#
Sphinx Decoders

Mosur K. Ravishankar (aka Ravi Mosur)
Sphinx Speech Group
School of Computer Science
Carnegie Mellon University
Pittsburgh, PA 15213

## What's Around and Where

In the table below, you will find information about the several versions of the Sphinx decoder. Descriptions in <legacy>gray</legacy> are older versions, and are not being maintained. Follow the links to find instructions on how to download the packages.

Name | Remarks
--- | ---

Sphinx 3.6 (Re-architected Version)

- Location: Open source, release available.
- Based on Sphinx-3.5.
- Here are several new features in Sphinx 3.6

- Further speed-up of CIGMMS in the 4 level GMM Computation Schemes (4LGC)
- Multiple regression classes an MAP adaptation in SphinxTrain
- Better support in using LM in Sphinx 3.X
- FSG search is now supported. This is adapted from Sphinx 2.
- Support of full triphone search in flat lexicon search
- Some support of different character sets other than of Sphinx 3.X. Models in multiple languages are now tested in Sphinx 3.X.

<legacy>Sphinx-3.5 (Live-mode APIs, Speaker Adaptation and Code Convergence)</legacy>

- Location: Open source, release available.
- Based on Sphinx-3.4 and Sphinx 3.0.
- Live-mode APIs are implemented an thoroughly tested
- Speaker adaptation based on single regression class is implemented.
- Four tools of s3.0 are now incorporated in Sphinx 3.x
  - `align (s3align in 3.0)`: Forced alignment
  - `allphone (s3allphone in 3.0)`: Allphone decoding
  - `astar (s3astar in 3.0)`: A* search, nbest generation
  - `dag (s3dag in 3.0)`: Shortest-path search
- The feature extraction libraries of sphinx 3 is now EXACTLY the same as SphinxTrain
- Corresponding changes in SphinxTrian
- Two new tools are introduced:
  - `mllr_solve` : compute the regression matrix based on MLLR algorithm.
  - `mllr_transform` : given a regression matrix, this program converts the mean based on linear transformation.
- The command line interface of all SphinxTrain's tools are now unified.

<legacy>Sphinx-3.4 (Fast GMM computation)</legacy>

- Location: Open source, module archive_s3/s3.4 in cvs tree.
- Based on Sphinx-3.3, Fast GMM computation is implemented
  - frame down-sampling
  - CI-based GMM selection
  - VQ-based and SVQ-based Gaussian Selection
  - Support of SVQ with arbitrary number of sub-vectors.
- Phoneme look-ahead
- Support class-based LM and multiple LM

<legacy>Sphinx-3.3 (fast decoder)</legacy>

- Location: Open source, module archive_s3/s3.3 in cvs tree.
- Fast Sphinx-3 decoder using lextree organization:
  - 5-10x real time speed on large vocabulary tasks (measured at 1999)
  - Continuous density acoustic models only
  - Batch-Mode or live operation
- Other tools
  - `gausubvq`: Sub-vector clustered acoustic model building, needed for fast acoustic model evaluation

<legacy>Sphinx-3.2</legacy>

- Location: Open source, module archive_s3/s3.2 in cvs tree.
- Same features as s3.3, but capable of batch-mode operation only.

Sphinx-3 (slow decoder)

- Location: Open source, module archive_s3/s3 in cvs tree.
- Original Sphinx-3 decoder
- Slow; 50-100x real time speed on large vocabulary tasks (measured at 1999)
- Any kind of acoustic model (discrete, semi-continuous, continuous, others)
- Major applications:
  - `s3decode` and `s3decode-anytopo`: Speech-to-text Decoding
  - `s3align`: Forced alignment
  - `s3allphone`: Allphone decoding
  - `s3astar`: A* search, nbest generation
  - `s3dag`: Shortest-path search
- Other utilities:
  - `stseg-read`: State-segmentation binary file reader
  - `sen2s2`: Sphinx-II "sendump" file creation from Sphinx-3 acoustic model

Sphinx-2 (fbs8)

- Location: Open source, release available.
- Sphinx-II decoder
- Real-time operation
- Semi-continuous, Sphinx-II acoustic models only (Sphinx-II format)
- User applications support:
  - Compiled into a library with a straightforward API for building speech-enabled applications
  - Continuous-listening support
  - Dynamic language model loading and switching
- Several test applications:
  - Basic dictation with and without "push-to-talk"
  - Basic audio recording and playback
  - Audio segmentation using the continuous listener
- Additional recognition modes:
  - Forced alignment
  - Allphone decoding
  - A* search, nbest generation
  - Shortest-path search

Last modified: Wed Jul 26 13:28:16 Eastern Daylight Time 2006