MPEG to SPH Converter

Extract MPEG audio as NIST SPHERE speech format online

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Video to Speech Corpus

Extract dialogue from MPEG video and package it as NIST SPHERE — skipping manual extraction when building speech research datasets.

NIST Standard

SPH output meets NIST SPHERE specifications exactly. Import directly into Kaldi, HTK, or any speech recognition framework.

Secure Handling

MPEG uploads are removed after conversion. SPH output files are deleted within 24 hours — your research materials stay confidential.

How to convert MPEG 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 (MPEG-1) is a foundational video and audio compression standard published in August 1993 by the Moving Picture Experts Group as ISO/IEC 11172. It was the first international standard for lossy compression of moving pictures and associated audio, establishing principles and techniques that would influence virtually all subsequent video codecs. MPEG-1 video achieves compression through a combination of motion-compensated prediction, discrete cosine transform coding, and variable-length entropy encoding, organized around three frame types: I-frames (intra-coded), P-frames (predicted), and B-frames (bidirectionally predicted). The standard targets bit rates around 1.5 Mbps for combined audio and video, producing quality comparable to VHS tape at SIF resolution (352x240 for NTSC). This compression level was specifically chosen to match the data throughput of 1x-speed CD-ROM drives, enabling the Video CD format that brought digital video to consumers in the early 1990s. The audio component, particularly Layer III (MP3), went on to become the most influential audio format in history. The I/P/B frame structure, motion estimation approach, and block-based transform coding established the architectural template followed by every major video codec since, from MPEG-2 through H.264 and beyond. Though long surpassed in compression efficiency, MPEG-1 remains supported by virtually all media software.
Initial release: August 1993
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 to SPH?

SPH is the NIST SPHERE standard for speech research. MPEG video dialogue becomes properly formatted data for ASR training and evaluation.

What tools handle SPH?

Kaldi, HTK, Praat, and the NIST SPHERE toolkit support SPH natively. It is the standard interchange format for speech audio research.

Does SPH compress the audio?

No — SPH stores PCM data without lossy compression. MPEG audio reaches SPHERE format at full quality for accurate speech processing.

Is MPEG-1 audio sufficient?

MPEG-1 audio provides adequate quality for speech research. Dialogue content is well-preserved through the extraction and SPH encoding process.

Can I convert many MPEG files?

Upload multiple MPEG videos and batch-convert to SPH. Efficient for building speech corpora from archived MPEG video collections.