Repository: huggingface/transformers (Python)
Task: Bug Fix

Issue:
return_dict in encodec is always set to True: 
### System Info


- `transformers` version: 4.42.0.dev0
- Platform: Linux-5.4.0-166-generic-x86_64-with-glibc2.29
- Python version: 3.8.10
- Huggingface_hub version: 0.23.3
- Safetensors version: 0.4.2
- Accelerate version: 0.29.1
- Accelerate config:    not found
- PyTorch version (GPU?): 2.2.2+cu121 (True)
- Tensorflow version (GPU?): 2.13.1 (True)
- Flax version (CPU?/GPU?/TPU?): 0.7.0 (cpu)
- Jax version: 0.4.13
- JaxLib version: 0.4.13
- Using distributed or parallel set-up in script?: <fill in>
- Using GPU in script?: <fill in>
- GPU type: NVIDIA DGX Display


### Reproduction

```
from transformers import EncodecConfig, EncodecModel, EncodecFeatureExtractor
import numpy as np 
import torch

signal = [np.random.randn(1065473), np.random.randn(1065473) ]
signal = EncodecFeatureExtractor()(signal)

model = EncodecModel(EncodecConfig())

result = model(torch.tensor(signal.input_values), return_dict = True)
print(type(result))
result2 = model(torch.tensor(signal.input_values), return_dict = False)
print(type(result2))
```

will print `<class 'transformers.models.encodec.modeling_encodec.EncodecOutput'>` even when `return_dict` is set to False. 


### Expected behavior

It should return a tuple when `return_dict` is set to False. 

cc @sanchit-gandhi 


Discussion:
https://github.com/huggingface/transformers/blob/dfaadfdcda8d2c2f564c94121d4618309c1ecdd5/src/transformers/models/encodec/modeling_encodec.py#L789

@kamilakesbi 
by default self.config.return_dict  is true so the or condition is always maintained and the function returns a dict.

Patch:
diff --git a/src/transformers/models/encodec/modeling_encodec.py b/src/transformers/models/encodec/modeling_encodec.py
--- a/src/transformers/models/encodec/modeling_encodec.py
+++ b/src/transformers/models/encodec/modeling_encodec.py
@@ -729,7 +729,7 @@ def decode(
                 Whether or not to return a [`~utils.ModelOutput`] instead of a plain tuple.
 
         """
-        return_dict = return_dict or self.config.return_dict
+        return_dict = return_dict if return_dict is not None else self.config.return_dict
 
         chunk_length = self.config.chunk_length
         if chunk_length is None:
@@ -786,7 +786,7 @@ def forward(
         >>> audio_codes = outputs.audio_codes
         >>> audio_values = outputs.audio_values
         ```"""
-        return_dict = return_dict or self.config.return_dict
+        return_dict = return_dict if return_dict is not None else self.config.return_dict
 
         if padding_mask is None:
             padding_mask = torch.ones_like(input_values).bool()


Test patch:
diff --git a/tests/models/encodec/test_modeling_encodec.py b/tests/models/encodec/test_modeling_encodec.py
--- a/tests/models/encodec/test_modeling_encodec.py
+++ b/tests/models/encodec/test_modeling_encodec.py
@@ -19,7 +19,6 @@
 import os
 import tempfile
 import unittest
-from typing import Dict, List, Tuple
 
 import numpy as np
 from datasets import Audio, load_dataset
@@ -375,31 +374,21 @@ def check_equivalence(model, tuple_inputs, dict_inputs, additional_kwargs={}):
                 tuple_output = model(**tuple_inputs, return_dict=False, **additional_kwargs)
                 dict_output = model(**dict_inputs, return_dict=True, **additional_kwargs)
 
-                def recursive_check(tuple_object, dict_object):
-                    if isinstance(tuple_object, (List, Tuple)):
-                        for tuple_iterable_value, dict_iterable_value in zip(tuple_object, dict_object):
-                            recursive_check(tuple_iterable_value, dict_iterable_value)
-                    elif isinstance(tuple_object, Dict):
-                        for tuple_iterable_value, dict_iterable_value in zip(
-                            tuple_object.values(), dict_object.values()
-                        ):
-                            recursive_check(tuple_iterable_value, dict_iterable_value)
-                    elif tuple_object is None:
-                        return
-                    else:
-                        self.assertTrue(
-                            torch.allclose(
-                                set_nan_tensor_to_zero(tuple_object), set_nan_tensor_to_zero(dict_object), atol=1e-5
-                            ),
-                            msg=(
-                                "Tuple and dict output are not equal. Difference:"
-                                f" {torch.max(torch.abs(tuple_object - dict_object))}. Tuple has `nan`:"
-                                f" {torch.isnan(tuple_object).any()} and `inf`: {torch.isinf(tuple_object)}. Dict has"
-                                f" `nan`: {torch.isnan(dict_object).any()} and `inf`: {torch.isinf(dict_object)}."
-                            ),
-                        )
-
-                recursive_check(tuple_output, dict_output)
+                self.assertTrue(isinstance(tuple_output, tuple))
+                self.assertTrue(isinstance(dict_output, dict))
+
+                for tuple_value, dict_value in zip(tuple_output, dict_output.values()):
+                    self.assertTrue(
+                        torch.allclose(
+                            set_nan_tensor_to_zero(tuple_value), set_nan_tensor_to_zero(dict_value), atol=1e-5
+                        ),
+                        msg=(
+                            "Tuple and dict output are not equal. Difference:"
+                            f" {torch.max(torch.abs(tuple_value - dict_value))}. Tuple has `nan`:"
+                            f" {torch.isnan(tuple_value).any()} and `inf`: {torch.isinf(tuple_value)}. Dict has"
+                            f" `nan`: {torch.isnan(dict_value).any()} and `inf`: {torch.isinf(dict_value)}."
+                        ),
+                    )
 
         for model_class in self.all_model_classes:
             model = model_class(config)