本文记录IOS平台下基于FFmpeg的视频解码器。该示例C语言的源代码来自于《最简单的基于FFMPEG SDL的视频播放器》。相关的概念就不再重复记录了。
源代码
项目的目录结构如图所示。
本文转载自网络，感谢原作者的分享，转载仅为分享干货知识，如有侵权欢迎联系作者进行删除处理。C代码位于ViewController.m文件中，内容如下所示。
代码语言：javascript复制/*
* 提示：该行代码过长，系统自动注释不进行高亮。一键复制会移除系统注释
* /** * 最简单的基于FFmpeg的视频解码器-IOS * Simplest FFmpeg IOS Decoder * * 雷霄骅 Lei Xiaohua * leixiaohua1020@126.com * 中国传媒大学/数字电视技术 * Communication University of China / Digital TV Technology * http://blog.csdn.net/leixiaohua1020 * * 本程序是IOS平台下最简单的基于FFmpeg的视频解码器。 * 它可以将输入的视频数据解码成YUV像素数据。 * * This software is the simplest decoder based on FFmpeg in IOS. * It can decode video stream to raw YUV data. * */ #import "ViewController.h"#include <libavcodec/avcodec.h>#include <libavformat/avformat.h>#include <libavutil/imgutils.h>#include <libswscale/swscale.h> @interface ViewController ()@end@implementation ViewController- (void)viewDidLoad { [super viewDidLoad]; // Do any additional setup after loading the view, typically from a nib.} - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; // Dispose of any resources that can be recreated.} - (IBAction)clickDecodeButton:(id)sender { AVFormatContext *pFormatCtx; int i, videoindex; AVCodecContext *pCodecCtx; AVCodec *pCodec; AVFrame *pFrame,*pFrameYUV; uint8_t *out_buffer; AVPacket *packet; int y_size; int ret, got_picture; struct SwsContext *img_convert_ctx; FILE *fp_yuv; int frame_cnt; clock_t time_start, time_finish; double time_duration = 0.0; char input_str_full[500]={0}; char output_str_full[500]={0}; char info[1000]={0}; NSString *input_str= [NSString stringWithFormat:@"resource.bundle/%@",self.inputurl.text]; NSString *output_str= [NSString stringWithFormat:@"resource.bundle/%@",self.outputurl.text]; NSString *input_nsstr=[[[NSBundle mainBundle]resourcePath] stringByAppendingPathComponent:input_str]; NSString *output_nsstr=[[[NSBundle mainBundle]resourcePath] stringByAppendingPathComponent:output_str]; sprintf(input_str_full,"%s",[input_nsstr UTF8String]); sprintf(output_str_full,"%s",[output_nsstr UTF8String]); printf("Input Path:%sn",input_str_full); printf("Output Path:%sn",output_str_full); av_register_all(); avformat_network_init(); pFormatCtx = avformat_alloc_context(); if(avformat_open_input(&pFormatCtx,input_str_full,NULL,NULL)!=0){ printf("Couldn't open input stream.n"); return ; } if(avformat_find_stream_info(pFormatCtx,NULL)<0){ printf("Couldn't find stream information.n"); return; } videoindex=-1; for(i=0; i<pFormatCtx->nb_streams; i ) if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO){ videoindex=i; break; } if(videoindex==-1){ printf("Couldn't find a video stream.n"); return; } pCodecCtx=pFormatCtx->streams[videoindex]->codec; pCodec=avcodec_find_decoder(pCodecCtx->codec_id); if(pCodec==NULL){ printf("Couldn't find Codec.n"); return; } if(avcodec_open2(pCodecCtx, pCodec,NULL)<0){ printf("Couldn't open codec.n"); return; } pFrame=av_frame_alloc(); 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)); 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); sprintf(info, "[Input ]%sn", [input_str UTF8String]); sprintf(info, "%s[Output ]%sn",info,[output_str UTF8String]); sprintf(info, "%s[Format ]%sn",info, pFormatCtx->iformat->name); sprintf(info, "%s[Codec ]%sn",info, pCodecCtx->codec->name); sprintf(info, "%s[Resolution]%dx%dn",info, pCodecCtx->width,pCodecCtx->height); fp_yuv=fopen(output_str_full,"wb "); if(fp_yuv==NULL){ printf("Cannot open output file.n"); return; } frame_cnt=0; time_start = clock(); while(av_read_frame(pFormatCtx, packet)>=0){ if(packet->stream_index==videoindex){ ret = avcodec_decode_video2(pCodecCtx, pFrame, &got_picture, packet); if(ret < 0){ printf("Decode Error.n"); return; } if(got_picture){ sws_scale(img_convert_ctx, (const uint8_t* const*)pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pFrameYUV->data, pFrameYUV->linesize); 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 //Output info char pictype_str[10]={0}; switch(pFrame->pict_type){ case AV_PICTURE_TYPE_I:sprintf(pictype_str,"I");break; case AV_PICTURE_TYPE_P:sprintf(pictype_str,"P");break; case AV_PICTURE_TYPE_B:sprintf(pictype_str,"B");break; default:sprintf(pictype_str,"Other");break; } printf("Frame Index: ]. Type:%sn",frame_cnt,pictype_str); frame_cnt ; } } av_free_packet(packet); } //flush decoder //FIX: Flush Frames remained in Codec while (1) { ret = avcodec_decode_video2(pCodecCtx, pFrame, &got_picture, packet); if (ret < 0) break; if (!got_picture) break; sws_scale(img_convert_ctx, (const uint8_t* const*)pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pFrameYUV->data, pFrameYUV->linesize); 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 //Output info char pictype_str[10]={0}; switch(pFrame->pict_type){ case AV_PICTURE_TYPE_I:sprintf(pictype_str,"I");break; case AV_PICTURE_TYPE_P:sprintf(pictype_str,"P");break; case AV_PICTURE_TYPE_B:sprintf(pictype_str,"B");break; default:sprintf(pictype_str,"Other");break; } printf("Frame Index: ]. Type:%sn",frame_cnt,pictype_str); frame_cnt ; } time_finish = clock(); time_duration=(double)(time_finish - time_start); sprintf(info, "%s[Time ]%fusn",info,time_duration); sprintf(info, "%s[Count ]%dn",info,frame_cnt); sws_freeContext(img_convert_ctx); fclose(fp_yuv); av_frame_free(&pFrameYUV); av_frame_free(&pFrame); avcodec_close(pCodecCtx); avformat_close_input(&pFormatCtx); NSString * info_ns = [NSString stringWithFormat:@"%s", info]; self.infomation.text=info_ns; } @end
*/运行结果
App在手机上运行后的结果如下图所示。单击“Decode”，将会把位于resource.bundle中的“sintel.mov”文件解码为“sintel.yuv”文件并存储于相同的目录下。
生成的文件如下图所示。
本文转载自网络，感谢原作者的分享，转载仅为分享干货知识，如有侵权欢迎联系作者进行删除处理。
