MyMediaTools

Convert MKV to DSS — Free Online Tool

Convert MKV video files to DSS (Digital Speech Standard) audio format using the ADPCM IMA OKI codec — the proprietary compression scheme used by Olympus, Philips, and Grundig dictation devices. This tool strips all video tracks and encodes only the audio into DSS's speech-optimized, low-bitrate format, running entirely in your browser with no file uploads.

FFmpeg Command

Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg

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Estimated output:

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How It Works

DSS is a narrow, purpose-built audio format designed exclusively for speech dictation on professional recording hardware. During this conversion, FFmpeg discards the MKV container along with all video streams, subtitle tracks, chapter markers, and additional audio tracks. The single audio stream is then re-encoded from scratch using the ADPCM IMA OKI codec — an adaptive delta pulse-code modulation scheme tuned for low-bitrate speech reproduction. Because ADPCM IMA OKI operates at a fixed, hardware-defined sample rate and bit depth, there are no configurable quality parameters: the codec determines the output characteristics entirely. The result is a compact DSS file compatible with professional dictation workflows and transcription software that expects this format.

What Each Flag Does

Flag What it does
ffmpeg Invokes the FFmpeg multimedia processing engine, which handles reading the MKV container, demuxing its streams, and encoding the output DSS file entirely within your browser via WebAssembly.
-i input.mkv Specifies the input Matroska file. FFmpeg reads and demuxes all streams from the MKV container — video, audio, subtitles, and chapters — making them available for selective processing in the next stages of the command.
-c:a adpcm_ima_oki Instructs FFmpeg to encode the audio stream using the ADPCM IMA OKI codec, which is the only audio codec the DSS format supports. This triggers a full re-encode of the audio at DSS's fixed speech-optimized parameters.
output.dss Defines the output filename and, critically, the .dss extension — FFmpeg uses this to select the DSS muxer, which automatically drops any video or subtitle streams since the DSS container is audio-only.

Common Use Cases

  • Extracting a spoken narration or voiceover recorded into an MKV screen capture and converting it into DSS format for import into dictation transcription software like Philips SpeechExec or Olympus Sonority.
  • Preparing a voice memo or interview recording embedded in an MKV file for playback on a legacy Olympus or Philips digital dictation device that only reads DSS files.
  • Converting MKV-wrapped lecture or conference recordings to DSS so they can be submitted to a transcription service that specifically requires the Digital Speech Standard format.
  • Archiving a single spoken-word MKV recording into DSS for long-term storage in a dictation management system that catalogs files by DSS container.
  • Stripping the video from an MKV talking-head recording and producing a DSS file for a legal or medical dictation workflow where DSS is the mandated delivery format.
  • Testing DSS compatibility of audio content sourced from an MKV file before committing to a bulk migration of a dictation archive.

Frequently Asked Questions

Yes — DSS is a lossy format, and the ADPCM IMA OKI codec it uses is designed specifically for low-bitrate speech, not music or high-fidelity audio. If your MKV contains AAC, FLAC, or Opus audio at high bitrates, the DSS output will sound noticeably lower in quality and bandwidth. DSS is engineered to preserve speech intelligibility on dictation hardware, so it is only appropriate when voice clarity — not audio fidelity — is the goal.
All of it is discarded. DSS is a purely audio-only format with no support for video streams, subtitle tracks, chapter markers, or multiple audio tracks. FFmpeg automatically drops these streams when targeting a DSS output container because ADPCM IMA OKI is the only codec the format supports, and the container has no mechanism to carry anything else. Only the first audio track from your MKV will be encoded into the output file.
No — DSS with the ADPCM IMA OKI codec does not expose configurable quality parameters the way formats like MP3 or AAC do. The codec operates at fixed internal parameters defined by the DSS specification and the hardware it was designed for. The FFmpeg command for this conversion intentionally omits any audio quality flags because they would have no meaningful effect on the output.
FFmpeg selects the first audio stream in the MKV by default. If your MKV contains multiple audio tracks — for example, multiple language dubs — and you need a specific track, you would need to run the command locally using a stream selector like '-map 0:a:1' to target the second audio track. The browser tool processes the default stream automatically.
Install FFmpeg on your desktop and run: ffmpeg -i input.mkv -c:a adpcm_ima_oki output.dss. This is the exact same command the browser tool executes and will handle files of any size on your local machine without memory constraints. The command is displayed on this page so you can copy it directly.
The browser tool processes one file at a time, but locally you can batch convert using a shell loop. On Linux or macOS: for f in *.mkv; do ffmpeg -i "$f" -c:a adpcm_ima_oki "${f%.mkv}.dss"; done. On Windows Command Prompt: for %f in (*.mkv) do ffmpeg -i "%f" -c:a adpcm_ima_oki "%~nf.dss". Both iterate over all MKV files in the current directory and produce a matching DSS file for each.

Technical Notes

DSS (Digital Speech Standard) is a proprietary format jointly developed by Olympus, Philips, and Grundig and is tightly coupled to professional dictation hardware and software ecosystems. Its sole audio codec, ADPCM IMA OKI, is a variant of Adaptive Differential Pulse-Code Modulation originally developed by OKI Semiconductor for telephony and voice recording applications. The codec achieves very low file sizes by encoding only the difference between successive audio samples, which works well for the narrow frequency range of human speech but degrades rapidly for music, ambient sound, or wideband audio. Because DSS has no concept of video, chapters, metadata containers, or multi-track audio, the richness of the MKV source — one of the most capable multimedia containers available — is almost entirely discarded in this conversion. MKV's support for embedded subtitles, multiple audio languages, and chapter navigation is irrelevant to a DSS workflow. One practical limitation: DSS files produced by FFmpeg may not be fully recognized by all proprietary dictation applications or older hardware firmware, since some implementations expect DSS headers written by licensed encoders. Compatibility should be tested against the target device or software before committing to a production workflow.

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