//
//  SJMoiveObject.h
//  SJLiveVideo
//
//  Created by king on 16/6/16.
//  Copyright © 2016年 king. All rights reserved.
//
 
#import "Common.h"
#import <UIKit/UIKit.h>
#import "NSString+Extions.h"
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libswscale//swscale.h>
 

 
@interface SJMoiveObject : NSObject
 
/* 解碼後的UIImage */
@property (nonatomic, strong, readonly) UIImage *currentImage;
 
/* 視訊的frame高度 */
@property (nonatomic, assign, readonly) int sourceWidth, sourceHeight;
 
/* 輸出影象大小。預設設定為源大小。 */
@property (nonatomic,assign) int outputWidth, outputHeight;
 
/* 視訊的長度，秒為單位 
 
*/
@property (nonatomic, assign, readonly) double duration;
 
/* 視訊的當前秒數 */
@property (nonatomic, assign, readonly) double currentTime;
 
/* 視訊的幀率 */
@property (nonatomic, assign, readonly) double fps;
 
/* 視訊路徑。 */
- (instancetype)initWithVideo:(NSString *)moviePath;
/* 切換資源 */
- (void)replaceTheResources:(NSString *)moviePath;
 
/* 重撥 */
- (void)redialPaly;
/* 從視訊流中讀取下一幀。返回假，如果沒有幀讀取（視訊）。 */
- (BOOL)stepFrame;
 
/* 尋求最近的關鍵幀在指定的時間 */
- (void)seekTime:(double)seconds;
 
@end

開始實現API
//
//  SJMoiveObject.m
//  SJLiveVideo
//
//  Created by king on 16/6/16.
//  Copyright © 2016年 king. All rights reserved.
//
 
#import "SJMoiveObject.h"
 
@interface SJMoiveObject ()
@property (nonatomic, copy) NSString *cruutenPath;
@end
 
@implementation SJMoiveObject
{
    AVFormatContext     *SJFormatCtx;
    AVCodecContext      *SJCodecCtx;
    AVFrame             *SJFrame;
    AVStream            *stream;
    AVPacket            packet;
    AVPicture           picture;
    int                 videoStream;
    double              fps;
    BOOL                isReleaseResources;
}
 
#pragma mark ------------------------------------
#pragma mark  初始化
- (instancetype)initWithVideo:(NSString *)moviePath {
     
    if (!(self=[super init])) return nil;
    if ([self initializeResources:[moviePath UTF8String]]) {
        self.cruutenPath = [moviePath copy];
        return self;
    } else {
        return nil;
    }
}
- (BOOL)initializeResources:(const char *)filePath {
     
    isReleaseResources = NO;
    AVCodec *pCodec;
    // 註冊所有解碼器
    avcodec_register_all();
    av_register_all();
    avformat_network_init();
    // 開啟視訊檔案
    if (avformat_open_input(&SJFormatCtx, filePath, NULL, NULL) != 0) {
        SJLog(@"開啟檔案失敗");
        goto initError;
    }
    // 檢查資料流
    if (avformat_find_stream_info(SJFormatCtx, NULL) < 0) {
        SJLog(@"檢查資料流失敗");
        goto initError;
    }
    // 根據資料流,找到第一個視訊流
    if ((videoStream =  av_find_best_stream(SJFormatCtx, AVMEDIA_TYPE_VIDEO, -1, -1, &pCodec, 0)) < 0) {
        SJLog(@"沒有找到第一個視訊流");
        goto initError;
    }
    // 獲取視訊流的編解碼上下文的指標
    stream      = SJFormatCtx->streams[videoStream];
    SJCodecCtx  = stream->codec;
#if DEBUG
    // 列印視訊流的詳細資訊
    av_dump_format(SJFormatCtx, 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; }
    // 查詢解碼器
    pCodec = avcodec_find_decoder(SJCodecCtx->codec_id);
    if (pCodec == NULL) {
        SJLog(@"沒有找到解碼器");
        goto initError;
    }
    // 開啟解碼器
    if(avcodec_open2(SJCodecCtx, pCodec, NULL) < 0) {
        SJLog(@"開啟解碼器失敗");
        goto initError;
    }
    // 分配視訊幀
    SJFrame = av_frame_alloc();
    _outputWidth = SJCodecCtx->width;
    _outputHeight = SJCodecCtx->height;
    return YES;
initError:
    return NO;
}
- (void)seekTime:(double)seconds {
    AVRational timeBase = SJFormatCtx->streams[videoStream]->time_base;
    int64_t targetFrame = (int64_t)((double)timeBase.den / timeBase.num * seconds);
    avformat_seek_file(SJFormatCtx,
                       videoStream,
                       0,
                       targetFrame,
                       targetFrame,
                       AVSEEK_FLAG_FRAME);
    avcodec_flush_buffers(SJCodecCtx);
}
- (BOOL)stepFrame {
    int frameFinished = 0;
    while (!frameFinished && av_read_frame(SJFormatCtx, &packet) >= 0) {
        if (packet.stream_index == videoStream) {
            avcodec_decode_video2(SJCodecCtx,
                                  SJFrame,
                                  &frameFinished,
                                  &packet);
        }
    }
    if (frameFinished == 0 && isReleaseResources == NO) {
        [self releaseResources];
    }
    return frameFinished != 0;
}
 
- (void)replaceTheResources:(NSString *)moviePath {
    if (!isReleaseResources) {
        [self releaseResources];
    }
    self.cruutenPath = [moviePath copy];
    [self initializeResources:[moviePath UTF8String]];
}
- (void)redialPaly {
    [self initializeResources:[self.cruutenPath UTF8String]];
}
#pragma mark ------------------------------------
#pragma mark  重寫屬性訪問方法
-(void)setOutputWidth:(int)newValue {
    if (_outputWidth == newValue) return;
    _outputWidth = newValue;
}
-(void)setOutputHeight:(int)newValue {
    if (_outputHeight == newValue) return;
    _outputHeight = newValue;
}
-(UIImage *)currentImage {
    if (!SJFrame->data[0]) return nil;
    return [self imageFromAVPicture];
}
-(double)duration {
    return (double)SJFormatCtx->duration / AV_TIME_BASE;
}
- (double)currentTime {
    AVRational timeBase = SJFormatCtx->streams[videoStream]->time_base;
    return packet.pts * (double)timeBase.num / timeBase.den;
}
- (int)sourceWidth {
    return SJCodecCtx->width;
}
- (int)sourceHeight {
    return SJCodecCtx->height;
}
- (double)fps {
    return fps;
}
#pragma mark --------------------------
#pragma mark - 內部方法
- (UIImage *)imageFromAVPicture
{
    avpicture_free(&picture);
    avpicture_alloc(&picture, AV_PIX_FMT_RGB24, _outputWidth, _outputHeight);
    struct SwsContext * imgConvertCtx = sws_getContext(SJFrame->width,
                                                       SJFrame->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,
              SJFrame->data,
              SJFrame->linesize,
              0,
              SJFrame->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 --------------------------
#pragma mark - 釋放資源
- (void)releaseResources {
    SJLog(@"釋放資源");
    SJLogFunc
    isReleaseResources = YES;
    // 釋放RGB
    avpicture_free(&picture);
    // 釋放frame
    av_packet_unref(&packet);
    // 釋放YUV frame
    av_free(SJFrame);
    // 關閉解碼器
    if (SJCodecCtx) avcodec_close(SJCodecCtx);
    // 關閉檔案
    if (SJFormatCtx) avformat_close_input(&SJFormatCtx);
    avformat_network_deinit();
}
@end