Subject: [codec] discussion topics pt 1

From: Michael Knappe <[email-masked]>
Date: Fri, 9 Jul 2010 08:34:19 -0700

Everyone,

Below is a discussion topic list that I sent out in April, along with my commentary and discussion summary from April where available included inline. Let’s take another round at reviewing these before Maastricht.

1. sample rates: which sample rate(s) will the proposed codec support? If more than one, will one of the sample rates be a MUST handled by all implementations, with the others optional dependent on the capabilities of the endpoint? Will each sample rate variation of the codec be treated as a unique codec as far as SDP negotiation is concerned?
[MEK] discussion on this indicated that even multiples of 8 kHz (16, 24, 32, 48) sampling were desired

2. joint stereo/channel coding: will joint channel coding be supported, perhaps optionally

3. multi-channel frame ordering: what channel naming and ordering scheme will we support or specify for packing variations of multiple channels in each frame?

4. packet loss concealment: will PLC be a mandatory component of the codec? Will the codec provide an implementation of PLC, but with the hooks to allow different and potentially improved (or network condition specific) implementations of PLC to be substituted in the codec?

5. bit-exact vs. bit-compatible: will all variations of the codec allow bit-compatible implementation, or will we specify a bit-exact variation of the codec (e.g. Specifying a bit-exact fixed point implementation of the lowest sample rate variation of the codec)?
[MEK] no general consensus here yet, with arguments for both (bit-exact allows test vector qualification of an implementation, while bit-compatible allows easier cross-platform porting and algorithmic updates/extensions)

6. reference use-cases and topologies: let’s start putting together a doc of use-cases and topologies that we expect the proposed codec to operate in. This will be useful for both determining implementation characteristics of the codec as well as its test regimen. Any takers for kicking this off?
[MEK] IMO, this is a very important text for us to put together

7. quality assessment / qualification process: we need to begin putting together a doc that details how we will assess the proposed codec, anyone interested in working on this?
[MEK] Christian and I are currently working on this, with a presentation set for Maastricht

Cheers,

Mike