MUSINGS: Let's talk about Roon (1.6) and DSP speed... (And an example of a poor quality "hi-res" classical recording.)

I mentioned a few weeks back in a comment that these days I've been using Roon for my music library and playback. A few years ago, I tried out Roon 1.2 and while good, it just wasn't quite compelling yet at that time for my needs. For years I've been using Logitech Media Server (LMS) given that most of my devices had been Squeezebox-based until recently. It certainly serves the purpose well to this day and in fact, I still run it on my server. I'll discuss why later...

I trust that you've already read or seen videos of Roon in operation so there's no need to cover the program's basics. In fact, I think I covered quite a bit of ground already back in early 2017 with the demonstration of Roon 1.2 on an Intel NUC and then subsequently talking about the use of Roon Bridge with the Raspberry Pi 3.

Since that time, with the newer versions, the program has, as expected, gotten better with even more features, more powerful user interface, etc... I appreciate the better support with display of track names and various settings with the older VFD Squeezeboxes. DSP has been added as of version 1.3 with support for room correction, upsampling options for PCM and conversion to DSD for DACs supporting the feature. We might look at measurements of these options in future blog posts. Of course, there's now also the ability to perform the first (and IMO only meaningful) MQA "unfold" in software as of version 1.5; not that I'm a fan of MQA of course.

For today's post, I'll highlight a few of the key benefits, discuss CPU and DSP speed, ending with a few suggestions I would love to see in future versions...

I. "Rich" Database for Music Library

The great thing about Roon is the rich metadata that the program imports to one's library. It truly is an amazing amount of information at one's fingertips. Everything you wanted to know about the albums and artists including reviews, bios, and credits of those that worked on the music. This information gets cross-linked so when you click on an artist for example, not only will you see the artist's albums but also all the albums where said individual contributed to, their collaborators, influences, and related artists.

I love having access to a song's lyrics to review and for many tracks, there's a karaoke-like feature where each line is highlighted synchronized to the playback. Great!

Timed lyrics... Time to sing along to the Wicked Soundtrack. :-)

There's also an easy way to view other art/images in the album directory and PDF booklets.

With this amount of cross-linked library information available, the "Discover" feature is a great way to highlight what's in the collection. It'll string together selected "featured artists" which I may have forgotten about, collaborations, albums released "this month in 1986" to consider, albums from the same record label, genres to listen to, etc...

At this point, I actually do not have a subscription to either Qobuz or Tidal but I do have about 12,000 albums in my collection and that's alot of music for any software. Which is also why it's great to have software that will do this "discovery" role of jogging my memory as to what I have collected over a lifetime thus far! (BTW, I'd love to try Qobuz, but not available in Canada at this point except through VPN.)

Playing a similar role is the "Roon Radio" feature which can be turned on and will search the collection for music of a similar genre that would go well with what was just played. A great way to listen to music while working on the computer or automatically cueing up some background tunes when friends are over.

Roon Radio... Typically turned on and ready to serve up some music similar to the playlist.

Remember if you like using your own ReplayGain settings to tell Roon to import those tags:

My preference is to tag the files with ReplayGain for -18LUFS as discussed previously. Even though Roon can do automatic volume leveling, having the tags in place is nice since many player software can use this info.

While Roon does a great job with importing the tracks and filling in the metadata, remember that this is no reason not to remain disciplined and consistent with maintaining tags in your library!

II. Broad Device Compatibility

I must say that I appreciate the Roon folks' dedication to supporting as many hardware platforms as possible. Getting the Squeezebox system in the "family" was an excellent move. So is support for the Google ChromeCast Audio. It is unfortunate that while the ChromeCast Audio has been discontinued, there are all kinds of ways to build Roon endpoints on-the-cheap with Raspberry Pi devices (consider RoPieee and my previous discussion on Roon Bridge for Pi).

Gradually, more devices (like my Oppo UDP-205) are acting as Roon endpoints natively. Of course, you can run Roon with any PC or Mac machine. Roon Server can also be run on a Linux machine. There's also the ROCK OS turnkey image for Intel NUC should you wish.

Notice even on my main computer, there are a number of potential output devices one can enable. Including the VB-Audio "Virtual Cable" that can be used to capture bit-perfect output.

Remember that hardware compatibility also extends to devices through AirPlay like to my Yamaha receiver. Android and Apple iOS devices are supported to control the system and also for playback through the phone/tablet. Excellent.

III. Technical Playback Abilities

Roon's DSP facilities work well based on some early investigations with measurements which I'll show another time. As I mentioned above, this software can handle room correction filters (convolution). We can perhaps also talk about this more in the days ahead. Suffice it to say that it works with my Acourate filters created over the years in my room.

My Acourate WAV correction filter activated. Note that 64-bit floating point format not accepted, converting down to 32-bit integer/float works.

For many audiophiles, the inclusion of upsampling filters may improve the built-in filtering for their DAC and also the realtime PCM-to-DSD playback works well.

As you can see, there's a good collection of settings for PCM-to-DSD conversion shown... Type of sampling rate conversion, SDM (5th order modulator selected), ability to transcode DSD sampling rate w/o PCM. Nice touch like the DSD-to-PCM gain setting for the user to tweak.

As you've probably seen many times already, Roon provides a refreshingly thorough display of all the DSP steps that happens from source file to playback such as this:

The source music is Zubin Mehta & Los Angeles Philharmonic's recording of Holst: The Planets, ripped from the SACD to 24/88.2. In this example, notice there's 24 to 64-bit conversion for internal calculations, volume leveled to target of -18LUFS, headroom slightly adjusted, upsampled to 352.8kHz using a "precise, linear phase" filter, it then applied 2-channel room correction with a complex 241k-taps filter, then converts the PCM to DSD64, and sent to the DAC via DoP using the WASAPI driver. All done at "2.8x" processing speed through my Intel i5-6500-based server; not bad considering all the steps in the process.

While Roon's DSP doesn't typically use as much processing power as HQPlayer explored recently, it is nonetheless demanding by the time you start throwing in convolution filter settings and upsampling to very high levels like PCM 705.6/768kHz. As a little testbed for bechmarking purposes, this is the performance for the 24/88.2 track upsampled to 24/768 using the SMSL iDEA as playback DAC connected to my Workstation computer but calculations performed on the i5-6500 Server:

The 24/88.2 --> 32/768 resampling on the left panel sounds okay with "1.2x" processing speed and just adequate headroom barring any major disruption in CPU or network usage (remember "1.0x" means it's capable of realtime processing without any margin to spare). I've tried 24/96 material as well and this humble 3.2GHz i5-6500 can handle this uncomplicated DSP path upsampling to 768kHz without issue.

However, on the right side, we see what happens with the addition of a 525k-taps room correction filter. The processing speed drops down to only "0.9x" which means it's inadequate to maintain smooth playback.

To be honest, in reality, I don't believe there's any audible benefits to such high 16X samplerates. I'm happy using the "Custom" setting and telling the software to do 8X upsampling to 352.8/384kHz:

As expected, realtime PCM-to-DSD can get very "heavy" with processing demands. The Intel i5-6500 CPU can muster up to DSD256 ("5th Order (CLANS)" modulator) playback without the convolution filter:

I didn't have any problem with the "1.3x" processing speed on the left which is a basic 24/88.2 --> DSD256 conversion and playback. By the way, it made no significant difference whether I used the various 5th or 7th order SDM settings. As we upsample that 24/88.2 track to DSD512, we run into problems with only "0.7x" processing speed (middle panel). And to the right is what happens if we go even further applying a convolution filter and upsampling to DSD512 - the processing speed drops down to "0.6x" only which is obviously unlistenable. These are the limits of the Intel i5-6500 as Roon Core.

As such, it's advisable to go with a more powerful desktop-class i7 machine if you want to try room correction DSP with DSD256 or anything to do with DSD512. Likewise, PCM 705.6/768kHz with room correction would generally require an i7 machine. (BTW, I have an Intel i7-7700K CPU coming as a drop-in replacement for my server computer soon and I'll report more on this with the same test settings above...)

IV. Internet Radio

You might not see this feature highlighted much but it's a great inclusion in Roon. Nice to just play some radio once awhile and listen to what's going on in other parts of the world... The easiest way I've found to add a station has been to just search for your favourite channel through TuneIn and paste the link into Roon. Here are a few channels to consider:

BBC News:
https://tunein.com/radio/BBC-World-Service-News-s24948/

Classical Music - KDFC San Francisco:
https://tunein.com/radio/KDFC-903-s35953/

Old Skool 80's/90's/modern rock/pop - The Cheese, New Zealand:
https://thecheese.co.nz/index.php/970-2/

Modern pop - Vancouver Z95.3:
https://tunein.com/radio/Z953-s31305/

And being a Canadian, CBC One for news/interviews and other good stuff :-).

CBC One live streams available:
https://www.cbc.ca/radio/includes/streams.html

Feel free to share links to radio stations you like in the comments below! I'd love to check some suggestions out.

V. A small wish list...

There is more I can say beyond the items above but I think this is good enough for now :-).

While Roon has advanced nicely and I applaud the company for all they have accomplished - impressed enough to buy a "lifetime subscription" - there are a few features I'd love to see implemented.

1. Allow lower bitrate streaming - MP3, please! At present, one could go into an "Audio Zone" and tell Roon to limit the bit-depth and samplerate... Something like this to set my computer playback to at most 16/48:

I have some old Squeezebox devices like the Squeezebox Radio in a remote corner of my home far from the wireless router that I stream at 256kbps to maintain reliability. While lossy MP3 is obviously not ideal for hi-fi listening, for more casual background listening or streaming through the home to the cellphone, perhaps listening with the Bluetooth headset while doing chores, lossy 192kbps is more than "good enough" quality IMO.

I can easily tell LMS to encode to MP3 for my "lo-fi" devices and it'll happily transcode at whatever bitrate I choose. Surely Roon can do something like this quite easily for those times when lossless is simply unnecessary? (Remember that MP3 is off patents now - freedom, baby!)

By all means, Roon should include warnings to the user to know when a "lossy signal path" has been selected. Hopefully users rarely need to use it, but let's just not exclude this pragmatic option when the need arises.

2. Allow remote streaming to endpoints across the internet. Again, Logitech Media Server is already able to stream around the world. (Remember this little test years ago. :-)

I haven't tried but one might be able to do this already with VPN access to the home network and I see that opening TCP ports 9100-9200 may allow remote control communications and UDP 9003 is used for discovery. However, until protected security is clearly in place to access the Roon Core, one should not just open router ports like this.

Remote streaming would be very useful in mobile applications and connecting to one's music library while at the office, on the road, on holidays, and business travel would be a nice touch. Since internet speed can be poor in some parts of the world or if one just doesn't want to use too much data, this is again why it would be nice to be able to set the endpoint to play a lossy MP3 or equivalent streams as per item 1 above.

3. Compressed DSD compatibility - WavPack support please! IMO DSD is screaming for compression support and currently the only game in town for open-sourced compression is with WavPack. As discussed previously, this will allow full tagging support along with lossless compression. LMS has been flexible enough to get WavPack 5 working without too much trouble. I trust it would not be too difficult for Roon to incorporate and take leadership in providing a new feature like this for those who have potentially substantial DSD music libraries.

For the sake of discussion/argument/perspective, IMO, this feature is more important than say being able to upsample to DSD512. I think it really makes a difference for those who are serious about collecting and archiving DSD material.

4. How about a few more options around the size of the album covers when browsing?
A small thing, mainly cosmetic. In Settings --> General, on can select "Yes" for "Allow for more covers and photos?" which will make the album cover icons smaller. A few more intermediate, larger, and smaller options might be nice depending on one's monitor resolution. For example, an even larger cover image size to view on 4K monitors would look great.

Mainly because of items (1) and (2) above, I still have a virtual machine on my server computer these days running LMS. I still have the need to access my music collection remotely, streamed at a slower MP3 256kbps rate every once awhile.

I'm sure there are bugs that need to be stomped out in Roon. Great to see that the issues I talked about in the Roon 1.2 post have almost been completely resolved (only issue is my 4-CD Tenology set is still not properly handled, probably to do with how I've been tagging it). I did run into a couple of instances where the cover chosen for an album was not the correct picture for some reason (and when you click on the album, it actually shows the correct image). Also, there are a few UI elements I'd change here and there to improve user focus. But I have to say that it's all working very nicely for me overall. No crashes for more than a month with 1.6 running on my Windows Server 2016 machine. The only time I needed to restart Roon was for a software update.

VI. Concluding Thoughts...

For anyone who's interested in music streaming software that's "One Ring Roon to rule them all!", I can certainly recommend looking at what Roon provides. It isn't cheap for a lifetime US$500 subscription or yearly US$119. It is nonetheless the best that I have seen and I can appreciate the work that these guys have put into the software.

Other than the cost of the software itself, remember that you need a reasonably powerful computer system for smooth operations. I don't think it's unreasonable to think of Roon as "high-end" software for high-fidelity audiophile systems. Roon Core runs well on my late-2015 built Intel i5-6500 Server for maintaining and streaming my relatively large Library. Remember that DSP is performed in the Core computer so make sure that it's not underpowered if you want to get stuff like PCM-to-DSD conversion done as discussed earlier.

A few words about the Intel NUC i7 machines. Remember that typically NUC's use the lower power processors, so obviously not all i7 machines are of the same speed category. For example, the NUC 7 Mainstream Kit NUC7i7BNH has the i7-7567U inside which is a dual core machine and significantly slower than quad core desktop i7's (it's only ~80% of my i5-6500 with multicore Cinebench tests). What you probably want as a faster i7 machine for DSP performance is something like the NUC8i7BEH, an actual quad core design with the i7-8559U inside which would be about 25% faster than my i5-6500 discussed above. However, to be competitive in heavy computation with a desktop i7-7700K that I'm getting, one would need to start looking at the Intel Hades Canyon NUC8i7HVK (~60% faster than the i5-6500). This is why I am curious about which i7 CPU was used in the Roon Nucleus+ machine given the results recently reported - my suspicion is that it's likely only at the level of the dual core NUC7i7BNH.

In 2019, there's an important balance to strike between computing power, power consumption, and heat dissipation. It's simply not practical to passively cool a 90W i7-7700K for silent operation in the sound room so one can upsample to DSD512 (assuming one cares to). The best cost-benefit ratio remains that of building a distributed model with the Roon Core server with powerful CPU in another room. Have an inexpensive low-power, silent streamer in the sound room. And tie it all together with a good ethernet "backbone" (10GbE, perhaps :-).

With all the metadata and album covers downloaded, there's quite a bit of data being managed by the computer in the Roon Library which should be backed up regularly:

Nice to have scheduled backups once awhile of the Roon Library. I'm not sure I'd want too many copies hanging around, so 3 backups every 30 days apart seems fine for me...

When I run a "Database Backup" of my Roon Library, this takes up about 15.2GB (gasp!) of storage which I think is an indicator of just how much data is gathered under the hood for my 12,000 album collection! I was quite surprised when I saw this number. It speaks to the amount (and perhaps value) of the rich metadata and images downloaded which is of course part of why Roon is not just software but also a "subscription".

One last thing I like about Roon. It supports multichannel, including DSP like multichannel convolution for room correction. While multichannel might not be in the sights of traditional "stereo" audiophiles, it is certainly a welcome feature for those of us who want immersive sound and have a collection of multichannel material already.

However, unless you're running a computer in your sound room currently with hi-res HDMI output, it can be a bit difficult to get high quality multichannel content to your playback system (likely an AV receiver). My hope is that at some point, users can put together an inexpensive, low-power multichannel Roon endpoint. It would be nice one day to control an inexpensive Raspberry Pi-like device running Roon Bridge headless controlled by the Roon app sending hi-res multichannel output to the AV receiver over HDMI. I think there's a market here for someone to do this and I believe the hardware is already there (Pi 3 B+ with decent CPU speed and gigabit ethernet?) even if the software isn't. For now, I believe RoPieee can only handle 2-ch/48kHz through the HDMI which is rather disappointing.

Until I see a good inexpensive multichannel streamer, I'm using an AmLogic S912-based TV box (running custom LibreElec) with HDMI output pointed at my multichannel FLAC directory over Samba. Works well and will easily stream 5.1/24/96 FLACs through the Kodi interface.

All in all, the Roon team has done some very impressive work. With digital audio and computer hardware having matured nicely, achieving fantastic fidelity these days, I think audiophiles will see the power and potential of the software side. IMO, Roon certainly will benefit from this recognition.

Bravo Roon Labs!

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In other news, I just want to mention that dynamic compression and limiting sadly every once awhile does show up with classical music. A friend recently read J.V. Serinus' review of Edgar Moreau's Offenbach & Gulda: Cello Concertos and went for the 24/96 "hi-res" download himself only to find this - track 1 "Grand Concerto for Cello in G Major, 'Concerto Militaire' - I. Allegro maestoso":

Ouch. That's a lot of peak limiting for a classical recording! No wonder Serinus noted that "the soundstage is somewhat limited, and the sound lacks life and sparkle". I had a listen and it ain't just "sparkle" that's missing, it's the presence of distortion every time the music gets louder. For classical music, this is rather "unfortunate", taking away from the overall exuberance of the piece.

I would strongly suggest folks like Serinus and Stereophile have a look in an audio editor once awhile for an "objective" take on the recordings before publishing a promotional piece like this review. I think it is good for audiophiles to at least point out these issues to other audiophiles. What's the point of using $1000 interconnects and $100,000 speakers if the recordings themselves are compromised? :-)

Shame on Warner / Parlophone / Erato for this kind of nonsense... Likewise the artists should be disappointed that their performances are being sold like this considering the legacy of excellent classical recordings over the years.

IMO, it's ridiculous to sell this as 24/96 because it's a waste of the resolution potential. The ongoing release of questionable recordings like this is working to kill high-resolution audio since the customer is definitely not going to be impressed (as discussed years ago, the Industry needs to look at better mastering for hi-res). The inability to provide an "elevated standard" of sound quality compared to just standard 16/44.1 makes hi-res meaningless.

It's March! Which means Spring Break is getting close :-).

Enjoy the music...