RM to SPH Converter

Extract NIST SPHERE audio from RealMedia recordings

Drop files here. 1 GB maximum file size or Sign Up
to
Facebook Amazon Microsoft Tesla Nestle Walmart L'Oreal

Audio Rescue

Save audio from obsolete RM format. SPH keeps your RealMedia content usable for speech research datasets.

Cloud Processing

SPH extraction from RM runs on our servers — no legacy software needed on your system.

Secure Pipeline

RM uploads are deleted after extraction. SPH output is purged from servers within 24 hours.

How to convert RM 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

RM (RealMedia) is a proprietary multimedia container format developed by RealNetworks beginning in 1997. The format was designed specifically for streaming media delivery over the internet, packaging RealVideo and RealAudio codecs into a container optimized for low-bandwidth playback. RM became one of the dominant streaming formats in the late 1990s and early 2000s, when RealPlayer was among the most widely installed media applications and RealNetworks pioneered the concept of buffered streaming video before broadband became widespread. The format uses constant bit rate encoding and a proprietary container structure that supports forward error correction, allowing reasonably smooth playback even over unreliable dial-up connections. RM files can contain multiple streams at different bit rates, enabling SureStream technology that adapts playback quality to available bandwidth in real time. The container supports metadata for title, author, and copyright information, and RealNetworks developed the RTSP and PNA streaming protocols alongside the format for efficient network delivery. Compression in RM was considered impressive for its era, delivering watchable video at bit rates as low as 20-30 kbps when competing approaches struggled. While RealMedia has been largely replaced by modern streaming technologies, RM files remain in archives from the early internet era, including news organizations, educational institutions, and media libraries that adopted RealMedia during its peak popularity.
Developer: RealNetworks
Initial release: 1997
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 RM to SPH?

SPH is designed for speech research datasets. Extract audio from dying RM format into a purpose-built alternative.

What uses SPH files?

Systems and applications built for speech research datasets accept SPH as their native audio input format.

Is SPH widely compatible?

SPH is a specialized format. SOX and dedicated tools handle it; general media players may not.

Will quality be sufficient?

SPH quality matches its intended purpose. Output depends on the quality of the RM source audio.

Can I batch convert?

Upload several RM files and extract SPH audio from each simultaneously for efficient processing.