opus - May 2017 - MDCT implementation and his overlapped relationship

Dear all

I'm working on the implementation of the MDCT for the processor
ARM-Cortex-M4 I'm trying  to replicate the behavior of the MDCT for several
overlapped values however I realized that current implementation of the
MDCT is very close to the theory only in case in which we have and overlap
exactly equal to N/2 where N is the size of the input vector as is shown in
the examples  for celt.

could you explain me if the implementation had been thought for different
overlapped values, or instead the implementation uses only the overlap
equal to N/2.

Additional I want to know in case of overlapped values different to N/2
which values had been considered.

Thanks for you support.

-- 
Diego Alejandro Parra Guzmán
Estudiante de ingeniería electrónica
Universidad distrital FJC
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Hi Diego,

You might find figure 3 or this paper useful:
https://jmvalin.ca/papers/aes135_opus_celt.pdf

It shows the MDCT window for a 5 ms frame, but the (non-zero) overlap is
always 120 samples regarless of the frame size. You can either see it as
partial overlap, or as a full-overlap with a window that has zeros on
the sides.

Cheers,

	Jean-Marc

On 11/04/17 05:04 AM, Diego Alejandro Parra Guzman
wrote:
> Dear all
> 
> I'm working on the implementation of the MDCT for the processor
> ARM-Cortex-M4 I'm trying  to replicate the behavior of the MDCT
> for several overlapped values however I realized that current
> implementation of the MDCT is very close to the theory only in case in
> which we have and overlap exactly equal to N/2 where N is the size of
> the input vector as is shown in the examples  for celt.
> 
> could you explain me if the implementation had been thought for
> different overlapped values, or instead the implementation uses only the
> overlap equal to N/2. 
> 
> Additional I want to know in case of overlapped values different to N/2
> which values had been considered.
> 
> Thanks for you support.
> 
> -- 
> Diego Alejandro Parra Guzmán
> Estudiante de ingeniería electrónica
> Universidad distrital FJC
> 
> 
> _______________________________________________
> opus mailing list
> opus at xiph.org
> http://lists.xiph.org/mailman/listinfo/opus
>

Dear all

In the paper section describes how CELT and SILK had implemented a look/up
head delay of (2.5ms), (5ms) respectively ,  could you explain me>

1) those values are fixed.
1)  how you  guarantee those values independent of the architecture's
performance.

Thanks so much


On Tue, Apr 18, 2017 at 10:05 AM, Diego Alejandro Parra Guzman <
daparrag at correo.udistrital.edu.co> wrote:
> thanks you so much for your answer.
>
> On Thu, Apr 13, 2017 at 8:59 AM, Jean-Marc Valin <jmvalin at
jmvalin.ca>
> wrote:
>
>> Hi Diego,
>>
>> You might find figure 3 or this paper useful:
>> https://jmvalin.ca/papers/aes135_opus_celt.pdf
>>
>> It shows the MDCT window for a 5 ms frame, but the (non-zero) overlap
is
>> always 120 samples regarless of the frame size. You can either see it
as
>> partial overlap, or as a full-overlap with a window that has zeros on
>> the sides.
>>
>> Cheers,
>>
>>         Jean-Marc
>>
>> On 11/04/17 05:04 AM, Diego Alejandro Parra Guzman wrote:
>> > Dear all
>> >
>> > I'm working on the implementation of the MDCT for the
processor
>> > ARM-Cortex-M4 I'm trying  to replicate the behavior of the
MDCT
>> > for several overlapped values however I realized that current
>> > implementation of the MDCT is very close to the theory only in
case in
>> > which we have and overlap exactly equal to N/2 where N is the size
of
>> > the input vector as is shown in the examples  for celt.
>> >
>> > could you explain me if the implementation had been thought for
>> > different overlapped values, or instead the implementation uses
only the
>> > overlap equal to N/2.
>> >
>> > Additional I want to know in case of overlapped values different
to N/2
>> > which values had been considered.
>> >
>> > Thanks for you support.
>> >
>> > --
>> > Diego Alejandro Parra Guzmán
>> > Estudiante de ingeniería electrónica
>> > Universidad distrital FJC
>> >
>> >
>> > _______________________________________________
>> > opus mailing list
>> > opus at xiph.org
>> > http://lists.xiph.org/mailman/listinfo/opus
>> >
>>
>
>
>
> --
> Diego Alejandro Parra Guzmán
> Estudiante de ingeniería electrónica
> Universidad distrital FJC
>


-- 
Diego Alejandro Parra Guzmán
Estudiante de ingeniería electrónica
Universidad distrital FJC
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