Speex dev - Feb 2008 - Determine number of 20ms frames in packet - without decoding

> Oh, you're right, inband handling is different, but it's a matter
of one
> flag, passed to functioin. Probably not that much to keep code DRY.
Well, let's first merge your code and then we'll see about possible
simplifications.
>> frame: 20 ms encoding
>> sub-frame: 5 ms encoding (internal)
>> layer: one frame of nb or sb
>> sb: sub-band
>> wb: nb+sb
>> uwb: nb+sb+sb
> 
> Hum... Then SPEEX_SUBMODE_BITS_PER_FRAME macro have
> wrong name. 
Well, I haven't quite defined whether a frame includes all
"layers" or
just one...
> This is what I was trying to ask in my previous mail.
> Now it return number of bits in one layer (nb or sb), while I expected
> it to return number of bits in one frame (nb or wb or uwb). I want
> to get information about frame sizes to estimate bitrate for CBR
> operation and bitrate bounds for VBR operation.
You know you can already specify the bit-rate directly instead of the
quality, right? Also, VBR now supports a "max rate" option.

	Jean-Marc

On 2/16/08, Jean-Marc Valin <jean-marc.valin@usherbrooke.ca>
wrote:
> > Oh, you're right, inband handling is different, but it's a
matter of one
> > flag, passed to functioin. Probably not that much to keep code DRY.
>
> Well, let's first merge your code and then we'll see about possible
> simplifications.
Waiting for your decision ;)
I guess you stopped on the fact you need to check my statement
about wb_skip_table?
> >> frame: 20 ms encoding
> >> sub-frame: 5 ms encoding (internal)
> >> layer: one frame of nb or sb
> >> sb: sub-band
> >> wb: nb+sb
> >> uwb: nb+sb+sb
> >
> > Hum... Then SPEEX_SUBMODE_BITS_PER_FRAME macro have
> > wrong name.
>
> Well, I haven't quite defined whether a frame includes all
"layers" or
> just one...
It would be good to define - it is very misleading for newcomers
as it is now. And I would like to say, that from user point of view
"frame" meaning all "layers" is natural, because most of
users
are not aware of any "layers" - they want to operate with encoded
packet as a whole and do not think of internals. Actually, I've got
some idea about "layers" only when was forced to write sample
number calculation code.
> > This is what I was trying to ask in my previous mail.
> > Now it return number of bits in one layer (nb or sb), while I expected
> > it to return number of bits in one frame (nb or wb or uwb). I want
> > to get information about frame sizes to estimate bitrate for CBR
> > operation and bitrate bounds for VBR operation.
>
> You know you can already specify the bit-rate directly instead of the
> quality, right? Also, VBR now supports a "max rate" option.
Sure. But in SDP you specify mode and not bitrate. ;) So I want
to operate with the same things as in SDP.

-- 
Regards,
Alexander Chemeris.

SIPez LLC.
SIP VoIP, IM and Presence Consulting
http://www.SIPez.com
tel: +1 (617) 273-4000

Alexander Chemeris wrote:
> On 2/16/08, Jean-Marc Valin <jean-marc.valin@usherbrooke.ca> wrote:
>>> Oh, you're right, inband handling is different, but it's a
matter of one
>>> flag, passed to functioin. Probably not that much to keep code DRY.
>> Well, let's first merge your code and then we'll see about
possible
>> simplifications.
> 
> Waiting for your decision ;)
> I guess you stopped on the fact you need to check my statement
> about wb_skip_table?
Oh, your table looked fine. I think it's mine that was wrong for the
"null mode" (which nobody ever uses I guess!).
> It would be good to define - it is very misleading for newcomers
> as it is now. And I would like to say, that from user point of view
> "frame" meaning all "layers" is natural, because most
of users
> are not aware of any "layers" - they want to operate with encoded
> packet as a whole and do not think of internals. Actually, I've got
> some idea about "layers" only when was forced to write sample
> number calculation code.
Well, turns out I use frame size for both meanings -- which normally
isn't a problem because few people are directly aware of the
"layers" in
the first place.
> Sure. But in SDP you specify mode and not bitrate. ;) So I want
> to operate with the same things as in SDP.
I see. BTW, you can ask the full bit-rate to the encoder or decoder.
It's only the mode that give you the layer's bit-rate (which we might
want to change).

	Jean-Marc