/*

     File: GSPlayerView.m

 Abstract: Player view using AVPlayerItemVideoOutput with chroma key filter.

  Version: 1.3

 Disclaimer: IMPORTANT:  This Apple software is supplied to you by Apple

 Inc. ("Apple") in consideration of your agreement to the following

 terms, and your use, installation, modification or redistribution of

 this Apple software constitutes acceptance of these terms.  If you do

 not agree with these terms, please do not use, install, modify or

 redistribute this Apple software.

 In consideration of your agreement to abide by the following terms, and

 subject to these terms, Apple grants you a personal, non-exclusive

 license, under Apple's copyrights in this original Apple software (the

 "Apple Software"), to use, reproduce, modify and redistribute the Apple

 Software, with or without modifications, in source and/or binary forms;

 provided that if you redistribute the Apple Software in its entirety and

 without modifications, you must retain this notice and the following

 text and disclaimers in all such redistributions of the Apple Software.

 Neither the name, trademarks, service marks or logos of Apple Inc. may

 be used to endorse or promote products derived from the Apple Software

 without specific prior written permission from Apple.  Except as

 expressly stated in this notice, no other rights or licenses, express or

 implied, are granted by Apple herein, including but not limited to any

 patent rights that may be infringed by your derivative works or by other

 works in which the Apple Software may be incorporated.

 The Apple Software is provided by Apple on an "AS IS" basis.  APPLE

 MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION

 THE IMPLIED WARRANTIES OF NON-INFRINGEMENT, MERCHANTABILITY AND FITNESS

 FOR A PARTICULAR PURPOSE, REGARDING THE APPLE SOFTWARE OR ITS USE AND

 OPERATION ALONE OR IN COMBINATION WITH YOUR PRODUCTS.

 IN NO EVENT SHALL APPLE BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL

 OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

 INTERRUPTION) ARISING IN ANY WAY OUT OF THE USE, REPRODUCTION,

 MODIFICATION AND/OR DISTRIBUTION OF THE APPLE SOFTWARE, HOWEVER CAUSED

 AND WHETHER UNDER THEORY OF CONTRACT, TORT (INCLUDING NEGLIGENCE),

 STRICT LIABILITY OR OTHERWISE, EVEN IF APPLE HAS BEEN ADVISED OF THE

 POSSIBILITY OF SUCH DAMAGE.

 Copyright (C) 2014 Apple Inc. All Rights Reserved.

 */

#import "GSPlayerView.h"

#define FREEWHEELING_PERIOD_IN_SECONDS 0.5

#define ADVANCE_INTERVAL_IN_SECONDS 0.1

@interface GSPlayerView ()

{

    AVPlayerItem *_playerItem;

    AVPlayerItemVideoOutput *_playerItemVideoOutput;

    CVDisplayLinkRef _displayLink;

    CMVideoFormatDescriptionRef _videoInfo;

    uint64_t _lastHostTime;

    dispatch_queue_t _queue;

}

@end

@interface GSPlayerView (AVPlayerItemOutputPullDelegate) <AVPlayerItemOutputPullDelegate>

@end

#pragma mark -

@implementation GSPlayerView

static CVReturn displayLinkCallback(CVDisplayLinkRef displayLink, const CVTimeStamp *inNow, const CVTimeStamp *inOutputTime, CVOptionFlags flagsIn, CVOptionFlags *flagsOut, void *displayLinkContext);

- (id)initWithFrame:(NSRect)frame

{

    self = [super initWithFrame:frame];

    if (self)

    {

        _videoInfo = nil;

        _queue = dispatch_queue_create(NULL, NULL);

        _playerItemVideoOutput = [[AVPlayerItemVideoOutput alloc] initWithPixelBufferAttributes:@{(id)kCVPixelBufferPixelFormatTypeKey: @(kCVPixelFormatType_32ARGB)}];

        if (_playerItemVideoOutput)

        {

            // Create a CVDisplayLink to receive a callback at every vsync

            CVDisplayLinkCreateWithActiveCGDisplays(&_displayLink);

            CVDisplayLinkSetOutputCallback(_displayLink, displayLinkCallback, (__bridge void *)self);

            // Pause the displayLink till ready to conserve power

            CVDisplayLinkStop(_displayLink);

            // Request notification for media change in advance to start up displayLink or any setup necessary

            [_playerItemVideoOutput setDelegate:self queue:_queue];

            [_playerItemVideoOutput requestNotificationOfMediaDataChangeWithAdvanceInterval:ADVANCE_INTERVAL_IN_SECONDS];

        }

        self.videoLayer = [[AVSampleBufferDisplayLayer alloc] init];

        self.videoLayer.bounds = self.bounds;

        self.videoLayer.position = CGPointMake(CGRectGetMidX(self.bounds), CGRectGetMidY(self.bounds));

        self.videoLayer.videoGravity = AVLayerVideoGravityResizeAspect;

        self.videoLayer.backgroundColor = CGColorGetConstantColor(kCGColorBlack);

        [self setLayer:self.videoLayer];

        [self setWantsLayer:YES];

        CIFilter *chromaKeyFilter = [CIFilter filterWithName:@"GSChromaKeyFilter"];

        [chromaKeyFilter setName:@"chromaKeyFilter"];

#if defined(MAC_OS_X_VERSION_10_9) && MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_9

        [self setLayerUsesCoreImageFilters:YES];

#endif

        [[self layer] setFilters:@[chromaKeyFilter]];

    }

    return self;

}

- (void)viewWillMoveToSuperview:(NSView *)newSuperview

{

    if (!newSuperview) {

        if (_videoInfo) {

            CFRelease(_videoInfo);

        }

        if (_displayLink)

        {

            CVDisplayLinkStop(_displayLink);

            CVDisplayLinkRelease(_displayLink);

        }

        dispatch_sync(_queue, ^{

            [_playerItemVideoOutput setDelegate:nil queue:NULL];

        });

    }

}

- (void)dealloc

{

    self.playerItem = nil;

    self.videoLayer = nil;

}

#pragma mark -

- (AVPlayerItem *)playerItem

{

    return _playerItem;

}

- (void)setPlayerItem:(AVPlayerItem *)playerItem

{

    if (_playerItem != playerItem)

    {

        if (_playerItem)

            [_playerItem removeOutput:_playerItemVideoOutput];

        _playerItem = playerItem;

        if (_playerItem)

            [_playerItem addOutput:_playerItemVideoOutput];

    }

}

- (NSColor *)chromaKeyColor

{

    return [NSColor colorWithCIColor:[self valueForKeyPath:@"layer.filters.chromaKeyFilter.inputColor"]];

}

- (void)setChromaKeyColor:(NSColor *)chromaKeyColor

{

    // The chromaKeyColor is bound to the value of the chromaKeyColorWell in the xib

    [self setValue:[CIColor colorWithCGColor:[chromaKeyColor CGColor]] forKeyPath:@"layer.filters.chromaKeyFilter.inputColor"];

}

#pragma mark -

- (void)displayPixelBuffer:(CVPixelBufferRef)pixelBuffer atTime:(CMTime)outputTime

{

    // CVPixelBuffer is wrapped in a CMSampleBuffer and then displayed on a AVSampleBufferDisplayLayer

    CMSampleBufferRef sampleBuffer = NULL;

    OSStatus err = noErr;

    if (!_videoInfo || !CMVideoFormatDescriptionMatchesImageBuffer(_videoInfo, pixelBuffer)) {

        if (_videoInfo) {

            CFRelease(_videoInfo);

            _videoInfo = nil;

        }

        err = CMVideoFormatDescriptionCreateForImageBuffer(NULL, pixelBuffer, &_videoInfo);

    }

    if (err) {

        NSLog(@"Error at CMVideoFormatDescriptionCreateForImageBuffer %d", err);

    }

    // decodeTimeStamp is set to kCMTimeInvalid since we already receive decoded frames

    CMSampleTimingInfo sampleTimingInfo = {

        .duration = kCMTimeInvalid,

        .presentationTimeStamp = outputTime,

        .decodeTimeStamp = kCMTimeInvalid

    };

    // Wrap the pixel buffer in a sample buffer

    err = CMSampleBufferCreateForImageBuffer(kCFAllocatorDefault, pixelBuffer, true, NULL, NULL, _videoInfo, &sampleTimingInfo, &sampleBuffer);

    if (err) {

        NSLog(@"Error at CMSampleBufferCreateForImageBuffer %d", err);

    }

    // Enqueue sample buffers which will be displayed at their above set presentationTimeStamp

    if (self.videoLayer.readyForMoreMediaData) {

        [self.videoLayer enqueueSampleBuffer:sampleBuffer];

    }

    CFRelease(sampleBuffer);

}

#pragma mark -

static CVReturn displayLinkCallback(CVDisplayLinkRef displayLink, const CVTimeStamp *inNow, const CVTimeStamp *inOutputTime, CVOptionFlags flagsIn, CVOptionFlags *flagsOut, void *displayLinkContext)

{

    GSPlayerView *self = (__bridge GSPlayerView *)displayLinkContext;

    AVPlayerItemVideoOutput *playerItemVideoOutput = self->_playerItemVideoOutput;

    // The displayLink calls back at every vsync (screen refresh)

    // Compute itemTime for the next vsync

    CMTime outputItemTime = [playerItemVideoOutput itemTimeForCVTimeStamp:*inOutputTime];

    if ([playerItemVideoOutput hasNewPixelBufferForItemTime:outputItemTime])

    {

        self->_lastHostTime = inOutputTime->hostTime;

        // Copy the pixel buffer to be displayed next and add it to AVSampleBufferDisplayLayer for display

        CVPixelBufferRef pixBuff = [playerItemVideoOutput copyPixelBufferForItemTime:outputItemTime itemTimeForDisplay:NULL];

        [self displayPixelBuffer:pixBuff atTime:outputItemTime];

        CVBufferRelease(pixBuff);

    }

    else

    {

        CMTime elapsedTime = CMClockMakeHostTimeFromSystemUnits(inNow->hostTime - self->_lastHostTime);

        if (CMTimeGetSeconds(elapsedTime) > FREEWHEELING_PERIOD_IN_SECONDS)

        {

            // No new images for a while.  Shut down the display link to conserve power, but request a wakeup call if new images are coming.

            CVDisplayLinkStop(displayLink);

            [playerItemVideoOutput requestNotificationOfMediaDataChangeWithAdvanceInterval:ADVANCE_INTERVAL_IN_SECONDS];

        }

    }

    return kCVReturnSuccess;

}

@end

#pragma mark -

@implementation GSPlayerView (AVPlayerItemOutputPullDelegate)

- (void)outputMediaDataWillChange:(AVPlayerItemOutput *)sender

{

    // Start running again.

    _lastHostTime = CVGetCurrentHostTime();

    CVDisplayLinkStart(_displayLink);

}

@end