audio

Apparently, Macromedia thought that synchronizing their animation with, probably, the VLB would be a good idea. Yet they dropped it and never released that out. It is probably not useful for animations (visual) to be properly synchronize when there is not audio. If you do have audio, you should synchronize the animation to the audio and drop visual frames as required to keep up with the audio.

struct swf_soundstreamhead {
	swf_tag			f_tag;		/* 18 or 45 */
	unsigned		f_compression : 4;
	unsigned		f_sound_rate : 2;
	unsigned		f_sound_size : 1;
	unsigned		f_sound_stereo : 1;
	unsigned		f_reserved : 4;
	unsigned		f_playback_rate : 2;
	unsigned		f_playback_size : 1;
	unsigned		f_playback_stereo : 1;
	unsigned short		f_sample_size;
	if(f_compression == 2) {
		signed short	f_latency_seek;
	}
};

The SoundStreamHead[2] tags define a sound effect which is to be loaded with a set of SoundStreamBlock tags. It defines the sound once and for all.

Streaming sound has a strong side effect when playing a movie: it will force a synchronization between the images and the audio. Thus some images may be dropped if the drawing isn't fast enough.

struct swf_definesound {
	swf_tag			f_tag;		/* 14 */
	unsigned short		f_sound_id;
	unsigned		f_sound_format : 4;
	unsigned		f_sound_rate : 2;
	unsigned		f_sound_is_16bits : 1;
	unsigned		f_sound_is_stereo : 1;
	unsigned long		f_sound_samples_count;
	unsigned char		f_sound_data[<variable size>];
};

A DefineSound tag declares a set of samples of a sound effect or a music.

The sound samples can be compressed or not, stereo or not and 8 or 16 bits. The different modes are not all available in version 2, although the same tag is used in newer versions with additional capabilities.

The f_sound_is_16bits is always set to 1 (16bits samples) if the samples are compressed (neither Rawnor Uncompressed).

The f_sound_rate represents the rate at which the samples are defined. The rate at which it will be played on the target computers may differ. The following equation can be used to determine the ...

struct swf_tag {
	unsigned short		f_tag_and_size;
	f_tag = f_tag_and_size >> 6;
	f_tag_data_size = f_tag_and_size & 0x3F;
	if(f_tag_data_size == 63) {
		unsigned long	f_tag_data_real_size;
	}
	else {
		f_tag_data_real_size = f_tag_data_size;
	}
};

struct swf_long_tag { /* i.e. the last 6 bits of f_tag_and_size = 0x3F */
	unsigned short		f_tag_and_size;
	f_tag = f_tag_and_size >> 6;
	unsigned long	f_tag_data_real_size;
};

The tag and size are saved in a 16 bits little endian unsigned integer. The tag is always aligned to a byte (not a bit). The size is defined in the lower 6 bits. And the short value is in a little endian format as expected by the declaration. If the size is 63 (0x3F), then another 4 bytes are read for the size. This is used for really large tags such as fonts with many characters, audio, video, or images.

Brief History

At the very beginning, a company created the SWF format to generate small vector animations on the Internet called Shockwave Flash (hence the name of the format, SWF.) It also included images. This company was bought by Macromedia around 1997 (if I recall properly). This is when Flash v3 was created. Since then, Macromedia created a new version about once a year up to version 8. At that time (in 2005/2006), Macromedia sealed a deal with Adobe which wanted to use the SWF format in their PDF files.

Today (May 1st, 2008), the SWF format is available for free to all.

There was ...

SSWF™ name

The name SSWF™ is used by Made to Order Software to reference its SWF library. You are welcome to use this name in reference the SSWF library if you use it in your own software.

SWF Format

Please, note that there is no restriction in using this document. However, the SWF format copyright holders are Macromedia and Adobe. There may be limits in what you can do using this format. If you are not sure, I suggest you contact a knowledgeable copyright and Software attorney who can help you decide what you can do with the SWF format.

Making a great thing even better!

		SSWF Support

Since it's initial release in 2002, SSWF has been extremely popular. Despite never being advertised, it has been downloaded more than 77,250 times just on SourceForge.net, has been converted to work on several Unix platforms not initially ...

Dear reader,

Yes. With all these terms, it is quite easy to get lost.

As a developer, my skills are quite extensive. I started with Logo, learned assembly language, BASIC, C, C++… and all these other languages in between, those that most people pass by such as Ada, Eiffel, Icon… And the languages you kind of have to learn because you’re in it: Bourne Shell, configuration files for 100 different software, Makefile, etc.

And once you know all of these languages, you think you’re done. Well… Not quite!

The web has got it’s own set of languages! It