wulkano/kap

APNG file size is huge - 15x larger than gifs

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#910 opened on Aug 11, 2020

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 (2 comments) (0 reactions) (0 assignees)JavaScript (11,043 stars) (548 forks)batch import
Help Wanted

Description

I exported the same short 8 second, 800x550 pixel clip at 15 FPS to mp4, gif and apng.

The mp4 is 76kb The gif is 870kb The apng is 12.6mb

According to these tests run using gifapng APNG should be smaller filesize than GIF.

There seems to be some major bloat/issue with the way Kap is exporting APNGs.

Gif Example test

All examples in zip (as Github doesnt support APNG) test-exports.zip

Contributor guide

Tech stack
javascriptelectron
Domain
desktopperformance
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Basic understanding of image encodingKnowledge of Kap's export pipeline
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60
Research direction
Start by examining the APNG export code in Kap's source repository, likely under the 'export' or 'formats' directory. Compare the generated APNG file structure to expected output from tools like gifapng. Look for issues such as duplicate frames, incorrect disposal methods, or lack of compression. The attached zip file contains example outputs for reference. Additionally, review the two existing comments on the issue for any hints or suggestions from the community.