AAC-LD and it's Vorbis Equivalent?

For low delay streaming, AAC-Low Delay would be good as the specification says that the encoding algorithm should have no more delay than 20ms. This would be acceptable given we can't usually notice a phasing difference with anything lower than 15ms.
But is there a vorbis equivalent? I don't think there is, but is it possible to get vorbis's input sample buffer low enough to have some latency like 50ms? Quality isn't the main concern yet, and I think, the higher the bitrate becomes, the more that effect negates the short buffer length. So if we use something stupid like a megabit for 2 channel, should sound alright?

Comments

Gregory said…
Hi Matt.

Ask and ye shall receive.

The 'Vorbis equivalent' of AAC-LD is a new codec called CELT.

Although CELT borrows some ideas from Vorbis and others from Speex it is a separate codec family. ... There would be sense in keeping any Vorbis baggage that would be counter productive in the codec since it wouldn't be compatible anyways (Just as Low Delay AAC isn't compatible with normal AAC).

CELT is targeted to achieve decent quality 22/24khz bandpass audio at around 40kbit/sec for speech and around 64kbit/sec for music. You can, of course, throw bits at it to achieve higher quality levels.

At 44kHz CELT total algorithmic delay of only 8.7 ms, less than half of that of AAC-LD.

CELT also offers good robustness to errors and packet loss.

Preliminary double-blind listening test on the current codec appear to be indicating quality roughly equal at the same bitrates to the commercial AAC-LD codec shipping with OSX (the only working AAC-LD codec I've been able to fine, I've not yet been able to get the reference code I found on the net working..).

The codec is still new and in very active development. The initial announcement was on December 8th. There have been a number of releases since then. More information can be found at http://www.celt-codec.org/, but unfortunately there are no audio samples up on the webpage yet but some will probably go up soon after the most recent round of tuning improvements has been completed. Feel free to download, compile, and try it yourself.
Unknown said…
So tonight I take my last pill of metronidazole... Will I be able to drink tomorrow night after work without any side effects? I've been dying for a beer!
Anonymous said…
So tonight I take my last pill of metronidazole... Will I be able to drink tomorrow night after work without any side effects? I've been dying for a beer!

Popular Posts