m-bain/whisperX

Potential optimisation: temp-file mode for load_audio() to reduce memory on long audio

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#1,440 opened on Jun 20, 2026

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enhancementhelp wanted

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Description

load_audio() currently buffers the entire ffmpeg output in Python memory via subprocess.run(capture_output=True). For very long audio (10h+ ≈ 1.15 GB raw PCM), this can cause OOM on constrained systems since the Python bytes buffer, numpy view, and float32 copy all coexist at peak.

A use_tmp_file=True option could write ffmpeg output to a temp file instead of piping to stdout, then read with np.fromfile(), keeping the raw PCM out of Python's heap entirely.

Originally proposed in #1221 (bundled with unrelated dep changes that have since landed).

Contributor guide

Research direction
Explore implementing a use tmp file option in load audio() to write ffmpeg output to a temp file and then read with np.fromfile(). Investigate the original discussion in #1221 for context. Test with long audio to measure memory savings.
Tech stack
python
Domain
backend
Issue type
Feature
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
PythonNumPy
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65