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

Jean-Marc Valin jean-marc.valin at usherbrooke.ca
Tue Jul 7 03:23:05 PDT 2009

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?



> 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
>> 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

More information about the celt-dev mailing list