Support fine-tuning (#944)

* support finetune

* add files for decoding giga

* support initializing modules

* add a fine-tune bash script

egs/librispeech/ASR/finetune.sh

@@ -0,0 +1,85 @@
+#!/usr/bin/env bash
+
+# fix segmentation fault reported in https://github.com/k2-fsa/icefall/issues/674
+export PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION=python
+
+set -eou pipefail
+
+stage=-1
+stop_stage=100
+
+# This is an example script for fine-tuning. Here, we fine-tune a model trained
+# on Librispeech on GigaSpeech. The model used for fine-tuning is 
+# pruned_transducer_stateless7 (zipformer). If you want to fine-tune model 
+# from another recipe, you can adapt ./pruned_transducer_stateless7/finetune.py 
+# for that recipe. If you have any problem, please open up an issue in https://github.com/k2-fsa/icefall/issues.
+
+# We assume that you have already prepared the GigaSpeech manfiest&features under ./data.
+# If you haven't done that, please see https://github.com/k2-fsa/icefall/blob/master/egs/gigaspeech/ASR/prepare.sh.
+
+dl_dir=$PWD/download
+
+. shared/parse_options.sh || exit 1
+
+log() {
+  # This function is from espnet
+  local fname=${BASH_SOURCE[1]##*/}
+  echo -e "$(date '+%Y-%m-%d %H:%M:%S') (${fname}:${BASH_LINENO[0]}:${FUNCNAME[1]}) $*"
+}
+
+if [ $stage -le -1 ] && [ $stop_stage -ge -1 ]; then
+  log "Stage -1: Download Pre-trained model"
+
+  # clone from huggingface
+  git lfs install
+  git clone https://huggingface.co/csukuangfj/icefall-asr-librispeech-pruned-transducer-stateless7-2022-11-11
+
+fi
+
+if [ $stage -le 0 ] && [ $stop_stage -ge 0 ]; then
+  log "Stage 0: Start fine-tuning"
+
+  # The following configuration of lr schedule should work well
+  # You may also tune the following parameters to adjust learning rate schedule
+  base_lr=0.005
+  lr_epochs=100
+  lr_batches=100000
+
+  # We recommend to start from an averaged model
+  finetune_ckpt=icefall-asr-librispeech-pruned-transducer-stateless7-2022-11-11/exp/pretrained.pt
+  export CUDA_VISIBLE_DEVICES="0,1"
+
+  ./pruned_transducer_stateless7/finetune.py \
+    --world-size 2 \
+    --master-port 18180 \
+    --num-epochs 20 \
+    --start-epoch 1 \
+    --exp-dir pruned_transducer_stateless7/exp_giga_finetune \
+    --subset S \
+    --use-fp16 1 \
+    --base-lr $base_lr \
+    --lr-epochs $lr_epochs \
+    --lr-batches $lr_batches \
+    --bpe-model icefall-asr-librispeech-pruned-transducer-stateless7-2022-11-11/data/lang_bpe_500/bpe.model \
+    --do-finetune True \
+    --finetune-ckpt $finetune_ckpt \
+    --max-duration 500
+fi
+
+if [ $stage -le 1 ] && [ $stop_stage -ge 1 ]; then
+  log "Stage 1: Decoding"
+
+  epoch=15
+  avg=10
+
+  for m in greedy_search modified_beam_search; do
+    python pruned_transducer_stateless7/decode_gigaspeech.py \
+    --epoch $epoch \
+    --avg $avg \
+    --use-averaged-model True \
+    --beam-size 4 \
+    --exp-dir pruned_transducer_stateless7/exp_giga_finetune \
+    --max-duration 400 \
+    --decoding-method $m
+  done
+fi