diff --git a/vllm/config/speech_to_text.py b/vllm/config/speech_to_text.py
index 3eafff1a3060..fe3532c9742d 100644
--- a/vllm/config/speech_to_text.py
+++ b/vllm/config/speech_to_text.py
@@ -17,10 +17,11 @@ class SpeechToTextConfig:
     16kHz audio input. The input audio will be automatically resampled to this
     rate before processing."""
 
-    max_audio_clip_s: int = 30
+    max_audio_clip_s: int | None = 30
     """Maximum duration in seconds for a single audio clip without chunking.
     Audio longer than this will be split into smaller chunks if
-    `allow_audio_chunking` evaluates to True, otherwise it will be rejected."""
+    `allow_audio_chunking` evaluates to True, otherwise it will be rejected. 
+    `None` means audio duration can be unlimited and won't be chunked."""
 
     overlap_chunk_second: int = 1
     """Overlap duration in seconds between consecutive audio chunks when
diff --git a/vllm/entrypoints/openai/speech_to_text.py b/vllm/entrypoints/openai/speech_to_text.py
index acfc8160a6d7..b6332d1941c1 100644
--- a/vllm/entrypoints/openai/speech_to_text.py
+++ b/vllm/entrypoints/openai/speech_to_text.py
@@ -477,7 +477,15 @@ async def _create_speech_to_text(
             }
             segment_class: type[SpeechToTextSegment] = segments_types[self.task_type]
             text = ""
+            chunk_size_in_s = self.asr_config.max_audio_clip_s
+            if chunk_size_in_s is None:
+                assert len(list_result_generator) == 1, (
+                    "`max_audio_clip_s` is set to None, audio cannot be chunked"
+                )
             for idx, result_generator in enumerate(list_result_generator):
+                start_time = (
+                    float(idx * chunk_size_in_s) if chunk_size_in_s is not None else 0.0
+                )
                 async for op in result_generator:
                     if request.response_format == "verbose_json":
                         segments: list[SpeechToTextSegment] = (
@@ -485,7 +493,7 @@ async def _create_speech_to_text(
                                 tokens=tuple(op.outputs[0].token_ids),
                                 segment_class=segment_class,
                                 request=request,
-                                start_time=idx * self.asr_config.max_audio_clip_s,
+                                start_time=start_time,
                             )
                         )
 
@@ -653,6 +661,10 @@ async def _speech_to_text_stream_generator(
     def _split_audio(
         self, audio_data: np.ndarray, sample_rate: int
     ) -> list[np.ndarray]:
+        assert self.asr_config.max_audio_clip_s is not None, (
+            f"{self.asr_config.max_audio_clip_s=} cannot be None to"
+            " split audio into chunks."
+        )
         chunk_size = sample_rate * self.asr_config.max_audio_clip_s
         overlap_size = sample_rate * self.asr_config.overlap_chunk_second
         chunks = []
diff --git a/vllm/model_executor/models/voxtral.py b/vllm/model_executor/models/voxtral.py
index cbba1af89190..63b26c789091 100644
--- a/vllm/model_executor/models/voxtral.py
+++ b/vllm/model_executor/models/voxtral.py
@@ -17,7 +17,11 @@
 from mistral_common.protocol.instruct.messages import UserMessage
 from mistral_common.protocol.instruct.request import ChatCompletionRequest
 from mistral_common.protocol.transcription.request import TranscriptionRequest
-from mistral_common.tokens.tokenizers.audio import Audio, AudioEncoder
+from mistral_common.tokens.tokenizers.audio import (
+    Audio,
+    AudioEncoder,
+    TranscriptionFormat,
+)
 from transformers import BatchFeature, TensorType, WhisperConfig
 from transformers.tokenization_utils_base import TextInput
 
@@ -157,13 +161,17 @@ def __call__(
 
             # pad if necessary
             # TODO(Patrick) - remove once mistral-common is bumped
-            sig = inspect.signature(self._audio_processor.pad)
-            if "is_online_streaming" in sig.parameters:
-                audio = self._audio_processor.pad(
-                    audio, self.sampling_rate, is_online_streaming=False
-                )
-            else:
-                audio = self._audio_processor.pad(audio, self.sampling_rate)
+            if (
+                self._audio_processor.audio_config.transcription_format
+                != TranscriptionFormat.STREAMING
+            ):
+                sig = inspect.signature(self._audio_processor.pad)
+                if "is_online_streaming" in sig.parameters:
+                    audio = self._audio_processor.pad(
+                        audio, self.sampling_rate, is_online_streaming=False
+                    )
+                else:
+                    audio = self._audio_processor.pad(audio, self.sampling_rate)
 
             audio_tokens = [self.begin_audio_token_id] + [
                 self.audio_token_id
diff --git a/vllm/model_executor/models/voxtral_streaming.py b/vllm/model_executor/models/voxtral_streaming.py
index 2e79e24e6f19..a89a0eedd8e7 100644
--- a/vllm/model_executor/models/voxtral_streaming.py
+++ b/vllm/model_executor/models/voxtral_streaming.py
@@ -3,10 +3,19 @@
 
 import math
 from collections.abc import Mapping
+from typing import Literal, cast
 
+import numpy as np
 import torch
+from mistral_common.protocol.instruct.chunk import RawAudio
+from mistral_common.protocol.transcription.request import (
+    StreamingMode,
+    TranscriptionRequest,
+)
+from mistral_common.tokens.tokenizers.audio import Audio
 
-from vllm.config.vllm import VllmConfig
+from vllm.config import ModelConfig, SpeechToTextConfig, VllmConfig
+from vllm.inputs.data import PromptType
 from vllm.logger import init_logger
 from vllm.model_executor.models.interfaces import MultiModalEmbeddings
 from vllm.model_executor.models.voxtral import (
@@ -27,6 +36,7 @@
 )
 from vllm.multimodal.profiling import BaseDummyInputsBuilder
 from vllm.sequence import IntermediateTensors
+from vllm.tokenizers import cached_tokenizer_from_config
 
 from .utils import (
     _flatten_embeddings,
@@ -205,13 +215,17 @@ def embed_multimodal(
             "For streaming you must provide an audio input at every step."
         )
 
-        multiple_of = self.audio_config.raw_audio_length_per_tok
-        assert all(
-            (this_audio := audio.shape[0]) % multiple_of == 0 for audio in audio_inputs
-        ), (
-            f"Every input audio waveform has to be a multiple of {multiple_of}, but"
-            f" one is {this_audio} with {(this_audio / multiple_of)=}."
-        )
+        def _truncate_left(
+            sample: torch.Tensor, mult_of: int, pos: int
+        ) -> torch.Tensor:
+            assert pos in [0, 1], pos
+            if (ctx := sample.shape[pos] % mult_of) != 0:
+                sample = sample[ctx:] if pos == 0 else sample[:, ctx:]
+                assert sample.shape[pos] > 0, (
+                    f"Sample is empty after truncation with ctx {ctx}"
+                )
+
+            return sample
 
         mel_features = [
             self.whisper_encoder.compute_whisper_melspec(audio).to(
@@ -219,11 +233,16 @@ def embed_multimodal(
             )
             for audio in audio_inputs
         ]
+
+        # we truncate the left most mel feature
+        # if the sequence length in impair
+        mel_features = [_truncate_left(mel, 2, 1) for mel in mel_features]
+
         seq_lens = [mel.shape[1] for mel in mel_features]
         # [total_num_20ms_frames, hidden_size]
         audio_embeddings = self.whisper_encoder.whisper_encoder.forward_conv(
             mel_features
-        )[0]
+        )
         conv_stride = self.whisper_encoder.whisper_encoder.total_stride
         audio_embeddings_per_sample = audio_embeddings.split(
             [s // conv_stride for s in seq_lens], dim=0
@@ -231,13 +250,55 @@ def embed_multimodal(
 
         # audio_embeddings per sample need to be divisible by 4
         pool_size = self.config.audio_config.block_pool_size
-        assert all(
-            (this_shape := sample.shape[0]) % pool_size == 0
+
+        audio_embeddings_per_sample = [
+            _truncate_left(sample, pool_size, 0)
             for sample in audio_embeddings_per_sample
-        ), f"Every audio embedding has to be a multiple of 4, but one is {this_shape}."
+        ]
 
         audio_embeddings_per_sample = [
             e.view(e.shape[0] // pool_size, e.shape[1] * pool_size)
             for e in audio_embeddings_per_sample
         ]
         return audio_embeddings_per_sample
+
+    @classmethod
+    def get_speech_to_text_config(
+        cls, model_config: ModelConfig, task_type: str
+    ) -> SpeechToTextConfig:
+        tokenizer = cached_tokenizer_from_config(model_config)
+        audio_config = tokenizer.instruct.audio_encoder.audio_config
+        sample_rate = audio_config.sampling_rate
+        return SpeechToTextConfig(
+            max_audio_clip_s=None,  # only limited by memory
+            sample_rate=sample_rate,
+            min_energy_split_window_size=None,
+        )
+
+    @classmethod
+    # for speech-to-text transcription
+    def get_generation_prompt(
+        cls,
+        audio: np.ndarray,
+        model_config: ModelConfig,
+        stt_config: SpeechToTextConfig,
+        language: str | None,
+        task_type: Literal["transcribe", "translate"],
+        request_prompt: str,
+        to_language: str | None,
+    ) -> PromptType:
+        tokenizer = cached_tokenizer_from_config(model_config)
+        audio = Audio(audio, int(stt_config.sample_rate), format="wav")  # lossless
+
+        req = TranscriptionRequest(
+            model=model_config.model,
+            audio=RawAudio.from_audio(audio),
+            language=language,
+            streaming=StreamingMode.OFFLINE,
+        )
+
+        tokenized = tokenizer.instruct.encode_transcription(req)
+        audio = (tokenized.audios[0].audio_array, stt_config.sample_rate)
+        prompts_dict = {"multi_modal_data": {"audio": audio}}
+        prompts_dict["prompt_token_ids"] = tokenized.tokens
+        return cast(PromptType, prompts_dict)
diff --git a/vllm/model_executor/models/whisper.py b/vllm/model_executor/models/whisper.py
index f1bae28debad..d1dadc3d5198 100644
--- a/vllm/model_executor/models/whisper.py
+++ b/vllm/model_executor/models/whisper.py
@@ -469,8 +469,10 @@ def __init__(
         self.max_source_positions = config.max_source_positions
         self.embed_scale = math.sqrt(embed_dim) if config.scale_embedding else 1.0
 
-        is_causal = getattr(config, "is_causal", False)
-        Conv1d = WhisperCausalConv1d if is_causal else partial(nn.Conv1d, padding=1)
+        self.is_causal = getattr(config, "is_causal", False)
+        Conv1d = (
+            WhisperCausalConv1d if self.is_causal else partial(nn.Conv1d, padding=1)
+        )
 
         self.conv1 = Conv1d(self.num_mel_bins, embed_dim, kernel_size=3)
         self.conv2 = Conv1d(embed_dim, embed_dim, stride=2, kernel_size=3)
@@ -485,7 +487,7 @@ def __init__(
         )
         self.layer_norm = nn.LayerNorm(config.d_model)
 
-        if is_causal and self.pos_embed_type != WhisperPosEmbedType.NOPE:
+        if self.is_causal and self.pos_embed_type != WhisperPosEmbedType.NOPE:
             raise ValueError(
                 "Only NOPE position embeddings are supported "
                 f"for causal models, but got {self.pos_embed_type}"
@@ -536,8 +538,11 @@ def forward_conv(
             hidden_states.append(embeds)
             input_is_batched = embeds.ndim > 2
         # Input to MHA must be B x T x D
-        if input_is_batched:
+        if input_is_batched or self.is_causal:
             # Models using WhisperEncoder may handle batching internally.
+            # If WhisperEncoder is causal, sequences
+            # are not padded to have identical seq length (T)
+            # => concat over feature dim
             hidden_states = torch.cat(hidden_states)
         else:
             hidden_states = torch.stack(hidden_states, dim=0)