Dolby Digital Plus

[kurse]

E-AC3 is a new file and I've seen alot of suff use it recently. Im wondering if it's as simple as being AC3 that goes up to 7.1 or if theres something better. And is AAC still a better codec than EAC-3 like it is with AC-3

[Cornucopia]

As per Wikipedia.

As the file is usually built on a combo of Base stream (AC3)+Enhanced stream (the "E" part), there can be no compression efficiency or quality advantage in the base part, as it MUST remain totally backward compatible with the original spec. Note, the above combo uses "dependent" stream structure, though it is possible to use instead an "independent" stream structure with the E part fully describing the whole program (though there is supposed to still be a base part duplicating the E, to maintain compatibility).

The AC3 base stream is well documented, but even though the E part continues to use a compatible syntax, it uses newer, proprietary code, which may or may not be based on the original spec (I suspect not). This portion likely uses newer techniques and is more efficient.

The legacy portion is older tech (a sort of fork of MP1 or MP2, IIRC), so it actually isn't even as efficient as MP3 (though MP3 has its own foibles & peculiarities). In terms of technique, and quality for musicality, in general, AAC (especially the later versions) is a better/more efficient codec. Whether it is more efficient or inherently better quality compared solely to the "E" portion remains to be seen (though it is an empirical problem), but ultimately they have different purposes in their market focus, E-AC3 being intended primarily for broadcast or optical consumer media, whereas AAC is usually meant for streaming and portable music (not that either one is forced to use only those markets).

I guess the biggest question is: what is YOUR intended purpose (and apps/devices) and your source format(s)? Seems to me, that is what should determine which would be best, because either one can be made to be transparently "near-lossless" if given sufficient bitrate. But if you start with a lossy source, it's usually better to just retain that source as-is, rather than re-encode just to have end-codec format uniformity.

Scott

[kurse]

This was very helpful. Thanks, Im going to use AAC