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# Audio Sources and Capture

HPE IDOL Speech Server processes both stored and live audio. Audio for processing can be acquired from the following sources:

- Audio devices, when processing live audio
- Various types of live media streams
- Media files, including audio and video files

HPE IDOL Speech Server cannot directly capture audio from an audio device or handle media streams. To present audio data to HPE IDOL Speech Server, you must either:

- Stream the audio data through a binary port
- Send the audio as a binary data block using either a base64-encoded string or a multipart/form-data POST request
- Provide video or audio files

Note: HPE IDOL Speech Server supports nearly all audio and video file formats if you set the `FfmpegDirectory` parameter in the `speechserver.cfg` configuration file. (For more information about this parameter, see the HPE IDOL Speech Server Reference.) If you do not set this parameter, HPE IDOL Speech Server accepts only 16-bit, linear Pulse Code Modulation (PCM) format WAV files.

For best results, an audio file should:

- Be captured using an optimally positioned microphone. See Audio Capture.
- Be free from clipping. See Clipping.
- Contain as little background noise as possible. See Background Noise.

An audio stream must also:

- Be decompressed into 16-bit linear, little-endian PCM data. See Audio Compression.
- Have a sampling rate of either 8 kHz (8,000 Hz) or 16 kHz (16,000 Hz). See Audio Sampling Rate.

The following sections provide more detail about each aspect of audio quality.

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