MPlay Batch

Batch write sequences from MPlay

View the Project on GitHub

MPlay Batch

Menu add-on for MPlay to quickly batch write sequences.

MPlay Batch Menu

Quick Installation

  1. Download and extract into mplay_batch
  2. Copy the entire mplay_batch folder to $HOUDINI_USER_PREF_DIR/packages
  3. Copy mplay_batch.json to $HOUDINI_USER_PREF_DIR/packages

Installation Filesystem Example

And you’re all set!


MPlay (the built-in tool for reviewing flipbooks) comes with a really useful feature for reviewing sequences, called the Sequence List. If you’re not familiar, if you click the filmstrip icon Filmstrip
Icon instead of hitting esc or the little red x, MPlay will start writing a new sequence to memory, while keeping the previous one available for viewing and comparison.

Sequence List Only

However, if you want to save the sequences out, it can be a little tedious doing them one by one! That’s where MPlay Batch comes in.

Read more about the Sequence List here.


Save Current Sequence

Saves the currently selected sequence to a directory.

Save Current Sequence

Save All Sequences

Saves all loaded sequences to a directory.

Save All Sequences

Export Video

Export Video

When this option is enabled, a video will be exported for each sequence you save instead of an image sequence.

A sequence of images is always written to disk. ffmpeg is used to convert the image sequence to a video, after which the image sequence is deleted.

Keep Image Sequence (Video)

When Keep Image Sequence (Video) is toggled on, the image sequence that was used to create the video is not deleted, and will remain in the same folder alongside the video.

You can specify the video format using the MPLAY_BATCH_VIDEO_FORMAT key if you’d like to use something other than the default mp4.

Note ffmpeg must be installed an available on the system’s PATH. If ffmpeg can’t be found, an image sequence will still be written, but no video will be exported, even if the option is toggled on.

Open Flipbook Directory

Launches the system’s file browser and navigates to the base flipbook directory (as set by MPLAY_BATCH_FLIPBOOK_DIR)

Open Flipbook Directory

By default, each sequence is saved like this:


Naming Breakdown

Example: Naming

So if you’re working in a hipfile called myproj_sickexplosion_v002.hip, and you ran Save Current Sequence for the first time, it would be saved as:


Each time you run Save Current Sequence, a new SUB_VERSION folder is created inside the FLIPBOOK_DIR. This helps keep subsequent writes unique.

New Sub-Version Directory

When running Save All Sequences, all sequences loaded in memory are written to disk inside of a single SUB_VERSION folder. Each sequence has a unique SEQUENCE_INDEX suffix appended to it. In general, they should write to disk in the same order they were written, however this is not guaranteed.

Multiple Sequence Save Result


Installation is easy using Houdini Packages.

You can copy this entire folder to anywhere that packages are scanned for. Easiest is probably in your HOUDINI_USER_PREF_DIR/packages folder. Once you’ve moved it there, just copy/move the package file mplay_batch.json directly into HOUDINI_USER_PREF_DIR/packages. The package is set up by default for this configuration.

Custom Installation Location

If you’d like to keep this package somewhere else, simply modify the MPLAY_BATCH_INSTALL_DIR key to something else, ie "$HOME/dev/mplay_batch" or "C:/Users/James/houdini_tools/mplay_batch". Just make sure that the mplay_batch.json file lives in a packages folder that Houdini will scan.

If you’re having any issues with setting up in an $HSITE, you can try checking out this post on the SideFX Forums.

Installing to an $HSITE Demo

As an example, a here is a demo of how I have set it up using my own $HSITE at home:

I do not claim that this is the only way, or even the best way. But it is a way.

For more info on $HSITE, see the docs.

  1. $HSITE is set in my environment to $HOME/dev/hsite

    HSITE variable on Windows

  2. Inside the $HSITE, there are folders for each Houdini Major.Minor version, as well as an external folder and a packages folder.

    Personal HSITE

    external serves as a location to dump any and all 3rd party plugins.


    packages contains packages that load the plugins according to the Houdini version that was launched.


  3. Inside of each $HSITE/houdiniMajor.Minor folder, there is a packages directory with a very simple package called packages.json (it can be called whatever you want).

    Inside HoudiniMajor.Minor

    The package just contains:

        "package_path": "$HSITE/packages"

    package_path is a special keyword that allows you to dynamically add other paths in which Houdini can scan for packages. If you prefer to set this at the system/environment level, you can also check out the HOUDINI_PACKAGE_DIR variable.

  4. $HSITE/packages contains the mplay_batch.json package. The only modifcation is that the MPLAY_BATCH_INSTALL_DIR key is now $HSITE/external/mplay_batch.

    By default, the package uses the houdini_version keyword to ensure the correct version of the tool is loaded for whatever version of Houdini was launched.

     "env": [
             "MPLAY_BATCH_INSTALL_DIR": "$HSITE/external/mplay_batch"

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There are a few parameters that can be customized via environment variables. The easiest place to set these would be in the package itself, though as long as they’re set somewhere (system variables, .bashrc, etc) they should be fine.


Environment Variable Default Description
MPLAY_BATCH_FLIPBOOK_DIR $JOB/flip1 Where sequences get saved
MPLAY_BATCH_EXTENSION jpg Image type to save
MPLAY_BATCH_PAD_SUB_VERSION 3 Zero Padding to add to the “Sub-version” suffix
MPLAY_BATCH_PAD_SEQ_INDEX 0 Zero Padding to add to each sequence’s suffix
MPLAY_BATCH_VIDEO_FORMAT mp4 Format to use with ffmpeg when writing videos

1 $JOB/flip is the default naming when creating a project using Houdini’s built-in File > New Project dialog.

Custom Variables, $JOB, $HIP, etc.

To use custom variables in the file pattern for MPLAY_BATCH_FLIPBOOK_DIR, just wrap it in __ instead of starting with $.

Example: Use a built-in Houdini Variable

Use $HIP/flipbooks as the default saving location:


Example: Editing the Package File

Here are some examples you can add to the env key in the package file:

		"MPLAY_BATCH_FLIPBOOK_DIR": "__JOB__/renders/flipbook"

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