sipeed/picoclaw · error

failed to copy file content: %w

Error message

failed to copy file content: %w

What it means

Thrown when io.Copy(part, bytes.NewReader(data)) fails while copying the already-in-memory audio bytes into the multipart buffer in WhisperTranscriber. Both ends are memory buffers; a copy error here requires bytes.Buffer write/allocation failure (out of memory). Under a healthy runtime this is unreachable.

Source

Thrown at pkg/audio/asr/whisper_transcriber.go:112

	logger.InfoCF("voice", "Starting whisper transcription from memory", map[string]any{
		"bytes":    len(data),
		"filename": filename,
		"model":    t.modelID,
		"provider": t.providerName,
	})

	var requestBody bytes.Buffer
	writer := multipart.NewWriter(&requestBody)

	part, err := writer.CreateFormFile("file", filename)
	if err != nil {
		logger.ErrorCF("voice", "Failed to create whisper form file", map[string]any{"error": err})
		return nil, fmt.Errorf("failed to create form file: %w", err)
	}

	if _, copyErr := io.Copy(part, bytes.NewReader(data)); copyErr != nil {
		logger.ErrorCF("voice", "Failed to copy whisper file content", map[string]any{"error": copyErr})
		return nil, fmt.Errorf("failed to copy file content: %w", copyErr)
	}

	if err = writer.WriteField("model", t.modelID); err != nil {
		logger.ErrorCF("voice", "Failed to write whisper model field", map[string]any{"error": err})
		return nil, fmt.Errorf("failed to write model field: %w", err)
	}

	if err = writer.WriteField("response_format", "json"); err != nil {
		logger.ErrorCF("voice", "Failed to write whisper response_format field", map[string]any{"error": err})
		return nil, fmt.Errorf("failed to write response_format field: %w", err)
	}

	if err = writer.Close(); err != nil {
		logger.ErrorCF("voice", "Failed to close whisper multipart writer", map[string]any{"error": err})
		return nil, fmt.Errorf("failed to close multipart writer: %w", err)
	}

	return t.doRequest(ctx, &requestBody, writer.FormDataContentType(), int64(len(data)))

View on GitHub (pinned to 49183d7e8d)

Solutions

1. Cap accepted audio size before transcription.
2. Raise memory limits or process audio in segments.
3. Pre-size the buffer (requestBody.Grow(len(data)+overhead)) to avoid repeated reallocation.

Example fix

// before
var requestBody bytes.Buffer
writer := multipart.NewWriter(&requestBody)

// after: pre-allocate to avoid mid-copy growth failure
var requestBody bytes.Buffer
requestBody.Grow(len(data) + len(data)/10 + 1024)
writer := multipart.NewWriter(&requestBody)

const maxInMemoryAudio = 100 << 20 // 100MB
if len(data) > maxInMemoryAudio {
    return fmt.Errorf("audio blob %d bytes exceeds in-memory limit %d", len(data), maxInMemoryAudio)
}

if _, err := whisper.TranscribeWithData(ctx, data, name); err != nil {
    if len(data) > maxInMemoryAudio {
        return errors.New("audio too large for in-memory transcription; use the file-based Transcribe")
    }
    return err
}

When it happens

Trigger: Allocation failure while doubling the buffer for a large audio blob; container OOM pressure with a multi-hundred-MB recording duplicated in memory (data + requestBody).

Common situations: Transcribing very long in-memory recordings inside memory-capped pods; the copy doubles peak RSS because the audio exists twice (data and multipart copy).

Related errors

• failed to write model_id field: %w
• failed to close multipart writer: %w
• failed to create form file: %w
• failed to write model field: %w
• failed to write response_format field: %w

AI-assisted analysis of sipeed/picoclaw@49183d7e8d (2026-08-15). Data as JSON: /api/errors/339e55d1499c087d. Report an issue: GitHub.