ULW Converter

Extract text from u-Law audio files (ULW)


Drop or upload your .ULW file
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How to extract text from your ULW file

  1. Click the "Select File" button above, and choose your ULW file.
  2. You’ll see a preview, if available.
  3. Click the "Convert file to..." button to extract text information.

Convert ULW to another file type

To convert ULW audio files to another format, you need Audacity or other Audio software.

Convert a file to ULW

To convert other file formats to the "Raw Companded Audio" file type, you need software like Audacity or a similar tool.


About ULW files

A .ULW file is a raw audio file encoded using the mu-law algorithm. This format is widely used in legacy digital telecommunications systems across North America and Japan to optimize human speech transmission over low-bandwidth connections. You can open and convert these files using open-source tools like Audacity or VLC media player, though you may need to manually specify the import settings. The primary disadvantage of a .ULW file is its raw nature. Because it often lacks a standard file header, most modern media players and web browsers cannot determine its sample rate (typically 8000 Hz) or channel count. This makes playback fail by default. The audio quality is also strictly limited to 8-bit companded data, meaning it sounds like a traditional telephone call. To make these files usable, you must convert them to standard formats. The best conversion target is a WAV file, which preserves the original audio without further compression loss. If file size is critical, converting to MP3 or OGG is practical for sharing. Because standard online converters rely on file headers to process audio, they often fail to handle headerless .ULW files correctly. We can inspect the file structure, determine the underlying audio data parameters, and transcode it to a supported format.

Convert.Guru analyzes your ULW file, detects the exact format, and lets you read the text inside.


FAQ

If you want to convert ULW file to MP3, WAV, AAC, FLAC, OGG, WMA, M4A, AIFF, OPUS, ALAC, APE or WV, you can use Audacity or similar software from the "Voice and Telephony Audio" category. In the File menu, look for Save As… or Export….

To convert MIDI, AAC, TTA, AU, WV, DTS, MID, FLAC, RA, MP3, PCM or WAV files to ULW, try Audacity or another comparable tool in the "Voice and Telephony Audio" category.



The ULW Converter Story

The history of Convert.Guru began over 25 years ago in California with Tom Simondi’s file-format database. A former contributor to Space Shuttle development and a software pioneer of the 1980s, Simondi established a trusted resource for file type analysis that was even referenced by Microsoft Windows XP. Today, we use modern technology to process and convert thousands of file formats while continually improving our ULW converter.