/*

     File: AVSETrimCommand.m

 Abstract: A subclass of AVSECommand which uses AVMutableComposition to trim a movie. This tool trims a movie to half its original length.

  Version: 1.0

 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) 2012 Apple Inc. All Rights Reserved.

 */

#import "AVSETrimCommand.h"

@implementation AVSETrimCommand

@synthesize mutableComposition;

- (void)performWithAsset:(AVAsset*)asset 

{

    AVAssetTrack *videoTrack = nil;

    AVAssetTrack *audioTrack = nil;

    // Check if the asset contains video and audio tracks

    if ([[asset tracksWithMediaType:AVMediaTypeVideo] count] != 0) {

        videoTrack = [[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];

    }

    if ([[asset tracksWithMediaType:AVMediaTypeAudio] count] != 0) {

        audioTrack = [[asset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];

    }

    CMTime insertionPoint = kCMTimeZero;

    NSError * error = nil;

    // Trim to half duration

    double halfDuration = CMTimeGetSeconds([asset duration])/2.0;

    CMTime trimmedDuration = CMTimeMakeWithSeconds(halfDuration, 1);

    // Check if a composition already exists, i.e., another tool has been applied

    if(!mutableComposition){

        // Create a new composition

        mutableComposition = [AVMutableComposition composition];

        // Insert half time range of the video and audio tracks from AVAsset 

        if(videoTrack != nil) {

            AVMutableCompositionTrack *vtrack = [mutableComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];

            [vtrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, trimmedDuration) ofTrack:videoTrack atTime:insertionPoint error:&error];

        }

        if(audioTrack != nil) {

            AVMutableCompositionTrack *atrack = [mutableComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];

            [atrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, trimmedDuration) ofTrack:audioTrack atTime:insertionPoint error:&error];

        }

    }else {

        // Remove the second half of the existing composition to trim

        [mutableComposition removeTimeRange:CMTimeRangeMake(trimmedDuration, [mutableComposition duration])];

    }

    // Notify AVSEDocument class to reload the player view with the changes

    [[NSNotificationCenter defaultCenter] 

     postNotificationName:AVSEReloadNotification 

     object:self];

}

@end