IOS上编译ffmpeg 播放本地 .h264视频(二)---播放本地文件

http://blog.csdn.net/u013028303/article/details/41116311

 

写在前面：iFrameExtractor 的确是个不错的开源工程，可以从里面学到不少东西，建议大家下来看看。但是在捣鼓的过程中发现它不能播放本地后缀.264的视频文件，没办法只好自己捣鼓。

主要思路：打开本地.h264文件，每次从里面取固定buff大小的数据，解码成一张张的图片最后逐张显示。 

一、在viewController.h中声明

 

@interface ViewController : UIViewController
{
    AVCodecContext *codec;
    AVPacket packetBuf;
    AVFrame *pFrame;
    AVPicture picture;

    struct SwsContext *img_convert_ctx;

}

@property (nonatomic) int outputWidth, outputHeight;

 

二、viewController.m

这里我用主线程来显示图片而用工作线程来解码。

NSThread *threadDecode = [[NSThread alloc] initWithTarget:self selector:@selector(decodeVideo) object:nil];
[threadDecode start];

下面是最重要的解码函数decodeVideo{}

1.首先是初始化以及设置解码器

avcodec_register_all();
av_register_all();

 

AVCodec *videoCodec = avcodec_find_decoder(CODEC_ID_H264);  //得到264的解码器
AVCodecParserContext *avParserContext = av_parser_init(CODEC_ID_H264);//得到解析帧类，主要用于后面的帧头查找
codec = avcodec_alloc_context3(videoCodec);//解码会话层
pFrame = avcodec_alloc_frame();

av_init_packet(&packetBuf);//初始化

packetBuf.data = NULL;
packetBuf.size = 0;

2.初始化一块内存来存储

#define MAX_LEN  1024 * 50

int readFileLen = 1;
char readBuf[MAX_LEN];
unsigned charchar *parseBuf;
int parseBufLen = 0;
int frameFinished = 10;

3.打开.264文件

FILEFILE *myH264 = fopen("/Users/Gizmosir/desktop/c4.h264", "r");

这里我直接把文件放在桌面用模拟器打开，所以用的是绝对路径。如果要用真机调试或者视频文件放在包内的，则：

 

NSString *path2 = [[NSBundle mainBundle] pathForResource:@"c4.h264" ofType:nil];
FILEFILE *myH264 = fopen([path2 cStringUsingEncoding:NSMacOSRomanStringEncoding], "r");

 

 

4.解码

 

while(readFileLen >0){

    readFileLen = fread(readBuf, 1, sizeof(readBuf), myH264);//
    if(readFileLen <= 0){
        break;
    }else{
        int handleLen = 0;
        int handleFileLen = readFileLen;

        while(handleFileLen >0){
            av_parser_parse2(avParserContext,codec, &parseBuf, &parseBufLen, readBuf + handleLen, handleFileLen, 0, 0, 0);//查找264帧头
            handleFileLen -= nLength;
            handleLen += nLength;

            if(parseBufLen <= 0){
                continue;//<span style="font-family: Arial, Helvetica, sans-serif;">查找不到帧头
            }

            packetBuf.size = parseBufLen;
            packetBuf.data = parseBuf;

            while (packetBuf.size > 0) {
                int decodeLen = avcodec_decode_video2(codec, pFrame, &frameFinished, &packetBuf);
                if(decodeLen <= 0){
                    break;//解码失败
                }
                packetBuf.size -= decodeLen;
                packetBuf.data += decodeLen;

                if (frameFinished >0) {//解码成功
                    avpicture_get_size(PIX_FMT_RGB24, codec->width, codec->height);

                    [self performSelectorOnMainThread:@selector(displayVideo) withObject:nil waitUntilDone:YES];//用主线程显示图片

                    [NSThread sleepForTimeInterval:0.2];//设置图片显示间隔
                }
            }
        }
    }
}

 

5.最后不要忘了释放

 

av_free(codec);
av_free_packet(&packetBuf);
av_frame_free(&pFrame);

接下来是显示函数displayVideo{}

self.outputWidth = 1980;
self.outputHeight = 1200;
imageView.image = self.currentImage;

在这里需要填上你自己播放视频的尺寸。

三、其余的函数：主要参考iFrameExtractor工程

-(void)setOutputWidth:(int)newValue {
    if (outputWidth == newValue) return;
    outputWidth = newValue;
}

-(void)setOutputHeight:(int)newValue {
    if (outputHeight == newValue) return;
    outputHeight = newValue;
    [self setupScaler];
}

-(void)setupScaler {

    // Release old picture and scaler
    avpicture_free(&picture);
    sws_freeContext(img_convert_ctx);

    // Allocate RGB picture
    avpicture_alloc(&picture, PIX_FMT_RGB24, outputWidth, outputHeight);

    // Setup scaler
    static int sws_flags =  SWS_FAST_BILINEAR;
    img_convert_ctx = sws_getContext(codec->width,
                                     codec->height,
                                     codec->pix_fmt,
                                     outputWidth,
                                     outputHeight,
                                     PIX_FMT_RGB24,
                                     sws_flags, NULL, NULL, NULL);
}

-(UIImage *)currentImage {
    if (!pFrame->data[0]) return nil;
    [self convertFrameToRGB];
    return [self imageFromAVPicture:picture width:outputWidth height:outputHeight];
}

-(void)convertFrameToRGB {
    sws_scale (img_convert_ctx, pFrame->data, pFrame->linesize,
               0, codec->height,
               picture.data, picture.linesize);

}

-(UIImage *)imageFromAVPicture:(AVPicture)pict width:(int)width height:(int)height {
    CGBitmapInfo bitmapInfo = kCGBitmapByteOrderDefault;
    CFDataRef data = CFDataCreateWithBytesNoCopy(kCFAllocatorDefault, pict.data[0], pict.linesize[0]*height,kCFAllocatorNull);
    CGDataProviderRef provider = CGDataProviderCreateWithCFData(data);
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    CGImageRef cgImage = CGImageCreate(width,
                                       height,
                                       8,
                                       24,
                                       pict.linesize[0],
                                       colorSpace,
                                       bitmapInfo,
                                       provider,
                                       NULL,
                                       NO,
                                       kCGRenderingIntentDefault);

    CGColorSpaceRelease(colorSpace);
    UIImage *image = [UIImage imageWithCGImage:cgImage];
    CGImageRelease(cgImage);
    CGDataProviderRelease(provider);
    CFRelease(data);

    return image;
}

到这里为止，播放本地.264文件的目标就完成了！