[CELT-dev] CELT 0.6.0 released, submitted as IETF draft

John Ridges jridges at masque.com
Mon Jul 6 20:53:44 PDT 2009

Actually I've got a noise gate in my app so my "silence" really *is* 
silence, but I didn't expect CELT to have all its features in yet. 
However my app is ready to accept zero sized packets whenever it starts 
getting them :-)

John Ridges

Gregory Maxwell wrote:
> On Mon, Jul 6, 2009 at 5:40 PM, John Ridges<jridges at masque.com> wrote:
>> Congrats JM. I've been looking forward to 0.6.0 for a while now, and
>> I've just integrated it into my app and it works great. I have just one
>> question though. I realize that the VBR implementation is brand-new and
>> isn't finished yet, but I would like to use it and was wondering if you
>> could give us all some idea of how you envision the VBR eventually
>> working (in other words, how the VBR parameter would affect the
>> bit-rate). Right now it appears to give me about half the bit-rate I ask
>> for when encoding silence, bit will sometimes increase up to around the
>> full bit-rate on occasion depending on the audio.
> As far as silence goes, if you're sending in true digital silence we
> should eventually have code which detects that and emits zero sized
> packets.  If you're sending in very quiet analog noise things are
> quite a bit harder because we can't be sure how loud the far end will
> have turned up their volume knob.
> The volume control knob problem is addressed in vorbis by the encoder
> running an envelope follower that works on the assumption that the
> loudest sound in the last X seconds will be considered to be Y dB.
> We'll probably have something like that in CELT anyways, and perhaps
> expose an API to set hard limits on the follower, so that your quiet
> near-silence would still get treated as silence.
> We're just not quite there yet.

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