I was of the idea that flash (more specifically Adobe's flash player browser plugin) probably uses some installed MP3 codecs (on the client machine) using OS APIs. I heard someone say that Flash supports MP3 natively. is that true?
I guess flash has it's own video and audio format. (FLV and something similar for audio).
This question can also be phrased as "Which audio/video formats does flash (plugin) support natively".
Thank you.
Flash player will play MP3 encoded audio with no problem. If Flash is supported by the target OS, then Flash will play the MP3s without any additional requirements beyond the prerequisite sound card and speakers. In addition, Flash has some awesome MP3 streaming functionality and a complete set of tools for buffering hosted files. This has been the case since at least Flash 6. One thing to keep in mind is that the MP3 source has to be from the same domain that the Flash SWF is hosted from, at least last I checked, for "security" reasons.
All of Flash's supported content types, including MP3, are supported natively. Flash doesn't require or use any codecs from the client OS.
Here's a handy list of Flash's supported video and audio codecs - but that's actually a bit out of date now, because it omits the Speex audio codec, which Flash supports as of version 10.
Side note: You mention FLV as being Flash's "own" format, but note that FLV isn't a codec, it's just a container file. The audio/video content inside will be encoded in one of the codecs linked above.