[CELT-dev] Seamless Looping

Jean-Marc Valin jean-marc.valin at usherbrooke.ca
Tue Jan 12 03:59:43 PST 2010


It's really hard to say what's going on without all the details, but it 
should be pretty easy for you to figure it out by looking at the signal 
at the sample level. CELT uses fixed frames with (in most modes) 128 
samples overlap, so it shouldn't be too confusing.


On 2010-01-11 23:31, Chen-Po Sun wrote:
> Hi,
> I've been working on seamless looping of our CELT encoded sound banks.
> One of the tricks we do to get seamless looping with mp3 is to prime the
> encoder by encoding last two frames of the source data first, then
> discarding the result before doing the actual encoding of the whole
> source data.
> I have found that with CELT, I am able to get seamless looping without
> having to do any of this.
> Just for kicks though, I decided to implement the same trick of decoding
> and discarding of the last two frames first anyway in our CELT encoder.
> With this I have found that it actually causes loops to not loop
> seamlessly, which surprised me. What would be the cause of this? It
> seems quite strange that it would loop okay without the "trick" but not
> with it.
> Encode settings are set as follows:
> error = FSBank_CELT_State.celt_encoder_ctl(celtencoder,
> error = FSBank_CELT_State.celt_encoder_ctl(celtencoder,
> error = FSBank_CELT_State.celt_encoder_ctl(celtencoder,
> Thanks for your help,
> --
> *Chen-Po Sun* | Programmer
> Firelight Technologies Pty Ltd.
> FMOD Sound System | www.fmod.org
> PH: +61 3 96635947 Fax: +61 3 96635951
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