data compression

RE: data compression

Sigurd — Thu, 01 Jun 2023 17:13:52 GMT

Hi,

[quote user="ziv123"]so its not clear for me if there is some implementation of Brotli compression algorithm in ncs ??[/quote]

No, this is not implemented in NCS.

RE: data compression

ziv123 — Wed, 31 May 2023 13:21:08 GMT

hello Sigurd

we gave up the lz4 cause it did not gave such good compression rate for our data.

i so in the ncs under the nrf dir that there is some reference to Brotli compression (by google) but i only saw include for the decoding, so its not clear for me if there is some implementation of Brotli compression algorithm in ncs ??

hope to read you soon

best regards

Ziv

RE: data compression

ziv123 — Thu, 11 May 2023 14:41:44 GMT

Hi,

[quote userid="15146" url="~/f/nordic-q-a/99596/data-compression/425138"]Did you have a look at this sample?[/quote]

yes i did look at the sample, it shows the basic default use of the lib, does not show how to integrate a dictionary

RE: data compression

Sigurd — Thu, 11 May 2023 14:02:21 GMT

Hi,

[quote user="ziv123"]since my motivation to run compression (p.s. - loss less) is to send less bytes OTA, to save on connection time with the central and battery.[/quote]

Ok, I see your use-case now.

[quote user=""]if so, how can i use it i did not find any example or guide on that ?[/quote]

Did you have a look at this sample? https://github.com/nrfconnect/sdk-zephyr/blob/main/samples/compression/lz4/src/main.c

RE: data compression

ziv123 — Wed, 10 May 2023 13:35:49 GMT

Hi,

[quote userid="15146" url="~/f/nordic-q-a/99596/data-compression/424877"]I think it's better to just send the data as soon as you get it. The time you spend on buffering and compressing the data, you could have spend that time sending the data instead.[/quote]

though i appreciate your thoughts on the matter i don't understand the "time" relevance to that matter, since my motivation to run compression (p.s. - loss less) is to send less bytes OTA, to save on connection time with the central and battery. and in any case the time it will take me to compress the chunks of data will not cause and delay in BLE transmission on waiting for the compression. the data is collected in the endpoint according to some scheduler and there is no need to transmit the data collected while collecting it, but only after all sampling process has finished so no real time requirements like that.

hope to read you soon

best regards

Ziv

RE: data compression

Sigurd — Wed, 10 May 2023 13:19:34 GMT

Hi,

This lz4 library does not seem to be commonly used, and as far as I can see, we are not using it for any of our nordic libraries and samples. If you need support on this lz4 library, then I think it's better to check with the Zephyr community.

When it comes to your use-case here, I think it's better to just send the data as soon as you get it. The time you spend on buffering and compressing the data, you could have spend that time sending the data instead.