本程序改造自雷神的示例代碼。雷神的原示例代碼中，部分解碼核心函數在FFMPEG4.0中已經被聲明爲廢棄，GCC編譯時會提示deprecated。所以我根據FFMPEG4.0最新代碼說明，進行了小小的改造，供需要的同學參考。
我的開發環境：
Ubuntu 14.04, GCC 4.8.4, FFMPEG 4.0, SDL 2.0.8.
編譯方法：
將代碼copy命名爲MyFirstPlayer.c，與Makefile放置於同一目錄下，執行 make 即可。
如果有編譯錯誤，一般是源於FFMPEG ./configure配置問題，可能某些lib庫未正確配置。或重新編譯FFMPEG，或單獨安裝對應的庫即可。
示例代碼：
/*
* A simple player with FFMPEG4.0 and SDL2.0.8.
* Only support video decoder, not support audio and subtitle.
* Created by LiuWei@20180524
* Reference: https://blog.csdn.net/leixiaohua1020/article/details/38868499
*/
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>
#include <SDL2/SDL.h>
#include <libavutil/imgutils.h>
/* Output YUV420P data as a file
* 0 means close */
#define OUTPUT_YUV420P 0
int main(int argc, char *argv[])
{
/* AVFormatContext contains:
* 1. iformat(AVInputFormat) : It's either autodetected or set by user.
* 2. oformat(AVOutputFormat): always set by user for output.
* 3. streams "array" of AVStreams: describe all elementary streams stored in the file.
* AVStreams are typically referred to using their index in this array. */
/* We can keep pFormatCtx as NULL. avformat_open_input() will allocate for it. */
AVFormatContext *pFormatCtx = NULL;
int i, videoindex, audioindex, titleindex;
AVCodecContext *pCodecCtx;
AVCodec *pCodec;
AVFrame *pFrame, *pFrameYUV;
AVStream *avStream;
AVPacket *packet;
unsigned char *out_buffer;
int y_size;
int ret;
struct SwsContext *img_convert_ctx;
char filepath[256] = {0};
/* SDL */
int screen_w, screen_h = 0;
SDL_Window *screen;
SDL_Renderer *sdlRenderer;
SDL_Texture *sdlTexture;
SDL_Rect sdlRect;
FILE *fp_yuv;
/* Parse input parameter. The right usage: ./myplayer xxx.mp4 */
if(argc < 2 || argc > 2) {
printf("Too few or too many parameters. e.g. ./myplayer xxx.mp4\n");
return -1;
}
if(strlen(argv[1]) >= sizeof(filepath)) {
printf("Video path is too long, %d bytes. It should be less than %d bytes.\n",
strlen(argv[1]), sizeof(filepath));
return -1;
}
strncpy(filepath, argv[1], sizeof(filepath));
/* Open the specified file(autodetecting the format) and read the header, exporting the information
* stored there into AVFormatContext. The codecs are not opened.
* The stream must be closed with avformat_close_input(). */
ret = avformat_open_input(&pFormatCtx, filepath, NULL, NULL);
if(ret != 0) {
printf("[error]avformat_open_input: %s\n", av_err2str(ret));
return -1;
}
/* Some formats do not have a header or do not store enough information there, so it it recommended
* that you call the avformat_find_stream_info() which tries to read and decode a few frames to find
* missing information.
* This is useful for file formats with no headers such as MPEG. */
ret = avformat_find_stream_info(pFormatCtx, NULL);
if(ret < 0) {
printf("[error]avformat_find_stream_info: %s\n", av_err2str(ret));
avformat_close_input(&pFormatCtx);
return -1;
}
/* Find out which stream is video, audio, and subtitle. */
videoindex = audioindex = titleindex = -1;
for(i = 0; i < pFormatCtx->nb_streams; i++) {
avStream = pFormatCtx->streams[i];
switch(avStream->codecpar->codec_type) {
case AVMEDIA_TYPE_VIDEO:
videoindex = i;
break;
case AVMEDIA_TYPE_AUDIO:
audioindex = i;
break;
case AVMEDIA_TYPE_SUBTITLE:
titleindex = i;
break;
}
}
if(videoindex == -1) {
printf("Didn't find a video stream.\n");
avformat_close_input(&pFormatCtx);
return -1;
}
/* Open video codec */
pCodecCtx = avcodec_alloc_context3(NULL); /* It should be freed with avcodec_free_context() */
if(!pCodecCtx) {
printf("[error]avcodec_alloc_context3() fail\n");
avformat_close_input(&pFormatCtx);
return -1;
}
ret = avcodec_parameters_to_context(pCodecCtx, pFormatCtx->streams[videoindex]->codecpar);
if(ret < 0) {
printf("[error]avcodec_parameters_to_context: %s\n", av_err2str(ret));
avcodec_free_context(&pCodecCtx);
avformat_close_input(&pFormatCtx);
return -1;
}
pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
if(pCodec == NULL) {
printf("Video Codec not found.\n");
avcodec_free_context(&pCodecCtx);
avformat_close_input(&pFormatCtx);
return -1;
}
ret = avcodec_open2(pCodecCtx, pCodec, NULL);
if(ret < 0) {
printf("[error]avcodec_open2: %s\n", av_err2str(ret));
avcodec_free_context(&pCodecCtx);
avformat_close_input(&pFormatCtx);
return -1;
}
/* Output info */
printf("-------------File Information-------------\n");
av_dump_format(pFormatCtx, 0, filepath, 0);
printf("------------------------------------------\n");
/* SDL */
pFrame = av_frame_alloc(); /* av_frame_free(&pFrame); */
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);
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 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());
#if OUTPUT_YUV420P
fclose(fp_yuv);
#endif
av_free(out_buffer);
av_frame_free(&pFrame);
av_frame_free(&pFrameYUV);
avcodec_free_context(&pCodecCtx);
avformat_close_input(&pFormatCtx);
return -1;
}
screen_w = pCodecCtx->width;
screen_h = pCodecCtx->height;
screen = SDL_CreateWindow("Simplest ffmpleg player's Window", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
screen_w, screen_h, SDL_WINDOW_OPENGL);
if(!screen) {
printf("SDL: could not create window - %s\n", SDL_GetError());
#if OUTPUT_YUV420P
fclose(fp_yuv);
#endif
av_free(out_buffer);
av_frame_free(&pFrame);
av_frame_free(&pFrameYUV);
avcodec_free_context(&pCodecCtx);
avformat_close_input(&pFormatCtx);
return -1;
}
sdlRenderer = SDL_CreateRenderer(screen, -1, 0);
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 */
/* For decoding, call avcodec_send_packet() to give the decoder raw compressed data in an AVPacket.
* call avcodec_receive_frame() in a loop until AVERROR_EOF is returned.
* On success, it will return an AVFrame containing uncompressed audio or video data. */
packet = (AVPacket *)av_malloc(sizeof(AVPacket));
av_init_packet(packet);
while(av_read_frame(pFormatCtx, packet) >= 0) {
// Only handle video packet
if(packet->stream_index != videoindex) {
av_packet_unref(packet);
av_init_packet(packet);
continue;
}
/* @return 0 on success
* AVERROR(EAGAIN): input is not accepted in the current state - user must read output with avcodec_receive_frame()
* AVERROR_EOF: the decoder has been flushed, and no new packets can be sent to it
* AVERROR(EINVAL): codec not opened, it is an encoder, or requires flush
* AVERROR(ENOMEM): failed to add packet to internal queue, or similar */
ret = avcodec_send_packet(pCodecCtx, packet);
if( ret < 0 )
continue;
/* Got frame */
do {
/* @return 0 on success, a frame was returned
* AVERROR(EAGAIN): output is not available in this state - user must try to send new input
* AVERROR_EOF: the decoder has been fully flushed, and there will be no more output frames
* AVERROR(EINVAL): codec not opened, or it is an encoder
* other negative values: legitimate decoding errors */
ret = avcodec_receive_frame(pCodecCtx, pFrame);
if(ret < 0)
break;
else if(ret == 0) { /* Got a frame successfully */
sws_scale(img_convert_ctx, (const unsigned char * const *)pFrame->data, pFrame->linesize, 0,
pCodecCtx->height, pFrameYUV->data, pFrameYUV->linesize);
/* SDL */
SDL_UpdateYUVTexture(sdlTexture, &sdlRect,
pFrameYUV->data[0], pFrameYUV->linesize[0],
pFrameYUV->data[1], pFrameYUV->linesize[1],
pFrameYUV->data[2], pFrameYUV->linesize[2]);
SDL_RenderClear(sdlRenderer);
SDL_RenderCopy(sdlRenderer, sdlTexture, NULL, &sdlRect);
SDL_RenderPresent(sdlRenderer);
/* SDL End */
SDL_Delay(40);
} else if(ret == AVERROR_EOF) {
avcodec_flush_buffers(pCodecCtx);
break;
}
} while(ret != AVERROR(EAGAIN));
av_packet_unref(packet);
av_init_packet(packet);
}
sws_freeContext(img_convert_ctx);
#if OUTPUT_YUV420P
fclose(fp_yuv);
#endif
SDL_Quit();
av_free(packet);
av_free(out_buffer);
av_frame_free(&pFrame);
av_frame_free(&pFrameYUV);
avcodec_close(pCodecCtx);
avcodec_free_context(&pCodecCtx);
avformat_close_input(&pFormatCtx);
return 0;
}
編譯使用的Makefile:
CC=gcc CCFLAGS=-I/usr/local/include -O2 LDFLAGS=-L/usr/local/lib -lavformat -lavfilter -lavcodec -lswresample -lavdevice -lavutil -lswscale -lpostproc -lpthread -lm -lx264 -lx265 -lz -lSDL2 TARGET=myplayer OBJS=MyFirstPlayer.o RM=rm -f STRIP=strip $(TARGET):$(OBJS) $(CC) -o $(TARGET) $(OBJS) $(LDFLAGS) # $(STRIP) $(TARGET) $(OBJS):%.o:%.c $(CC) -c $(CCFLAGS) $< -o $@ clean: $(RM) $(TARGET) $(OBJS) *~
