Query about Opus and ADPCM Codec

[khodidas]

Hi,

We are using Nordic thingy 52 HW and their SDK for our Evaluation purpose. We are using Nordic thingy 52 microphone code directly. That firmware is using ADPCM codec which is having compression ratio 4 (E.g. 512 bytes are compressed to 128 bytes) I wanted to know that if we use Opus codec in that code how much compression ratio will we get? Our requirement is to get more compression ratio than ADPCM than what is the best codec which we can use. Is that example available for Opus and any other Codec which have more compression ration than ADPCM?

Regards

Khodidas

[ovrebekk]

Hi

Opus is a very flexible codec, and allows a variety of compression ratios depending on the sound quality you need. 

In general increasing the bitrate gives you better quality, but also higher CPU utilization. 

For some recommendations on what bitrate to go for please have a look here:
https://wiki.hydrogenaud.io/index.php?title=Opus#Speech_encoding_quality

I would recommend using CELT mode rather than SILK mode, as the later uses a lot of RAM and CPU. 

To get started with Opus the easiest is probably to download the Smart Remote 3 firmware, and extract the code from there (drv_audio_codec_opus.c). 
https://www.nordicsemi.com/Software-and-tools/Reference-Designs/nRFready-Smart-Remote-3-for-nRF52-Series/Download#infotabs

Best regards
Torbjørn

[nrf_user_32]

Hello ovrebekk, the "Download .zip archive" link for Smart Remote 3 firmware at https://www.nordicsemi.com/Software-and-tools/Reference-Designs/nRFready-Smart-Remote-3-for-nRF52-Series/Download#infotabs appears broken.  Would you please fix it?  Thank you.

[ovrebekk]

Hi 

In general I would recommend opening a new ticket if you have a question not directly related to the existing case. 

Could you try to download the zip again?

I followed the link just now and have no problem opening the zip. 

I included the file below if you still can't download it from the webpage:

nRF ready Smart Remote 3 for nRF52 Series software files.zip

Best regards
Torbjørn

[nrf_user_32]

Thanks much @ovrebekk.  I am now able to download the zip file, but unfortunately the only zip I am able to download is the zip of software files.  Also the link you provided seems to be for the software files, not the firmware files.  I will open a new ticket.

[ovrebekk]

Sounds good, if it is a problem with the site our web people can take a look at it. 

I will close this case then