diff --git a/README.md b/README.md
index 7c20a9d..cfa8b49 100644
--- a/README.md
+++ b/README.md
@@ -24,8 +24,8 @@ end
 Read from a file:
 
 ```elixir
-r = Xav.new_reader!("./some_mp4_file.mp4")
-{:ok, %Xav.Frame{} = frame} = Xav.next_frame(r)
+r = Xav.Reader.new!("./some_mp4_file.mp4")
+{:ok, %Xav.Frame{} = frame} = Xav.Reader.next_frame(r)
 tensor = Xav.Frame.to_nx(frame)
 Kino.Image.new(tensor)
 ```
@@ -33,8 +33,8 @@ Kino.Image.new(tensor)
 Read from a camera:
 
 ```elixir
-r = Xav.new_reader!("/dev/video0", device?: true)
-{:ok, %Xav.Frame{} = frame} = Xav.next_frame(r)
+r = Xav.Reader.new!("/dev/video0", device?: true)
+{:ok, %Xav.Frame{} = frame} = Xav.Reader.next_frame(r)
 tensor = Xav.Frame.to_nx(frame)
 Kino.Image.new(tensor)
 ```
@@ -42,7 +42,7 @@ Kino.Image.new(tensor)
 Speech to text:
 
 ```elixir
-r = Xav.new_reader!("../sample.mp3", read: :audio)
+r = Xav.Reader.new!("../sample.mp3", read: :audio)
 
 {:ok, whisper} = Bumblebee.load_model({:hf, "openai/whisper-tiny"})
 {:ok, featurizer} = Bumblebee.load_featurizer({:hf, "openai/whisper-tiny"})
@@ -57,8 +57,8 @@ serving =
 # read a couple of frames
 frames =
   for _i <- 0..200 do
-    {:ok, frame} = Xav.next_frame(r)
-    Xav.to_nx(frame)
+    {:ok, frame} = Xav.Reader.next_frame(r)
+    Xav.Frame.to_nx(frame)
   end
 
 batch = Nx.Batch.concatenate(frames)
diff --git a/lib/decoder.ex b/lib/decoder.ex
index fed3ba8..1bd4358 100644
--- a/lib/decoder.ex
+++ b/lib/decoder.ex
@@ -3,15 +3,27 @@ defmodule Xav.Decoder do
   Audio/video decoder.
   """
 
+  @typedoc """
+  Supported codecs.
+  """
   @type codec() :: :opus | :vp8
 
   @type t() :: reference()
 
+  @doc """
+  Creates a new decoder.
+  """
   @spec new(codec()) :: t()
   def new(codec) do
     Xav.NIF.new_decoder(codec)
   end
 
+  @doc """
+  Decodes an audio or video frame.
+
+  Video frames are always in the RGB format.
+  Audio samples are always interleaved.
+  """
   @spec decode(t(), binary(), integer(), integer()) :: {:ok, Xav.Frame.t()} | {:error, atom()}
   def decode(decoder, data, pts, dts) do
     case Xav.NIF.decode(decoder, data, pts, dts) do
diff --git a/lib/reader.ex b/lib/reader.ex
index 92d0aa2..a41270b 100644
--- a/lib/reader.ex
+++ b/lib/reader.ex
@@ -1,14 +1,14 @@
 defmodule Xav.Reader do
   @moduledoc """
-  Media reader.
+  Audio/video files reader.
   """
 
   @typedoc """
   Reader options.
 
-  * `read` - determines which stream to read from a file with both audio and video.
+  * `read` - determines which stream to read from a file.
   Defaults to `:video`.
-  * `device?` - determines whether path points to video camera. Defaults to `false`.
+  * `device?` - determines whether path points to the camera. Defaults to `false`.
   """
   @type opts :: [read: :audio | :video, device?: boolean]
 
@@ -28,8 +28,8 @@ defmodule Xav.Reader do
   @doc """
   The same as new/1 but raises on error.
   """
-  @spec new!(String.t(), opts) :: t()
-  def new!(path, opts) do
+  @spec new!(String.t(), opts()) :: t()
+  def new!(path, opts \\ []) do
     case new(path, opts) do
       {:ok, reader} -> reader
       {:error, reason} -> raise "Couldn't create a new reader. Reason: #{inspect(reason)}"
@@ -37,16 +37,16 @@ defmodule Xav.Reader do
   end
 
   @doc """
-  Creates a new media reader.
+  Creates a new audio/video reader.
 
-  Both reading from a file and video camera is supported.
-  In case of video camera, v4l2 driver is required and FPS are 
+  Both reading from a file and from a video camera are supported.
+  In case of using a video camera, the v4l2 driver is required, and FPS are 
   locked to 10.
 
   Microphone input is not supported.
   """
   @spec new(String.t(), opts()) :: {:ok, t()} | {:error, term()}
-  def new(path, opts) do
+  def new(path, opts \\ []) do
     read = opts[:read] || :video
     device? = opts[:device?] || false
 
@@ -80,9 +80,11 @@ defmodule Xav.Reader do
   end
 
   @doc """
-  Reads next frame.
+  Reads the next frame.
 
-  Frame is always decoded. Video frames are always in RGB format.
+  A frame is always decoded. 
+  Video frames are always in the RGB format.
+  Audio samples are always interleaved.
   """
   @spec next_frame(t()) :: {:ok, Xav.Frame.t()} | {:error, :eof}
   def next_frame(%__MODULE__{reader: reader}) do
diff --git a/lib/xav.ex b/lib/xav.ex
deleted file mode 100644
index 80ab1e7..0000000
--- a/lib/xav.ex
+++ /dev/null
@@ -1,20 +0,0 @@
-defmodule Xav do
-  @moduledoc """
-  Main module for interacting with `Xav`.
-
-  `Xav` is an Elixir wrapper over FFmpeg intended for
-  reading file and network based media streams.
-
-  It doesn't map FFmpeg functions one to one but rather
-  wraps them in bigger building blocks creating a litte
-  higher abstraction level.
-  """
-
-  defdelegate new_reader!(path, opts \\ []), to: Xav.Reader, as: :new!
-
-  defdelegate new_reader(path, opts \\ []), to: Xav.Reader, as: :new
-
-  defdelegate next_frame(reader), to: Xav.Reader
-
-  defdelegate to_nx(frame), to: Xav.Frame
-end
diff --git a/test/reader_test.exs b/test/reader_test.exs
new file mode 100644
index 0000000..047441b
--- /dev/null
+++ b/test/reader_test.exs
@@ -0,0 +1,53 @@
+defmodule Xav.ReaderTest do
+  use ExUnit.Case, async: true
+
+  test "new/1" do
+    assert {:ok, %Xav.Reader{}} = Xav.Reader.new("./test/fixtures/sample_h264.mp4")
+    assert {:error, _reason} = Xav.Reader.new("non_existing_input")
+  end
+
+  test "new!/1" do
+    %Xav.Reader{} = Xav.Reader.new!("./test/fixtures/sample_h264.mp4")
+    assert_raise RuntimeError, fn -> Xav.Reader.new!("non_existing_input") end
+  end
+
+  test "next_frame/1" do
+    {:ok, r} = Xav.Reader.new("./test/fixtures/sample_h264.mp4")
+    # test reading 5 seconds
+    for _i <- 0..(30 * 5), do: assert({:ok, %Xav.Frame{}} = Xav.Reader.next_frame(r))
+  end
+
+  # @tag :debug
+  # test "next_frame/1 audio" do
+  #   {:ok, r} = Xav.Reader.new("./test/fixtures/sample.mp3", read: :audio)
+
+  #   for _i <- 0..5 do
+  #     assert({:ok, %Xav.Frame{} = frame} = Xav.Reader.next_frame(r))
+  #     IO.inspect({byte_size(frame.data), frame})
+  #   end
+  # end
+
+  test "to_nx/1" do
+    {:ok, r} = Xav.Reader.new("./test/fixtures/sample_h264.mp4")
+    {:ok, frame} = Xav.Reader.next_frame(r)
+    %Nx.Tensor{} = Xav.Frame.to_nx(frame)
+  end
+
+  test "eof" do
+    {:ok, r} = Xav.Reader.new("./test/fixtures/one_frame.mp4")
+    {:ok, _frame} = Xav.Reader.next_frame(r)
+    {:error, :eof} = Xav.Reader.next_frame(r)
+  end
+
+  @formats [{"h264", "h264"}, {"h264", "mkv"}, {"vp8", "webm"}, {"vp9", "webm"}, {"av1", "mkv"}]
+  Enum.map(@formats, fn {codec, container} ->
+    name = "#{codec} #{container}"
+    file = "./test/fixtures/sample_#{codec}.#{container}"
+
+    test name do
+      {:ok, r} = Xav.Reader.new(unquote(file))
+      # test reading 5 seconds
+      for _i <- 0..(30 * 5), do: assert({:ok, %Xav.Frame{}} = Xav.Reader.next_frame(r))
+    end
+  end)
+end
diff --git a/test/xav_test.exs b/test/xav_test.exs
deleted file mode 100644
index cac020b..0000000
--- a/test/xav_test.exs
+++ /dev/null
@@ -1,53 +0,0 @@
-defmodule XavTest do
-  use ExUnit.Case
-  doctest Xav
-
-  test "new_reader/1" do
-    assert {:ok, %Xav.Reader{}} = Xav.new_reader("./test/fixtures/sample_h264.mp4")
-    assert {:error, _reason} = Xav.new_reader("non_existing_input")
-  end
-
-  test "new_reader!/1" do
-    %Xav.Reader{} = Xav.new_reader!("./test/fixtures/sample_h264.mp4")
-    assert_raise RuntimeError, fn -> Xav.new_reader!("non_existing_input") end
-  end
-
-  test "next_frame/1" do
-    {:ok, r} = Xav.new_reader("./test/fixtures/sample_h264.mp4")
-    # test reading 5 seconds
-    for _i <- 0..(30 * 5), do: assert({:ok, %Xav.Frame{}} = Xav.next_frame(r))
-  end
-
-  # @tag :debug
-  # test "next_frame/1 audio" do
-  #  {:ok, r} = Xav.new_reader("./test/fixtures/sample.mp3", false)
-  #  for _i <- 0.. 5 do
-  #    assert({:ok, %Xav.Frame{}=frame} = Xav.next_frame(r))
-  #    IO.inspect({byte_size(frame.data), frame})
-  #  end
-  # end
-
-  test "to_nx/1" do
-    {:ok, r} = Xav.new_reader("./test/fixtures/sample_h264.mp4")
-    {:ok, frame} = Xav.next_frame(r)
-    %Nx.Tensor{} = Xav.Frame.to_nx(frame)
-  end
-
-  test "eof" do
-    {:ok, r} = Xav.new_reader("./test/fixtures/one_frame.mp4")
-    {:ok, _frame} = Xav.next_frame(r)
-    {:error, :eof} = Xav.next_frame(r)
-  end
-
-  @formats [{"h264", "h264"}, {"h264", "mkv"}, {"vp8", "webm"}, {"vp9", "webm"}, {"av1", "mkv"}]
-  Enum.map(@formats, fn {codec, container} ->
-    name = "#{codec} #{container}"
-    file = "./test/fixtures/sample_#{codec}.#{container}"
-
-    test name do
-      {:ok, r} = Xav.new_reader(unquote(file))
-      # test reading 5 seconds
-      for _i <- 0..(30 * 5), do: assert({:ok, %Xav.Frame{}} = Xav.next_frame(r))
-    end
-  end)
-end