VOX to FLAC Converter

Archive Dialogic VOX telephony audio in lossless FLAC

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Settings

Set the number of audio channels. This setting is most useful when downmixing channels (e.g., from 5.1 to stereo).
Set the sample rate of the audio. Music with a full spectrum (20 Hz — 20 kHz) requires values not lower than 44.1 kHz to achieve transparency. More info can be found on the wiki.
Adjust the audio volume by selecting a number of decibels. For example, -10 dB decreases the volume by 10 decibels.

vox

VOX is a headerless audio format built around Dialogic ADPCM encoding, widely adopted in telephony, interactive voice response (IVR) systems, and voice mail platforms since the 1980s. Each audio sample is compressed into 4 bits using an algorithm developed by Oki Electric and implemented in hardware on Dialogic Corporation's telephony interface cards. VOX files typically use a sampling rate of 6000 or 8000 Hz, producing extremely compact recordings optimized for speech intelligibility rather than musical fidelity. Because the format carries no header, playback software must know the sample rate and encoding parameters in advance — a trade-off that reduces overhead but demands careful file management. The primary advantage of VOX is storage efficiency: a one-minute voice recording at 8 kHz occupies roughly 240 KB, making it practical for systems storing thousands of prompts. Dialogic ADPCM conforms to the ITU-T G.726 standard, ensuring interoperability across telephony equipment from different vendors. Even as modern call centers migrate to IP-based systems with codecs like Opus, vast libraries of VOX recordings persist in legacy IVR deployments and compliance archives worldwide.
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flac

FLAC (Free Lossless Audio Codec) delivers mathematically perfect audio reproduction at roughly half the size of an uncompressed WAV file. Maintained by the Xiph.Org Foundation and released in 2001, it quickly became the de facto open standard for lossless music archival. The encoder applies linear prediction to model each audio block, then codes the residual through Rice partitioning — exploiting the statistical distribution of prediction errors for strong compression without discarding data. Bit depths up to 32 and sample rates up to 655 kHz are supported, exceeding the requirements of high-resolution recordings. Hardware support is extensive: smartphones, car stereos, Blu-ray players, and virtually every desktop media application decode FLAC natively. Streaming services such as Tidal and Amazon Music use FLAC for lossless tiers, underscoring industry trust in the codec. Three standout benefits make FLAC compelling. First, complete bit-for-bit restoration of the original signal upon decoding. Second, embedded metadata via Vorbis comments and album art keeps libraries organized without sidecar files. Third, open-source licensing means no patents or royalties, removing legal friction for developers and hardware vendors.
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Lossless Archival

FLAC preserves every sample from the decoded VOX stream. Ideal for compliance recording archives and long-term voice data storage.

Telephony to Archive

Move Dialogic IVR recordings into a lossless archival format — no further quality degradation, guaranteed.

Bulk Archival

Upload entire libraries of VOX call recordings and produce FLAC archives in a single batch session.

How to convert VOX to FLAC

1

Select files from Computer, Google Drive, Dropbox, URL or by dragging it on the page.

2

Choose flac or any other format you need as a result (more than 200 formats supported)

3

Let the file convert and you can download your flac file right afterwards

About formats

VOX is a headerless audio format built around Dialogic ADPCM encoding, widely adopted in telephony, interactive voice response (IVR) systems, and voice mail platforms since the 1980s. Each audio sample is compressed into 4 bits using an algorithm developed by Oki Electric and implemented in hardware on Dialogic Corporation's telephony interface cards. VOX files typically use a sampling rate of 6000 or 8000 Hz, producing extremely compact recordings optimized for speech intelligibility rather than musical fidelity. Because the format carries no header, playback software must know the sample rate and encoding parameters in advance — a trade-off that reduces overhead but demands careful file management. The primary advantage of VOX is storage efficiency: a one-minute voice recording at 8 kHz occupies roughly 240 KB, making it practical for systems storing thousands of prompts. Dialogic ADPCM conforms to the ITU-T G.726 standard, ensuring interoperability across telephony equipment from different vendors. Even as modern call centers migrate to IP-based systems with codecs like Opus, vast libraries of VOX recordings persist in legacy IVR deployments and compliance archives worldwide.
Initial release: 1983
FLAC (Free Lossless Audio Codec) delivers mathematically perfect audio reproduction at roughly half the size of an uncompressed WAV file. Maintained by the Xiph.Org Foundation and released in 2001, it quickly became the de facto open standard for lossless music archival. The encoder applies linear prediction to model each audio block, then codes the residual through Rice partitioning — exploiting the statistical distribution of prediction errors for strong compression without discarding data. Bit depths up to 32 and sample rates up to 655 kHz are supported, exceeding the requirements of high-resolution recordings. Hardware support is extensive: smartphones, car stereos, Blu-ray players, and virtually every desktop media application decode FLAC natively. Streaming services such as Tidal and Amazon Music use FLAC for lossless tiers, underscoring industry trust in the codec. Three standout benefits make FLAC compelling. First, complete bit-for-bit restoration of the original signal upon decoding. Second, embedded metadata via Vorbis comments and album art keeps libraries organized without sidecar files. Third, open-source licensing means no patents or royalties, removing legal friction for developers and hardware vendors.
Initial release: July 20, 2001

Frequently Asked Questions

Why convert VOX to FLAC?

FLAC preserves audio losslessly. For compliance archival of call recordings, FLAC ensures no further quality degradation from the VOX source.

What can open FLAC files?

VLC, foobar2000, Winamp, most Android players, and modern Apple devices all support FLAC playback.

Is the FLAC output truly lossless?

FLAC is lossless from the decoded VOX PCM. The 4-bit ADPCM decoding step is the quality determinant — FLAC preserves that result perfectly.

How big will the FLAC file be?

FLAC will be larger than VOX since it stores full PCM. For 8 kHz voice, expect moderate sizes — still very manageable.

Can I search FLAC archives later?

FLAC files can be converted to any format later without additional quality loss. They serve as perfect master copies for long-term storage.

VOX to FLAC Quality Rating

3.0 (1 votes)
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