#91 Native support for SACD ISO images in UltraISO ISZ format

[duckrubbert]

Hello Maxim,

Could you consider adding native support for SACD ISO images stored in the UltraISO .isz format?

The desired behavior would be to open an SACD ISZ directly in foobar2000, without first extracting it back to a full ISO, or mounting in virtual drive.

I tested this with an SACD ISO compressed to ISZ using UltraISO. After mounting the resulting ISZ with DAEMON Tools, foobar2000 was able to read it as a normal SACD ISO from the virtual drive. But, this worked with old foo_input_sacd version 1.3.7. (In version 2.0.25, i had an crash).

I also verified that the ISZ compression is lossless: after extracting the ISZ back to ISO, the MD5 checksum was identical to that of the original ISO.

Some observations from my tests:

An SACD ISO containing DSD audio compressed to approximately 60% of the original ISO size using UltraISO's Heavy Compression setting.
But, an SACD ISO containing already-compressed DST streams (including 2.0- and 5.0-channel DST) compressed very poorly: the resulting ISZ was approximately 99% of the original ISO size, i.e. practically the same size as the source ISO.
Therefore, ISZ seems particularly useful for SACD ISOs containing DSD rather than already-compressed DST.

I have not found an existing Feature Request for ISZ support in the SACD Decoder project.

Thank you for considering this feature.