmpeg.AVERROR(ffmpeg.EAGAIN) || ret == ffmpeg.AVERROR_EOF)
                    {
                        Console.WriteLine("Failed to send video packet for decoding");
                        break;
                    }

                    while (ret >= 0)
                    {
                        ret = ffmpeg.avcodec_receive_frame(videoCodecContext, frame);
                        if (ret < 0 && ret != ffmpeg.AVERROR(ffmpeg.EAGAIN) && ret != ffmpeg.AVERROR_EOF)
                        {
                            Console.WriteLine("Failed to receive video frame after decoding");
                            break;
                        }

                        // Process and display video frame

                        // Release frame resources
                        ffmpeg.av_frame_unref(frame);
                    }
                }

                // Release packet resources
                ffmpeg.av_packet_unref(packet);
            }

            // Release resources
            ffmpeg.avformat_close_input(&videoInputContext);
            ffmpeg.avcodec_close(videoCodecContext);

            ffmpeg.avformat_free_context(videoInputContext);
            ffmpeg.av_frame_free(&frame);
            ffmpeg.av_packet_free(&packet);
        }
    }
}

在示例代码中，您需要将"video_device_path"替换为实际的视频设备路径。示例代码打开视频设备并查找视频流。然后，找到视频解码器并打开解码器。最后，使用`avcodec_send_packet()`方法将视频数据包发送给解码器，并使用`avcodec_receive_frame()`方法接收解码后的帧。

请注意，这只是一个基本示例，实际使用时可能需要根据您的具体需求进行更多的参数设置和错误处理。还可以根据需要进行帧处理、显示或保存等操作。

希望这个示例能对您有所帮助！如果您有任何更具体的问题，请随时提问。