ffmpeg学习文章-用ffmpeg做一个简单的iOS播放器

雷神博客
http://blog.csdn.net/leixiaohua1020/article/details/42658139

http://trac.ffmpeg.org/wiki/CompilationGuide/MacOSX

玩转 FFmpeg 的 7 个小技巧
http://itindex.net/detail/4071-ffmpeg

ffmpeg裁剪合并视频
http://itindex.net/detail/38530-ffmpeg-合并-视频

FFmpeg使用手册 - ffplay 的常用命令
http://blog.chinaunix.net/uid-11344913-id-5750263.html

FFMPeg一般使用的流程：

1、av_register_all();//注册所有文件格式和编解码库
2、avformat_network_init();//打开网络视频流
3、av_open_input_file();//读取文件头部把信息保存到AVFormatContext结构体
4、av_find_stream_info();//为pFormatCtx->streams填充上正确的信息
5、CODEC_TYPE_VIDEO;//通过判断得到视频流类型
6、avcodec_find_decoder();//查找解码器
7、avcodec_open();//打开编解码器
8、avcodec_alloc_frame();//分配空间保存帧数据
9、av_read_frame();//不断从流中提取帧数据
10、avcodec_decode_video();//解码视频流
11、avcodec_close();//关闭解码器
12、avformat_close_input_file();//关闭输入文件

一、本播放器原理:

通过ffmpeg对视频进行解码,解码出每一帧图片,然后根据一定时间播放每一帧图

二、iOS 集成 ffmpeg

1.下载脚本 [ffmpeg脚本](https://github.com/kewlbear/FFmpeg-iOS-build-script)

2. 根据上面链接的 README 进行编译

3.集成到项目,新建工程,将编译好的静态库以及头文件导入工程

1466252896529247.png

导入依赖库

1466252896115673.png

设置头文件路径,路径一定要对,不然胡找不到头文件

image.png

先 command + B 编译一下,确保能编译成功

代码实现：
新建一个OC文件

#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>


@interface SGVideoModel : NSObject

/* 解码后的UIImage */
@property (nonatomic, strong, readonly) UIImage *currentImage;

/* 视频的frame高度 */
@property (nonatomic, assign, readonly) int sourceWidth, sourceHeight;

/* 输出图像大小。默认设置为源大小。 */
@property (nonatomic,assign) int outputWidth, outputHeight;

/* 视频的长度，单位为秒 */
@property (nonatomic, assign, readonly) double duration;

/* 视频的当前秒数 */
@property (nonatomic, assign, readonly) double currentTime;

/* 视频的帧率 */
@property (nonatomic, assign, readonly) double fps;

/* 视频路径。 */
- (instancetype)initWithVideo:(NSString *)videoPath;
/* 切换资源 */
- (void)replaceTheResources:(NSString *)videoPath;
/* 重播 */
- (void)replay;
/* 从视频流中读取下一帧。如果没有帧读取（视频）,返回假。 */
- (BOOL)stepFrame;

/* 在指定的时间寻找最近的关键帧 */
- (void)seekTime:(double)seconds;
@end

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

@interface SGVideoModel()
{
    AVFormatContext *formatCtx;
    AVCodecContext *codecCtx;
    AVFrame *frame;
    AVStream *stream;
    AVPacket packet;
    AVPicture picture;
    int videoStream;
    int fps;
    BOOL isReleaseResources;

}
@property (nonatomic, copy) NSString *currentPath;
@end

@implementation SGVideoModel
-(instancetype)initWithVideo:(NSString *)videoPath{
     if (!(self=[super init])) return nil;
    if ([self initializeResources:[videoPath UTF8String]]) {
        self.currentPath = [videoPath copy];
        return self;
    }else{
        return nil;
    }
}
- (BOOL)initializeResources:(const char *)filePath{
    isReleaseResources = NO;
    AVCodec *pCodec;
    //注册所有解码器
    avcodec_register_all();
    av_register_all();
    avformat_network_init();
    //打开视频文件
    if (avformat_open_input(&formatCtx, filePath, NULL, NULL) !=0) {
        NSLog(@"打开文件失败");
        goto initError;
    }
    //检查数据流
    if (avformat_find_stream_info(formatCtx, NULL)<0) {
        NSLog(@"检查数据流失败");
        goto initError;
    }
    //检查数据流，找到第一个视频流
    if ((videoStream = av_find_best_stream(formatCtx, AVMEDIA_TYPE_VIDEO, -1, -1, &pCodec, 0))<0) {
        NSLog(@"没有找到第一个视频流");
        goto initError;
    }
    //获取视频流编解码上下文的指针
    stream = formatCtx->streams[videoStream];
    codecCtx = stream->codec;

#if DEBUG
   //打印视频流的详细信息
    av_dump_format(formatCtx, videoStream, filePath, 0);
#endif
    if (stream->avg_frame_rate.den && stream->avg_frame_rate.num) {
        fps = av_q2d(stream->avg_frame_rate);
    }else{
        fps = 30;
    }
    //查找解码器
    pCodec = avcodec_find_decoder(codecCtx->codec_id);
    if (pCodec == NULL) {
        NSLog(@"没有找到解码器");
        goto initError;
    }

    //打开解码器
    if (avcodec_open2(codecCtx, pCodec, NULL) < 0) {
        NSLog(@"打开解码器失败");
        goto initError;
    }

    //分配视频帧
    frame = av_frame_alloc();
    _outputWidth = codecCtx->width;
    _outputHeight = codecCtx->height;
    return YES;
initError:
    return NO;
}

/* 在指定的时间寻找最近的关键帧 */
- (void)seekTime:(double)seconds{
    if (formatCtx == NULL) {
        [self initializeResources:[self.currentPath UTF8String]];
    }
    AVRational timeBase = formatCtx->streams[videoStream]->time_base;
    int64_t targetFrame = (int64_t)((double)timeBase.den / timeBase.num*seconds);
    avformat_seek_file(formatCtx, videoStream, 0, targetFrame, targetFrame, AVSEEK_FLAG_FRAME);
    avcodec_flush_buffers(codecCtx);

}
/* 从视频流中读取下一帧。如果没有帧读取（视频）,返回假。 */
- (BOOL)stepFrame{

    int frameFinished = 0;
    while (!frameFinished && av_read_frame(formatCtx, &packet) >= 0) {
        if (packet.stream_index == videoStream) {
            avcodec_decode_video2(codecCtx, frame, &frameFinished, &packet);
        }
    }
    if (frameFinished == 0 && isReleaseResources == NO) {
        [self releaseResources];
    }
    return frameFinished !=0;
}
/* 切换资源 */
- (void)replaceTheResources:(NSString *)videoPath{
    if (!isReleaseResources) {
        [self releaseResources];
    }
    self.currentPath = [videoPath copy];
    [self initializeResources:[videoPath UTF8String]];
}
- (void)replay{
    [self initializeResources:[self.currentPath UTF8String]];
}
#pragma mark  重写属性访问方法
- (void)setOutputWidth:(int)outputWidth{
    if (_outputWidth == outputWidth) return;
    _outputWidth = outputWidth;
}
- (void)setOutputHeight:(int)outputHeight{
    if (_outputHeight == outputHeight) return;
   _outputHeight = outputHeight;
}
- (UIImage *)currentImage{

    if (!frame->data[0]) return nil;

    return [self imageFromAVPicture];
}
- (double)duration{
    return (double)formatCtx->duration/AV_TIME_BASE;
}
- (double)currentTime{
    AVRational timeBase = formatCtx->streams[videoStream]->time_base;
    return packet.pts * (double)timeBase.num/timeBase.den;
}
- (int)sourceWidth{
    return codecCtx->width;
}

-(int)sourceHeight{
    return codecCtx->height;
}
-(double)fps{
    return fps;
}
#pragma mark - 内部方法
- (UIImage *)imageFromAVPicture{

    //attribute_deprecated
    avpicture_free(&picture);
    avpicture_alloc(&picture, AV_PIX_FMT_RGB24, _outputWidth, _outputHeight);
    struct SwsContext *imgConvertCtx = sws_getContext(frame->width, frame->height, AV_PIX_FMT_YUV420P, _outputWidth, _outputHeight, AV_PIX_FMT_RGB24, SWS_FAST_BILINEAR, NULL, NULL, NULL);
    if (imgConvertCtx == nil) return nil;

    sws_scale(imgConvertCtx, frame->data, frame->linesize, 0, frame->height, picture.data, picture.linesize);
    sws_freeContext(imgConvertCtx);
    CGBitmapInfo bitmapInfo = kCGBitmapByteOrderDefault;
    CFDataRef data = CFDataCreate(kCFAllocatorDefault,
                              picture.data[0],
                              picture.linesize[0] * _outputHeight);

    CGDataProviderRef provider = CGDataProviderCreateWithCFData(data);
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    CGImageRef cgImage = CGImageCreate(_outputWidth,
                                   _outputHeight,
                                   8,
                                   24,
                                   picture.linesize[0],
                                   colorSpace,
                                   bitmapInfo,
                                   provider,
                                   NULL,
                                   NO,
                                   kCGRenderingIntentDefault);
    UIImage *image = [UIImage imageWithCGImage:cgImage];
    CGImageRelease(cgImage);
    CGColorSpaceRelease(colorSpace);
    CGDataProviderRelease(provider);
    CFRelease(data);

    return image;
}
#pragma mark - 释放资源
- (void)releaseResources{
    isReleaseResources = YES;
    //释放RGB
    avpicture_free(&picture);
    //释放frame
    av_packet_unref(&packet);
    //释放YUV frame
    av_free(frame);
    //关闭解码器
    if (codecCtx)  avcodec_close(codecCtx);
    if (formatCtx) avformat_close_input(&formatCtx);
    avformat_network_deinit();
}

在SB 拖一个 UIImageView 控件和按钮并连好线

#import "ViewController.h"
#import "SGVideoModel.h"

#define LERP(A,B,C) ((A)*(1.0-C)+(B)*C)

@interface ViewController ()
@property (weak, nonatomic) IBOutlet UIImageView *imageView;
@property (weak, nonatomic) IBOutlet UIButton *playBtn;
@property (weak, nonatomic) IBOutlet UIButton *replayBtn;
@property (weak, nonatomic) IBOutlet UILabel *fpsLabel;
@property (weak, nonatomic) IBOutlet UILabel *timeLabel;
@property (nonatomic, strong) SGVideoModel *video;
@property (nonatomic, assign) float lastFrameTime;
@end

@implementation ViewController
@synthesize imageView, fpsLabel, playBtn, video;
- (void)viewDidLoad {
    [super viewDidLoad];
    //播放网络视频
    self.video = [[SGVideoModel alloc] initWithVideo:@"http://leyu-dev-livestorage.b0.upaiyun.com/leyulive.pull.dev.iemylife.com/leyu/e5d0490f46f343479418a21c42b779aa/recorder20171228103406.mp4"];

    //播放本地视频
    //  self.video = [[SGVideoModel alloc] initWithVideo:[NSString bundlePath:@"Dalshabet.mp4"]];
    //  self.video = [[SGVideoModel alloc] initWithVideo:@"/Users/king/Desktop/Stellar.mp4"];
    //  self.video = [[SGVideoModel alloc] initWithVideo:@"/Users/king/Downloads/Worth it - Fifth Harmony ft.Kid Ink - May J Lee Choreography.mp4"];
    //  self.video = [[SGVideoModel alloc] initWithVideo:@"/Users/king/Downloads/4K.mp4"];

    //播放直播
    //  self.video = [[SGVideoModel alloc] initWithVideo:@"http://live.hkstv.hk.lxdns.com/live/hks/playlist.m3u8"];


    //设置video
    //  video.outputWidth = 800;
    //  video.outputHeight = 600;
    //  self.audio = [[SGVideoModel alloc] initWithVideo:@"/Users/king/Desktop/Stellar.mp4"];
    //  NSLog(@"视频总时长>>>video duration: %f",video.duration);
    //  NSLog(@"源尺寸>>>video size: %d x %d", video.sourceWidth, video.sourceHeight);
    //  NSLog(@"输出尺寸>>>video size: %d x %d", video.outputWidth, video.outputHeight);
    //
    //  [self.audio seekTime:0.0];
    //  NSLog(@"%f", [self.audio duration])
    //  AVPacket *packet = [self.audio readPacket];
    //  NSLog(@"%ld", [self.audio decode])

    int tns, thh, tmm, tss;
    tns = video.duration;
    thh = tns / 3600;
    tmm = (tns % 3600) / 60;
    tss = tns % 60;


    //    NSLog(@"fps --> %.2f", video.fps);
    ////        [ImageView setTransform:CGAffineTransformMakeRotation(M_PI)];
    //    NSLog(@"%02d:%02d:%02d",thh,tmm,tss);
}

- (IBAction)playBtnClick:(UIButton *)sender {

    playBtn.enabled = NO;
    _lastFrameTime = -1;

    [video seekTime:0.0];
    [NSTimer scheduledTimerWithTimeInterval: 1 / video.fps
                                 target:self
                               selector:@selector(displayNextFrame:)
                               userInfo:nil
                                repeats:YES];
}
- (IBAction)replayBtnClick:(UIButton *)sender {

    if (playBtn.enabled) {
        [video replay];
        [self playBtnClick:playBtn];
    }
}

-(void)displayNextFrame:(NSTimer *)timer {
    NSTimeInterval startTime = [NSDate timeIntervalSinceReferenceDate];
    //    self.TimerLabel.text = [NSString stringWithFormat:@"%f s",video.currentTime];
    self.timeLabel.text  = [self dealTime:video.currentTime];
    if (![video stepFrame]) {
        [timer invalidate];
        [playBtn setEnabled:YES];
        return;
    }
    imageView.image = video.currentImage;
    float frameTime = 1.0 / ([NSDate timeIntervalSinceReferenceDate] - startTime);
    if (_lastFrameTime < 0) {
       _lastFrameTime = frameTime;
    } else {
        _lastFrameTime = LERP(frameTime, _lastFrameTime, 0.8);
    }
    fpsLabel.text = [NSString stringWithFormat:@"fps %.0f",_lastFrameTime];
}

- (NSString *)dealTime:(double)time {

    int tns, thh, tmm, tss;
    tns = time;
    thh = tns / 3600;
    tmm = (tns % 3600) / 60;
    tss = tns % 60;


    //        [ImageView setTransform:CGAffineTransformMakeRotation(M_PI)];
    return [NSString stringWithFormat:@"%02d:%02d:%02d",thh,tmm,tss];
}

如果遇到如下报错，请导入系统CoreMedia与VideoToolBox框架：

Undefined symbols for architecture arm64:
  "_CMBlockBufferCreateWithMemoryBlock", referenced from:
      _videotoolbox_common_end_frame in libavcodec.a(videotoolbox.o)
  "_VTDecompressionSessionWaitForAsynchronousFrames", referenced from:
      _videotoolbox_common_end_frame in libavcodec.a(videotoolbox.o)
  "_VTDecompressionSessionInvalidate", referenced from:
      _av_videotoolbox_default_free in libavcodec.a(videotoolbox.o)
  "_CMSampleBufferCreate", referenced from:
      _videotoolbox_common_end_frame in libavcodec.a(videotoolbox.o)
  "_VTDecompressionSessionDecodeFrame", referenced from:
      _videotoolbox_common_end_frame in libavcodec.a(videotoolbox.o)
  "_kCMFormatDescriptionExtension_SampleDescriptionExtensionAtoms", referenced from:
      _av_videotoolbox_default_init2 in libavcodec.a(videotoolbox.o)
  "_CMVideoFormatDescriptionCreate", referenced from:
      _av_videotoolbox_default_init2 in libavcodec.a(videotoolbox.o)
  "_VTDecompressionSessionCreate", referenced from:
      _av_videotoolbox_default_init2 in libavcodec.a(videotoolbox.o)
ld: symbol(s) not found for architecture arm64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

image.png

代码实现参照http://bbs.520it.com/forum.php?mod=viewthread&tid=707