[opus] Patches for adding 120 ms encoding

[Christian Hoene]

Hi Felica,

 

yes, this is the only reason to have larger frames is on bandwidth limited links having a gross (physical) bit rates of 10kbps per channel.

 

Decades ago I calculated with figure (for AMR-NB but the same holds for Opus).

 



 

https://www.tkn.tu-berlin.de/fileadmin/fg112/Hard_Software_Components/Software/hoene_07_2004_paper.pdf

 

Von: Felicia Lim [mailto:flim at google.com] 
Gesendet: Freitag, 10. Juni 2016 16:59
An: Christian Hoene <christian.hoene at symonics.com>
Betreff: Re: [opus] Patches for adding 120 ms encoding

 

Yes, that's right. In that case, a longer frame size means that we can reduce header overhead.

 

On Fri, Jun 10, 2016 at 4:45 PM Christian Hoene <christian.hoene at symonics.com <mailto:christian.hoene at symonics.com> > wrote:

Hello Felicia,

 

what are the reason to support 120 ms frame sizes? Links with a very low throughput?

 

With best regards,

 

Christian Hoene

 

 

Von: opus [mailto:opus-bounces at xiph.org <mailto:opus-bounces at xiph.org> ] Im Auftrag von Felicia Lim
Gesendet: Freitag, 10. Juni 2016 16:19
An: Jean-Marc Valin <jmvalin at jmvalin.ca <mailto:jmvalin at jmvalin.ca> >; opus at xiph.org <mailto:opus at xiph.org> 
Betreff: Re: [opus] Patches for adding 120 ms encoding

 

Hi, I wondered if are there any further thoughts on these patches? 

 

Thanks,

Felicia

 

On Thu, Jun 2, 2016 at 2:13 PM Felicia Lim <flim at google.com <mailto:flim at google.com> > wrote:

OK, I've amended the second patch and also added 80 and 100 ms. 

 

Thanks, 

Felicia

 

On Thu, Jun 2, 2016 at 7:20 AM Jean-Marc Valin <jmvalin at jmvalin.ca <mailto:jmvalin at jmvalin.ca> > wrote:

On 06/01/2016 02:06 PM, Felicia Lim wrote:
> That was my intention with refactoring out the subframe encoding and
> repacketizing bit. Or do you mean I should merge the explicit check for
> 120 ms frame and the existing checks for 40/60 ms wideband?

What I mean is that this line in opus_encoder.c:

if (frame_size > st->Fs/50 && (st->mode == MODE_CELT_ONLY ||
st->bandwidth > OPUS_BANDWIDTH_WIDEBAND))

can probably be extended to also cover 80/100/120 ms. One difference is
that it would also need to trigger for SILK-only > 60 ms.

Cheers,

        Jean-Marc

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