Specify endianess of pcm samples

[padenot]

In the wild, PCM can be in little endian or big endian. Because most of the time they come from RIFF files and RIFF files are little endian, implementations (certainly Firefox, probably Chrome?) have assumed little endian. RIFX files exist but are somewhat rare, that would be big endian RIFF files.

I propose that we standardize Web Codecs facilities to be little endian. We can always register new pcm types if a big endian ends up being needed.

[chrisguttandin]

I think AIFF files are also a notable example for files that contain big endian data by default. But they can also contain little endian encoded data.

[padenot]

That's correct.