Raspberry Pi 4 sound quality

[Tim Curtis]

Disk speed test using G-Tech Slim 500MB external 5400. USB3. Formatted as ext4. Connected to USB3 on Pi-4.


Using Blackmagic disk speed test:

9MB/s read and write when Pi-4 is connected via WiFi only [In the U.K., both the Pi3B+ and Pi4 max out at 150Mbps on 5GHz AC WiFi.]

50MB/s read and write when Pi-4 is connected via ethernet. [About 400Mbps - which is what I understand the Airport Extreme puts out via ethernet]

85MB/s read and write when disk is connected directly to Mac.

When I shifted over to Pi I thought I could get away with keeping HFS+ on the external disk connected to the Pi. After numerous inabilities to write to the disk via the Mac, and read permissions issues, reformatting as ext4 has stabilised things.

Disk speed test using G-Tech Slim 500MB external 5400. USB3. Formatted as ext4. Connected to USB3 on Pi-4.
...

So what you're really measuring is the performance of the Pi-4 as a NAS for your Mac, both on WiFi and hardwired, not its USB 3 disk interface speed, right?

If the drive with the music is directly connected to the Pi-4 by USB3, how the Pi-4 performs as a NAS is immaterial to the sound quality (and this is the Sound quality sub-forum).  What matters there is the local hard drive performance of the Pi-4.

If you do want to evaluate its performance potential in a NAS role, then adding in bandwidth-limited devices like the Airport Extreme just muddies the waters.  Directly connect the Pi-4 to your Mac, first via Ethernet, then via 5GHz WiFi, and finally by 2.4GHz WiFi.  Run the benchmarks in each configuration.  Don't throw the Airport Extreme (and all of your other network traffic) into the mix.

Why did you want the Pi-4 volume to be formatted as HFS+?

Hi,

It was a 'real world' test due to having three Pi4s streaming music. It was not a benchmark test.

Three Pi4s accessing the same music directory, plus a Mac uploading a file to the music directory, for example. The Pi3+B could not handle that due to limitations of USB2 [stuttering, sound quality etc.,] . The Pi4s [or one Pi4] with USB3 seem to be able to.

The Pi-4 volume [I presume you mean the external disk?] had been formatted as HFS+ for a couple of years and I did not want to reformat it. Call me lazy and all that... but I was just looking for a simple streaming solution to replace four Airport Expresses connected to four DACs.

I understand the rest of your [might I say slightly condescending...] post. Might you be able to advise me on: how I can get the Pi3 or Pi4 to output more than 150Mbps in either 2.4Ghz or 5Ghz mode? Because I can guarantee without running any test that is the most I am going to be getting from the USB3 drive via WiFi... circa 9MB/s.. :-)

Hello.  I understand better what your goal was and what you were testing.  Thank you for taking the time to explain.  

I did not intend to be condescending; after about 35 years in engineering dealing primarily with other engineers, my social skills have become somewhat atrophied.  

The best WiFi benchmark I've seen is about 11MB/s, and I understand that the WiFi shares the bus with USB 2.0 so that's probably a serious bottleneck. The only options I can think of are external, perhaps a USB 3.0 WiFi dongle, which will probably cost as much or more than the Pi-4, or a router configured as a WiFi bridge.

Integrated WiFi/BT chip connects to the SoC via the SDIO and UART interfaces and is thus separate from the USB bus.