MPEG-2 to SPH Converter

Get NIST Sphere audio from MPEG-2 video quickly

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Corpus Standard

SPH is the format for major speech corpora — extracting from MPEG-2 creates research-ready audio data.

Fast Extraction

Audio extraction skips video processing — your MPEG-2-to-SPH conversion finishes in seconds, not minutes.

Secure Files

MPEG-2 uploads are erased immediately after conversion. SPH outputs are deleted within 24 hours.

How to convert MPEG-2 to SPH

1

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

2

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

3

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

About formats

MPEG-2 is a widely deployed video and audio compression standard developed by the Moving Picture Experts Group and approved in 1995 as ISO/IEC 13818. Building on the foundations of MPEG-1, MPEG-2 was designed to handle higher bit rates and resolutions, particularly interlaced video for broadcast television, making it suitable for applications ranging from standard-definition TV to high-definition content. The standard introduces the concept of profiles and levels, allowing implementations to target specific capability tiers — from the Simple Profile for basic applications to the High Profile supporting 4:2:2 chroma for professional broadcast. MPEG-2 became the compression backbone of digital television worldwide, adopted by DVB, ATSC, and ISDB standards, and it serves as the video codec for DVD-Video, bringing movie-quality video to the consumer market. The transport stream layer provides robust multiplexing with error resilience features essential for broadcast delivery over noisy channels, while the program stream variant serves storage-oriented applications like DVDs. MPEG-2 supports resolutions up to 1920x1152 in the Main Profile at High Level, with bit rates reaching 80 Mbps in professional configurations. Although newer codecs like H.264 and HEVC offer substantially better compression efficiency, MPEG-2 remains entrenched in broadcast infrastructure, cable and satellite systems, and billions of DVD discs in circulation worldwide.
Initial release: 1995
SPH is the file extension for audio stored in the NIST SPHERE (SPeech HEader REsources) format, a standard created by the U.S. National Institute of Standards and Technology around 1990. Built for speech research, SPH files carry a 1024-byte ASCII header packed with metadata — database identifiers, channel counts, sample rates, byte ordering, and compression type — making every recording self-describing. The underlying audio is typically 16-bit linear PCM sampled at 16 kHz, though other configurations are permitted. Researchers at NIST, DARPA, and universities worldwide rely on SPH for distributing speech corpora such as TIMIT, Switchboard, and the LDC collections that underpin modern automatic speech recognition systems. A key advantage is that the human-readable header lets scripts parse recording metadata without binary decoding. The format's strict standardization also eliminates ambiguity when sharing datasets across institutions and platforms. Because SPH files store uncompressed PCM, they preserve full audio fidelity — critical when training acoustic models where even small artifacts can skew results.
Initial release: 1990

Frequently Asked Questions

Why convert MPEG-2 to SPH?

SPH is the standard for speech research corpora like TIMIT and Switchboard.

How do I open SPH files?

NIST tools, Kaldi, HTK, and SoX.

Is only the audio extracted?

Yes — the video portion of the MPEG-2 file is discarded. Only the audio track is saved as SPH.

Can I convert multiple files?

Upload several MPEG-2 videos at once and extract SPH audio from each simultaneously in a single batch.

Are my uploads secure?

MPEG-2 files are deleted immediately after conversion. SPH outputs are removed from our servers within 24 hours.