由于项目需要，开始入门FFMPEG，记录一下入门中遇到的问题和解决的方法。
一、VS2015配置FFMPEG
配置可以参考这篇文章，简单的三步。https://blog.youkuaiyun.com/hustlx/article/details/51014307
配置注意不要配置错平台就行了，即下面两个图要对应，否则会出现一堆找不到文件的错误。
最后一步的这段代码，插入stdafx.h中就行了，或者就放在main函数前面
extern "C"
{
#include "include\libavcodec\avcodec.h"
#include "include\libavformat\avformat.h"
#include "include\libavutil\channel_layout.h"
#include "include\libavutil\common.h"
#include "include\libavutil\imgutils.h"
#include "include\libswscale\swscale.h"
#include "include\libavutil\imgutils.h"
#include "include\libavutil\opt.h"
#include "include\libavutil\mathematics.h"
#include "include\libavutil\samplefmt.h"
};
#pragma comment(lib, "avcodec.lib")
#pragma comment(lib, "avformat.lib")
#pragma comment(lib, "avdevice.lib")
#pragma comment(lib, "avfilter.lib")
#pragma comment(lib, "avutil.lib")
#pragma comment(lib, "postproc.lib")
#pragma comment(lib, "swresample.lib")
#pragma comment(lib, "swscale.lib")配置完成后运行一下下面这段代码，可以检测是否配置成功
int main( int argc , char* argv [])
{
printf ( " % s", avcodec_configuration ());
system("pause");
return 0;
} 显示这一堆东西的话，应该就是成功了：--disable-static --enable-shared --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libcaca --enable-libfreetype --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-decklink --enable-zlib
二、配置SDL
步骤基本上和上面一样，到SDL官网https://www.libsdl.org/下载SDL2-devel-2.0.10-VC.zip就行了
然后配置方式和上面基本相同，也是把include和lib文件夹里的东西copy到工程目录对应的目录就行了。
需要注意的一点就是SDL的lib文件里的SDL2.ddl文件不要放到工程的lib里，直接放到工程目录就行了，否则会报错说找不到SDL2.ddl。
三、运行雷霄骅大佬的博客里面的代码
链接https://blog.youkuaiyun.com/leixiaohua1020/article/details/38868499
下面记录一下代码中需要修改的地方：
1.出现avcodec_decode_video2()、av_free_packet()、av_register_all()等函数声明已否决
参考这篇文章可以解决 https://blog.youkuaiyun.com/qq_24854861/article/details/79757120
然后还有一个av_register_all()函数声明被否决，参考https://www.jianshu.com/p/ebb219ec1c0f这篇文章，可以发现新版本的FFMPEG已经不需要在最前面调用这个函数了。
2.出现LNK1561：必须定义入口点
明明有main函数，还提示这个错误。是因为在SDL_main.h中
解决方法，在链接》高级》入口点输入“WinMainCRTStartup”就行了。
3. 运行有问题，白屏或者绿屏
由于第一个问题，换掉了一些函数，通过查看这些函数的定义，发现返回值的意义是有变化的，比如原来的是返回非0成功，但是改过后是返回0成功，所以做如下修改
改过后就能够使用了。
下面贴出修改过的代码，希望能够帮助到刚入门的同学。最后再次感谢雷霄骅大佬，大家可以去关注一波，里面非常多的干货。
#include "stdafx.h"
#define OUTPUT_YUV420P 0
// 本程序实现了视频文件的解码和显示(支持HEVC，H.264，MPEG2等)。
int main(int argc, char *argv[])
{
AVFormatContext *pFormatCtx;
int i, videoindex;
AVCodecContext *pCodecCtx;
AVCodec *pCodec;
AVFrame *pFrame, *pFrameYUV;
unsigned char *out_buffer;
AVPacket *packet;
int y_size;
int ret, got_picture;
struct SwsContext *img_convert_ctx;
char filepath[] = "video_h265.h265";
//SDL---------------------------
int screen_w = 0, screen_h = 0;
SDL_Window *screen;
SDL_Renderer* sdlRenderer;
SDL_Texture* sdlTexture;
SDL_Rect sdlRect;
FILE *fp_yuv;
//av_register_all();
avformat_network_init();
pFormatCtx = avformat_alloc_context(); //申请AVFormatContext类型变量并初始化默认参数
//打开一个文件并解析。可解析的内容包括：视频流、音频流、视频流参数、音频流参数、视频帧索引
if (avformat_open_input(&pFormatCtx, filepath, NULL, NULL) != 0) {
printf("Couldn't open input stream.\n");
return -1;
}
if (avformat_find_stream_info(pFormatCtx, NULL)<0) {
printf("Couldn't find stream information.\n");
return -1;
}
videoindex = -1;
//遍历文件中的视频流，应该是看一下传入的视频是否能够被解析
for (i = 0; i<pFormatCtx->nb_streams; i++)
//if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
if (pFormatCtx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO){
videoindex = i;
break;
}
if (videoindex == -1) {
printf("Didn't find a video stream.\n");
return -1;
}
//pCodecCtx = pFormatCtx->streams[videoindex]->codec;
pCodecCtx = avcodec_alloc_context3(NULL); //申请AVCodecContext类型变量并初始化默认参数
avcodec_parameters_to_context(pCodecCtx, pFormatCtx->streams[videoindex]->codecpar);
//printf("%u",pCodecCtx->codec_id);//AV_CODEC_ID_HEVC
pCodec = avcodec_find_decoder(pCodecCtx->codec_id);//获取解码器
if (pCodec == NULL) {
printf("Codec not found.\n");
return -1;
}
if (avcodec_open2(pCodecCtx, pCodec, NULL)<0) {
printf("Could not open codec.\n");
return -1;
}
pFrame = av_frame_alloc(); //AVFrame存放从AVPacket中解码出来的原始数据
pFrameYUV = av_frame_alloc();
out_buffer = (unsigned char *)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);
packet = (AVPacket *)av_malloc(sizeof(AVPacket));
//Output Info-----------------------------
printf("--------------- File Information ----------------\n");
av_dump_format(pFormatCtx, 0, filepath, 0);
printf("-------------------------------------------------\n");
img_convert_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt,
pCodecCtx->width/2, pCodecCtx->height/2, AV_PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL);
#if OUTPUT_YUV420P
fp_yuv = fopen("output.yuv", "wb+");
#endif
if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) {
printf("Could not initialize SDL - %s\n", SDL_GetError());
return -1;
}
screen_w = pCodecCtx->width;
screen_h = pCodecCtx->height;
//SDL 2.0 Support for multiple windows
screen = SDL_CreateWindow("Simplest ffmpeg player's Window", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
screen_w/2, screen_h/2,
SDL_WINDOW_OPENGL);
if (!screen) {
printf("SDL: could not create window - exiting:%s\n", SDL_GetError());
return -1;
}
sdlRenderer = SDL_CreateRenderer(screen, -1, 0);
//IYUV: Y + U + V (3 planes)
//YV12: Y + V + U (3 planes)
sdlTexture = SDL_CreateTexture(sdlRenderer, SDL_PIXELFORMAT_IYUV, SDL_TEXTUREACCESS_STREAMING, pCodecCtx->width, pCodecCtx->height);
sdlRect.x = 0;
sdlRect.y = 0;
sdlRect.w = screen_w;
sdlRect.h = screen_h;
//SDL End----------------------
while (av_read_frame(pFormatCtx, packet) >= 0) {
if (packet->stream_index == videoindex) {
//ret = avcodec_decode_video2(pCodecCtx, pFrame, &got_picture, packet);//错误时返回负值，否则返回已使用的字节数，如果无法解压缩任何帧，则返回零。
//got_picture 如果无法解压缩任何帧，则为零，否则为非零。
ret = avcodec_send_packet(pCodecCtx, packet); //成功返回0
got_picture = avcodec_receive_frame(pCodecCtx, pFrame); //got_picture = 0 success, a frame was returned
if (ret != 0) {
printf("Decode Error.\n");
return -1;
}
if (got_picture == 0) {
sws_scale(img_convert_ctx, (const unsigned char* const*)pFrame->data, pFrame->linesize, 0, pCodecCtx->height,
pFrameYUV->data, pFrameYUV->linesize);
#if OUTPUT_YUV420P
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
//SDL---------------------------
#if 0
SDL_UpdateTexture(sdlTexture, NULL, pFrameYUV->data[0], pFrameYUV->linesize[0]);
#else
SDL_UpdateYUVTexture(sdlTexture, &sdlRect,
pFrameYUV->data[0], pFrameYUV->linesize[0],
pFrameYUV->data[1], pFrameYUV->linesize[1],
pFrameYUV->data[2], pFrameYUV->linesize[2]);
#endif
SDL_RenderClear(sdlRenderer);
SDL_RenderCopy(sdlRenderer, sdlTexture, NULL, &sdlRect);
SDL_RenderPresent(sdlRenderer);
//SDL End-----------------------
//Delay 40ms
SDL_Delay(10);
}
}
//av_free_packet(packet);
av_packet_unref(packet);
}
//flush decoder
//FIX: Flush Frames remained in Codec
while (1) {
//ret = avcodec_decode_video2(pCodecCtx, pFrame, &got_picture, packet);
ret = avcodec_send_packet(pCodecCtx, packet);
got_picture = avcodec_receive_frame(pCodecCtx, pFrame); //got_picture = 0 success, a frame was returned
if (ret != 0)
break;
if (got_picture == 0)
break;
sws_scale(img_convert_ctx, (const unsigned char* const*)pFrame->data, pFrame->linesize, 0, pCodecCtx->height,
pFrameYUV->data, pFrameYUV->linesize);
#if OUTPUT_YUV420P
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
//SDL---------------------------
SDL_UpdateTexture(sdlTexture, &sdlRect, pFrameYUV->data[0], pFrameYUV->linesize[0]);
SDL_RenderClear(sdlRenderer);
SDL_RenderCopy(sdlRenderer, sdlTexture, NULL, &sdlRect);
SDL_RenderPresent(sdlRenderer);
//SDL End-----------------------
//Delay 40ms
SDL_Delay(40);
}
sws_freeContext(img_convert_ctx);
#if OUTPUT_YUV420P
fclose(fp_yuv);
#endif
SDL_Quit();
av_frame_free(&pFrameYUV);
av_frame_free(&pFrame);
avcodec_close(pCodecCtx);
avformat_close_input(&pFormatCtx);
system("pause");
return 0;
}
stdafx.h
// stdafx.h : 标准系统包含文件的包含文件，
// 或是经常使用但不常更改的
// 特定于项目的包含文件
#pragma once
#include <stdio.h>
extern "C"
{
#include "include\libavcodec\avcodec.h"
#include "include\libavformat\avformat.h"
#include "include\libavutil\channel_layout.h"
#include "include\libavutil\common.h"
#include "include\libavutil\imgutils.h"
#include "include\libswscale\swscale.h"
#include "include\libavutil\imgutils.h"
#include "include\libavutil\opt.h"
#include "include\libavutil\mathematics.h"
#include "include\libavutil\samplefmt.h"
#include "SDL\SDL.h"
};
#pragma comment(lib, "avcodec.lib")
#pragma comment(lib, "avformat.lib")
#pragma comment(lib, "avdevice.lib")
#pragma comment(lib, "avfilter.lib")
#pragma comment(lib, "avutil.lib")
#pragma comment(lib, "postproc.lib")
#pragma comment(lib, "swresample.lib")
#pragma comment(lib, "swscale.lib")
#pragma comment(lib, "SDL2.lib")
#pragma comment(lib, "SDL2main.lib")
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