remotion-dev/remotion · error

Pitch shifter was not initialized.

Error message

Pitch shifter was not initialized.

What it means

Inside pitchShiftAudioIterator, the shifter is created lazily when a segment starts. The null check before append is a defensive invariant: if control flow ever reaches append without a shifter having been constructed, it throws this error. It should be unreachable in normal use and indicates corrupted segment/state handling in the streaming pipeline.

Source

Thrown at packages/media/src/audio/pitch-shift.ts:614

			const previousSegmentFinalSlice = flush();
			if (previousSegmentFinalSlice) {
				yield previousSegmentFinalSlice;
			}

			sampleRate = nextSampleRate;
			numberOfChannels = nextNumberOfChannels;
			segmentStart = slice.timelineTimestamp;
			segmentInputFrames = 0;
			segmentOutputFrames = 0;
			shifter = new StreamingPitchShifter({
				numberOfChannels,
				sampleRate,
				toneFrequency,
			});
		}

		if (!shifter) {
			throw new Error('Pitch shifter was not initialized.');
		}

		segmentInputFrames += planar[0].length;
		const output = shifter.append(planar);
		if (output[0].length > 0) {
			yield makeAudioBufferSlice({
				audio: output,
				timelineTimestamp: segmentStart + segmentOutputFrames / sampleRate,
				sampleRate,
			});
			segmentOutputFrames += output[0].length;
		}
	}

	const finalSlice = flush();
	if (finalSlice) {
		yield finalSlice;
	}

View on GitHub (pinned to a6a7485a9a)

Solutions

1. Use pitchShiftAudioIterator unmodified with a valid audio iterator as input
2. Ensure yielded slices have real buffers with valid sampleRate/numberOfChannels (skip empty slices)
3. Upgrade @remotion/media to latest — if reachable, it is a bug worth reporting
4. Do not mix internal pitch-shift helpers from different package versions

// Only feed valid slices into pitchShiftAudioIterator
for await (const slice of iterator) {
  if (!slice.buffer.buffer || slice.buffer.buffer.sampleRate <= 0) continue;
}

try {
  yield* pitchShiftAudioIterator(audioIterator, toneFrequency);
} catch (e) {
  if (e instanceof Error && e.message === 'Pitch shifter was not initialized.') {
    console.error('Pitch shift pipeline received malformed audio segments');
  } else throw e;
}

When it happens

Trigger: Custom or patched iterator code reaching the append call while startsNewSegment failed to create a shifter; calling pitchShiftAudioIterator internals with an iterator that yields slices lacking valid sampleRate/numberOfChannels so shifter construction paths are bypassed.

Common situations: Forked/modified versions of pitchShiftAudioIterator; feeding empty or malformed audio buffers; upgrading @remotion/media and mixing internal helpers across versions.

Related errors

• Cannot append audio after the time stretcher was finalized.
• The time stretcher has already been finalized.
• No audio stream found in '${input_path}'. Ensure the video c
• Could not determine duration of ${src}, but "loop" was set.
• No audio track found

AI-assisted analysis of remotion-dev/remotion@a6a7485a9a (2026-09-02). Data as JSON: /api/errors/b89a1470d84f96a4. Report an issue: GitHub.