> ## Documentation Index
> Fetch the complete documentation index at: https://comfytv.org/llms.txt
> Use this file to discover all available pages before exploring further.
# Audio Time / Pitch
> Change speed, shift pitch, or time-stretch a track — with a high-quality phase-vocoder option that keeps pitch and tempo independent.
## What this node does
**Audio Time / Pitch** re-times or re-pitches audio. In the fast FFmpeg modes it uses `atempo`, `asetrate`/`aresample`, and `areverse`. In the two **HQ** modes it uses a StaffPad-style phase vocoder that stretches time or shifts pitch without the "chipmunk" side effect of naive resampling.
It takes a `COMFYTV_AUDIO` snapshot (or a `COMFYTV_VIDEO`, whose audio track is used) and outputs processed `COMFYTV_AUDIO` plus an `fx_spec`. It has a ▶ **Run**. The HQ modes require an audio input and refuse to run when the change would be a no-op.
To feed native ComfyUI `AUDIO` in or out, insert a **Bridge** — see [bridges.md](https://github.com/jtydhr88/ComfyTV/blob/main/docs/bridges.md).
## When to use it
* Speed a clip up or slow it down while keeping the pitch natural (`pitch_hq` isn't needed — use `stretch_hq`).
* Transpose a vocal or instrument by a musical interval without changing its length (`pitch`/`pitch_hq`).
* Reverse a track for a whoosh/riser effect.
## Parameters
### mode
Which operation to run. Options:
* **speed** (default) — change tempo *and* pitch together (via `atempo`), like playing a record faster.
* **pitch** — shift pitch by semitones while preserving length (resample + `atempo`).
* **pitch\_hq** — same, but via a phase vocoder for higher quality. Requires audio; errors if **semitones = 0**.
* **stretch\_hq** — change tempo only, preserving pitch, via phase vocoder. Requires audio; errors if **tempo = 1.0**.
* **reverse** — play the track backwards.
### tempo
Playback speed multiplier, **0.25–4.0** (default **1.0**). Used by `speed` and `stretch_hq`. 2.0 = twice as fast, 0.5 = half speed. Errors if left at 1.0 in those modes (nothing to do).
### semitones
Pitch shift in semitones, **-24 to +24** in 0.5 steps (default **0.0**). Used by `pitch` and `pitch_hq`. +12 = one octave up. Errors if left at 0 in those modes.
## Outputs
| Output | Type | Meaning |
| ------------ | ---------------- | ----------------------------------------------------------------------------- |
| **audio** | `COMFYTV_AUDIO` | The re-timed / re-pitched audio |
| **fx\_spec** | `COMFYTV_FXSPEC` | The effect as a spec (FFmpeg modes only); HQ modes emit an empty extra output |
## Tips
* `speed` is the fast, "record-player" behavior; use `stretch_hq` when you need to keep the pitch musical.
* `pitch` (FFmpeg) is quick but can smear transients; `pitch_hq` sounds cleaner at the cost of processing time.
* Only the FFmpeg modes produce a usable `fx_spec` for chaining — the HQ modes render directly.
## Related nodes
* **Audio Modulation** — vibrato for continuous pitch wobble rather than a fixed shift.
* **FX Chain** — renders multiple `fx_spec` steps (the FFmpeg modes) in a single pass.