VOB to HTK Converter

Extract VOB DVD audio into HTK speech format online

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DVD to Speech Data

Extract dialogue from VOB DVD files and save as HTK — ready for Hidden Markov Model training and acoustic analysis research.

Server-Side Extraction

VOB files can be large. Our servers handle the extraction and HTK encoding — no local toolkit installation required.

Data Protection

VOB uploads are removed after conversion. HTK output is deleted within 24 hours — your research speech data stays private.

How to convert VOB to HTK

1

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

2

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

3

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

About formats

VOB (Video Object) is the primary container format used on DVD-Video discs, defined as part of the DVD specification developed by the DVD Forum. The format first appeared with the DVD standard finalized in September 1996 and has since been used on billions of DVD discs produced worldwide. VOB files are based on the MPEG-2 program stream format, containing multiplexed MPEG-2 video alongside audio in AC-3 (Dolby Digital), DTS, MPEG-1 Layer II, or LPCM formats. Beyond audio and video, VOB files also carry DVD subtitle streams as bitmap overlays, navigation data for menu interaction, and chapter point information. The files reside in the VIDEO_TS directory on a DVD disc, with naming conventions (VTS_01_1.VOB, etc.) reflecting the title and part structure of the content. Individual VOB files are limited to approximately 1 GB to accommodate the UDF file system requirements, with longer content spanning multiple files seamlessly. The format supports both NTSC (720x480) and PAL (720x576) video resolutions at bit rates up to 9.8 Mbps for combined audio and video. Integration of video, multi-track audio, subtitles, and navigation into a single program stream made VOB a complete solution for consumer movie delivery. While streaming and newer disc formats have supplanted DVD for new content, VOB remains hugely relevant for accessing the vast library of existing DVD content.
Developer: DVD Forum
Initial release: September 1996
HTK is the native waveform container for the Hidden Markov Model Toolkit, a software suite developed at Cambridge University's Engineering Department for speech recognition research. First distributed in 1993, HTK rapidly became a reference platform in computational linguistics labs worldwide, and its file format followed suit. Each file stores a sequence of parameter vectors or raw samples prefixed by a 12-byte header specifying the number of frames, the frame period in 100 ns units, the byte count per frame, and a type code indicating the data kind — options range from waveform PCM to Mel-frequency cepstral coefficients and filter-bank energies. This versatility lets a single container carry both source audio and extracted features without changing parsers. The deliberately minimal header avoids alignment padding or optional chunks, making the format trivial to read from C, Python, or MATLAB with a few lines of binary I/O. Three advantages underpin HTK's lasting relevance: tight integration with the HTK training and recognition pipeline, deterministic byte layout that eliminates parser ambiguity, and widespread adoption in academic corpora.
Initial release: 1993

Frequently Asked Questions

Why convert VOB to HTK?

HTK is the format for the Hidden Markov Model Toolkit. DVD VOB files with dialogue become speech training data for recognition research.

What is HTK audio?

HTK stores single-channel 16-bit PCM audio. It is purpose-built for the Cambridge HTK speech recognition and analysis framework.

Does VOB surround audio work?

HTK is mono. DVD multi-channel audio from VOB is downmixed to a single channel — standard procedure for speech processing work.

Is dialogue quality preserved?

HTK stores uncompressed 16-bit PCM. Dialogue from DVD VOB files retains full clarity for recognition training and analysis.

Can I process many VOB chapters?

Upload multiple VOB files and batch-convert them to HTK. Build a speech dataset from an entire DVD in one operation.