FrameCompressor.m

/*

File: FrameCompressor.m

Abstract: Declares the implementation for the FrameCompressor abstract class
which wraps a QuickTime compression session and allows compression of
CVPixelBuffers using arbitrary codecs. The FrameCompressor is initialized
with the compression codec to use, the dimensions of the CVPixelBuffers
to be passed and compression session options (cannot be nil). Compressing
frames is achieved by calling -compressFrameOnSeparateThread and passing 
the CVPixelBuffer representing the frame along with optional timestamp 
and duration (pass -1.0 if undefined). When the frame is compressed, 
the -doneCompressingFrame method is called with the resulting encoded 
frame (this method is implemented by subclasses). Use the method -flushFrames 
to ensure no frames are pending for compression.

Version: 1.0

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*/

#import <OpenGL/CGLMacro.h>

#import "FrameReader.h"
#import "FrameCompressor.h"
#import "MyController.h"


static 	ICMCompressionSessionRef	mCompressionSession = NULL;

// Called when image compression for a frame has completed. Compression
// is initiated by the ICMCompressionSessionEncodeFrame function. Once
// compression of the frame has completed, we add it to the track media for
// the movie.
static OSStatus FrameOutputCallback(void* encodedFrameOutputRefCon, ICMCompressionSessionRef session, OSStatus error, ICMEncodedFrameRef frame, void* reserved)
{
	if(error == noErr)
	{
		//Simply forward to the FrameMovieExporter instance
		[FrameMovieExporter doneCompressingFrame:frame];
	}
	
	return error;
}

// During image compression this routine is called to indicate the status of
// the compression operation. We'll use this to determine when the buffer
// is free so we can mark the reader object as free/available.
static void SourceFrameTrackingCallback(void *sourceTrackingRefCon, ICMSourceTrackingFlags sourceTrackingFlags, void *sourceFrameRefCon, void *reserved)
{
    /*
    * Indicates that this is the last call for this sourceFrameRefCon.
    */
    if (sourceTrackingFlags & kICMSourceTracking_LastCall)
    {
    }

    /*
    * Indicates that the session is done with the source pixel buffer
    * and has released any reference to it that it had.
    */
	if (sourceTrackingFlags & kICMSourceTracking_ReleasedPixelBuffer)
	{
		FrameReader *readerObj = (FrameReader *)sourceTrackingRefCon;
		QueueController *frameQController = [readerObj queueController];
		
		// The compressor is finished with the reader object, so let's
		// put it back into the free queue so it can be used again
		[frameQController addItemToFreeQ:readerObj];
	}

}

@interface FrameCompressor (PrivateMethods)

+(void)createSharedCompressionSession:(CodecType)codec pixelsWide:(unsigned)width pixelsHigh:(unsigned)height options:(ICMCompressionSessionOptionsRef)options compressionTimeScale:(TimeScale)timescale;
- (void)compressFrameSynchronized:(id)param;

@end

@implementation FrameCompressor (PrivateMethods)

// Create a single shared compression session for use with all subclasses
// of the FrameCompressor class. This compression session is used to
// compress screen reader frames so that they may be subsequently added
// to our movie.
+(void)createSharedCompressionSession:(CodecType)codec pixelsWide:(unsigned)width pixelsHigh:(unsigned)height options:(ICMCompressionSessionOptionsRef)options compressionTimeScale:(TimeScale)timescale
{
	ICMEncodedFrameOutputRecord		record = {FrameOutputCallback, NULL, NULL};
	OSStatus					theError;

	if (!mCompressionSession)
	{
		//Create compression session
		theError = ICMCompressionSessionCreate(kCFAllocatorDefault, width, height, codec, timescale, options, NULL, &record, &mCompressionSession);
		if(theError) 
		{
			NSLog(@"ICMCompressionSessionCreate() failed with error %i", theError);
		}		
	}
}

// Compress a frame.
// This routine makes use of the @synchronized
// directive for locking the block of code which performs
// the compression operation.
// The @synchronized directive takes a single parameter
// which is the object you want to be used as the key
// for locking the code. The compiler then creates a
// mutex lock based on that object. Threads attempting
// to lock the same object block until the current 
// synchronized block finishes executing.
- (void)compressFrameSynchronized:(id)param
{
	NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

	@synchronized([FrameCompressor class])
	{
		FrameReader	*frameReaderObj = (FrameReader *)param;
		
		// This blocks until the async texture transfer from
		// the GPU to system memory is complete.
		CVPixelBufferRef pixelBuffer = [frameReaderObj readScreenAsyncFinish];
		
		if (pixelBuffer)
		{
			OSStatus theError = -1;
			// compress the frame using our compression session
			ICMSourceTrackingCallbackRecord callBackRec = 
			{
				/*
				* The callback function pointer.
				*/
				SourceFrameTrackingCallback,

				/*
				* The callback's reference value.
				*/
				param // sourceTrackingRefCon
			};
			NSTimeInterval timestamp = [(FrameReader *)param bufferReadTime];
			NSTimeInterval duration = NAN;

			TimeScale compressionTimeScale = ICMCompressionSessionGetTimeScale (mCompressionSession);
			// Present frames to the compression session. Encoded frames may or
			// may not be output before the function returns.
			theError = ICMCompressionSessionEncodeFrame(mCompressionSession, pixelBuffer, 
						(timestamp >= 0.0 ? (SInt64)(timestamp * compressionTimeScale) : 0), 
						(duration >= 0.0 ? (SInt64)(duration * compressionTimeScale) : 0), 
						((timestamp >= 0.0 ? kICMValidTime_DisplayTimeStampIsValid : 0) | (duration >= 0.0 ? kICMValidTime_DisplayDurationIsValid : 0)), 
						NULL, &callBackRec, (void *)NULL);

			if(theError)
			{
				NSLog(@"ICMCompressionSessionEncodeFrame() failed with error %i", theError);
			}
		}
		else	// an error occurred
		{
			// we got an error, so put this reader object back into the free queue
			QueueController *frameQController = [frameReaderObj queueController];
			[frameQController addItemToFreeQ:frameReaderObj];
		}
	}

	[pool release];
}

@end

@implementation FrameCompressor


#pragma mark ---------- Initialization/Cleanup ----------

+ (void) initialize
{
	//Make sure QuickTime is initialized
	EnterMovies();
}

- (id) init
{
	//Make sure client goes through designated initializer
	[self doesNotRecognizeSelector:_cmd];
	return nil;
}

// Initialize a FrameCompressor object with the specified codec,
// width/height, compressor options and timescale
- (id) initWithCodec:(CodecType)codec pixelsWide:(unsigned)width pixelsHigh:(unsigned)height options:(ICMCompressionSessionOptionsRef)options compressionTimeScale:(TimeScale)timescale
{	
	//Check parameters
	if((codec == 0) || (width == 0) || (height == 0) || (options == NULL) || timescale == 0) {
		[self release];
		return nil;
	}
	
	self = [super init];
	{
		[FrameCompressor createSharedCompressionSession:codec pixelsWide:width pixelsHigh:height options:options compressionTimeScale:timescale];
	}
	
	return self;
}

+ (id) alloc
{
	//Prevent direct allocation of this abstract class
	if(self == [FrameCompressor class])
	{
		[self doesNotRecognizeSelector:_cmd];
	}
	
	return [super alloc];
}

- (void) dealloc
{
	//Release resources
	if(mCompressionSession)
	{
		ICMCompressionSessionRelease(mCompressionSession);
		mCompressionSession = NULL;
	}

	[super dealloc];
}

#pragma mark ---------- Compression Options ----------

// Display the compression dialog for the user, but first restore the settings
// from the previous user defaults
+ (ICMCompressionSessionOptionsRef) userOptions:(CodecType*)outCodecType frameRate:(double*)outFrameRate autosaveName:(NSString*)name
{
	long						flags = scAllowEncodingWithCompressionSession;
	ICMMultiPassStorageRef			nullStorage = NULL;
	SCTemporalSettings			temporalSettings;
	SCSpatialSettings				spatialSettings;
	ComponentResult				theError;
	ICMCompressionSessionOptionsRef	options;
	ComponentInstance			component;
	QTAtomContainer				container;
	NSData*					data;
	Boolean					enable = true;
	
	//Open default compression dialog component
	component = OpenDefaultComponent(StandardCompressionType, StandardCompressionSubType);
	if(component == NULL) {
		NSLog(@"Compression component opening failed");
		return NULL;
	}
	SCSetInfo(component, scPreferenceFlagsType, &flags);
	
	//Restore compression settings from user defaults
	if([name length]) {
		data = [[NSUserDefaults standardUserDefaults] objectForKey:name];
		if(data) {
			container = NewHandle([data length]);
			if(container) {
				[data getBytes:*container];
				theError = SCSetSettingsFromAtomContainer(component, container);
				if(theError)
				NSLog(@"SCSetSettingsFromAtomContainer() failed with error %i", theError);
				QTDisposeAtomContainer(container);
			}
		}
	}
	
	//Display compression dialog to user
	theError = SCRequestSequenceSettings(component);
	if(theError) {
		if(theError != 1)
		NSLog(@"SCRequestSequenceSettings() failed with error %i", theError);
		CloseComponent(component);
		return NULL;
	}
	
	//Save compression settings in user defaults
	if([name length]) {
		theError = SCGetSettingsAsAtomContainer(component, &container);
		if(theError)
		NSLog(@"SCSetSettingsFromAtomContainer() failed with error %i", theError);
		else {
			data = [NSData dataWithBytes:*container length:GetHandleSize(container)];
			[[NSUserDefaults standardUserDefaults] setObject:data forKey:name];
			QTDisposeAtomContainer(container);
		}
	}
	
	//Copy settings from compression dialog
	theError = SCCopyCompressionSessionOptions(component, &options);
	if(theError) {
		NSLog(@"SCCopyCompressionSessionOptions() failed with error %i", theError);
		CloseComponent(component);
		return NULL;
	}
	if(outCodecType) {
		SCGetInfo(component, scSpatialSettingsType, &spatialSettings);
		*outCodecType = spatialSettings.codecType;
	}
	if(outFrameRate) {
		SCGetInfo(component, scTemporalSettingsType, &temporalSettings);
		*outFrameRate = Fix2X(temporalSettings.frameRate);
	}
	CloseComponent(component);
	
	//Explicitely turn off multipass compression in case it was enabled by the user as we do not support it
	theError = ICMCompressionSessionOptionsSetProperty(options, kQTPropertyClass_ICMCompressionSessionOptions, kICMCompressionSessionOptionsPropertyID_MultiPassStorage, sizeof(ICMMultiPassStorageRef), &nullStorage);
	if( theError ) {
		NSLog(@"ICMCompressionSessionOptionsSetProperty() failed with error %i", theError);
	}

	// We must set this flag to enable P or B frames.
	theError = ICMCompressionSessionOptionsSetAllowTemporalCompression( options, true );
	if( theError ) {
		NSLog(@"ICMCompressionSessionOptionsSetAllowTemporalCompression() failed with error %i", theError);
	}
	
	// We must set this flag to enable B frames.
	theError = ICMCompressionSessionOptionsSetAllowFrameReordering( options, true );
	if( theError ) {
		NSLog(@"ICMCompressionSessionOptionsSetAllowFrameReordering() failed with error %i", theError);
	}
	
	// Set the maximum key frame interval, also known as the key frame rate.
	theError = ICMCompressionSessionOptionsSetMaxKeyFrameInterval( options, 30 );
	if( theError ) {
		NSLog(@"ICMCompressionSessionOptionsSetMaxKeyFrameInterval() failed with error %i", theError);
	}

	// This allows the compressor more flexibility (ie, dropping and coalescing frames).
	theError = ICMCompressionSessionOptionsSetAllowFrameTimeChanges( options, true );
	if( theError ) {
		NSLog(@"ICMCompressionSessionOptionsSetAllowFrameTimeChanges() failed with error %i", theError);
	}
	
	// We need durations when we store frames.
	theError = ICMCompressionSessionOptionsSetDurationsNeeded( options, true );
	if( theError ) {
		NSLog(@"ICMCompressionSessionOptionsSetDurationsNeeded() failed with error %i", theError);
	}

	// Enable the compressor to call the encoded-frame callback from a different thread. 
	theError = ICMCompressionSessionOptionsSetProperty(options, kQTPropertyClass_ICMCompressionSessionOptions, kICMCompressionSessionOptionsPropertyID_AllowAsyncCompletion, sizeof(Boolean), &enable);
	if( theError ) {
		NSLog(@"SCCopyCompressionSessionOptions() failed with error %i", theError);
	}

	return (ICMCompressionSessionOptionsRef)[(id)options autorelease];
}

#pragma mark ---------- Compression Methods ----------

// Call another routine to perform the compression on a separate thread
- (BOOL) compressFrameOnSeparateThread:(FrameReader *)frameReaderObj
{
	[NSThread detachNewThreadSelector:@selector(compressFrameSynchronized:) toTarget:self withObject:frameReaderObj];

	return YES;
}

// Force the compression session to complete encoding frames. 
+ (BOOL) flushFrames
{
	OSStatus	theError;

    // we must make sure only one thread at a time is accessing
    // the compression session
	@synchronized([FrameCompressor class])
	{
		//Flush pending frames in compression session
		theError = ICMCompressionSessionCompleteFrames(mCompressionSession, true, 0, 0);
		if(theError)
            NSLog(@"ICMCompressionSessionCompleteFrames() failed with error %i", theError);
	}
	
	return (theError == noErr ? YES : NO);
}

// Placeholder for additional processing you may want to do
+ (void) doneCompressingFrame:(ICMEncodedFrameRef)frame
{
	//Do any additional processing here
}

@end