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

Jean-Marc Valin Jean-Marc.Valin at USherbrooke.ca
Tue Jul 7 10:19:40 PDT 2009


Quoting John Ridges <jridges at masque.com>:

> Actually I think the API you've defined is a good one (I can't think of
> a better interface offhand). The only thing I'm a little disappointed
> about is that the bit-rate doesn't decrease as dramatically as I'd like
> when there is essentially very quite audio (like it does in Speex), but
> I also realize that as a full-fidelity codec even soft audio might
> require a relatively high bit-rate to make sure it's faithfully
> reproduced. So I'll just work with whatever miracles you folks can pull
> off with the VBR. I have a #define that sets the VBR as a percentage of
> the maximum bit-rate. Right now I have it set to 50%, but maybe in the
> future I can set it closer to 100%.

Just keep in mind that the current VBR code is more of a quick hack to show it
can be done. Expect it to improve a lot in the future (yes, reducing the rate
during silence is definitely on the list).

Cheers,

    Jean-Marc

> Regards,
>
> John Ridges
>
>
> Jean-Marc Valin wrote:
> > John Ridges a écrit :
> >
> >> I found where I was off by a factor of two, so, yes, VBR does appear to
> >> work exactly the way you describe. In the future do you think you'll
> >> keep it working this way or do you have plans to change its behavior as
> >> it gets more advanced (I've noticed that it rarely gives you a bit-rate
> >> below the target bit-rate)? Tha
> >>
> >
> > Do you mean "working this way" as in the API or as the way it changes
> > the bit-stream. The latter will definitely improve with time. The API
> > may or may not change depending on the feedback we get. Is the current
> > API sufficient for you or would you prefer something different?
> >
> > Cheers,
> >
> > 	Jean-Marc
> >
> >
> >
> >> John Ridges
> >>
> >>
> >> Jean-Marc Valin wrote:
> >>
> >>> Hi John,
> >>>
> >>> The way VBR currently works is that you control the (approximate)
> >>> bit-rate target with CELT_SET_VBR_RATE and then the argument you pass to
> >>> the encoder is just the *maximum* bit-rate allowed. So if the maximum
> >>> isn't important, you just pass a large value there and control the rate
> >>> with CELT_SET_VBR_RATE.
> >>>
> >>> Cheers,
> >>>
> >>>     Jean-Marc
> >>>
> >>> John Ridges a écrit :
> >>>
> >>>
> >>>> 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.
> >>>>
> >>>> Thanks,
> >>>>
> >>>> John Ridges
> >>>>
> >>>> celt-dev-request at xiph.org wrote:
> >>>>
> >>>>
> >>>>> Message: 1
> >>>>> Date: Sun, 05 Jul 2009 20:37:40 -0400
> >>>>> From: Jean-Marc Valin <jean-marc.valin at usherbrooke.ca>
> >>>>> Subject: [CELT-dev] CELT 0.6.0 released, submitted as IETF draft
> >>>>> To: celt-dev <celt-dev at xiph.org>
> >>>>> Message-ID: <4A514754.4020101 at usherbrooke.ca>
> >>>>> Content-Type: text/plain; charset=ISO-8859-1
> >>>>>
> >>>>> Hi everyone,
> >>>>>
> >>>>> I'm pleased to announce version 0.6.0 of CELT, with many quality
> >>>>> improvements. This includes better stereo coupling, better handling of
> >>>>> transients, and better handling of highly tonal signals. In addition,
> >>>>> packet loss robustness has been improved through the optional use of
> >>>>> independent (intra) frames. CELT now supports a larger dynamic range,
> >>>>> suitable for encoding 24-bit audio (float version only). There is
> >>>>> also a
> >>>>> very early VBR implementation.
> >>>>>
> >>>>> Now, 0.6.0 is also the version that just got submitted as an "IPR-free
> >>>>> codec" Internet draft:
> >>>>> http://www.ietf.org/internet-drafts/draft-valin-celt-codec-00.txt
> >>>>>
> >>>>> For those who aren't aware of it, there is an ongoing discussion about
> >>>>> creating an IETF working group for standardising unencumbered audio
> >>>>> codecs that everyone can use. There will be a BoF at the next IETF
> >>>>> meeting (26-31 July) in Stockholm to discuss that. I encourage those
> >>>>> interested in taking part in the mailing list discussion (
> >>>>> https://www.ietf.org/mailman/listinfo/codec ) and/or attending the BoF
> >>>>> in Stockholm. I will be co-chairing this BoF with Jason Fischl from
> >>>>> Skype.
> >>>>>
> >>>>> Cheers,
> >>>>>
> >>>>>     Jean-Marc
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>
> >>>>
> >>>
> >>>
> >>
> >>
> >
> >
> >
>
>
>






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