Differences between SACD ISO vs DSF(DIFF)


#1

I use JRiver MC19.

I have multi channels DSF files extracted from SACD ISO via sacd_extract. When these files are placed in JRiver, the DSF file size is as much as 2.5x the size of ISO for the same single song. Obviously ISO is a compressed format.

But what shocks me most is I can actually notice an obvious difference in sound quality between SACD ISO and its DSF. I can’t say which is of better quality but the difference is very obvious.

Has anyone out there share this same observation ?


#2

Welcome, daviddich!

Under the SACD specification, multi-channel DFF tracks are required to be compressed using DST, a lossless compression format. The compression factor is roughly 2.5:1. When you converted to DSF, you uncompressed the files and thus they are bigger by that amount.

Unless there was a problem decompressing/converting the files or with your player they should sound identical.


#3

As Elk mentioned iso’s are compressed. But there’s a remote chance that you are accidentally playing the front left and front right out of the multichannel section of the ISO instead of the stereo section. Double check that in JRiver MC (I add a channels column to all of my views.)

Anyway in iso’s the multichannel sections are compressed (using DST) and empirically about 1/2 of my iso’s also have the stereo section compressed. Doing the decompression uses significant CPU power. Some systems are more sensitive to the CPU load than others when playing. Unfortunately there are a “billion” things that can contribute to this so (if you care) you might need to visit some places like the Computer Audiophile (http://www.computeraudiophile.com) or the Computer Audio Asylum (http://www.audioasylum.com/cgi/tv.mpl?forum=pcaudio) for some insight or advice. There are also some threads here with some things that people have done.


#4

Hi Ted

I have a few ISO files that I’ve converted to dsf n dff. So now I have [ in my storage} the 2 channel as well as the multi channel files that take up tons of space.

Can I just trash or archive the multi dsf/dff files without any effect on the remaining 2 channel ones? Logic says YES but I would hate to have to start all over again.

G


#5

Yes. the multichannel files are completely independent from the stereo files.


#6

Thanx

I figured so but thought I would check with a real expert.

So since some ISO files come with only 2 channel, must the combined ones be converted to extract the multi files to save space?


#7

SACDs (and hence ISOs from SACDs) can have up to three “sections”, CD audio, SACD stereo, SACD multichannel. To be an SACD it has to have, well, SACD music. I know of no multichannel only SACDs, there are plenty of stereo only SACDs and also plenty of SACDs with no redbook layer.

When a SACD has both stereo and multichannel often (but not always) they have the same program. Some may have bonus tracks in stereo, multichannel or both.

Multichannel is always compressed with DST, typically at about 2:1. The stereo may also be compressed with DST.

If you are going to delete/erase the MC material then at one extreme you may go from individual tracks taking two times the space that the ISO uses (from a compressed stereo only iso, I don’t know why but they do exist) to the other extreme of individual tracks taking about 1/4 the ISO space for a disk which had uncompressed stereo and multichannel tracks.

Personally I like to keep my music in the original format, but I understand that people may have other concerns/issues.


#8

Deutsche Grammophon issued a series of SACD’s under the Eloquence sublabel which had CD Stereo and SACD MC and no SACD Stereo.


#9

Welcome, DrPSARenaud!

An interesting bit of information.