最簡單的YUV422轉jpg的例程

源碼：

/**

 * 最簡單的基于FFmpeg的圖像編碼器

 * Simplest FFmpeg Picture Encoder

 *

 * 雷霄骅 Lei Xiaohua

 * [email protected]

 * 中國傳媒大學/數字電視技術

 * Communication University of China / Digital TV Technology

 * http://blog.csdn.net/leixiaohua1020

 *

 * 本程式實作了YUV420P像素資料編碼為JPEG圖檔。是最簡單的FFmpeg編碼方面的教程。

 * 通過學習本例子可以了解FFmpeg的編碼流程。

 */



#include <stdio.h>



#define __STDC_CONSTANT_MACROS



#ifdef _WIN32

//Windows

extern "C"

{

#include "libavcodec/avcodec.h"

#include "libavformat/avformat.h"

};

#else

//Linux...

#ifdef __cplusplus

extern "C"

{

#endif

#include <libavcodec/avcodec.h>

#include <libavformat/avformat.h>

#ifdef __cplusplus

};

#endif

#endif



#define IMG_WIDTH 640
#define IMG_HEIGHT 480

int main(int argc, char* argv[])

{

    AVFormatContext* pFormatCtx;

    AVOutputFormat* fmt;

    AVStream* video_st;

    AVCodecContext* pCodecCtx;

    AVCodec* pCodec;



    uint8_t* picture_buf;

    AVFrame* picture;

    AVPacket pkt;

    int y_size;

    int got_picture=0;

    int size;



    int ret=0;



    FILE *in_file = NULL;                            //YUV source

    int in_w=IMG_WIDTH,in_h=IMG_HEIGHT;                           //YUV's width and height

    const char* out_file = "yuv422.jpg";    //Output file



    in_file = fopen("/home/jon/yuv422.yuv", "rb");



    av_register_all();



    //Method 1

    pFormatCtx = avformat_alloc_context();

    //Guess format

    fmt = av_guess_format("mjpeg", NULL, NULL);

    pFormatCtx->oformat = fmt;

    //Output URL

    if (avio_open(&pFormatCtx->pb,out_file, AVIO_FLAG_READ_WRITE) < 0){

        printf("Couldn't open output file.");

        return -1;

    }



    //Method 2. More simple

    //avformat_alloc_output_context2(&pFormatCtx, NULL, NULL, out_file);

    //fmt = pFormatCtx->oformat;



    video_st = avformat_new_stream(pFormatCtx, 0);

    if (video_st==NULL){

        return -1;

    }

    pCodecCtx = video_st->codec;

    pCodecCtx->codec_id = fmt->video_codec;

    pCodecCtx->codec_type = AVMEDIA_TYPE_VIDEO;

    pCodecCtx->pix_fmt = AV_PIX_FMT_YUVJ422P;



    pCodecCtx->width = in_w;

    pCodecCtx->height = in_h;



    pCodecCtx->time_base.num = 1;

    pCodecCtx->time_base.den = 25;

    //Output some information

    av_dump_format(pFormatCtx, 0, out_file, 1);



    pCodec = avcodec_find_encoder(pCodecCtx->codec_id);

    if (!pCodec){

        printf("Codec not found.");

        return -1;

    }

    if (avcodec_open2(pCodecCtx, pCodec,NULL) < 0){

        printf("Could not open codec.");

        return -1;

    }

    picture = av_frame_alloc();

    size = avpicture_get_size(pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height);

    picture_buf = (uint8_t *)av_malloc(size);

    if (!picture_buf)

    {

        return -1;

    }

    avpicture_fill((AVPicture *)picture, picture_buf, pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height);



    //Write Header

    avformat_write_header(pFormatCtx,NULL);



    y_size = pCodecCtx->width * pCodecCtx->height;

    av_new_packet(&pkt,y_size*3);

    //Read YUV

    if (fread(picture_buf, 1, y_size*2, in_file) <=0)

    {

        printf("Could not read input file.");

        return -1;

    }

    picture->data[0] = picture_buf;              // Y

    picture->data[1] = picture_buf+ y_size;      // U

    picture->data[2] = picture_buf+ y_size*3/2;  // V



    //Encode

    ret = avcodec_encode_video2(pCodecCtx, &pkt,picture, &got_picture);

    if(ret < 0){

        printf("Encode Error.\n");

        return -1;

    }

    if (got_picture==1){

        pkt.stream_index = video_st->index;

        ret = av_write_frame(pFormatCtx, &pkt);

    }



    av_free_packet(&pkt);

    //Write Trailer

    av_write_trailer(pFormatCtx);



    printf("Encode Successful.\n");



    if (video_st){

        avcodec_close(video_st->codec);

        av_free(picture);

        av_free(picture_buf);

    }

    avio_close(pFormatCtx->pb);

    avformat_free_context(pFormatCtx);



    fclose(in_file);



    return 0;

}
           

生成的圖檔(yuv422.jpg)：