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audiocodecs

Anonymous (anonymous@undisclosed.example.com) — 2026-01-22T11:06:08+00:00

Audio Codec Conversions

1.0 Convert between Audio Formats

Semplice's Audio Processing menu, Option 2 allows you to convert from ten input formats to seven possible output formats, four of which are lossless and three of which are lossy. A common use for this functionality is to non-destructively convert a bunch of FLACs into a much smaller bunch of MP3s for use on an SD card to be played in the car on a long journey, for example. Another use I have for this capability is to convert the ISOs that are produced by ripping an SACD into a bunch of FLACs that I can actually listen to with the Giocoso music player.

I should just clarify, too, that when I say there are “four lossless” output formats, three of them are all FLAC, just at different bit-depths and sample rates. You have your 16-bit 44.1KHz CD-Audio standard FLACs; a 24-bit, 88.2KHz high resolution FLAC; and a 24-bit, 176.4KHz super high resolution FLAC. The fourth lossless format is AIFF (the Audio Interchange File Format).

2.0 Configuration Options

The three lossy output formats are provided to allow you to generate music files which are much smaller than FLACs would be, but still have acceptable audio quality (or, at least, acceptable for noisy environments, such as cars, trains and planes!) They achieve their small output file sizes by literally throwing away audio data: that loss of data is exactly what makes them “lossy”. Ideally, the data they throw away is stuff a normal human ear couldn't discern anyway: super high frequencies, for example, or a gently plucked harp string hidden behind an almighty cymbal crash: the aim to is to output something that still sounds decent to most people but which doesn't pretend to be a perfect representation of the input source.

All lossy codecs can be configured to be aggressive or conservative about their lossiness. That is, you can generally switch on something that makes them favour smaller file sizes over audio quality, or vice versa. Semplice is configured by default to output at “average” audio quality, regardless of which lossy output codec is selected, that is about the middle ground in the fight between file size and audio fidelity: this is controlled by the configuration parameter (see the Miscellaneous menu, Option 1) Lossy codec quality setting (1-9):

The default value of '4' shown here is about the mid-way point of a 1 to 9 quality scale. That's important, because the quality scale actually works in different directions for MP3s than it does for OGGs or WMAs. In the world of MP3, for example, a quality setting of 9 will result in dreadful audio, but tiny files and a quality setting of 1 will result in near-CD quality audio, but much larger file sizes. On the other hand, the rules are entirely reversed for OGGs and WMAs: for them, a quality of 9 will sound great, and 1 will sound horrible. This weird reversal of 'quality scale' is why Semplice defaults to a setting of 4, which is about in the middle of all lossy codec's quality settings and so applies more-or-less equally to them all. Start altering the quality one way of another, however, and you need to be aware in which direction you're shifting it and what results it will have on your favourite codec outputs!

You will note from the above screenshot, too, that a second configuration parameter affects the way Semplice converts audio: should it Delete the source files after conversion or not? The default answer here is “no”: it means that, once the audio conversion process has finished, both the original files and their converted equivalents will be present on disk, for you to sort out manually at your leisure. If you set this parameter to 'yes', however, then the source files are automatically deleted after conversion, leaving only the newly-converted outputs.

There is an important exception to this 'delete input sources automatically' setting, however: if you convert ISOs to anything at all, the source ISO is never deleted after conversion. ISOs are entire SACD images, so deleting them is a big event… so big, indeed, that sorting them out is always left for you to do yourself!

3.0 Converting Audio

The audio conversion process only works on a folder full of audio files of one sort or another: as usual, either launch Semplice from within such a folder, or tap the W key after launching the program to select a working folder that contains such files. Tapping the Audio Processing menu, Option 2 then brings up a variant of the following screen:

Here you'll see a list of possible input formats but you'll only see listed those formats that actually exist within the working folder, so it's most unlikely you'll see a long list of formats such as you see above. Rather more likely is this sort of thing:

Now I'm only seeing FLACs listed as an input format because my working folder only contains FLAC files: there's no point offering you WMA as an input format, for example, if no such files exist, after all!

If your working folder contains zero files of a type that Semplice can work with, you'll see this error message instead:

Also be aware that working with ISOs (on Linux platforms) requires the installation of the sacd external program. The installation of this helper program is is something Semplice aims to automate as part of its own installation -but if it failed to install it for some reason, though ISO will still be detected in the working folder and thus displayed on the input format selection list, the program will eventually error out when you go to pick an output format, with the error message mentioning the need to install sacd manually. If that happens to you, the instructions for manually installing sacd on various Linux distros are listed below (see Section 4.0 below). Most new Semplice installs will get the sacd installation correct, however, so you shouldn't need to get down and dirty in those thick weeds!

Anyway, your job is simply to up- and down-arrow until an appropriate input format is highlighted and then to hit the [Spacebar] to select it: an asterisk will appear in the brackets to indicate a format has been selected. You can arrow onto another format and hit the [Spacebar] again to change the selection, but only one audio format can be selected at a time. If you are happy with your selection, you can just press [Enter] to confirm it (or click on the [OK] button). If you select the [Cancel] button, you'll be returned to the Audio Processing menu with nothing at all having been modified on your hard disk.

Pressing [Enter] (or clicking [OK]) triggers the display of this screen:

Here you select the output format -that is, the codec you want to use to encode your converted files. Five distinct codecs are provided, though FLAC is offered in three flavours so that there are seven possible options displayed. The three FLAC options are lossless codecs, as is AIFF; MP3, OGG and WMA are all lossy codecs.

For an old person such as myself, there's literally no point in transcoding to either of the high resolution FLAC formats: there's no way I'm ever going to hear the difference between them and standard CD-Audio FLAC. But if you have golden ears or merely wish to preserve as much of the original audio signal ripped off an SACD, for example, then feel free to pick one of the other FLAC formats. Hi-res FLACs will be about four times the size of a standard FLAC; super hi-res FLACs will be about eight times the size.

Be aware that if you are converting from ISO or DSF, you will not be shown the option to output to lossy formats but only to the lossless ones. That's simply a function of what lossy codecs can cope with: the bitrate stored in DSF and ISOs is so high that lossless codecs simply tend to crash when confronted with it. If you really wanted to convert an ISO to, say, an MP3 therefore, you'll have to first convert the ISO to standard FLAC and then do a second conversion of FLAC to MP3. ISOs and DSFs are the only input codecs that have this restriction placed upon them.

Once again, your job is to up- and down-arrow through the list of output formats until the one you want is highlighted and then press [Spacebar] to select it. An asterisk will appear in the brackets next to your selected option. You can change that selection by arrowing to a new format item and pressing the spacebar again but only one output format at a time can be selected.

Once you've selected an output format, press [Enter] or click [OK] and the conversion process will immediately begin:

You'll see a confirmation message at the bottom of the screen, reminding you of your choices of input and output formats, along with a spinner indicating the passage of time and work being done. To help speed up these conversions, Semplice always converts in a parallel-processing mode, with multiple threads -up to the number of CPU cores your PC has available to it- all being put to use simultaneously. After the conversion is complete, you'll simply be returned to the Audio Processing menu.

What you'll see in your file manager will depend on whether you switched on the 'Delete source files' configuration parameter. If you didn't (and let the default apply), you'd see something like this:

You'll notice that there are four FLACs here, along with four 'just now' created MP3s: the source and output files co-exist on disk without drama, and the conversion process has been entirely non-destructive to the originals. You'll notice too, I hope, that the MP3s seem to have embedded album art. If you were to inspect one of them with a tool such as kid3, for example, you'd actually see it's even better than that:

That's to say: if the source files were tagged, the output files will be similarly tagged too. There's no particular guarantee about this, though, as it depends on the vagaries of the codecs involved. Here, for example, I converted FLACs into WMAs:

Not only does the WMA not appear to have any album art, but some of the metadata tags have been doubled up, with occasionally different results: look how ARTIST is in there twice, but with the same metadata each time, whereas the COMMENT tag is in there twice, but once it's blank and only the second occurrence has data in it. The short version is that FLAC-to-anything conversions should generally preserve metadata mostly correctly, but you should always check and be prepared to correct. Lossy-to-something-else conversions are likely to be more problematic still but a lot of the metadata should be preserved, nonetheless.

Anyway, regardless of the specifics of tagging in the output files: if you had instead switched on the option to Delete source files configuration option, your file manager would now only show that the output files exist. The source files would have been automatically deleted, without prior warning or seeking confirmation:

Depending on your choice of output format, however, the surviving file names might look a bit different from the originals. Obviously, if you'd picked MP3, OGG or WMA output formats, the files would now have those extensions attached to the end of their names. More interestingly, however: if you'd picked any of the FLAC output options, the file names (as you see above) would now either have a '16' or a '24' in their file names, indicating whether standard (16-bit) or either of the high resolution (24-bit) FLAC output options were selected. Removing the 'bit-depth indicator' from file names is something you can do, if you want to, by yourself later on. Incidentally, if you were to convert FLAC to HiRes FLAC, you'd obviously end up with original-filename-24.flac. If you were then to perform a second conversion from FLAC to Super Hires FLAC, you might wonder how Semplice would cope, since that would seem to imply creating a new file called original-filename-24.flac, which exactly matches the existing name, and therefore would seem to be impossible. Well, Semplice simply sticks a second bit-depth indicator in the filename, so you'd actually end up with a file called original-filename-24-24.flac, which is a unique name and thus causes no file creation errors. I hasten to add that it makes absolutely no sense to 'up-convert' FLACs in this way! By converting a standard FLAC to a Super Hires one, you add nothing to the audio data in the file: it remains a standard audio signal, just occupying about 8 times as much space as it used to!

Summing up therefore: using a working folder full of audio files, take Audio Processing menu Option 2 and you'll be prompted to select an input and output format. Conversion from the one to the other results in new files being created on disk, but the original files will still be safe in their original format unless you've explicitly configured Semplice to delete them. Lossy codecs have a quality setting that determines the balance between audio fidelity and filesize: the default quality setting is a middling compromise between the two factors, but you can configure a different quality setting if you like. Just be aware that MP3 quality settings work in reverse to those of OGGs or WMAs. If one of the FLAC options is chosen as an output format, the bit-depth of the chosen format will be added to the output files' names. Whilst you can run the audio conversion process multiple times over the same set of files, it is not usually sensible to do so: converting lossy to other lossy formats results in compounded loss of audio fidelity, and converting FLACs to other forms of FLAC adds nothing to the already perfect audio fidelity of the original.

4.0 Manually Installing Sacd

Semplice Version 2 makes an effort to install all its software dependencies automatically, including the sacd program that is needed to convert ISO files ripped from SACDs into WAV files (which Semplice can then convert into other audio formats, of course). Unfortunately, sacd is seldom in the standard software repositories for most Linux distros, so installing it becomes a matter of downloading its source code and then, literally, compiling that into a usable binary executable. That sounds troublesome -and it can certainly be a messy sort of operation if you're not used to it! That's why Semplice tries to automate this compilation process during its own initial installation.

You can test whether Semplice's efforts worked by simply opening a command prompt and typing the command:

sacd

You should see a response similar to this:

If you see that sort of usage help text, it means sacd is installed correctly and functioning properly: you need read no further in this section, therefore!

Try as it might, however, Semplice cannot guarantee that its sacd installation efforts will succeed. If they don't for one reason or another, you will have seen above (Section 3) that subsequent attempts to use Semplice to convert an ISO ripped from an SACD will fail with a warning message about sacd not being available on your PC. If that happens to you and you want to correct it, these are the steps you'd need to take, with the details varying by distro, as you'd probably expect, as follows:

4.1 Arch-based Distros

On Arch, Endeavour, Manjaro, Garuda and similar distros, you can actually install sacd directly from the Arch User Repository (AUR), using a command such as:

yay -S sacd

If you're using pamac or another front-end to the AUR, substitute in an equivalent command as appropriate. In theory, your AUR front-end should ensure all appropriate software dependencies are pulled down for you automatically. The sacd source code will then be compiled into a working binary for you, without any further effort on your part.

4.2 Other Distros

Other distros tend not to have sacd in their standard repositories -and if they do, it's not guaranteed to be the one that Semplice has been written to work with. Therefore, you need to take things in two stages. First, add software to your system to allow it to compile new binaries from source code, like so:

Debian: sudo apt install git cmake binutils pkg-config build-essential python3 python3-dev
Ubuntu: sudo apt install git cmake binutils pkg-config build-essential python3 python3-dev
Fedora: sudo apt install git cmake binutils pkg-config gcc kernel-devel python python-devel
OpenSuse: sudo zypper install -t pattern devel_basis ….followed by…. sudo zypper install cmake python python-devel git

Note that the 'python3-dev' package may have been renamed for your distro: if you get warned that no such package exists, try replacing that name with python3-is-dev.

The second step is accomplished by typing the following sequence of commands into a terminal session:

cd
git clone https://github.com/Sound-Linux-More/sacd.git
cd sacd
make
sudo make install

And that should be that: once sacd has been installed, you can clear up the debris left behind from this entire build process by issuing the commands:

cd
rm -rf sacd

These commands merely remove the source code folders, not the installed, compiled executables. If you type the command sacd at this point, you should see the display of advice on how to run the program properly shown in the first screenshot of this section.

Note that on Ubuntu 22.10, I had to issue one extra command to make the operating system aware of where, precisely, all the shared files that sacd depends on were actually copied to: that distro seems to build things into /usr/lib64 rather than vanilla /usr/lib, and that makes sacd itself think the files it depends on are missing. A simple sudo ldconfig /usr/lib64 issued before you type the 'make' command, will fix that problem, though. Any distro in the Ubuntu family is likely to be affected by the same problem, of course (and fixed by the same fix!)

Note also that macOS is rather different from anything else (inevitably!): on that platform, conversion of ISOs does not use the “sacd” program, but instead uses one called sacd_extract which Semplice includes as part of its own installation routine (it's stored in $HOME/.local/share/semplice2/bin). Functionally, it makes no difference to what has been described above.

If this all seems a lot of a palaver to go through for just getting to listen to some classical music, remember: you wanted to swim in the sea of SACD! If you don't do SACD ripping, you don't need to do any of this… and if you do, you only have to do this once!

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specanalysis

Anonymous (anonymous@undisclosed.example.com) — 2026-01-22T11:06:20+00:00

Spectrum Analysis

1.0 Introduction

You've seen (in the section on performing audio codec conversions) that it's perfectly possible to use Semplice's audio conversion features to convert some input file into something that looks as if it's a Super High Resolution FLAC. So if someone were to sell you a super-dooper high resolution FLAC for lots of cash, how do you know it's a “proper” FLAC and not merely a crappy MP3 that's been converted to look like a good FLAC? One thing you could try to do is see whether high frequency sounds have been thrown away from your file's audio signature: that's something lossy codecs do routinely but which true FLACs would never do. If only there were a way to analyse a folder full of FLACs and produce some kind of analysis of the sound contained in it to let you see whether high frequency sounds were present! Well, of course, that's exactly what Semplice's Audio Processing menu Option 3 lets you do.

As with all of Semplice's options, make sure either that you launch Semplice from within a folder full of FLACs, or use the W key to select a folder of FLACs as the new working folder.

2.0 Generating a Spectrum Analysis graph

With an appropriate working folder set, taking Audio Processing menu Option 3 immediately results in this sort of output:

A message appears at the bottom of the main Semplice screen, saying that 'Frequency Analysis is in progress' and a spinner indicates the passage of time: depending on the recording, how long it is and how high the FLAC resolution is, analysis can take anywhere from a few seconds to a minute or so. Be patient! Also be aware that, for the performance of the frequency analysis, Semplice requires double the disk space occupied by the original FLACs in its tmp folder (i.e., $HOME/.local/share/semplice2/tmp). When you finish the analysis, this space is freed back up.

Immediately the analysis is complete, a pop-up window will appear in which a colourful spectrum analysis graph is displayed. You return back to Semplice by closing this pop-up window, whenever you're ready to do so. The pop-up is always a fixed size, such that the graph component of it is displayed at 1024×768 pixels (except on macOS, for reasons I haven't yet worked out!)

3.0 Understanding Spectrum Analysis Graphs

The graphs display time in the x-axis and sound frequency in the y-axis. The x-axis should represent the entire duration of all the FLACs in the current working folder when played one after the other, with its start over on the left and its conclusion over on the right. At each time segment along the x-axis, the audio frequencies present in the audio signal at that moment are plotted vertically, with different colours representing different intensities of sound. Very white/yellow colours indicate 'a lot of this frequency in the signal here', and purple or black indicates 'very little of this frequency here'. Interpreting this spectrum analysis graph is a bit of an art form and I'm not going to be able to get into every nuance and detail here! But let's start by taking a closer look at this particular graph:

The first thing we notice is that there is some pink/purple colouring all the way up to the top of the graph (which is said to represent a frequency of 21,533Hz. Look especially around the 445 seconds mark: we have three intense bands of colour, the third of which is easily 'shooting pink' up above the 18,000Hz band. That's the mark of a true FLAC: remember that MP3s dispose of higher frequencies because you're allegedly unable to hear them for the most part. So if this was an MP3 that had been converted to a FLAC, we'd expect to see a sharp cut-off of frequencies above the (approximate) 16,000Hz region.

Let me just put that to the test, though. I'll use the Audio Processing menu Option 2 to convert the same FLACs which have just produced that graph to MP3s, then I'll re-convert them back to FLACs from there. Finally, I'll produce the spectrum analysis of the freshly-created FLAC-from-MP3:

You can see the difference at once, even if the difference isn't audible to tired, old ears! Here, there's a very obvious and unsubtle cut-off of all frequencies above 16,000Hz, though the occasional peak pops up that gets into the 17,226Hz region. That's the hallmark of a lossy file that's been 'upsampled' to look like a FLAC.

The same trick can distinguish between 'real' high resolution FLACs and ordinary ones that have been made to resemble high resolution ones: you'd expect high-resolution FLACs to have frequencies well into the 22kHz range -maybe even into the 40kHz range. If you see a sharp cut-off at around the 20kHz range, you're dealing with a 'high resolution' signal that isn't particular high resolution!

4.0 Scratch Detection

Another use for this business of spectrum analysis is to be able to tell whether your CD rips are scratch- and blemish-free, without actually having to listen to it from go to woe. For example:

At first glance, this all seems fine, with frequencies going to the 20kHz range, so a 'proper' FLAC… but if you look carefully…

…at around the 83.8 minute mark, and again at the 125 minute mark, there seem to be transitory spikes well above the general frequency cut-off, into the 22kHz range. Those look suspicious, and I'd want to listen to this opera at around those times to make sure the rip was acceptable. When I extracted the audio from around the second of those spikes (which is a little bit pinker and thus more intense, than the earlier one), this is what I heard:

la-fiamma-gardelli-1985-16-44100.mp3

If you are listening around 13 to 15 seconds into that sample, you'll hear what your eyes only previously saw …and, like me, you'll conclude that I need to re-rip that CD!

Spectrum analysis is not an infallible tool for click detection, though: I couldn't hear anything wrong in the opera around the earlier 83.87 minute mark, for example -though something is clearly not quite right there! But even finding one flaw in my rip by mere visual inspection is good enough for me!

5.0 Final Thoughts

Finally, I just wanted to head off a common question I sometimes get on this subject. Let's re-display that original spectrum analysis:

Do you notice anything odd in that graph, displaying just above the 15,503.91 frequency mark? There's in fact a horizontal line of purple going right through the entire recording at that frequency: that looks very peculiar, very artificial and very undesirable. At my age, I doubt I could here a 15.5kHz frequency -but it's well within the audible range for young people. It's a fairly faint purple, so the intensity of this sound (especially when compared to the bright orange fire of the lower frequencies that underlies it most of the time) is such that, again, it's probably the case that few people are going to hear it: but the spectrum graph doesn't lie. The frequency is there when it shouldn't be …and it's potentially audible. So what is it?

Well, there are a couple of possible explanations. Back in the ancient days of yore, we used to use computer monitors that used Cathode Ray Tubes (CRT). They had an electron gun that scans back and forth across the phosphor screen, drawing the image on it. In countries that use the NTSC TV standard, that horizontal scanning frequency is 15.734kHz. In countries that use PAL or SECAM it's 15.625kHz. So, if the recording studio had a computer monitor somewhere in the vicinity, it's quite possible that it caused the low-level 'hum' that horizontal line represents.

It could also be just general electrical interference, but the 15.something kHz frequencies for these horizontal lines is a bit of a giveaway that its very specific interference of the CRT variety!

It is thus likely that recordings older than the 1980s would not have such a line: computer monitors were not exactly widely used before about then. It's also likely that recordings newer than, say, 2005 would not have such a line either: we started using flat panel LED monitors around then, though phasing out the old CRTs wouldn't have happened instantaneously. So only in that short window of time when use of computers with CRT monitors was reasonably common would this be an issue: an interesting historical curiosity!

There's nothing you can do about this, really: the frequency is baked in to the recording thanks to the technology used for around 30 years. It's possible a re-mastering might be able to eliminate it: a good notch filter might take out the offending frequency without making too obvious a change to the music signal… but it's certainly not something you can readily do for yourself!

Anyway: that's spectrum analysis. It's probably not something you'd use a lot of, but it's there as a handy way of checking for flaws in your digital FLACs and for ensuring that if you've paid extra for lossless FLACs, that's what you're actually getting!

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