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whisper.cpp

Tool, speech, by ggerganov

Assessment

The dependable live transcriber: the same request shape on a 4 GB AMD card and on a CPU, so a caller can list two homes and fail over. Use the small English model for calls and a larger one in batch where time does not matter.

2026-10-09

Strengths

  • Live speech-to-text on small or odd GPUs through Vulkan, and on CPUs
  • One binary, one HTTP endpoint, the same request shape everywhere
  • The small English model answers a ten-second clip in a couple of seconds on modest hardware

Limitations

  • Accuracy on crosstalk and accents trails the large models
  • A GPU build shares the card with everything else and slows when the card fills

whisper.cpp is the C/C++ port of OpenAI's Whisper speech-recognition models, from the same author as llama.cpp.[1] It runs on CPUs and, through Vulkan, Metal or CUDA, on GPUs that the Python stack cannot use, including small AMD cards. Its server example answers a multipart POST of audio with JSON text.

What it is for

Live calls: a caller speaks, a clip is posted, text comes back in a second or two, and the conversation goes on. Batch transcription of recordings with a larger model when accuracy matters more than latency.

Two homes, one shape

Because the request is the same on every build, a client can keep a list of servers and try the next when one does not answer.[2] A GPU build on one machine and a CPU build on another is the pattern: the call is always heard, even while the GPU box is busy or down.

Things to know

  • On a shared small card, a full card slows transcription about twenty times while every health check says fine; health-check with a real clip, not a ping.
  • small.en is the right model for live English; large-v3-turbo for batch, in faster-whisper or here.
  • Silence detection in front of the model saves more time than any other tuning.

History

  • 2026-10-09: article written and published.
  • 2026-10-09: entry created.

References

  1. whisper.cpp on GitHub ^
  2. whisper.cpp server ^

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