TweetFollow Us on Twitter

March 94 - SOMEWHERE IN QUICKTIME

SOMEWHERE IN QUICKTIME

CROSS-PLATFORM COMPATIBILITY AND MULTIPLE-MOVIE FILES

JOHN WANG

[IMAGE QT_column_final_rev1.GIF]

The success of QuickTime since its introduction in December of 1991 has been extraordinary; not only are there now countless applications and multimedia products for QuickTime on the Macintosh platform, but QuickTime has been successful for cross-platform developers as well. QuickTime for Windows, shipping since November of 1992, is becoming an important tool for Windows multimedia developers. Because movies can be created with QuickTime on the Macintosh and then used unaltered with QuickTime for Windows, developers are able to create a movie once and use it on both systems. This capability has been available since the 1.0 release of QuickTime.

To satisfy your curiosity and help you out with your own QuickTime products, this column discusses how to create movie files that are cross-platform compatible and then gives techniques for storing and accessing multiple movies in a single file (which currently poses a problem in the cross-platform environment).

CREATING CROSS PLATFORM-COMPATIBLE MOVIE FILES
The structure you choose for your QuickTime movie files will depend in part on the platform your movies will run on. This is because the Macintosh file system is different from other file systems in that there can be up to two forks in every file: a data fork and a resource fork. The data fork is the standard file for I/O that most file systems support. The resource fork, however, is unique to the Macintosh. It's a "database" of resources that can be randomly accessed via the Resource Manager.

There are two components to a movie file: themovie resource atom  -- a small data structure describing the movie, its tracks, and the tracks' media -- and themovie data atom, containing the movie's data such as video and sound. A typical movie file on the Macintosh consists of a movie resource atom in the resource fork and a movie data atom in the data fork. Storing the movie resource atom in the resource fork with resource type 'moov' allows easy random access to the data it contains. The movie data atom is stored in the data fork as sequential data, which optimizes playback performance.

Because file systems on other platforms don't support a resource fork, a movie that is to be used on other platforms must have its movie resource atom stored in the data fork of the movie file. This type of file is called asingle-fork file because the movie resource atom and the movie data atom are both stored in the data fork of the movie file, and the resource fork is not used.

Movies that will be played on both Macintosh and non-Macintosh platforms can use a file in which the movie resource atom is redundantly stored in both the resource fork and the data fork of the file. The movie data atom is, as always, stored only in the data fork. For lack of a better term, this type of file is also often called a single-fork file since the resource fork of the movie file can be ignored.

The simplest way to create a single-fork movie file for cross-platform compatibility is to use the Movie Converter application from the QuickTime Starter Kit (available from Apple-authorized dealers). The Save As dialog in this application has a checkbox that allows a movie to be stored in thesingle-fork format. However, the QuickTime API can easily be used to add this capability to any application. You simply call either FlattenMovie or FlattenMovieData with the flattenAddMovieToDataFork flag set. When called with this flag set, FlattenMovie places the movie resource atom in both forks, while FlattenMovieData puts it only in the data fork, leaving the resource fork untouched.

Movie files that are created with FlattenMovie orFlattenMovieData with the flattenAddMovieToDataForkflag set are compatible with both QuickTime and QuickTime for Windows because QuickTime is able to retrieve the movie resource atom and the movie data from the data fork alone on either platform.

MULTIPLE-MOVIE FILES FOR THE MACINTOSH
We'll return to cross-platform issues in a moment, but first let's take a look at the simple case of multiple-movie files: those that will be used only on the Macintosh platform. You can create such files in one of two ways, depending on whether you want the resulting file to be self-contained (that is, to contain all of the movie information in one file). Both of these methods have their benefits and drawbacks. The one that will work best for you depends on your implementation and performance testing.

To create a self-contained multiple-movie file for the Macintosh, you can use the FlattenMovie call (without the flattenAddMovieToDataFork flag set) to append an entire movie to an existing movie file. This adds the movie resource atom to the resource fork and the movie data atom to the data fork of the file.

The second method creates a multiple-movie file that's not self-contained, but instead consists entirely of movie resource atoms that reference other movie files containing the movie data atoms. This technique can be useful if, for example, you're writing an interactive CD application that uses multiple movies and you want to store all the movie resource atoms in a single file that's relatively small. This file can be copied locally to a hard disk for faster access. The drawback of this approach is that you have to handle multiple files rather than have everything in one file. The excerpt below from the sample code provided on the CD demonstrates -- without error checking, for better readability -- how easy it is to add an existing movie's resource atom to a movie file.

// Open source movie file to add.
OpenMovieFile(&reply.sfFile, &sourceRefNum, fsRdWrPerm);
NewMovieFromFile(&theMovie, sourceRefNum, &resId,
    movieName, 0, (Boolean *) 0);
CloseMovieFile(sourceRefNum);

// Write out to the collection file.
currentResFile = CurResFile();
UseResFile(collectionRefNum);
myResId = 0;
AddMovieResource(theMovie, collectionRefNum, &myResId,
    movieName);
UseResFile(currentResFile);

// Clean up.
DisposeMovie(theMovie);

AddMovieResource does more than just add the movie resource atom: it updates the data references so that the new movie will refer to the correct movie data file.

Accessing multiple-movie files for Macintosh-only use is easy. You just use the Resource Manager to access the movie resource atoms in the resource fork of the file. The following excerpt from the sample code on the CD uses the Resource Manager to access the various movies. (The code on the CD adds the resource names of all the movies to a menu; your code can of course do whatever it wants with the movies.)

currentResFile = CurResFile();
UseResFile(theRefNum);
movieCount = Count1Resources('moov');
for (i=1; i<=movieCount; i++) {
	movieResource = Get1IndResource('moov', i);
	// Do whatever you want with this movie.
	. . .
	ReleaseResource(movieResource);
}
UseResFile(currentResFile);

CROSS-PLATFORM MULTIPLE-MOVIE FILES
To create a multiple-movie file that's cross-platform compatible, you just repeatedly call FlattenMovie orFlattenMovieData with the flattenAddMovieToDataForkflag set, as described earlier under "Creating Cross Platform-Compatible Movie Files." Accessing such a file, however, is complicated. Since it's a single-fork file, you can't access the movie resource atoms randomly as with the Resource Manager. There's also a problem with accessing the atoms directly; to understand this problem, you need to know how a single-fork movie file is structured.

The movie data atom appears before the movie resource atom in a single-fork file. The first four bytes of the movie data atom contain the size of the atom. (Figure 4-2 inInside Macintosh: QuickTime , page 4-5, illustrates this structure.) This permits QuickTime to skip over the movie data atom to find the movie resource atom. If you place several movies in the same file, the movie data atoms are interleaved with the movie resource atoms.

Here's the problem: A bug in QuickTime through its current version (1.6.1) causes the size field in the movie data atoms to be filled in incorrectly. The illustration below shows how QuickTime currently creates a single-fork movie file in which FlattenMovieData has been called multiple times. The atom size in the first movie data atom takes you to the last movie resource atom rather than the first movie resource atom. Therefore, you can locate only the last movie in the file.

[IMAGE QT_column_final_rev2.GIF]

This bug will be fixed in the next version of QuickTime. The solution for now is to use the wrapper function called BetterFlattenMovieData, included on this issue's CD. This function, when called multiple times, creates a single-fork file in which the size and type fields of all atoms contain the correct information.

To locate the movies in a file with correct size and type fields, you traverse the data fork and read in those fields of each atom to determine its size and whether it's a movie resource atom. When you know the size of the atom, it's easy to skip over it and access the next atom. Of course, the last atom is reached when the end of the file is reached. The following code from the CD demonstrates how you would do this.

// Locate the file offset of the movie resource
// atom stored at the specified index.
if (FSpOpenDF(theFile, fsRdPerm, &myRefNum)	== noErr) {
	currentLoc = 0;
	doneCounter = index;
	*fileOffset = 0;
	while ((doneCounter > 0)) {
		if (err = SetFPos(myRefNum, fsFromStart, currentLoc))
			return(err);
		readLength = 8;
		if (err = FSRead(myRefNum, &readLength, header))
			return(err);
	if (header[1] == 'moov')
		doneCounter--;
	*fileOffset = currentLoc;
	currentLoc += header[0];
	}
	FSClose(myRefNum);
} else
	return (err);
return (noErr);

MOVING ON
I'm happy to see that QuickTime is being used in new and exciting ways. By taking full advantage of the cross-platform and multiple-movie capabilities of QuickTime, you can bring your products to new heights. The sample code on the CD will start you on your way. Enjoy!

JOHN WANG (AppleLink WANG.JY) is often seen sneaking around the Apple campus with a heavy duffle bag that one would think to be dozens of 8*24 GC cards that John is trying to get out of harm's way. But, in truth, John is protecting unknowing strangers from his two attack dogs, shown above. *

For information on movie resource formats, see Chapter 4 of Inside Macintosh: QuickTime.  *

Thanks to Peter Hoddie, Don Moccia, and Brigham Stevens for reviewing this column. *

 
AAPL
$524.94
Apple Inc.
+5.93
MSFT
$40.01
Microsoft Corpora
-0.39
GOOG
$536.10
Google Inc.
-20.44

MacTech Search:
Community Search:

Software Updates via MacUpdate

PDFpenPro 6.2 - Advanced PDF toolkit for...
PDFpenPro allows users to edit PDF's easily. Add text, images and signatures. Fill out PDF forms. Merge or split PDF documents. Reorder and delete pages. Even correct text and edit graphics! Create... Read more
PDFpen 6.2 - Edit and annotate PDFs with...
PDFpen allows users to easily edit PDF's. Add text, images and signatures. Fill out PDF forms. Merge or split PDF documents. Reorder and delete pages. Even correct text and edit graphics! Features... Read more
Monolingual 1.5.9 - Remove unwanted OS X...
Monolingual is a program for removing unnecesary language resources from OS X, in order to reclaim several hundred megabytes of disk space. It requires a 64-bit capable Intel-based Mac and at least... Read more
Maya 2015 - Professional 3D modeling and...
Maya is an award-winning software and powerful, integrated 3D modeling, animation, visual effects, and rendering solution. Because Maya is based on an open architecture, all your work can be scripted... Read more
Starcraft II: Wings of Liberty 1.1.1.180...
Download the patch by launching the Starcraft II game and downloading it through the Battle.net connection within the app. Starcraft II: Wings of Liberty is a strategy game played in real-time. You... Read more
Sibelius 7.5.0 - Music notation solution...
Sibelius is the world's best-selling music notation software for Mac. It is as intuitive to use as a pen, yet so powerful that it does most things in less than the blink of an eye. The demo includes... Read more
Typinator 5.9 - Speedy and reliable text...
Typinator turbo-charges your typing productivity. Type a little. Typinator does the rest. We've all faced projects that require repetitive typing tasks. With Typinator, you can store commonly used... Read more
MYStuff Pro 2.0.16 - Create inventories...
MYStuff Pro is the most flexible way to create detail-rich inventories for your home or small business. Add items to MYStuff by dragging and dropping existing information, uploading new images, or... Read more
TurboTax 2013.r17.002 - Manage your 2013...
TurboTax guides you through your tax return step by step, does all the calculations, and checks your return for errors and overlooked deductions. It lets you file your return electronically to get... Read more
TrailRunner 3.8.769 - Route planning for...
Note: While the software is classified as freeware, it is actually donationware. Please consider making a donation to help support development. TrailRunner is the perfect companion for runners,... Read more

Latest Forum Discussions

See All

Livescribe 3 Smartpen Review
Made by: Livescribe Price: $149.99 for Livescribe 3 Hardware/iOS Integration Rating: 4.5 out of 5 stars Usability Rating: 4 out of 5 stars Reuse Value Rating: 4.75 out of 5 stars Build Quality Rating: 4.5 out of 5 stars Overall Rating: 4.44 out of... | Read more »
Unpossible Review
Unpossible Review By Carter Dotson on April 17th, 2014 Our Rating: :: RALPH WIGGUM APPROVESUniversal App - Designed for iPhone and iPad Unpossible is much better than its English!   | Read more »
Hitman GO Review
Hitman GO Review By Carter Dotson on April 17th, 2014 Our Rating: :: GO HITMAN, GO!Universal App - Designed for iPhone and iPad Hitman GO is not the obvious way to do a mobile version of the Hitman series, but it’s an incredibly... | Read more »
Monster High Ghouls and Jewels is a Frea...
Monster High Ghouls and Jewels is a Freaky Fashion-Forward Match-3 Puzzler Posted by Rob Rich on April 17th, 2014 [ permalink ] | Read more »
Dinosaur Train A to Z Review
Dinosaur Train A to Z Review By Amy Solomon on April 17th, 2014 Our Rating: :: DINO DETAILSUniversal App - Designed for iPhone and iPad Dinosaur Train A to Z is an educational app about dinosaurs that includes In-App Purchases... | Read more »
Easter Comes to Junk Jack X – Bringing N...
Easter Comes to Junk Jack X – Bringing New Crafts, Chemistry, and More Posted by Rob Rich on April 17th, 2014 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Call of Cookie Review
Call of Cookie Review By Jordan Minor on April 17th, 2014 Our Rating: :: COOKIE CRUMBLESUniversal App - Designed for iPhone and iPad Call of Cookie proves that plants aren’t the only fighting foods out there.   | Read more »
Corel Launches Video Editing App Pinnacl...
Corel Launches Video Editing App Pinnacle Studio for iPhone, Updates iPad Version for iOS 7 Posted by Tre Lawrence on April 17th, 2014 [ | Read more »
Bad Vamp Review
Bad Vamp Review By Jennifer Allen on April 17th, 2014 Our Rating: :: BASIC VAMPIRIC ADVENTURESUniversal App - Designed for iPhone and iPad Run or destroy the vampires in this simple, single-screen game that lacks real bite.   | Read more »
The Shadow Sun gets a New Update, Goes o...
The Shadow Sun gets a New Update, Goes on Sale for the First Time Since its Release Posted by Tre Lawrence on April 17th, 2014 [ permalink ] | Read more »

Price Scanner via MacPrices.net

Hyundai Brings Apple CarPlay To The 2015 Sona...
Hyundai Motor America has announced it will bring Apple CarPlay functionality to the 2015 Sonata. CarPlay is pitched as a smarter, safer and easier way to use iPhone in the car and gives iPhone users... Read more
Updated iPads Coming Sooner Than We Had Thoug...
MacRumors, cites KGI securities analyst Ming Chi Kuo, well-respected as an Apple product prognisticator, saying that Apple will introduce an upgraded iPad Air and iPad mini in 2014/Q3, meaning the... Read more
Toshiba Unveils New High And Low End Laptop M...
Toshiba has announced new laptop models covering both the high-end and low-end of the notebook computer spectrum. Toshiba 4K Ultra HD Laptop Toshiba’s new Satellite P55t features one of the world’s... Read more
Save up to $270 with Apple refurbished 13-inc...
The Apple Store has Apple Certified Refurbished October 2013 13″ Retina MacBook Pros available starting at $1099, with models up to $270 off MSRP. Apple’s one-year warranty is standard, and shipping... Read more
Apple now offering refurbished iPad mini with...
The Apple Store has Certified Refurbished 2nd generation iPad minis with Retina Displays now available starting at $339. Apple’s one-year warranty is included with each model, and shipping is free.... Read more
Microsoft Blinks – Drops Microsoft Office 365...
Microsoft has dropped the annual subscription fee for Microsoft Office 365 Personal – which is needed in order to create and edit documents in Microsoft Office for iPad. However, Apple’s iOS and OS X... Read more
New AVG Vault Apps for iOS and Android Help K...
AVG Technologies N.V. an online security company for 177 million active users, has announced the launch of its latest mobile application, AVG Vault. The free app introduces an innovative user... Read more
Free Local Carrot iPhone App Helps Find Fresh...
I love fresh vegetables. I’m not a vegan, although I was for several years in the 1980s, but fresh vegetables and other whole foods are still my dietary mainstays as a matter of taste rather than... Read more
CarSO Pro – Car Service and Finance Manager/O...
Lviv, Ukraine-based BM-Studios’ CarSO Pro is a tool to manage operations concerning your car. Never forget to change the oil or prolong the insurance for your car. Remember when you’ve done the car... Read more
Apple refurbished iPad Airs available startin...
Apple is now offering Certified Refurbished iPad Airs for up to $140 off MSRP. Apple’s one-year warranty is included with each model, and shipping is free. The following Airs are available today: -... Read more

Jobs Board

*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
*Apple* Retail - Manager - Holyoke - Apple I...
Job Summary Keeping an Apple Store thriving requires a diverse set of leadership skills, and as a Manager, you’re a master of them all. In the store’s fast-paced, Read more
*Apple* Retail - Manager - Apple (United Sta...
Job SummaryKeeping an Apple Store thriving requires a diverse set of leadership skills, and as a Manager, you're a master of them all. In the store's fast-paced, dynamic Read more
*Apple* Solutions Consultant (ASC) - Apple (...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Reseller's store. The ASC's role is to grow Apple Read more
*Apple* Retail - Market Leader - Cincinnati...
…challenges of developing individuals, building teams, and affecting growth across Apple Stores. You demonstrate successful leadership ability - focusing on excellence Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.