debit.nl

A while ago I was playing with SWF generation within Flash itself.
I read the Adobe SWF specs and now I'm able to generate SWF's from FLV's and MP3's or both.

A simple Flash 10 example, haven't tested all possible MP3 rates so if someone encounters a bug, please let me know.
(Just found out that some MP3's with embedded art-work won't work... added to my TODO's).

Code snippet which writes the MP3 data to a SWF bytearray:

while(mp3.audioFrames.length > currentAudioFrame)
{
	var needSamples:int = 0.001 * ((1000/(__frameRate))*i) * audioRate;
	var startSamples:int = currentSamples;
	var audioData:ByteArray = new ByteArray();
 
	while(mp3.audioFrames.length > currentAudioFrame && currentSamples< needSamples)
	{
		var aframe:AudioFrame = AudioFrame(mp3.audioFrames[currentAudioFrame]);
		audioData.writeBytes(aframe.frameData);
		currentSamples = (currentAudioFrame+1) * (576*2);
		currentAudioFrame++;
	}
 
	var samples:int = currentSamples - startSamples;
	var seek:int = startSamples ? needSamples - startSamples : 0;
 
	var af:AudioFrame = mp3.audioFrames[i] as AudioFrame;
	_swfBytes.writeShort(createHeader(SWFTags.SOUNDSTREAMBLOCK,63));
	_swfBytes.writeInt(audioData.length+4);
	_swfBytes.writeShort(samples);
	_swfBytes.writeShort(seek);
	_swfBytes.writeBytes(audioData);
	_swfBytes.writeShort(createHeader(SWFTags.PLACE_OBJECT2,3)); //Place frame data
	_swfBytes.writeByte(1);
	_swfBytes.writeShort(1); //depth
	_swfBytes.writeShort(createHeader(SWFTags.SHOWFRAME,0));
 
	i++;
}

This way I write all SWF headers the correct way and not like most other code out there which uses a precompiled SWF and replace the sound object.

Bernard Actionscript, Flash