Checking .blend metadata to see if it was created in 2.8?

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1

How do I know before opening a .blend file which version it was created in?

Or is there metadata available I may access prior to attempting to open a .blend file?

I ask because I need to know which version of Blender I should supply as the path to open a .blend from a subprocess call:

allBlendFiles = glob.glob1(dest_directory, "*.blend") #get all .blends in a dir
blendFile = allBlendFiles[0] #for simplicity, just use the first .blend
src_directory = os.path.join(dest_directory, blendFile)#abs path to the .blend

LEGACY_MODE = blendFile.meta???.version < (2, 80, 0) #HOW CAN ACCESS VERSION OF .blend FILE?

if LEGACY_MODE:
    #Path to Blender 2.79
    blenderRuntimePath = r"C:\Program Files\Blender Foundation\Blender\blender.exe",
else:
    #Path to Blender 2.8
    blenderRuntimePath = r"C:\Program Files\Blender Foundation\Blender28\blender.exe",

subprocess.check_call([
    blenderRuntimePath, #THIS PATH CHANGES BASED ON THE VERSION OF .blend IT IS OPENING
    src_directory,
    r"--background",
    r"--python",
    r"C:\Projects\Automation\BuildCharacter.py"
])

Thanks

2

Yes, it’s possible, you can do it by hand, or by means of something like file command (common in Unix). Uncompressed files always start with ASCII bytes “BLENDER”, two bytes (32/64 bits and endianess markers), then 3 bytes that store version in ASCII. Examples “BLENDER-v264” or “BLENDER-v280”.

Using file magic tools should make it easier with compressed files (file -z example.blend), otherwise you have to uncompress yourself and examine the result as above. Python’s filemagic wraps libmagic, but quick read of docs makes no mention of compression support.

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3

You are correct, how naive of me not to open one with a .txt editor :sweat_smile:

Anyways, just as you suggest after inspecting with txt editor I see the first few bytes of the file as ASCII:
BLENDER-v279RENDH -or- BLENDER-v280RENDH

Very simple, Thank you!!

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4

Beware, REND is really common (chunk headers are 4 bytes, H is “data”), but not always there, I have one example starting as “BLENDER-v279GLOB” and remember seeing “TEST” too. The part you want is just up to the 3 numbers (first 12 bytes).

You may want to check doc/blender_file_format/BlendFileReader.py, BTW. Some parts are what you want, ignore the rest.

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