[CELT-dev] Just a question on how things are going

John Ridges jridges at masque.com
Fri Aug 6 11:03:06 PDT 2010

Hi Jean-Marc,

In my case, I'm afraid the IETF standard is much too far away for me to 
wait. So I guess what you're saying is that waiting for the frozen 
bitstream for someone (like me) who's only using CELT isn't that 
important because CELT probably won't be improved upon as a standalone 
codec after the bitstream is frozen anyway. It seems kind of a shame but 
I can understand your reasons for it.

I've got one quick question if you don't mind. Do you know offhand at 
what bitrate the pitch predictor ceased to be useful? In my application 
my minimum bitrate is 35 Kbits/sec. If the pitch predictor helped at 
that bitrate, I might want to settle on a version of CELT that still had 
it. Thanks,

John Ridges

On 8/6/2010 11:21 AM, Jean-Marc Valin wrote:
> Hi John,
> John Ridges <jridges at masque.com> a écrit :
>> I was just wondering if maybe you would consider a "blog-like" text file
>> in the codebase where you just jot down your thoughts about why you are
>> making a change, and where you think you are headed.
> Actually, I was planning on commenting more on my LiveJournal blog: 
> http://jmspeex.livejournal.com/
>> For example, I
>> noticed today that you completely removed the pitch prediction code. It
>> would be nice to know if you did that because you're moving away from
>> using it as a speech codec, or you just found that the pitch predictor
>> just wasn't making any difference. I realize that such a "blog" might
>> elicit endless debate from the peanut gallery on every change you make,
>> so I'll understand if you think it's a bad idea.
> The reasons for the change are:
> 1) Pitch has always been useful only on a narrow range of bit-rates
> 2) It's responsible for a large increase in complexity
> 3) CELT is going to end up merged in the IETF interactive codec, which 
> will also include SILK for voice.
>> Also I was hoping you might give us a sense of how close you think you
>> are to a 1.0 candidate. I don't want to put you on the spot, but for
>> those of us that might be deploying a product with CELT soon, if we
>> thought you were just cleaning up we might be willing to wait a little
>> while so we could deploy with the frozen bitstream. If, on the other
>> hand, you still have a bunch of ideas to try out, we'll work with what
>> you have (kindly) given us so far. (I guess one clue is that you're
>> quickly running out of 0.x version numbers :-)
> As things are now, it's quite likely that CELT will eventually cease 
> to exist as a stand-alone codec and instead be included in the IETF 
> codec. That codec would basically get the best of SILK and CELT. We're 
> progressing quickly on this, but I couldn't really tell you when it 
> would be frozen (depends on the working group). On the CELT side, I'm 
> working hard on pretty much freezing that part of the bit-stream, so 
> there's light at the end of the tunnel. For that reason, I'd like to 
> see it being tested a lot to make sure that the final bit-stream is good.
> Cheers,
>      Jean-Marc

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