add condition ctc_prefix_beam_search decode.

paddlespeech/s2t/models/wav2vec2/wav2vec2_ASR.py

@@ -128,7 +128,7 @@ class Wav2vec2ASR(nn.Layer):
         # with other batch decoding mode
         elif decoding_method == 'ctc_prefix_beam_search':
             assert feats.shape[0] == 1
-            if tokenizer is None:
+            if tokenizer is None and sb_pipeline is False:
                 hyp = self.ctc_prefix_beam_search(feats, beam_size)
                 res = [text_feature.defeaturize(hyp)]
                 res_tokenids = [hyp]