ffplay 命令

ffplay -video_size 640x480 -pix_fmt nv12 -i nv12.yuv
ffplay -video_size 640x480 -pix_fmt yuv420p -i i420.yuv

将yuv 数据写入文件

//Objective-c 写法
void writeNV12(void *src_y, int src_stride_y,
               void *src_uv, int src_stride_uv,
               int width, int height)
{
    
    NSMutableData *dat = [[NSMutableData alloc] init];
    [dat appendData:[NSData dataWithBytes:src_y length:src_stride_y*height]];
    [dat appendData:[NSData dataWithBytes:src_uv length:src_stride_uv*height/2]];
    
    NSString *path = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES).firstObject;
    path = [path stringByAppendingPathComponent:@"nv12.yuv"];
    
    NSLog(@"file path = %@ ============",path);
    
    if (![[NSFileManager defaultManager] fileExistsAtPath:path]) {
        [[NSFileManager defaultManager] createFileAtPath:path contents:nil attributes:nil];
    }
    
    NSFileHandle *fileHandle = [NSFileHandle fileHandleForWritingAtPath:path];
    [fileHandle seekToEndOfFile];
    [fileHandle writeData:dat];
    [fileHandle closeFile];
    
}

//C 语言写法
void writeI420(void *src_y, int src_stride_y,
               void *src_u, int src_stride_u,
               void *src_v, int src_stride_v,
               int width, int height)
{
    
    static FILE* m_pOutFile = nullptr;
    if (!m_pOutFile) {
        std::string home{std::getenv("HOME")};
        std::string path = home + "/i420.yuv";
        m_pOutFile = fopen(path.c_str(), "a+");
        printf("======== nv12_before_scale = %s\n",path.c_str());
    }
    //write y
    fwrite(src_y, 1, height * src_stride_y, m_pOutFile);
    //write u
    fwrite(src_u, 1, height / 2 * src_stride_u, m_pOutFile);
    //write v
    fwrite(src_v, 1, height / 2 * src_stride_v, m_pOutFile);
}