---
title: "Application Metrics caught my broken size estimator"
description: "Cliparr’s video size estimator was intended to predict output size from target bitrate multiplied by clip duration, but real-world results could vary because its VBR encoder changes bitrate with content. Rather than manually testing a matrix of formats, codecs, and quality settings, the author extracted the browser-based export engine into Cliparr Convert, a standalone static converter, and instrumented it with anonymous Sentry Application Metrics. Completed conversions record actual and estimated bytes, their ratio and delta, plus attributes such as output format, quality, and estimator basis; counters also track conversion completion and the progressive web app installation funnel. The resulting dashboard exposed an estimate that was off by 83% and supports grouping real usage by conversion conditions, while sending only numeric metrics and not media, filenames, or URLs."
---

# Application Metrics caught my broken size estimator

[Sentry](https://yomu.fyi/company/sentry) · Kyle Tryon · Sep 1, 2026

**Type:** Problem & solution

## Summary

Cliparr’s video size estimator was intended to predict output size from target bitrate multiplied by clip duration, but real-world results could vary because its VBR encoder changes bitrate with content. Rather than manually testing a matrix of formats, codecs, and quality settings, the author extracted the browser-based export engine into Cliparr Convert, a standalone static converter, and instrumented it with anonymous Sentry Application Metrics. Completed conversions record actual and estimated bytes, their ratio and delta, plus attributes such as output format, quality, and estimator basis; counters also track conversion completion and the progressive web app installation funnel. The resulting dashboard exposed an estimate that was off by 83% and supports grouping real usage by conversion conditions, while sending only numeric metrics and not media, filenames, or URLs.

## Context

The estimator used target bitrate and clip duration, but the author was unsure whether that formula remained accurate across devices, browsers, formats, codecs, and quality settings. Manual testing appeared promising but would not systematically capture real-world usage, while the self-hosted application’s on-device processing and privacy-sensitive community made opt-in telemetry unsuitable for the current setup.

## Approach / What changed

The export engine was separated from Cliparr’s editor and released as Cliparr Convert, a fully static, in-browser converter on the public site. Anonymous Sentry Application Metrics record conversion sizes, estimate ratios and deltas, estimator basis, output format, quality, and other attributes, while counters measure conversion completion and the PWA installation funnel. Only numeric metrics leave the browser.

## Takeaways

- Variable bitrate encoding changes bitrate according to video content, so actual output size can differ substantially from a bitrate-duration estimate; one observed estimate was off by 83%.
- Distribution metrics capture actual size, estimate delta, and estimate ratio for every completed conversion, with attributes enabling aggregation by format, quality, and estimator basis.
- The converter sends numeric telemetry rather than media, filenames, or URLs, and counters break PWA installation into stages from prompt availability through completed installation.

**Tags:** [Monitoring](https://yomu.fyi/topic/monitoring), [Observability](https://yomu.fyi/topic/observability), [Video](https://yomu.fyi/topic/video)

- Source: [Sentry](https://blog.sentry.io/metrics-caught-ai-size-estimate)
- Source URL: https://blog.sentry.io/metrics-caught-ai-size-estimate
- Ingested by Yomu: 2026-09-01T16:00:45.570Z

[Read original post](https://blog.sentry.io/metrics-caught-ai-size-estimate)