google/brotli

using brotli compression on embedded iot with limited RAM

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#1,018 opened on Jun 6, 2023

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help wanted

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Description

hello brotli i want to use the brotli compression which gave good compression rates on the type of data i need to compress (tested with the cli tool) . but before digging on how to use brotli compression in my (zephyr OS based) application i want to make sure its possible. in total the RAM of my device is 64k (ARM cortex M4 64Mhz), so with all the rest of the application i would say that max footprint can be ~4k, preferably smaller (including buffer for input by chunks of 256/512 bytes max). i do not care so much for speedy compression but rather have compress rate high as possible.

can brotli work in this conditions ? are the windows and other allocation sizes configurable ? i read that it uses a dictionary - what size of dictionary will it use for ~32kbyte of data ?

hope to read you soon best regards Ziv

Contributor guide

Research direction
Check the brotli C API documentation for memory allocation control and window size configuration. Look at the brotli encoder options struct for max compressed size and window bits. For 32KB input, the dictionary size is about 120KB? Actually brotli uses a static dictionary of ~120KB from RFC 7932 (maybe 120KB). But you can disable dictionary or use smaller window. Test with the CLI using window and dictionary flags to see RAM usage.
Tech stack
c
Domain
backend
Issue type
Research
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
Cembedded systems basics
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60