[Flac-dev] FLAC format

Ingo Ralf Blum ingoralfblum at gmx.de
Mon Oct 1 09:31:06 PDT 2001


> I'm starting now to compile the ACM codec. I don't know how long it will
> take, since I do it in my free time, but I guess it will not take to long.
> About Mark Powell's comment, with an ACM codec there will be a lot of
> Windows GUIs for FLAC.
> I'm writing this message to talk about the FLAC format. The GUIs for the
> Audio Codec Manager, including Winamp and Windows Media Player for decoding
> and CodAxe for encoding, can use any format with a codec registered in the
> system using the RIFF file format. In this ACM codec's implementation, all
> data, including the "fLaC" marker and the metadata blocks, is placed by the
> Audio Codec Manager encoder's GUI in the RIFF's data area. Actually, I
> couldn't find any other way for doing this. The inconvenient is that the
> files written this way can't be read by any other than the Audio Codec
> Manager.

That's what I wanted to say a month ago.

> I have two suggestions to solve this problem: the reference decoder could be
> modified to understand the RIFF structure or the FLAC format could be
> changed to meet the RIFF format. The first solution's inconvenient is that
> there will be some data repeated, which is not a good idea in a compression
> format. I don't know if the amount of space waste is relevant here. The
> second solution's inconvenient is that a format change will break the
> compatibility with previous versions. It's not good either. What do you
> think?

Using a WAV file makes the thing not streamable, unless the RIFF structure isn't
checked. But you can't guarantee that.

> Another thing: it will be necessary to register the wave format, the
> manufacturer id and the product id with Microsoft. It's a little hard for me
> to do this here from Brazil. Are you in USA? You can keep the ACM codec's
> copyright, I just want my name in the code files as the original developer.

Have you tried to use a WAVEFORMATEXTENSIBLE? This should make registration



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