pandemonium_engine_docs/tutorials/animation/playing_videos.rst

.. _doc_playing_videos:

Playing videos
==============

Godot supports video playback with the :ref:`class_VideoPlayer` node.

Supported playback formats
--------------------------

The only supported format in core is **Ogg Theora** (not to be confused with Ogg
Vorbis audio). It's possible for extensions to bring support for additional
formats, but no such extensions exist yet as of July 2022.

H.264 and H.265 cannot be supported in core Godot, as they are both encumbered
by software patents. AV1 is royalty-free, but it remains slow to decode on the
CPU and hardware decoding support isn't readily available on all GPUs in use
yet.

WebM is supported in core in Godot 3.x, but support for it will be removed in 4.0
as it proved to be too buggy and difficult to maintain.
Therefore, **using WebM is not recommended**.

.. note::

    You may find videos with an ``.ogg`` or ``.ogx`` extensions, which are generic
    extensions for data within an Ogg container.

    Renaming these file extensions to ``.ogv`` *may* allow the videos to be
    imported in Godot. However, not all files with ``.ogg`` or ``.ogx``
    extensions are videos - some of them may only contain audio.

Setting up VideoPlayer
----------------------------

1. Create a VideoPlayer node using the Create New Node dialog.
2. Select the VideoPlayer node in the scene tree dock, go to the inspector
   and load an ``.ogv`` file in the Stream property.

   - If you don't have your video in Ogg Theora format yet, jump to
     :ref:`doc_playing_videos_recommended_theora_encoding_settings`.

3. If you want the video to play as soon as the scene is loaded, check
   **Autoplay** in the inspector. If not, leave **Autoplay** disabled and call
   ``play()`` on the VideoPlayer node in a script to start playback when
   desired.

Handling resizing and different aspect ratios
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

By default in Godot 4.0, the VideoPlayer will automatically be resized to match
the video's resolution. You can make it follow usual :ref:`class_Control` sizing
by enabling **Expand** on the VideoPlayer node.

To adjust how the VideoPlayer node resizes depending on window size,
adjust the anchors using the **Layout** menu at the top of the 2D editor
viewport. However, this setup may not be powerful enough to handle all use
cases, such as playing fullscreen videos without distorting the video (but with
empty space on the edges instead). For more control, you can use an
:ref:`class_AspectRatioContainer` node, which is designed to handle this kind of
use case:

Add an AspectRatioContainer node. Make sure it is not a child of any other
container node. Select the AspectRatioContainer node, then set its **Layout** at
the top of the 2D editor to **Full Rect**. Set **Ratio** in the
AspectRatioContainer node to match your video's aspect ratio. You can use math
formulas in the inspector to help yourself. Remember to make one of the operands
a float. Otherwise, the division's result will always be an integer.

.. figure:: img/playing_videos_aspect_ratio_container.png
   :figclass: figure-w480
   :align: center
   :alt: AspectRatioContainer's Ratio property being modified in the editor inspector

   This will evaluate to (approximately) 1.777778

Once you've configured the AspectRatioContainer, reparent your VideoPlayer
node to be a child of the AspectRatioContainer node. Make sure **Expand** is
disabled on the VideoPlayer. Your video should now scale automatically
to fit the whole screen while avoiding distortion.

.. seealso::

    See :ref:`doc_multiple_resolutions` for more tips on supporting multiple
    aspect ratios in your project.

Displaying a video on a 3D surface
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Using a VideoPlayer node as a child of a :ref:`class_Viewport` node,
it's possible to display any 2D node on a 3D surface. For example, this can be
used to display animated billboards when frame-by-frame animation would require
too much memory.

This can be done with the following steps:

1. Create a :ref:`class_Viewport` node. Set its size to match your video's size
   in pixels.
2. Create a VideoPlayer node *as a child of the Viewport node* and specify
   a video path in it. Make sure **Expand** is disabled, and enable **Autoplay** if needed.
3. Create a MeshInstance node with a PlaneMesh or QuadMesh resource in its Mesh property.
   Resize the mesh to match the video's aspect ratio (otherwise, it will appear distorted).
4. Create a new SpatialMaterial resource in the **Material Override** property
   in the GeometryInstance section.
5. Enable **Local To Scene** in the SpatialMaterial's Resource section (at the bottom).
   This is *required* before you can use a ViewportTexture in its Albedo Texture property.
6. In the SpatialMaterial, set the **Albedo > Texture** property to **New ViewportTexture**.
   Edit the new resource by clicking it, then specify the path to the Viewport node
   in the **Viewport Path** property.
7. Enable **Albedo Tex Force sRGB** in the SpatialMaterial to prevent colors
   from being washed out.
8. If the billboard is supposed to emit its own light, enable
   **Flags > Unshaded** to improve rendering performance.

See :ref:`doc_viewports` and the
`GUI in 3D demo <https://github.com/godotengine/godot-demo-projects/tree/master/viewport/gui_in_3d>`__
for more information on setting this up.

Video decoding conditions and recommended resolutions
-----------------------------------------------------

Video decoding is performed on the CPU, as GPUs don't have hardware acceleration
for decoding Theora videos. Modern desktop CPUs can decode Ogg Theora videos at
1440p @ 60 FPS or more, but low-end mobile CPUs will likely struggle with
high-resolution videos.

To ensure your videos decode smoothly on varied hardware:

- When developing games for desktop platforms, it's recommended to encode in
  1080p at most (preferably at 30 FPS). Most people are still using 1080p or
  lower resolution displays, so encoding higher-resolution videos may not be
  worth the increased file size and CPU requirements.
- When developing games for mobile or web platforms, it's recommended to encode
  in 720p at most (preferably at 30 FPS or even lower). The visual difference
  between 720p and 1080p videos on a mobile device is usually not that
  noticeable.

Playback limitations
--------------------

There are several limitations with the current implementation of video playback in Godot:

- Seeking a video to a certain point is not supported.
- Changing playback speed is not supported. VideoPlayer also won't follow
  :ref:`Engine.time_scale<class_Engine_property_time_scale>`.
- Looping is not supported, but you can connect a VideoPlayer's
  :ref:`finished <class_VideoPlayer_signal_finished>` signal to a function
  that plays the video again. However, this will cause a black frame to be
  visible when the video restarts. This can be worked around by adding a fade to
  black in the video file before the video ends, or by hiding the video for one
  frame and displaying a TextureRect with a screenshot of the first frame of the
  video until the video is restarted.
- Streaming a video from a URL is not supported.

.. _doc_playing_videos_recommended_theora_encoding_settings:

Recommended Theora encoding settings
------------------------------------

A word of advice is to **avoid relying on built-in Ogg Theora exporters** (most of the time).
There are 2 reasons you may want to favor using an external program to encode your video:

- Some programs such as Blender can render to Ogg Theora. However, the default
  quality presets are usually very low by today's standards. You may be able to
  increase the quality options in the software you're using, but you may find
  the output quality to remain less than ideal (given the increased file size).
  This usually means that the software only supports encoding to constant bit
  rate (CBR), instead of variable bit rate (VBR). VBR encoding should be
  preferred in most scenarios as it provides a better quality to file size
  ratio.
- Some other programs can't render to Ogg Theora at all.

In this case, you can **render the video to an intermediate high-quality format**
(such as a high-bitrate H.264 video) then re-encode it to Ogg Theora. Ideally,
you should use a lossless or uncompressed format as an intermediate format to
maximize the quality of the output Ogg Theora video, but this can require a lot
of disk space.

`HandBrake <https://handbrake.fr/>`__
(GUI) and `FFmpeg <https://ffmpeg.org/>`__ (CLI) are popular open source tools
for this purpose. FFmpeg has a steeper learning curve, but it's more powerful.

Here are example FFmpeg commands to convert a MP4 video to Ogg Theora. Since
FFmpeg supports a lot of input formats, you should be able to use the commands
below with almost any input video format (AVI, MOV, WebM, …).

.. note::

   Make sure your copy of FFmpeg is compiled with libtheora and libvorbis support.
   You can check this by running ``ffmpeg`` without any arguments, then looking
   at the ``configuration:`` line in the command output.

Balancing quality and file size
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The **video quality** level (``-q:v``) must be between ``1`` and ``10``. Quality
``6`` is a good compromise between quality and file size. If encoding at a high
resolution (such as 1440p or 4K), you will probably want to decrease ``-q:v`` to
``5`` to keep file sizes reasonable. Since pixel density is higher on a 1440p or
4K video, lower quality presets at higher resolutions will look as good or
better compared to low-resolution videos.

The **audio quality** level (``-q:a``) must be between ``-1`` and ``10``. Quality
``6`` provides a good compromise between quality and file size. In contrast to
video quality, increasing audio quality doesn't increase the output file size
nearly as much. Therefore, if you want the cleanest audio possible, you can
increase this to ``9`` to get *perceptually lossless* audio. This is especially
valuable if your input file already uses lossy audio compression. See
`this page <https://wiki.hydrogenaud.io/index.php?title=Recommended_Ogg_Vorbis#Recommended_Encoder_Settings>`__
for a table listing Ogg Vorbis audio quality presets and their respective
variable bitrates.

FFmpeg: Convert while preserving original video resolution
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The following command converts the video while keeping its original resolution.
The video and audio's bitrate will be variable to maximize quality while saving
space in parts of the video/audio that don't require a high bitrate (such as
static scenes).

::

    ffmpeg -i input.mp4 -q:v 6 -q:a 6 output.ogv

FFmpeg: Resize the video then convert it
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The following command resizes a video to be 720 pixels tall (720p), while
preserving its existing aspect ratio. This helps decrease the file size
significantly if the source is recorded at a higher resolution than 720p:

::

    ffmpeg -i input.mp4 -vf "scale=-1:720" -q:v 6 -q:a 6 output.ogv