Dear all, Sorry for this simple and maybe stupid question, I'm working in the implementation of opus for ARMv7e microcontroller using a library CMSIS/DSP used to calculate the CFFT and MDCT based on the DCT-IV. my question is: In the implementation of Celt you have used a fixed length CFFT equal to 1920, I want to know if there is some issues which can appear if a change that configuration for a cfft of size 2048, some of you could give me some support about that?, I ask because the library which I'm using doesn't support 1920 size. please let me know, I you need I could be more specific. thanks you so much. -- Diego Alejandro Parra Guzmán Estudiante de ingeniería electrónica Universidad distrital FJC -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.xiph.org/pipermail/opus/attachments/20170412/3c0242ca/attachment.html>
Dear all. According with my question. CELT CFFT size configuration I'm not completely sure about how the kiss_fft works for sizes which are not power of two, as occur in the case of celt which calculate the mdct using a fft sizes of 480, 240, 120, and 60, I guess that internally the input data is padded with zeros in order to compute efficiently the mdct using the Cooley and Tukey algorithm. If I'm correct. Means that technically, I could compute the fft using the padding strategy and adjust the output such as kissfft done, someone could confirm if that is possible. thanks cheers On Wed, Apr 12, 2017 at 2:27 PM, Diego Alejandro Parra Guzman < daparrag at correo.udistrital.edu.co> wrote:> Dear all, > > Sorry for this simple and maybe stupid question, I'm working in the > implementation of opus for ARMv7e microcontroller using a library CMSIS/DSP > used to calculate the CFFT and MDCT based on the DCT-IV. my question is: > > > In the implementation of Celt you have used a fixed length CFFT equal to > 1920, I want to know if there is some issues which can appear if a change > that configuration for a cfft of size 2048, some of you could give me some > support about that?, I ask because the library which I'm using doesn't > support 1920 size. > > please let me know, I you need I could be more specific. > > thanks you so much. > > -- > Diego Alejandro Parra Guzmán > Estudiante de ingeniería electrónica > Universidad distrital FJC >-- Diego Alejandro Parra Guzmán Estudiante de ingeniería electrónica Universidad distrital FJC -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.xiph.org/pipermail/opus/attachments/20170413/1bb76ad4/attachment.html>
On 13/04/17 05:04 AM, Diego Alejandro Parra Guzman wrote:> I'm not completely sure about how the kiss_fft works for sizes which are > not power of two, as occur in the case of celt which calculate the mdct > using a fft sizes of 480, 240, 120, and 60, I guess that internally the > input data is padded with zeros in order to compute efficiently the mdct > using the Cooley and Tukey algorithm.No, the FFT is *not* padded. The Cooley-Tukey algorithm can be implemented for radices other than 2. The kiss-fft-derived code in Opus implements radices 2, 3, and 5. You *cannot* use padding here. Jean-Marc> If I'm correct. Means that technically, I could compute the fft using > the padding strategy and adjust the output such as kissfft done, someone > could confirm if that is possible. > > thanks > cheers > > On Wed, Apr 12, 2017 at 2:27 PM, Diego Alejandro Parra Guzman > <daparrag at correo.udistrital.edu.co > <mailto:daparrag at correo.udistrital.edu.co>> wrote: > > Dear all, > > Sorry for this simple and maybe stupid question, I'm working in the > implementation of opus for ARMv7e microcontroller using a library > CMSIS/DSP used to calculate the CFFT and MDCT based on the DCT-IV. > my question is: > > > In the implementation of Celt you have used a fixed length CFFT > equal to 1920, I want to know if there is some issues which can > appear if a change that configuration for a cfft of size 2048, some > of you could give me some support about that?, I ask because the > library which I'm using doesn't support 1920 size. > > please let me know, I you need I could be more specific. > > thanks you so much. > > -- > Diego Alejandro Parra Guzmán > Estudiante de ingeniería electrónica > Universidad distrital FJC > > > > > -- > 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 >