diff --git a/tests/test_subsamplers.py b/tests/test_subsamplers.py
index 32f708fa..e6a5b5f0 100644
--- a/tests/test_subsamplers.py
+++ b/tests/test_subsamplers.py
@@ -188,7 +188,7 @@ def test_audio_rate_subsampler(sample_rate, n_audio_channels):
         audio_bytes = aud_f.read()
 
     streams = {"audio": [audio_bytes]}
-    subsampler = AudioRateSubsampler(sample_rate, {"audio": "mp3"}, n_audio_channels)
+    subsampler = AudioRateSubsampler(sample_rate, "mp3", n_audio_channels)
 
     subsampled_streams, _, error_message = subsampler(streams)
     assert error_message is None
diff --git a/video2dataset/subsamplers/audio_rate_subsampler.py b/video2dataset/subsamplers/audio_rate_subsampler.py
index 48d94038..ad8b12e1 100644
--- a/video2dataset/subsamplers/audio_rate_subsampler.py
+++ b/video2dataset/subsamplers/audio_rate_subsampler.py
@@ -12,12 +12,13 @@ class AudioRateSubsampler:
     """
     Adjusts the frame rate of the videos to the specified frame rate.
     Args:
-        frame_rate (int): Target frame rate of the videos.
+        sample_rate (int): Target sample rate of the audio.
+        encode_format (str): Format to encode in (i.e. m4a)
     """
 
-    def __init__(self, sample_rate, encode_formats, n_audio_channels=None):
+    def __init__(self, sample_rate, encode_format, n_audio_channels=None):
         self.sample_rate = sample_rate
-        self.encode_formats = encode_formats
+        self.encode_format = encode_format
         self.n_audio_channels = n_audio_channels
 
     def __call__(self, streams, metadata=None):
@@ -27,7 +28,7 @@ def __call__(self, streams, metadata=None):
             with tempfile.TemporaryDirectory() as tmpdir:
                 with open(os.path.join(tmpdir, "input.m4a"), "wb") as f:
                     f.write(aud_bytes)
-                ext = self.encode_formats["audio"]
+                ext = self.encode_format
                 try:
                     # TODO: for now assuming m4a, change this
                     ffmpeg_args = {"ar": str(self.sample_rate), "f": ext}
diff --git a/video2dataset/subsamplers/frame_subsampler.py b/video2dataset/subsamplers/frame_subsampler.py
index 845c6677..e3c1b572 100644
--- a/video2dataset/subsamplers/frame_subsampler.py
+++ b/video2dataset/subsamplers/frame_subsampler.py
@@ -22,6 +22,7 @@ class FrameSubsampler(Subsampler):
             yt_subtitle: temporary special case where you want a frame at the beginning of each yt_subtitle
                          we will want to turn this into something like frame_timestamps and introduce
                          this as a fusing option with clipping_subsampler
+        encode_format (str): Format to encode in (i.e. mp4)
 
     TODO: n_frame
     TODO: generalize interface, should be like (frame_rate, n_frames, sampler, output_format)
@@ -31,10 +32,11 @@ class FrameSubsampler(Subsampler):
     # output_format - save as video, or images
     """
 
-    def __init__(self, frame_rate, downsample_method="fps"):
+    def __init__(self, frame_rate, downsample_method="fps", encode_format="mp4"):
         self.frame_rate = frame_rate
         self.downsample_method = downsample_method
         self.output_modality = "video" if downsample_method == "fps" else "jpg"
+        self.encode_format = encode_format
 
     def __call__(self, streams, metadata=None):
         # TODO: you might not want to pop it (f.e. in case of other subsamplers)
diff --git a/video2dataset/subsamplers/resolution_subsampler.py b/video2dataset/subsamplers/resolution_subsampler.py
index 59224546..46545f92 100644
--- a/video2dataset/subsamplers/resolution_subsampler.py
+++ b/video2dataset/subsamplers/resolution_subsampler.py
@@ -23,20 +23,23 @@ class ResolutionSubsampler(Subsampler):
         height (int): Height of video.
         width (int): Width of video.
         video_size (int): Both height and width.
+        encode_format (str): Format to encode in (i.e. mp4)
     """
-
     def __init__(
         self,
         resize_mode: Literal["scale", "crop", "pad"],
         height: int = -1,
         width: int = -1,
         video_size: int = -1,
+        encode_format: str = "mp4",
     ):
         if video_size > 0 and (height > 0 or width > 0):
             raise Exception("Either set video_size, or set height and/or width")
+        self.resize_mode = resize_mode
         self.height = height if video_size < 0 else video_size
         self.width = width if video_size < 0 else video_size
-        self.resize_mode = resize_mode
+        self.video_size = video_size
+        self.encode_format = encode_format
 
     def __call__(self, streams, metadata=None):
         video_bytes = streams["video"]
diff --git a/video2dataset/workers/subset_worker.py b/video2dataset/workers/subset_worker.py
index 9e6e142a..20d77eb8 100644
--- a/video2dataset/workers/subset_worker.py
+++ b/video2dataset/workers/subset_worker.py
@@ -114,9 +114,15 @@ def process_shard(
         # The subsamplers might change the output format, so we need to update the writer
         writer_encode_formats = self.encode_formats.copy()
         if self.subsamplers["audio"]:
-            writer_encode_formats["audio"] = self.subsamplers["audio"][0].encode_formats["audio"]
+            assert (
+                len({s.encode_format for s in self.subsamplers["audio"]}) == 1
+            )  # assert that all audio subsamplers have the same output format
+            writer_encode_formats["audio"] = self.subsamplers["audio"][0].encode_format
         if self.subsamplers["video"]:
-            writer_encode_formats["video"] = self.subsamplers["video"][0].encode_formats["video"]
+            assert (
+                len({s.encode_format for s in self.subsamplers["video"]}) == 1
+            )  # assert that all video subsamplers have the same output format
+            writer_encode_formats["video"] = self.subsamplers["video"][0].encode_format
 
         # give schema to writer
         sample_writer = self.sample_writer_class(