Fallback to native implementations

[andreas-eriksson]

Would it be possible to automatically fallback to native codecs in the library on Windows computers that does not have the Media Feature Pack installed?

[saucecontrol]

I'm not sure I fully understand the ask. You can basically achieve that today by registering the additional native codecs with removeExisting: false.

By default, all Microsoft-published WIC codecs will be registered first on Windows, before the CodecManager.Configure action runs. With removeExisting: false on plugin registration, they will leave the WIC mapping in place and add their own mappings after, leaving WIC with higher priority.

[andreas-eriksson]

Does it always register the WIC codecs on Windows or does MagicScaler check if the Media Feature Pack is available?

I currently have the following check to see if it is installed so that I can then register native codecs.

internal static bool MediaFeaturePackExists()
{
    using var hklm = RegistryKey.OpenBaseKey(RegistryHive.LocalMachine, RegistryView.Registry64);
    using var key = hklm.OpenSubKey(@"SOFTWARE\Microsoft\Windows\CurrentVersion\Setup\WindowsFeatures\WindowsMediaVersion");
    return key != null;
}

[andreas-eriksson]

I think I have misunderstood how things work. I had a browse through the source and WIC codecs are only added if they are available.

PhotoSauce/src/MagicScaler/Codecs/CodecManager.cs

Line 291 in fa68cdc

cc.UseWicCodecs(WicCodecPolicy.BuiltIn);

This makes it easier for me as I can the do what you proposed and always add the native codecs as well.

[saucecontrol]

That's correct. The WIC codecs are treated as plugins to the pipeline -- they're just registered automatically for convenience. UseWicCodecs enumerates the codecs installed in WIC (through the registry), so there's no need to do your own check for installation of the media pack.

For reference, the codec collection passed to the ConfigureCodecs action will contain anything registered by UseWicCodecs. You are free to examine that collection and make whatever changes you like before the collection is locked in by the pipeline after the action completes.