# SlimCodec — 100% Client-Side Image, Video & Audio Compression Workbench

> SlimCodec is a zero-upload multimedia compression workbench running 100% inside the browser via Canvas 2D, OfflineAudioContext, CompressionStream, and MediaRecorder. SlimCodec compresses PNG images (Median-Cut 16–256 color quantization + Floyd-Steinberg dithering + Deflate), WebP/JPEG photos (100% EXIF/GPS metadata stripped), WAV/MP3/FLAC audio (4-bit IMA ADPCM 0x0011 4:1 encoding & polyphase resampling), and MP4/WebM videos (resolution, FPS & bitrate transcoding) with real-time PSNR (dB) and SSIM telemetry across 4 languages while uploading 0 bytes to any server.

## Key Capabilities & Technical Specifications
- **PNG-8 Median-Cut Quantizer & Deflate Repackager**: Partitions 32-bit RGBA pixel buffers into 16–256 indexed `PLTE`/`tRNS` entries with optional Floyd-Steinberg error-diffusion dithering and native `CompressionStream("deflate")`, reducing PNG byte size by 55%–80%.
- **Perceptual WebP / JPEG Re-Encoder & Metadata Stripper**: Rebuilds pixel buffers on an offscreen Canvas to strip 100% of camera EXIF, GPS coordinates, and IPTC/XMP tags while applying 1%–100% quality quantization and 4K/1080p/720p downscaling.
- **Objective Visual Fidelity Telemetry (PSNR & SSIM)**: Computes exact Mean Squared Error (MSE), Peak Signal-to-Noise Ratio (PSNR in dB), and Structural Similarity Index (SSIM, 0–1) between original and compressed images in browser memory.
- **4-Bit IMA ADPCM (RIFF 0x0011) & PCM Audio Compressor**: Downsamples stereo/mono audio (48 kHz, 44.1 kHz, 22.05 kHz, 16 kHz, 8 kHz) via `OfflineAudioContext` and encodes 4-bit IMA ADPCM blocks for 75%–88% byte savings with in-browser A/B playback.
- **Client-Side Video Bitrate & Frame-Rate Transcoder**: Uses `HTMLCanvasElement.captureStream` and `MediaRecorder` (VP9/VP8/MP4) to scale resolution (1080p/720p/480p), cap frame rate (60/30/24/15 fps), and enforce target bitrates (300 kbps–2.5 Mbps).

## Canonical Entry Points
- [Live Multimedia Compressor (Auto-detected Locale)](https://compress.llmland.io/): Main interactive image, audio, and video compression workbench.
- [Codec Algorithms & Rate-Distortion Methodology](https://compress.llmland.io/principles/): Mathematical formulas, quantization tables, and FAQ.
- [Simplified Chinese (简体中文)](https://compress.llmland.io/zh-Hans/) · [中文压缩算法原理](https://compress.llmland.io/zh-Hans/principles/)
- [Traditional Chinese (繁體中文)](https://compress.llmland.io/zh-Hant/) · [繁體壓縮演算法原理](https://compress.llmland.io/zh-Hant/principles/)
- [English](https://compress.llmland.io/en/) · [English Codec Methodology](https://compress.llmland.io/en/principles/)
- [Japanese (日本語)](https://compress.llmland.io/ja/) · [日本語圧縮アルゴリズム原理](https://compress.llmland.io/ja/principles/)

## Machine-Readable Resources
- [Full Technical Specification & FAQ (llms-full.txt)](https://compress.llmland.io/llms-full.txt): Complete codec equations, rate-distortion metrics, and multilingual FAQ.
- [XML Sitemap](https://compress.llmland.io/sitemap.xml): Canonical URLs with reciprocal `xhtml:link` `hreflang` annotations.

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