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how to fine-tune 'beam' 'latbeam' and 'acwt'

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Fei Xiong
2014-11-02
2015-03-23
  • Fei Xiong

    Fei Xiong - 2014-11-02

    Hi Kaldis,

    recently I am using Kaldi for ASR with our own feature type, which has almost 600 dimension.
    definitely it is much larger than e.g. #39 of MFCC+d+dd.
    if I understood correctly, I need to adjust the 'beam' beam width to larger than e.g. 13 to get
    through the mono and triphone training.
    otherwise, I got warnings: No alignment found!
    during decoding, I always got warnings: "no final-state reached"
    hence, the WER also reaches almost 100%.

    I would like to ask:
    whether there are some rules of thumb to adjust these values:
    --beam
    --latbeam
    --acwt

    I tested with WSJ corpus, and tried lots of combinations of the above parameters e.g. as
    --beam 60 (retry with 240)
    --latbeam 36
    --acwt 0.008333 (1/120 with lmwt 120)

    feat dim = 657

    num_gauss(15000) and num_leaves(2500) are kept the same as the default Kaldi script.

    however, still got the warning: "no final-state reached", resulting in experiments fail !
    please help to suggestion which way should I adjust these parameters...
    thanks in advance ~

    Fei

     
    • Jan "yenda" Trmal

      I think that is too high dimension for common gmm/sgmm system. So even if
      you find beam width that will cause the decoding succeed, i don't think
      the performance of such system will be any good.
      You should either use lda ( or other dimensionality reduction method) or
      (better) train a nnet system.

      Y.

      Y.
      On Nov 2, 2014 10:41 PM, "Fei Xiong" xffmqjx@users.sf.net wrote:

      Hi Kaldis,

      recently I am using Kaldi for ASR with our own feature type, which has
      almost 600 dimension.
      definitely it is much larger than e.g. #39 of MFCC+d+dd.
      if I understood correctly, I need to adjust the 'beam' beam width to
      larger than e.g. 13 to get
      through the mono and triphone training.
      otherwise, I got warnings: No alignment found!
      during decoding, I always got warnings: "no final-state reached"
      hence, the WER also reaches almost 100%.

      I would like to ask:
      whether there are some rules of thumb to adjust these values:
      --beam
      --latbeam
      --acwt

      I tested with WSJ corpus, and tried lots of combinations of the above
      parameters e.g. as
      --beam 60 (retry with 240)
      --latbeam 36
      --acwt 0.008333 (1/120 with lmwt 120)
      feat dim = 657

      num_gauss(15000) and num_leaves(2500) are kept the same as the default
      Kaldi script.

      however, still got the warning: "no final-state reached", resulting in
      experiments fail !
      please help to suggestion which way should I adjust these parameters...
      thanks in advance ~

      Fei

      how to fine-tune 'beam' 'latbeam' and 'acwt'
      https://sourceforge.net/p/kaldi/discussion/1355348/thread/d5872c77/?limit=25#26b5


      Sent from sourceforge.net because you indicated interest in
      https://sourceforge.net/p/kaldi/discussion/1355348/

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      • Fei Xiong

        Fei Xiong - 2014-11-03

        Hi Jan,

        thanks for the info.
        HLDA and DNN work fine for such large dim. features.
        however, just would like to compare if we feed these features directly to GMM/SGMM,
        what the WER will be.

        Fei

         
      • Fei Xiong

        Fei Xiong - 2014-11-06

        Hi Jim,

        do you know the relation of the beam width between HtK and Kaldi,
        e.g. from HTK, beam is typically set to "250" until "2000"
        from Kaldi scripts, it is chosen as beam '13' until retry_beam '13*4'

        then how to correspond each other of these settings?
        some scaling factor from Kaldi to HTK for this beam width?

        thanks in advance !
        Fei

         
        • Daniel Povey

          Daniel Povey - 2014-11-06

          In Kaldi we scale the acoustics down and in HTK they scale the
          language-model scale up, so there is a difference of a factor of 10 that
          comes from that.
          The (beam,retry_beam) seems to be (10,40) in most of the Kaldi scripts.
          Dan

          On Thu, Nov 6, 2014 at 10:06 AM, Fei Xiong xffmqjx@users.sf.net wrote:

          Hi Jim,

          do you know the relation of the beam width between HtK and Kaldi,
          e.g. from HTK, beam is typically set to "250" until "2000"
          from Kaldi scripts, it is chosen as beam '13' until retry_beam '13*4'

          then how to correspond each other of these settings?
          some scaling factor from Kaldi to HTK for this beam width?

          thanks in advance !
          Fei


          how to fine-tune 'beam' 'latbeam' and 'acwt'
          https://sourceforge.net/p/kaldi/discussion/1355348/thread/d5872c77/?limit=25#26b5/ed6b/ee1a


          Sent from sourceforge.net because you indicated interest in
          https://sourceforge.net/p/kaldi/discussion/1355348/

          To unsubscribe from further messages, please visit
          https://sourceforge.net/auth/subscriptions/

           
        • Paul Dixon

          Paul Dixon - 2014-11-06

          Kaldi scales down the acoustic cost:
          cost = am_cost * am_scale + lm_cost (am_scale < 1)
          HTK scales up the lm_cost:
          cost = am_cost + lm_cost * lm_scale (lm_scale > 1)

          On 6 November 2014 16:06, Fei Xiong xffmqjx@users.sf.net wrote:

          Hi Jim,

          do you know the relation of the beam width between HtK and Kaldi,
          e.g. from HTK, beam is typically set to "250" until "2000"
          from Kaldi scripts, it is chosen as beam '13' until retry_beam '13*4'

          then how to correspond each other of these settings?
          some scaling factor from Kaldi to HTK for this beam width?

          thanks in advance !
          Fei


          how to fine-tune 'beam' 'latbeam' and 'acwt'
          https://sourceforge.net/p/kaldi/discussion/1355348/thread/d5872c77/?limit=25#26b5/ed6b/ee1a


          Sent from sourceforge.net because you indicated interest in
          https://sourceforge.net/p/kaldi/discussion/1355348/

          To unsubscribe from further messages, please visit
          https://sourceforge.net/auth/subscriptions/

           
  • Fei Xiong

    Fei Xiong - 2014-11-08

    Hi Dan, hi Paul,

    thanks for the explanations.
    after fine-tuning the 'acwt' but keeping the 'beam' untouched, now some reasonable decoding results come out !

    Fei

     
  • Amiel Tadesse

    Amiel Tadesse - 2015-03-23
     

    Last edit: Amiel Tadesse 2015-03-23