ffmpeg入门（四）解码部分代码整理

朴灿烈づ我的快乐病毒、 2022-08-20 05:13 173阅读 0赞

通过调试，最终下面的代码，在VS2013版本上已经调试通过，并且也能从mp4或者其他文件格式转成yuv的格式。所以备忘录收藏下：

#include <iostream>
    using namespace std;
    
    #ifdef __cplusplus
    extern "C"{
    #endif
    #include "libavcodec/avcodec.h"
    #include "libavformat/avformat.h"
    #include "libswscale/swscale.h"
    #include "libavutil/pixfmt.h"
    #include "libavutil/imgutils.h"
    
    int main(int argc, char** argv)
    {
        av_register_all();
    
        avformat_network_init();
    
        AVFormatContext *pFormatCtx;
        int ret = 0;
    
        char filepath[] = "D:\\G\\project\\01_31_1\\Debug\\1.mp4";
    
        pFormatCtx = avformat_alloc_context();
        if (avformat_open_input(&pFormatCtx, filepath, NULL, NULL) != 0)
        {
            cout << "Couldn't not open input stream." << endl;
            return -1;
        }
    
        av_dump_format(pFormatCtx, 0, filepath, 0);
    
        do 
        {
            if (avformat_find_stream_info(pFormatCtx, NULL) < 0)
            {
                cout << "Couldn't not find stream info." << endl;
                break;
            }
    
            int videoIndex = -1;
            unsigned int i = 0;
            for (; i < pFormatCtx->nb_streams; i++)
            {
                if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO)
                {
                    videoIndex = i;
                    break;
                }
            }
    
            if (videoIndex == -1)
            {
                cout << "can't find a video stream." << endl;
                break;
            }
    
            AVCodecContext  *pCodecCtx;
            pCodecCtx = pFormatCtx->streams[videoIndex]->codec;
            AVCodec *pCodec = NULL;
            pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
            cout << "codec_id:" << pCodecCtx->codec_id << endl;
            if (NULL == pCodec)
            {
                cout << "Fail to find decoder" << endl;
                break;
            }
    
            if (avcodec_open2(pCodecCtx, pCodec, NULL) < 0)
            {
                cout << "Fail to avcodec_open2 " << endl;
                break;
            }
    
            do 
            {
                AVPacket *packet = (AVPacket *)av_malloc(sizeof(AVPacket));
                AVFrame *pFrame = av_frame_alloc();
                AVFrame *pFrameYUV = av_frame_alloc();
                int got_picture = 0;
                struct SwsContext *img_convert_ctx;
                av_dump_format(pFormatCtx, 0, filepath, 0);
                uint8_t *out_buffer;
                out_buffer = (uint8_t *)av_malloc(av_image_get_buffer_size(AV_PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height, 1));
                av_image_fill_arrays(pFrameYUV->data, pFrameYUV->linesize, out_buffer, AV_PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height, 1);
                img_convert_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height, AV_PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL);
                if (NULL == img_convert_ctx)
                {
                    cout << "img_convert_ctx is wrong!" << endl;
                    break;
                }
                cout << pCodecCtx->width << "-----" << pCodecCtx->height << endl;
                FILE *fp_yuv = NULL;
                fopen_s(&fp_yuv, "output.yuv", "wb+");
                while (av_read_frame(pFormatCtx, packet) >= 0)
                {
                    if (packet->stream_index == videoIndex)
                    {
                        ret = avcodec_decode_video2(pCodecCtx, pFrame, &got_picture, packet);
                        if (ret < 0)
                        {
                            cout << "decode error.\n";
                            break;
                        }
                        if (got_picture)
                        {
                            sws_scale(img_convert_ctx, (const uint8_t* const*)pFrame->data, pFrame->linesize, 0,
                                pCodecCtx->height, pFrameYUV->data, pFrameYUV->linesize);
    
                            //  420
                            //cout << "123" << endl;
    #if 1
                            int y_size = pCodecCtx->width*pCodecCtx->height;
                            fwrite(pFrameYUV->data[0], 1, y_size, fp_yuv);    //Y   
                            fwrite(pFrameYUV->data[1], 1, y_size / 4, fp_yuv);  //U  
                            fwrite(pFrameYUV->data[2], 1, y_size / 4, fp_yuv);  //V  
    #endif
                        }
                    }
                    av_packet_unref(packet);
                }
                av_frame_unref(pFrameYUV);
                av_frame_unref(pFrame);
    
                cout << "=====>" << endl;
            } while (0);
    
            avcodec_close(pCodecCtx);
        } while (0);
    
        avformat_close_input(&pFormatCtx);
    
        getchar();
    
        return 0;
    }
    
    #ifdef __cplusplus
    }
    #endif