07-04-2023, 03:53 PM
(07-04-2023, 08:45 AM)Nutul Wrote: @Tim Curtis
out of curiosity, what might be the overall increase of "things" running in the background in the past two / three years or so, which could result in an increased system load?
The playback pipeline hasn't changed since the very first release of moOde almost 10 years ago. It's still just MPD -> ALSA -> Device. It's also the same Web Stack (PHP/NGINX/Sqlite) that provides the WebUI and the same job processing daemon (worker.php) for handling config changes. Processor load during playback on an out-of-the-box, no features enabled system today is same as in the past and is around 1% on multi-core Pi's.
Turning various features on for example any of the Renderers, Auto-shuffle, SoX, CamillaDSP, Local Display etc results in their processes being loaded and executed and system load increasing accordingly.
Here are some system load examples from 3 of my systems all of which deliver fantastic sound quality for me :-) While the results below are typical I've run much higher loads on these systems up to 90% CPU utilization in some cases when experimenting and no change in sound quality whatsoever.
These systems are all running: moOde 8.3.3 | Linux: 6.1.21-v8+ #1642 | aarch64 (64-bit) | RaspiOS: 11.7
System 1
--------
Model: Pi-4B 1.1 2GB
Audio: Allo Revolution DAC
Features enabled:
- None
pi@sig:~ $ moodeutl -m
CPU: 1.5 GHz, LOAD: 1% 48C | MEM: 10% used | DISK: 10% used, 26G free | PHP: 4 workers
System 2
--------
Model: Pi-3B+ 1.3 1GB
Audio: ProtoDAC TDA1387 X8
Features enabled:
- CamillaDSP, MPD/CamillaDSP volume proxy, Auto-shuffle, Mount Monitor, Airplay, Bluetooth
pi@moode:~ $ moodeutl -m
CPU: 1.4 GHz, LOAD: 3% 52C | MEM: 27% used | DISK: 10% used, 26G free | PHP: 5 workers
System 3
--------
Model: Pi-3B+ 1.3 1GB
Audio: ProtoDAC TDA1387 X8
Features enabled:
- CamillaDSP, MPD/CamillaDSP volume proxy, Auto-shuffle, Mount Monitor, Airplay, Local Display
pi@kef:~ $ moodeutl -m
CPU: 1.4 GHz, LOAD: 7% 51C | MEM: 45% used | DISK: 10% used, 26G free | PHP: 6 workerss
Regarding tweaks and sound quality:
The assertion by some that system load or OS tweaks affect sound quality is patently false because there is simply no hard evidence to support those claims. By hard evidence I'm not referring to someone else's "ears", I mean detailed data and signal traces that others can scrutinize and use to try and reproduce and confirm the claims. But of course these bogus claims keep popping up on audio Forums because they appeal directly to the nature of audio enthusiasts to want to tweak things.
I should mention that there is one case where system load does in fact affect sound quality and that is when the load is extreme for example a pegged CPU (100% utilization). In that case there will be long (in CPU time) interruptions in the processing of audio data in the pipeline and thus the continuous flow of audio data is interrupted and audible glitches are produced that also show up on signal traces and typically correlate directly to buffer underrun entries reported in logs.
My advice when considering any assertion by someone that this or that OS tweak improves sound quality is to ask them for the hard evidence. Don't just accept their claim at face value, and remember that the mind is easily influenced by false assertions especially if they cooporate with biases toward those assertions that an indivual may already have.
I should also remind everyone that moOde including it's component parts are all Open Source which means that you can freely examine and analyze the source code and see for yourself exactly how everything works and whats happening to the audio data. If you find any defects in the code affecting audio data report them and if they are credible they will be investigated.
