MUSINGS/HOW-TO: Raspberry Pi 4 "Touch" Audio Streamer, and CRAAP settings! ;-) The decline of public feedback, virtual showrooms, value-added content and Darko Audio?

Left - Raspberry Pi 4B, Right - Raspberry Pi 3B. Heatsinks installed on both boards.

Back in August, I wrote an update on building and running the of Raspberry Pi "Touch" audio streamer with RoPieee software. The article was still written with the Raspberry Pi 3B(+) in mind.

Well, on Prime Day recently, I was able to get a Raspberry Pi 4, 4GB "Starter Kit" for a price I could not resist. It's nice to have all the parts including the appropriately sized heatsinks, ready-to-use microSD card, and 5V/3A USB-C power supply. For now, I have no need for the Pi 4 case and the micro-HDMI cables can go in my box of miscellaneous cables.

For audio streaming purposes, a basic 2GB Pi 4 kit (<US$55) would be even cheaper and works just as well. Given the minimal difference in cost, no point going with a 1GB model although that would still be fine - remember the Pi 3 was limited to 1GB. There is also an 8GB Pi 4 but that's a huge amount of memory for just an audio streaming "appliance"!

Here she is, the Raspberry Pi 4 board itself:

The Pi 4 is based on Broadcom's BCM2711 SoC containing a quad-core 64-bit out-of-order capable ARM Cortex-A72 CPU running at a stock 1.5GHz. This is quite a powerful processor considering the price and size.

Before I put it into the "Touch" case, I installed the heat sinks on the SoC/CPU, memory chip, and the small USB controller between the USB connectors. I plugged in a keyboard, my 4K monitor, and used the included Raspbian OS microSD card to 'feel' the speed as a desktop machine:

Clearly it's much faster than the previous Pi 3B and B+. But having said this, it's still a slower machine than modern laptops and desktops. Web browsing shows some latency but this is the first Pi I've used where the GPU is good enough for smooth YouTube watching while the CPU is speedy enough to manage browsing in another window.

I wanted to make sure that I updated the EEPROM to the latest version if there is one. Since release, the Pi 4 has received updates that have improved power utilization and lowered temperatures which is essential for audio streaming IMO - remember, no fans in the sound room! Note that if you have one of the newer Pi 4 version 1.2 boards like I have here, you should be up-to-date already.

Looks like the September 3, 2020 version is already installed in mine.

Here's the basic procedure if you need to do an update:

Make sure to update the OS first and possibly install rpi-eeprom package:

$ sudo apt-get update
$ sudo apt-get full-upgrade
$ sudo apt-get install rpi-eeprom

Then check the EEPROM version which should show something like in the black screen capture above:

$ sudo rpi-eeprom-update

If like me there's no need to update, you're good. Otherwise install update and reboot:

$ sudo rpi-eeprom-update -a
$ sudo reboot

[Note: you don't need to run Raspberry Pi OS a.k.a. Raspbian to run rpi-eeprom-update. RoPieee has this command already installed and you can access it through ssh into the machine as we'll be doing below.]

So after this, I followed the instructions discussed previously to install the RoPieee image to microSD (Step 6). We then put the microSD in the Pi 4 slot and it's time to put the new Pi 4 in the SmartiPi Touch 2 case:

And for the sake of air flow, let's use the Pi 4 backing but without the fan in place, notice I've also installed the USB-C / microUSB Y-cable to power the Pi 7" touchscreen and Pi 4 board:

I'll leave you with the rest of the install...

Here's the final product - almost the same look on the outside but clearly quite different internals. The external difference is that the ethernet cable is coming out above the USB connectors now:

Notice I have a 90° USB adaptor. Likewise, for cosmetics, one could get a 90° ("down angle") ethernet cable so it doesn't stick out as much.

It's CRAAP™ time! :-)

I did not run into any issues with overheating as-is. The CPU has a thermal protection mechanism to throttle speed if it ever approaches 85°C by default. Audio streaming with RoPieee almost never exceeds 20% CPU utilization from what I can see, even with high-resolution 32/768 streams.

However, since I do like to save energy and I wanted to ensure that the Pi 4 runs cool while fanless, let's use some Convoluted Rationalizations And Audiophile Perceptions (CRAAP)™ to customize configuration settings as we had done in the past with the Pi 3 and Pi 3B+!

Since the Pi 4 is way more powerful than needed for basic audio streaming, let's underclock and undervolt this baby while maintaining more than adequate speed using RoPieee(XL). I'm sure you can do something very similar with piCorePlayer, just that I don't have pCP running currently on the Pi 4.

What we need to do is to edit the /boot/config.txt file.

1. ssh into the RoPieee Pi 4. Look at your router settings or on the RoPieee screen to see what the local IP address is. Mine is 192.168.1.197. So for me, open a Command Prompt in Windows and issue this:

ssh root@192.168.1.197

Password is "ropieee".

Alternatively if you prefer, use software like PuTTY:

Log in as root, and password as "ropieee".

2. Install a text editor like nano. Alas, I don't think there is a text editor installed by default in RoPieee. Remember that RoPieee is based on Arch Linux so package installation is different than typical Raspbian (which is Debian-based like Ubuntu):

pacman -S nano

3. Now go into the /boot directory and "nano config.txt" to edit the file:

4. Now copy and past these CRAAP settings into the config.txt file:

# Archimago's CRAAP Pi 4B Settings...
# October 14, 2020

# CPU speed control - normally 1500MHz, min 600
arm_freq=1200
arm_freq_min=300

# CPU voltage control - SYSTEM DEPENDENT!
over_voltage=-3
over_voltage_min=-4

# SDRAM control, normally 3200 - again, watch system dependent voltage
sdram_freq=2400
sdram_freq_min=300
over_voltage_sdram=-3

core_freq_min=200
gpu_freq_min=200

gpu_mem = 256

# Keep it cooler! Throttle at max 75C.
temp_limit=75

As you can see, I'm highlighting the "Edit --> Paste" function for the Windows Command Prompt in the screenshot above to show how the text was pasted in. After that, CTRL-O to "Write Out" the config.txt file and CTRL-X to get out of nano.

When editing the config.txt file, notice that there are some configurations that you don't want to mess with, for example near the bottom from initramfs onward, leave those items alone.

You might have noticed in the screen capture above, my "over_voltage_sdram" setting is -4 rather than the -3 I have in the text to copy. I'm being conservative with the values to copy-and-paste just in case it causes problems if too aggressive. Remember that these values can be "system dependent" in that some boards will be stable with lower voltages than others. Feel free to undervolt even more, recognizing that this could crash your machine or it might not restart (in which case you might need to reload the RoPieee image to the microSD and restart the install process, no harm done). For my machine, "over_voltage=-4" and "over_voltage_min=-5" also work fine and I didn't bother trying to go any lower as it's unlikely to yield much further power saving/heat reduction.

5. Reboot the Pi 4.

reboot now

That should be it... The Pi 4 "Touch"/RoPieee streamer should reboot as expected.

You can ssh back into the RoPieee device and from the command prompt, issue:

watch vcgencmd measure_clock arm

And notice that the CPU will not go above 1.2GHz when streaming to the device to confirm that the settings are working. You can also issue this to keep an eye on your SoC temperature to make sure it never goes high:

watch vcgencmd measure_temp

Here's a quick test of how cool the CRAAP'ed Pi 4 "Touch" Streamer stays. While monitoring CPU speed and SoC temperatures, I had Roon upsample music to 32/384 pushed to RoPieee playing for 30 minutes with the older stock Raspberry Pi 3B (1.2GHz): 

With no optimizations, we see that the temperature rose to almost 57°C over 30 minutes. Remember, this is just the old Pi 3B from 2017, not the newer Pi 3B+ from 2018 which would likely run even warmer on this test.

Here's how the CRAAP'ed Raspberry Pi 4 "Touch" did:

As you can see, we've capped the speed to 1.2GHz as per our CRAAP settings, same as the stock Pi 3. After 30 minutes of 32/384 streaming, it only rose to 52°C from an idle temperature of 42°C in 20°C ambient room temperature.

You can imagine that it would be rare to "need" 32-bit/384kHz for any extended streaming! Even if I were to upsample 44.1/48kHz material, I'd cap it at 176.4/192kHz; everything else from 88.2/96+kHz can just be played natively to the DAC. As such, normally the Pi 4 temperature would simply be running comfortably in the mid-40's while in daily use.

Nice that there's plenty of overhead before the throttle temperature of 75°C. In fact, in my testing with these underclocked settings, I can hammer the quad-core CPU using multi-threaded sysbench at 100% with the passive heatsink for >20 minutes without surpassing 73°C while underclocked/undervolted. Without the CRAAP settings, the Pi 4 would surpass 75°C in less than 5 minutes at stock 1.5GHz and voltage.

I've updated RoPieee to the beta version twice already (currently version 2.618Beta) and it looks like updates do no touch config.txt so the CRAAP adjustments should stay put.

Bottom line... The underclocked, undervolted Pi 4 runs cooler than a stock Pi 3 without any active cooling, is faster (notice the higher Pi 4 BogoMIPS value even though not trustworthy numbers), and of course there are the benefits of higher bandwidth USB 3.0 ports (VIA VL805) and independent "true" gigabit ethernet (Broadcom BCM54213) rather than the Pi 3B's 100Mbps ethernet and 3B+ with its shared ethernet-USB bus with a maximum of ~300Mbps.

As for whether the CRAAP'ed Pi 4 "Touch" streamer "sounds better" from an "Audiophile Perceptions" point of view, I will leave it to you, dear audiophiles and Golden Ears as you listen and experiment for yourselves. Obviously doing this will reduce power consumption, "strain" on the CPU and memory, and "load" on the power supply.

There is of course the matter of "Bits Are Bits". :-)

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So do I recommend building a Pi streamer with the Pi 4? After playing with this device and determining that in fact I have no worries about overheating without active cooling, absolutely! Keep an eye on a good deal as we enter the late-year holiday season and go for it.

Having said this, although the Pi 4 is an improvement over the Pi 3B and B+ models, it's still very much "overqualified" as a simple audio streamer IMO so I don't think there's a need to upgrade if you already have a good Pi 3-based streamer. Yes, we can say the quad Cortex-A72 (ARMv8) processors are even better, USB 3.0 ports are good, true gigabit ethernet is a real improvement to bandwidth, there's updated Bluetooth 5.0/dual-band WiFi and even faster DDR4 RAM is awesome! But seriously folks, I was able to stream 32/768 quite well to my RME ADI-2 Pro FS R DAC using the old Pi 3B (not even B+) over ethernet already - across the audiophile-approved Nighthawk S8000 ethernet switch of course. :-) [BTW, I know the Nighthawk S8000 switch is hard to find these days... Something inexpensive with data traffic control like the NETGEAR GS308T will do the job although certainly not as cool looking!]

Just to give you an idea, many contemporary streamers like the Bluesound NODE 2i still use a dual-core Cortex-A9 running at 1GHz with less RAM (probably just 256MB RAM). Newer devices like the Naim Uniti machines have a quad-core 1GHz NXP iMX6; also of the 32-bit Cortex-A9 generation with around 512MB RAM. Auralic's streaming Vega G2 DAC is similar with a quad-core Cortex-A9 processor at 1GHz and 1GB DDR3 RAM they call the "Tesls G1" (I believe some of the "Tesla G1" products might by clocked at 800MHz). More recently, Auralic touts that their Aries G2 streamer has a "Tesla G2" platform that's "50% faster" because of its 1.2GHz quad-core Cortex-A9 with 2GB DDR3 RAM. By the way, anyone know where Auralic is coming up with the "37,500MIPS" number? Doesn't look like standard Dhrystone or Linpack benchmark MIPS. Notice that they're all Cortex-A9 processors which belong to the ARMv7 architecture. Of course the end user should not care about this technical stuff if it works well. Rather, it's a reminder that audio streaming isn't really hard work for modern low-power processors.

Maybe one day, I'll try out the Pi 4 as a 4K video/audio streamer running LibreELEC or similar. Remember, the Pi 4 has dual micro-HDMI outputs capable of 4K/60fps and hardware decode of H.265/HEVC video streams so it's quite well-endowed as a video playback machine. While HDMI audio bitstreaming DTS-HDMA, TrueHD + Atmos seems to be working, at this time however, it looks like 4K and HDR playback still hasn't been figured out yet so I'm in no hurry to run it as a "TV box". For now, I'm sticking with this system of 4K/60fps/HDR streaming with multichannel audio.

I haven't looked in depth at the processing capability, but maybe in the days ahead we can see local audio DSP capabilities built into the streaming software to tap the CPU with its SIMD "Neon" capabilities.

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To end off, in other news, I find it interesting that Darko.Audio closed off public comments to his YouTube videos. In fact, it looks like many (most?) comments left over the years are now gone. This is in addition to the fact that a few years ago (2017) he stopped allowing comments on his main website and the comments prior to that seem inaccessible as well.

For the YouTube comments at least, he claims that this is because of time issues and "my channel isn’t a platform for hate speech or self-aggrandising asshattery". So... He's basically saying that a number of his viewers are disgruntled trolls of some subspecies leaving unwelcomed droppings on his posts. While of high production value, realize that the content he puts up is rather basic with little actual depth. Were there that many "conspiracy theories" and "crazy/offensive/self-entitled" comments? Even if he closes off the comments starting now, why not leave the ones already posted months or even a year ago (like for this video)? Clearly the bottom line is he's not interested in feedback, period. I hope those who took time to write a message whether supportive or disagreeing with him over the years take note of this. While a website is the private property of the person who runs it, there is still something to be said about respecting worthwhile contributions from those who took the time to formulate a thoughtful response.

It appears that some of the more noble potential of the Internet as a mechanism to allow the public to express opinions, promote debate, and expand knowledge may have gone sideways in recent years, I still think there's no need to step back from allowing viewers/readers to leave feedback, is there? After all, we're just talking about consumer electronics, right? Reasonably well conceived articles, opinions, produced in good faith with honest attempts at reality testing need not fear public scrutiny. Inappropriate comments I believe will be dismissed by reasonable viewers/readers and unless highly offensive, can generally be ignored as these will simply look bad for the person leaving the message.

I wonder. Is Darko's frustrations with some (many?) of the comments actually a problem with those who leave such messages, or is there perhaps something wrong with his content, creating disharmony or furthering controversy? I would be curious what kind of comments he considers conspiratorial, for example. Considering that the audiophile Industry routinely promotes "snake oil", is there truly no potential that he might even be participating in low-level "conspiracies" around false claims? For example, thoughtless promotion which may yield self-serving benefits (eg. ad revenue) of supposedly audible differences between digital cables in support of questionable companies that peddle in that stuff could be considered a kind of "conspiracy", right? (I discussed a little about this here.)

In the big picture, this leads back to the question of what role some of these audiophile channels play (including this and this). Is this journalism with the aim of unbiased fact-based reporting in which case Darko probably should be more open to feedback (welcoming and learning from fact-checks)? Or is he more of a salesman who realizes that he will be criticized because of inherent biases in the "reporting" due to sponsorships and allegiances? In that case, his job is to build an aura of trustworthiness that ultimately promotes the wishes of the sponsors, a willingness to sacrifice truth for sales.

Considering what must be high on the list of priorities for YouTube sites like Darko's - monetization, with recent addition of ad content to the videos, I noticed - I don't think it's unfair to speculate that some of these public comments he found distasteful might have disagreed with his opinions (or at least the impression/image he wants to covey in his videos). To be clear, I have no problem with monetization but would prefer to see value-added content like for example the investigations and critical reviews that take place on a popular channel like Linus Tech Tips while still maintaining ad sponsorship. This is not what Darko does; his videos are more of a polished "friendly showroom" for the products and favored interviews of Industry actors without demonstrating latitude in critical thinking, sometimes promoting untrue opinions, and now not open to public feedback. The videos are bright, clean, with IMO at times distracting depth-of-field closeups interspersed with "hip" music which I guess is intended to target younger audiophiles. I suppose these days, with diminishing numbers of actual brick-and-mortar audio shops and this year with pandemic closures, it's inevitable that such a "virtual show-and-tell" niche has become more important for building interest in new products for companies. To me, much of this is simply a modern relative of the infomercial - with just as much honest feedback allowed.

It's fascinating watching the "evolution" of media and how consumers are marketed to. In the "old days" we just had magazines and stores. We could ask questions of the salespeople and the occasional reader response gets printed in the "Letters to the Editor" every month. Public comments attached to articles and videos on the Internet changed much of that, and I think in a good way on the whole. Maybe after a couple of decades now, we're heading back to a "shut-up and listen to me" kind of presentation in certain parts of the advertising universe as they become intolerant of scrutiny especially as the digital products mature and more creative ways of framing products and benefits need to be found.

Furthermore, we have all kinds of "push" marketing, social media, and countless ways for any of us to advertise products these days. For example, today's post will probably sell a few Pi 4's and I'll make a few Amazon bucks to buy some Christmas gifts if purchased through the links (no guys, I ain't gonna get rich doing this ;-). But I bought the Pi 4 kit with my own money and I do hope that at least this post provided some useful ideas and went beyond just more questionable subjective claims about how something sounds or unashamedly making obviously false statements. Value-added discussions that might be educational or suggestions to "do something new" have generally been the motivations for why I post - the idea of bringing value to the reader is ultimately the intent.

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Stay safe dear audiophiles, try not to let the news of the day get you down, enjoy the audio toys, and of course I hope you're enjoying some sweet music!