decode lattice

[Andreas Stolcke]

In message <1077638057.403b73a921e70 at sms.ed.ac.uk>you wrote:
> Hi, 
>  
> We are using the sri lm 1.4 toolkit. As for now we have created a lattice in 
> the htk format and a 2gram model in the Arpa format. It is not clear from the
>  
> manual page how to decode this lattice uing the 2-gram model. Can you give us
>  
> the correct options for the lattice-tool to accomplish this if this is the 
> correct tool to use? 
>  
> thank you, 
> Gregor 

Gregor,

You would run lattice-tool twice, first to rescore the lattices with your
LM, then to extract the best hypothesis.

For LM rescoring use options

	lattice-tool -read-htk -write-htk -order 2 -lm LM -no-nulls

For 1-best decoding use

	lattice-tool -read-htk -htk-lmscale LMWEIGHT -viterbi-decode

You could also perform posterior-based (confusion network) decoding using

	lattice-tool -read-htk -htk-lmscale LMWEIGHT -posterior-decode

where LMWEIGHT is the weight given to the LM scores relative to the 
acoustic model scores.

Of course you need to add options specifying the location of input/output
lattices. 

A future version of lattice-tool will probably allow you to combine these
two steps into a single run, but for now you have to do it this way.

--Andreas