[ASR] Conformer global tokens in local attention #6253

sam1373 · 2023-03-19T17:31:54Z

What does this PR do ?

Adds Longformer-style attention for Conformer encoder (limited context + few tokens with full context attention). Unlike with just limited context attention, when using global tokens model needs to be fine-tuned with this approach to get good results. After fine-tuning results are improved particularly on long audio (even if it's much longer than training data). When using the default Fast Conformer configs with this attention, inference on audio above 1 hour is supported.

Collection: ASR

Changelog

Add option to use global tokens
Adds corresponding test
Configs for training Conformer with this attention and mention in docs

Usage

Add the following parameters to the Conformer encoder in config:

    self_attention_model: rel_pos_local_attn # longformer-style attention (sliding window + global tokens)
    global_tokens: 1 # number of tokens that attend and are attended to by all tokens
    global_attn_separate: false # whether global tokens should use separate q,k,v layers

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PR Type:

New Feature
Bugfix
Documentation

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Signed-off-by: sam1373 <[email protected]>

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tests/collections/asr/test_asr_local_attn.py

titu1994

Overall it looks good, some minor changes commented. @VahidooX for final review

titu1994 · 2023-03-24T22:50:04Z

examples/asr/conf/fastconformer/fast-conformer-long_ctc_bpe.yaml

+
+# This version uses Longformer-style attention in order to handle longer audio
+
+name: "FastConformer-CTC-BPE"


Add long-context

titu1994 · 2023-03-24T22:50:50Z

examples/asr/conf/fastconformer/fast-conformer-long_ctc_bpe.yaml

+
+    # Feed forward module's params
+    ff_expansion_factor: 4
+


Add a Note regarding the sections that are the primary difference compared to original model config

titu1994 · 2023-03-24T22:51:29Z

examples/asr/conf/fastconformer/fast-conformer-long_transducer_bpe.yaml

+
+# This version uses Longformer-style attention in order to handle longer audio
+
+name: "FastConformer-Transducer-BPE"


Name update

titu1994 · 2023-03-24T22:51:38Z

examples/asr/conf/fastconformer/fast-conformer-long_transducer_bpe.yaml

+    # Feed forward module's params
+    ff_expansion_factor: 4
+
+    # Multi-headed Attention Module's params


Same as above

titu1994 · 2023-03-24T22:54:39Z

nemo/collections/asr/parts/submodules/multi_head_attention.py

+            if self.global_tokens > 0:
+                # compute sum of global and local attn
+                x = self._compute_attn_output_with_global_indices(
+                    value_vectors=v.transpose(1, 2),


Add shape info as comment here

titu1994 · 2023-03-24T22:55:00Z

nemo/collections/asr/parts/submodules/multi_head_attention.py

+                    max_num_global_attn_indices=max_num_global_attn_indices,
+                    is_index_global_attn_nonzero=is_index_global_attn_nonzero,
+                    is_local_index_global_attn_nonzero=is_local_index_global_attn_nonzero,
+                    w=w,


Use better keyword variable name

titu1994 · 2023-03-24T22:56:15Z

nemo/collections/asr/parts/submodules/multi_head_attention.py

+        return self.linear_out(x.reshape(n_batch, -1, self.h * self.d_k)[:, :T])
+
+    @staticmethod
+    def _get_global_attn_indices(is_index_global_attn: torch.Tensor) -> Tuple:


How about make this protected instead of private? Put _ at the end of the method name

titu1994 · 2023-03-24T22:56:35Z

nemo/collections/asr/parts/submodules/multi_head_attention.py

+            is_local_index_no_global_attn_nonzero,
+        )
+
+    def _compute_attn_probs_global_key(


Same as above

titu1994 · 2023-03-24T22:56:54Z

nemo/collections/asr/parts/submodules/multi_head_attention.py

+
+        return attn_output_only_global + attn_output_without_global
+
+    def _compute_global_attn_output_from_hidden(


Same as above

VahidooX

LGTM! Left some minor comments.

docs/source/asr/models.rst

VahidooX · 2023-03-31T20:17:59Z

examples/asr/conf/fastconformer/fast-conformer-long_ctc_bpe.yaml

@@ -0,0 +1,203 @@
+# It contains the default values for training a Fast Conformer-CTC ASR model, large size (~120M) with CTC loss and sub-word encoding.


Is it nice to have "-" and "_" in the name at the same time?

examples/asr/conf/fastconformer/fast-conformer-long_ctc_bpe.yaml

nemo/collections/asr/parts/submodules/conformer_modules.py

nemo/collections/asr/modules/conformer_encoder.py

examples/asr/conf/fastconformer/fast-conformer-long_ctc_bpe.yaml

Signed-off-by: sam1373 <[email protected]>

for more information, see https://pre-commit.ci

Signed-off-by: sam1373 <[email protected]>

nemo/collections/asr/parts/submodules/multi_head_attention.py

Signed-off-by: sam1373 <[email protected]>

VahidooX

LGTM! Just left some minor comments. Let's wait for the second round of review from @titu1994.

examples/asr/conf/fastconformer/fast-conformer-long_ctc_bpe.yaml

Signed-off-by: sam1373 <[email protected]>

VahidooX

LGTM!

* global tokens Signed-off-by: sam1373 <[email protected]> * test, configs, docs Signed-off-by: sam1373 <[email protected]> * [pre-commit.ci] auto fixes from pre-commit.com hooks for more information, see https://pre-commit.ci * update Signed-off-by: sam1373 <[email protected]> * style Signed-off-by: sam1373 <[email protected]> * [pre-commit.ci] auto fixes from pre-commit.com hooks for more information, see https://pre-commit.ci * names, comments Signed-off-by: sam1373 <[email protected]> * move comment Signed-off-by: sam1373 <[email protected]> * import Signed-off-by: sam1373 <[email protected]> * docs Signed-off-by: sam1373 <[email protected]> * docs Signed-off-by: sam1373 <[email protected]> * disable note Signed-off-by: sam1373 <[email protected]> --------- Signed-off-by: sam1373 <[email protected]> Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com> Signed-off-by: hsiehjackson <[email protected]>

sam1373 added 2 commits March 17, 2023 16:40

global tokens

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sam1373 and others added 3 commits March 19, 2023 10:32

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[ASR] Conformer global tokens in local attention #6253

[ASR] Conformer global tokens in local attention #6253

sam1373 commented Mar 19, 2023 •

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		# This version uses Longformer-style attention in order to handle longer audio

		name: "FastConformer-CTC-BPE"


		# This version uses Longformer-style attention in order to handle longer audio

		name: "FastConformer-Transducer-BPE"


		return attn_output_only_global + attn_output_without_global

		def _compute_global_attn_output_from_hidden(

		@@ -0,0 +1,203 @@
		# It contains the default values for training a Fast Conformer-CTC ASR model, large size (~120M) with CTC loss and sub-word encoding.

[ASR] Conformer global tokens in local attention #6253

[ASR] Conformer global tokens in local attention #6253

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sam1373 commented Mar 19, 2023 • edited Loading

What does this PR do ?

Changelog

Usage

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sam1373 commented Mar 19, 2023 •

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