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Trying to get to grips with the abilities of blender when used purely as a python library (without any GUI interactions). (Forgive my lack of knowledge and misuse of words)

The code examples and documentation I am finding seem geared towards scripts to apply when content is already present within the blender GUI. (e.g. Extract sequence of frames from imported MP4 - scripted?)

Does an example exist in documentation for loading external files into a blender virtual stage? e.g. 1 picture node and 1 video node and (secondarily) exporting the rendered output (e.g. video with an image overlaid) as an image sequence.

I've been looking through https://www.blender.org/api/blender_python_api_2_72_release/info_quickstart.html and http://wiki.blender.org/index.php/Dev:Py/Scripts but I haven't been able so far to find a good starting point for my knowledge level.

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OhNoez Woez
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  • For a simple conversion from video files to image sequences consider using ffmpeg. –  Feb 09 '16 at 16:52

1 Answers1

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This script accepts the movie file and output directory as command line arguments, then loads the video file as a video sequence editor (VSE) clip and renders it out as frames (by default as PNG, change if needed).

It automatically sets the render resolution and frame duration according to the video file.

import bpy, sys

# Take movie clip filepath and output directory as command line arguments
movieFilePath, OutputPath = sys.argv[-2:]

S  = bpy.context.scene
mc = bpy.data.movieclips.load( movieFilePath )

# Set render resolution to match movie clip
S.render.resolution_x          = mc.size[0]
S.render.resolution_y          = mc.size[1]
S.render.resolution_percentage = 100

# Set number of frames to match movie clip length
S.frame_start = 0
S.frame_end   = mc.frame_duration

# Set render format and output folder
S.render.image_settings.file_format = 'PNG'
S.render.filepath                   = OutputPath

# Load clip to sequencer
se = bpy.context.scene.sequence_editor_create()
se.sequences.new_clip( "MyClip", mc, 0, 0 )

# Render animation to create image sequence
bpy.ops.render.render( animation = True, write_still = True )

To use it, save the script file, then run blender from the command line and provide the filepath and output directory as arguments:

blender -b -P movie_to_images.py -- C:/MyMovie.avi C:/OutputFolder/
TLousky
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  • How would I go about overlaying the current frame number onto the sequence? (apologies if I shouldn't be asking follow up questions in comments) – OhNoez Woez Feb 09 '16 at 12:41
  • In blender 2.76 there are new "text" effect strips in the Video Sequence Editor. You can add these for each frame with the frame number as the text. You can see good examples of this in use in the textSync addon: http://www.blendernation.com/2016/02/04/textsync2d3d-enhanced-subtitling-in-blender/ – TLousky Feb 09 '16 at 12:58
  • do the command line arguments expect a blend file? Should I be using a different blender executable? This is the output 
    blender -b test.py Sockets.mp4 ~/out
found bundled python: /Applications/blender.app/Contents/MacOS/../Resources/2.76/python
read blend: .../test.py
Error: Failed to read blend file '.../test.py', not a blend file

Blender quit
`
    – OhNoez Woez Feb 09 '16 at 16:08
  • Yeah, and another parameter. Forgot! Edited answer to reflect the necessary changes. – TLousky Feb 09 '16 at 16:08
  • Does the blend file need to contain anything? – OhNoez Woez Feb 09 '16 at 16:10
  • Nope, it can be completely empty. – TLousky Feb 09 '16 at 16:10
  • Let us continue this discussion in chat. – OhNoez Woez Feb 09 '16 at 16:13
  • @OhNoezWoez - found the issues and fixed 'em. Have a go at the updated script. – TLousky Feb 09 '16 at 16:46