Retired Document
Important: This sample code may not represent best practices for current development. The project may use deprecated symbols and illustrate technologies and techniques that are no longer recommended.
Relevant replacement documents include:
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 |
Disclaimer: IMPORTANT: This Apple software is supplied to you by Apple |
Computer, 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 Computer, |
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) 2007 Apple Inc. All Rights Reserved. |
*/ |
#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 |
Copyright © 2007 Apple Inc. All Rights Reserved. Terms of Use | Privacy Policy | Updated: 2007-08-30