[Aachen]

> You can now change the duration of your audio clips without affecting their pitch non-destructively. Audacity 3.4 uses a new time stretching algorithm specifically made for music, which outperforms many of the commercially available options.

Way to bury the lede! What's this magic algorithm being spoken of, how does it work so well?

> A more detailed overview of these changes can be found in our <a>changelog</a>.

The changelog is even more terse, saying only which key combo activates it :(

A way bigger deal to me is mentioned at the bottom of the "other changes" in said changelog: Opus support!

Edit: wait, under "libraries" it says

> lib-time-and-pitch implements a time stretching algorithm originating in Staffpad. It currently is one of the highest-quality time stretching algorithms for music on the market.

Staffpad links to https://staffpad.net and seems to be some music app. The library name links to a Microsoft repository (https://github.com/audacity/audacity/tree/e4bc052201eb0e6e22...) with no readme. The source code is documentation enough :)

[Slow_Hand]

I was curious myself, so I downloaded Audacity and tried.

It's a granular time-stretch algorithm. By the sound of the artifacts at extreme settings it's akin to the 'Complex Pro' algorithm in Ableton Live (if you have any reference to that) and seems to be equally effective at a wide variety of sources (percussion, vocals, full records).

Is it better than most commercial offerings? Hard to say after a brief test, but it's not bad!

I suspect it's plenty good for the needs of Audacity's audience, who are unlikely to be demanding audio pros. As an audio professional I would never use Audacity, but if you need a quick, free, and (relatively) simple option to time-stretch a file, then it should fit the bill.

[skrebbel]

What's the regular go-to tool for audio pros? Adobe Audition or something else? I'm from the age when Sound Forge was considered leading (and Audition, then named CoolEdit, was its cheapo shareware competitor) so I'm probably way behind the times.

[Slow_Hand]

I'll clarify first that I word in record production. I don't work in audio post-production (film, video, tv, etc). While some of the tools do overlap, the industry standards for each discipline will differ, so I can't speak to the video side of things.

For my work the standard DAWs are Pro Tools, Logic Pro, Cubase, and Ableton Live. There are lots of options each with their own strengths, but any of these will do a great job. I think it comes down to the person's workflow preferences. Certain disciplines will favor different DAWs.

Other than that Izotope (programs like RX and Ozone) are doing cutting-edge work for audio restoration. There are certain companies that are competitive or exceed them in certain situations, but Izotope is the company you're most likely to see working professionals use these days for general utility.

It can be more nuanced than that, but I don't know if you're asking for a deeper explanation.

[okbrown]

It's still apps like Sound Forge, Wavelab etc. I use audacity mostly for the loopback feature to record audio from various "sources"

Though with this new update, I thought I could stop using Sound Forge but quickly realised it doesn't have a real time pitch control on play back (think the pitch control on a turntable) so I will be keeping with Sound Forge untill then.

[vintermann]

Do you really make enough from being an audio professional that price doesn't matter?

Whether you do or not, there are a hell of a lot of hawkers of software and "hardware" alike, who stand ready to sell their overpriced "professional" tools to people who fail to make it in the music industry (which is going to be most of them, regardless of tools or even skills). A high sticker price is a way to prove your commitment - to oneself, at least. The end market is less likely to care.

[hurryer]

Good professional audio hardware is not overpriced. Sure, there are $15k microphones but you absolutely do not need those, a $1k one is top quality and not expensive if you use it regularly.

You are confusing it with audiophile gear.

Regarding Audacity, it's missing tons of features and it's UI is bad. Just like Gimp vs Photoshop. I did some audio production and Audacity is just not usable beyond the most basic operations, and even those are a bit of pain.

[orlp]

> a $1k one is top quality

$100 gets you a SM57 which probably has been on more platinum albums than any other mic.

[seanw444]

Exactly. After a certain point, you get diminishing returns. $100 gets you probably 85-90% of the way there, which is certainly more than enough. People forget that a good mic and a good DAW do not fix a bad take. The price of the tools is less important than their proper usage, and simply recording things well.

You don't even need an SM57. I know for a fact the iPhone mic and iPhone Garageband has been one artist's success.

[Slow_Hand]

The SM57 is a great mic in some situations. A lot of situations even. But saying that an artist can use an SM57 or an iPhone mic on a hit record and is sufficient is missing the point.

Steven Soderbergh has shot several feature films on an iPhone and the movies were still great, but they're nowhere close to unlocking the full potential of visual expression that you'd get with more refined tools.

Artists who are serious about their craft will keep an SM57 and an iPhone mic in their color palette (Frank Ocean comes to mind), but that's all they are for serious practitioners: a creative choice.

[Slow_Hand]

The SM57 is a workhorse of a mic. It's great in a pinch and probably a desert island choice. It's earned it's classic status for a reason and is probably on more records and stages in the last 40 years than anything else. Great mic... to a point.

That said, the ceiling of what's possible is far higher than what an SM57 can deliver. Not to diminish it. In some instances it's perfect, but one wouldn't have to look far to find better choices, depending on the context and needs of the record.

A Toyota Corolla (don't @ me, I'm not a car person) might be a low-cost, reliable choice in a pinch, but it's far from embodying what automobiles are capable of.

[hurryer]

As a dynamic microphone, SM57 is only usable in the studio for certain kinds of vocals/instruments - the loud ones.

You wouldn't want to record an acoustic guitar ballad on it.

[lozenge]

Ableton Live Suite costs 750 USD? Not much for a lifetime license of something that you would use on every project. Plus there's the ability to collaborate with other professionals that depends on the Ableton project file format.

Edit: Mind you, it contains software instruments, sound packs and MIDI effects allowing you to add synthesized music to recorded music. Audacity only manipulates existing audio and you will need to bring in other software if you want to add synthesised audio which in Audacity will just be treated as extra audio tracks rather than MIDI. That will obviously make it more difficult to produce music. It would be like having to rasterise every layer instead of using a vector graphics to build an illustration.

[Slow_Hand]

Yes. I'm seasoned enough and do the work often enough to be discerning about my choice of tools. An amateur cook might not worry about their choice of chef's knife, but someone doing the work every day is going to make the investment in tools that enable them to express themselves at their full potential, and with minimal resistance. These tools may sometimes appear overpriced to outsiders, but for a regular user it makes a big difference and is worth the investment.

I've also been around the block long enough to know what tools are worth investing in and which to avoid, so I'm not worried about vendors with bad value add.

The "Mixdown Industrial Complex" that provokes gear lust in audio professionals is not something I worry about at this point. I'm mostly satisfied on the tools that I use and the shiny new thing doesn't interest me like it once did. The focus now is on the work.

[westcoast49]

> better than most commercial offerings

The audacity!

[thowawa47827]

<3

[RicoElectrico]

How is granular time stretch different from OLA or WSOLA?

[heycosmo]

The time stretch algorithm is implemented in https://github.com/audacity/audacity/blob/master/libraries/l... particularly functions _time_stretch and _process_hop. It looks to me like a classic phase vocoder with vertical phase coherence (c.f. https://en.wikipedia.org/wiki/Phase_vocoder).

The basic idea is this. For a time-stretch factor of, say, 2x, the frequency spectrum of the stretched output at 2 sec should be the same as the frequency spectrum of the unstretched input at 1 sec. The naive algorithm therefore takes a short section of signal at 1s, translates it to 2s and adds it to the result. Unfortunately, this method generates all sorts of unwanted artifacts.

Imagine a pure sine wave. Now take 2 short sections of the wave from 2 random times, overlap them, and add them together. What happens? Well, it depends on the phase of each section. If the sections are out of phase, they cancel on the overlap; if in phase, they constructively interfere.

The phase vocoder is all about overlapping and adding sections together so that the phases of all the different sine waves in the sections line up. Thus, in any phase vocoder algorithm, you will see code that searches for peaks in the spectrum (see _time_stretch code). Each peak is an assumed sine wave, and corresponding peaks in adjacent frames should have their phases match.

[QuantumGood]

The old "Change Tempo" effect still works much better for voice.

[Blackthorn]

Is there a comparison of different algorithms and how they work anywhere? I only know of two, and I'd really like to understand them better.

The two I know of are Paulstretch (which is really only for super-duper-long stretching) and Lent 1989 ("An Efficient Method for Pitch Shifting Digital Sampled Sounds"), which can be thought of as a form of granular synthesis but isn't really what most people think of when they hear that term.

[ksherlock]

This is the PR I believe

Time stretching 2 of 6 make audio track stretching effective

https://github.com/audacity/audacity/pull/5041

[bdhcuidbebe]

> The library name links to a Microsoft repository.

You link to the official audacity and chose to (incorrectly) describe it as ”a Microsoft repository”

Why being dishonest?

[Aachen]

If I say GitHub repository, does the sentence then make sense to you? I tend to forget that GH is Microsoft's similar to how people around here forget WhatsApp is Facebook or random brands are Nestlé, so I try to get in the habit of calling things by the parent brand to decrease the obfuscation

Maybe I should simply have said git, though. Didn't think of that until now at the end of writing this reply. No dishonesty intended, quite the opposite in fact

[bdhcuidbebe]

”a microsoft repository” implies that the audacity project is handled by microsoft, which false.

If you must state ownership you could have done so with something like ”a microsoft-hosted repository”.

Most of us have been around since before microsoft bought github.

[swyx]

it would be nice to at least know in what ways it "outperforms many of the commercially available options.". is this asking too much?

[TheAceOfHearts]

Tangential to this, I've noticed significant differences in audio quality when listening to audiobooks at 2x speed on VLC vs MPV. In particular MPV doesn't seem as clipped.

A bit of an open ended question, but is there anything more I could do to process the audiobook to make it sound even better at 2x?

[ddejohn]

> A bit of an open ended question, but is there anything more I could do to process the audiobook to make it sound even better at 2x?

Sounds like you could download Audacity 3.4 and make a 2x version of your audiobook files using their new time stretching algorithm.

[fbdab103]

2x! What kind of books are you reading? I have gone as far as 1.4-1.5x, but that feels about the best I can do without having to be laser focused on just listening (ie not doing chores or other minor activities as is my habit).

[jai_]

Staffpad and Audacity are both software under the ownership (?) of Muse Group.

Staffpad is recent acquisition which is why they are now able to share technology like this: https://mu.se/

[beepbooptheory]

I just feel like, for just stretching stuff and staying in pitch, any off-the-shelf FFT-based method has near perfect results within a meaningful range anyway. It has felt like a solved problem for a while? What does the "high-quality" mean here?

[colanderman]

Most stretching algorithms I've heard have noticeable "ghosting" of transients, and tend to muddle synthesizer tones (due to discarding phase information). I am very curious to test this one.

[willis936]

Is this different than paul stretching with infinite duration?

[Slow_Hand]

Yes. The Audacity algorithm is a granular time-stretch, whereas PaulStretch is an FFT Transform for time-stretching.

Depending on your needs, you'd want to favor one over the other. Granular stretches are far less CPU intensive and have significantly lower latency than an FFT Transform. The granular algorithm will likely have better transient fidelity at small time-stretch intervals (between 0.5x - 2x speeds), whereas FFTs tend to smear the transient information.

Where FFT transforms really excel is in maintaining or transforming formants and harmonic information. Especially at extreme pitch or time settings. Granular algorithms can only stretch so far before you hear the artifacts. FFTs are far more graceful for dramatic transforms.

[dmix]

> a new time stretching algorithm specifically made for music, which outperforms many of the commercially available options.

I wonder how it compares to Ableton Live, warping was always a big part of Abelton.