---

（關於FFmpeg的編譯包，運用的是3.2.2，能夠不同編譯包API局部有變化：下載地址：後續上傳）
視頻采集後經過硬件編碼為H264，然後經過網絡傳輸（RTSP、RTMP）協議。
當我們失掉H264編碼的數據後需求停止解碼，從而將數據復原，停止播放。

iphone是有硬件解碼的，但是並沒有提供相關API，一切我們沒有方法停止硬件解碼，只能經過軟件解碼–ffmpeg。

失掉YUV格式的數據後有兩種處理方案：

方案 內容 評價 方案一 運用 ffmpeg中 的函數 int sws_scale(struct SwsContext *c, const uint8_t *const srcSlice[],const int srcStride[], int srcSliceY, int srcSliceH, uint8_t *const dst[], const int dstStride[]);轉成CIImage ->UIIamge 轉化效率很低、耗功能 方案二 將YUV數據交給OpenGL ES 經過shader轉化為RGB格式然後渲染到面上 OpenGL可以調用顯卡的一些借口、效率更高

本文引見如何解碼，經過opengl顯示下一篇文章會有引見

解碼H264 Demo構造、留意FFmpeg所需的依賴庫

定義YUV構造，新建DecodeH264Data_YUV.h文件

//
//  H264DecoderDemo
//
//  Created by xoxo_X on 2017/2/11.
//  Copyright © 2017年 xoxo_X. All rights reserved.
//
#ifndef _DECODEH264DATA_YUV_
#define _DECODEH264DATA_YUV_

#pragma pack(push, 1)

typedef struct H264FrameDef
{
    unsigned int    length;
    unsigned char*  dataBuffer;

}H264Frame;

typedef struct  H264YUVDef
{
    unsigned int    width;
    unsigned int    height;
    H264Frame       luma;
    H264Frame       chromaB;
    H264Frame       chromaR;

}H264YUV_Frame;


#pragma pack(pop)

#endif

解碼.m文件

//
//  H264Decoder.m
//  H264DecoderDemo
//
//  Created by 馮士魁 on 2017/2/11.
//  Copyright © 2017年 馮士魁. All rights reserved.
//

#import "H264Decoder.h"

@implementation H264Decoder
@synthesize updateDelegate;
- (id)init{

    if(self = [super init]){
        pCodec = NULL;
        pCodecCtx = NULL;
        pVideoFrame = NULL;

        av_register_all();
        avcodec_register_all();

        pCodec = avcodec_find_decoder(AV_CODEC_ID_H264);
        if (!pCodec) {
            printf("Codec not find\n");
        }
        pCodecCtx = avcodec_alloc_context3(pCodec);

        if (!pCodecCtx) {
            printf("alloc codec context error\n");
        }

        avcodec_open2(pCodecCtx, pCodec, NULL);

        pVideoFrame = av_frame_alloc();
    }
        return self;
}

- (void)dealloc{
    if (!pCodecCtx) {
        avcodec_close(pCodecCtx);
        pCodecCtx = NULL;
    }

    if (!pVideoFrame) {
        av_frame_free(&pVideoFrame);
    }
    [super dealloc];
}
- (int)DecodeH264Frames: (unsigned char*)inputBuffer withLength:(int)aLength
{


    int gotPicPtr=0;
    int result=0;

    av_init_packet(&pAvPackage);
    pAvPackage->data=(unsigned char*)inputBuffer;
    pAvPackage->size=aLength;
    //解碼
    result=avcodec_decode_video2(pCodecCtx, pVideoFrame, &gotPicPtr, &pAvPackage);

    //假如視頻尺寸更改，我們丟掉這個frame
    if((pictureWidth!=0)&&(pictureWidth!=pCodecCtx->width)){
        pictureWidth=pCodecCtx->width;
        return -1;
    }
    //YUV 420 Y U V  
    if(gotPicPtr)
    {

        unsigned int lumaLength= (pCodecCtx->height)*(MIN(pVideoFrame->linesize[0], pCodecCtx->width));
        unsigned int chromBLength=((pCodecCtx->height)/2)*(MIN(pVideoFrame->linesize[1], (pCodecCtx->width)/2));
        unsigned int chromRLength=((pCodecCtx->height)/2)*(MIN(pVideoFrame->linesize[2], (pCodecCtx->width)/2));

        H264YUV_Frame    yuvFrame;
        memset(&yuvFrame, 0, sizeof(H264YUV_Frame));

        yuvFrame.luma.length = lumaLength;
        yuvFrame.chromaB.length = chromBLength;
        yuvFrame.chromaR.length =chromRLength;

        yuvFrame.luma.dataBuffer=(unsigned char*)malloc(lumaLength);
        yuvFrame.chromaB.dataBuffer=(unsigned char*)malloc(chromBLength);
        yuvFrame.chromaR.dataBuffer=(unsigned char*)malloc(chromRLength);

        copyDecodedFrame(pVideoFrame->data[0],yuvFrame.luma.dataBuffer,pVideoFrame->linesize[0],
                         pCodecCtx->width,pCodecCtx->height);
        copyDecodedFrame(pVideoFrame->data[1], yuvFrame.chromaB.dataBuffer,pVideoFrame->linesize[1],
                         pCodecCtx->width / 2,pCodecCtx->height / 2);
        copyDecodedFrame(pVideoFrame->data[2], yuvFrame.chromaR.dataBuffer,pVideoFrame->linesize[2],
                         pCodecCtx->width / 2,pCodecCtx->height / 2);

        yuvFrame.width=pCodecCtx->width;
        yuvFrame.height=pCodecCtx->height;


        dispatch_sync(dispatch_get_main_queue(), ^{
         //這個時分回到主線程將yuv數據放到opengl中   
            [self updateYUVFrameOnMainThread:(H264YUV_Frame*)&yuvFrame];
        });

        free(yuvFrame.luma.dataBuffer);
        free(yuvFrame.chromaB.dataBuffer);
        free(yuvFrame.chromaR.dataBuffer);

    }
    av_free_packet(&pAvPackage);

    return 0;
}
void copyDecodedFrame(unsigned char *src, unsigned char *dist,int linesize, int width, int height)
{

    width = MIN(linesize, width);

    for (NSUInteger i = 0; i < height; ++i) {
        memcpy(dist, src, width);
        dist += width;
        src += linesize;
    }

}
- (void)updateYUVFrameOnMainThread:(H264YUV_Frame*)yuvFrame
{
    if(yuvFrame!=NULL){
        if([self.updateDelegate respondsToSelector:@selector(updateDecodedH264FrameData: )]){
            [self.updateDelegate updateDecodedH264FrameData:yuvFrame];
        }
    }
}


@end

解碼.h文件

//
//  H264Decoder.h 解碼
//  H264DecoderDemo
//
//  Created by 馮士魁 on 2017/2/11.
//  Copyright © 2017年 馮士魁. All rights reserved.
//

#import <Foundation/Foundation.h>
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>
#import "DecodeH264Data_YUV.h"

@protocol updateDecodedH264FrameDelegate <NSObject>

@optional
- (void)updateDecodedH264FrameData:(H264YUV_Frame *)yuvFrame;

@end

@interface H264Decoder : NSObject{
    int         pictureWidth;

    AVCodec         *pCodec;
    AVCodecContext  *pCodecCtx;
    AVFrame         *pVideoFrame;

    AVPacket        *pAvPackage;

}
@property (nonatomic,assign)id<updateDecodedH264FrameDelegate>updateDelegate;
- (id)init;
-(int)decodeH264Frames:(unsigned char *)inputBuffer withLength:(int)aLength;

@end

【ios 解碼H264為YUV格式】的相關資料介紹到這裡，希望對您有所幫助！ 提示：不會對讀者因本文所帶來的任何損失負責。如果您支持就請把本站添加至收藏夾哦！