iOS realtime transcribe not working

API
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1

socket already connected，the server returns:

{"type":"transcription_session.created","event_id":"event_BcDKtTDUdeFyOyWMs47Ih","session":{"id":"sess_BcDKtax3dByqsWhB5qwDq","object":"realtime.transcription_session","expires_at":1748449227,"input_audio_noise_reduction":null,"turn_detection":{"type":"server_vad","threshold":0.5,"prefix_padding_ms":300,"silence_duration_ms":200},"input_audio_format":"pcm16","input_audio_transcription":null,"client_secret":null,"include":null}}

When I start recording and send the iOS microphone recording data, the server returns

{"type":"input_audio_buffer.speech_started","event_id":"event_BcDT5OFY89Xu0CrTaunvl","audio_start_ms":31764,"item_id":"item_BcDT5FKyHr4KcuMi5mSYa"}
{"type":"input_audio_buffer.speech_stopped","event_id":"event_BcDT5psuRv8h46Z0LchIX","audio_end_ms":32352,"item_id":"item_BcDT5FKyHr4KcuMi5mSYa"}
{"type":"input_audio_buffer.committed","event_id":"event_BcDT5Mp1ButDL7IAWEf6U","previous_item_id":null,"item_id":"item_BcDT5FKyHr4KcuMi5mSYa"}
{"type":"conversation.item.created","event_id":"event_BcDT5YLLBURAxfBM0HrTz","previous_item_id":null,"item":{"id":"item_BcDT5FKyHr4KcuMi5mSYa","object":"realtime.item","type":"message","status":"completed","role":"user","content":[{"type":"input_audio","transcript":null}]}}
{"type":"input_audio_buffer.speech_started","event_id":"event_BcDT6uvclm1kRRQCkK6hA","audio_start_ms":33716,"item_id":"item_BcDT6pi2wZH30hzis5HIB"}
{"type":"input_audio_buffer.speech_stopped","event_id":"event_BcDT6NM13R6ud4WKTrWpA","audio_end_ms":34592,"item_id":"item_BcDT6pi2wZH30hzis5HIB"}
{"type":"input_audio_buffer.committed","event_id":"event_BcDT647bymtMuvkjtA26Q","previous_item_id":"item_BcDT5FKyHr4KcuMi5mSYa","item_id":"item_BcDT6pi2wZH30hzis5HIB"}
{"type":"conversation.item.created","event_id":"event_BcDT6Iu6bMtWhQutC71al","previous_item_id":"item_BcDT5FKyHr4KcuMi5mSYa","item":{"id":"item_BcDT6pi2wZH30hzis5HIB","object":"realtime.item","type":"message","status":"completed","role":"user","content":[{"type":"input_audio","transcript":null}]}}

The recording data conversion method is as follows：

inputNode.installTap(onBus: 0, bufferSize: 4096, format: format) { [weak self] buffer, time in
    guard let self = self else { return }
    guard let int16Data = self.downsampleAndConvertToPCM16(buffer: buffer, inputFormat: format) else {
        return
    }
    
    let base64Audio = int16Data.base64EncodedString()
    let message: [String: Any] = [
        "type": "input_audio_buffer.append",
        "audio": base64Audio
    ]
    if let jsonData = try? JSONSerialization.data(withJSONObject: message),
       let jsonString = String(data: jsonData, encoding: .utf8) {
        self.socket?.write(string: jsonString)
    }
    
}

func downsampleAndConvertToPCM16(buffer: AVAudioPCMBuffer, inputFormat: AVAudioFormat) -> Data? {
    let outputFormat = AVAudioFormat(commonFormat: .pcmFormatInt16,
                                     sampleRate: 24000,
                                     channels: 1,
                                     interleaved: true)!

    let converter = AVAudioConverter(from: inputFormat, to: outputFormat)!
    let outputBuffer = AVAudioPCMBuffer(pcmFormat: outputFormat, frameCapacity: AVAudioFrameCount(outputFormat.sampleRate) * 2)!

    var error: NSError?
    let inputBlock: AVAudioConverterInputBlock = { _, outStatus in
        outStatus.pointee = .haveData
        return buffer
    }

    converter.convert(to: outputBuffer, error: &error, withInputFrom: inputBlock)

    guard error == nil, let convertedData = outputBuffer.int16ChannelData else {
        print("转换失败: \(String(describing: error))")
        return nil
    }

    let frameLength = Int(outputBuffer.frameLength)
    let data = Data(bytes: convertedData.pointee, count: frameLength * 2)
    return data
}

When I send input_audio_buffer.commit, the server returns:

{"type":"error","event_id":"event_BcDTA3vEhwpQYpbo9M6hR","error":{"type":"invalid_request_error","code":"input_audio_buffer_commit_empty","message":"Error committing input audio buffer: buffer too small. Expected at least 100ms of audio, but buffer only has 0.00ms of audio.","param":null,"event_id":null}}