How to handle the Up/Down sampling of data while writing the transcoder application for A-law to Gsmamrwb

Rohit Yadav

Hi All,

I am trying to write the code for a transcoding application that transcode the alaw format speech into the gsmamrwb format.

I have to provide the o/p of alaw as the i/p of gsmamrwb. But as we all know alaw works in 8khz and gsmamrwb works in 16khz, so I have to upsample the data and then use it for further processing.

I am using the "gsmwbamrenc_tii.l64" library of gsmamrwb encoder.

Can any one tell me how to do this upsampling on DSPC8681E, not on Host Machine? Is there any variable or parameter that I have to set to get it done?

Find the reference code in the attachment-

Thanks,

Rohit

ipc.tar

over 7 years ago

0 Raja over 7 years ago

TI__Guru* 81335 points

I am working with experts to answer this. Thank you for your patience.

0 lding over 7 years ago in reply to Raja

TI__Guru* 95265 points

Rohit,

WB-AMR encoder (gsmwbamrenc_tii.l64) only takes PCM input sampled at 16,000 Hz. For any 8000 Hz A/u-law PCM samples, you need to do conversion outside of the WB-AMR library.

If you don't want to do it with a host machine, then some coding needs done for this in C6678 DSP. The A/U-law to linear PCM conversion and upsampling algorithm/code should be easily found. Also, there is TI VOLIB library for free download, which has "Sample Frequency Converter (SFC): Decimation by 2 and interpolation by 2." in VPE module. software-dl.ti.com/.../index_FDS.html

Regards, Eric

Processors

Processors forum

How to handle the Up/Down sampling of data while writing the transcoder application for A-law to Gsmamrwb