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funasr_onnx streaming Paraformer returns inconsistent structures for empty results #3791
Description
Description
funasr_onnx.paraformer_online_bin.Paraformer.__call__ returns different structures when there is no recognition result, depending on which path is taken:
| case | return value |
|---|---|
non-final call, no tokens (infer → asr_res = []) |
[] |
| final call handled as one chunk, decoder runs but text is empty | [{'preds': ['', []]}] |
final call split into two chunks, neither chunk has a result (lines 172-186 merge into res = {}) |
[{}] |
The last case means callers that read res[0]["preds"] after checking if res: hit KeyError: 'preds'; they have to check for an empty dict as well.
Reproduction
main (fbbfe01), iic/speech_paraformer-large_asr_nat-zh-cn-16k-common-vocab8404-online v2.0.5 exported to ONNX, onnxruntime 1.20.1, CPU. Silence is enough to trigger it; chunk_size=[5, 10, 5] (the package default) is used, so this is unrelated to #3789.
import numpy as np
from funasr_onnx.paraformer_online_bin import Paraformer
model = Paraformer(model_dir, batch_size=1, chunk_size=[5, 10, 5], quantize=False)
for n_final in (9600, 16000):
cache = {}
r1 = model(np.zeros(9600, np.float32), param_dict={"cache": cache, "is_final": False})
r2 = model(np.zeros(n_final, np.float32), param_dict={"cache": cache, "is_final": True})
print(n_final, r1, r2)Output:
9600 [] [{'preds': ['', []]}]
16000 [] [{}]
Question
What is the intended return value when there is no result? Returning [] in the split-final path, consistent with the non-final path, looks simplest, but I am not sure whether existing callers rely on [{}] or on [{'preds': ['', []]}]. If you confirm the expected contract, I can send a small PR with a regression test.
Activity
ychy7001 commentedon Oct 24, 2026
Follow-up after checking the unmodified fbbfe01 runtime with the official v2.0.5 FP32 export (onnxruntime 1.20.1 CPU,
chunk_size=[5, 10, 5], no patches).Correction to the table in the description. The single-chunk empty-text result is
[{"preds": ("", [])}]with a tuple underpreds. The['', []]I listed comes from the split-final path, and my 9600-sample final call in the original reproduction also takes that path, so it does not show the single-chunk type:Reproducible trigger.
[{}]breaks the access pattern inruntime/python/onnxruntime/demo_paraformer_online.py(if len(rec_result) > 0: rec_result[0]["preds"][0]):I could only trigger it with all-silence input and a final chunk larger than the demo's usual step. AISHELL-1 speech followed by 0–5 s of silence, stepped at 9600 samples, did not trigger it, so I am not claiming that trailing silence generally crashes the demo.
Proposed fix. Only
return [res] if res else []at the end of the split-final merge, with regression tests (PR to follow). Tuple/list normalization is out of scope. A caller could in theory use[{}]as a status signal; the change makes the no-result case consistent withinfer(), which returns[].