[Krutsch]

Hi All,

I ran some ad-hoc experiments last night with my new BDP-1 and different audio file formats.

With Redbook (44.1/16) Apple Lossless (ALAC), mpd seems to hover around 50% CPU usage during playback.
With MP3 (320 CBR/LAME), mpd hovers around 30% CPU usage.

In both cases, the CPU usage was pretty constant, although it jumps a little bit at the start of a new track.

With AIFF (big endian), even with 96/24 files, mpd stabilizes at 3% - 4%, also with a small jump when starting a new track. Wow, an order of magnitude lower CPU utilization? I was surprised to see those results, running top during playback.

So my question is this: is there a sonic advantage in minimizing CPU utilization? That is, does high CPU utilization emit enough wide-band noise to impact delivery of PCM?

I suspect this is something that has been debated, and I'm not trying to start anything, but I am sincerely curious what the thinking is on this topic.

Thanks, Ken

[barrows]

I think so.  Anytime a processor has to unpack a compressed data stream there is going to be more CPU usage.  More CPU usage means more noise generated throughout the system, and some of that noise will get to the DAC and potentially degrade performance.
I decided a long time ago to just store files as aiff, this way I g\have good mete data suppport, but my server does not have to do any heavy lifting.  Hard drive space is cheap

[R. Daneel]

Hi fellas!

Ken, this is fascinating!

For months I've been searching on some information regarding the CPU usage on the BDP-1 and I assure you, this is the only thread that covers that topic!

My concern is this - sometimes the BDP-1 will cause short interruptions in playback when playing 24/192 FLAC files. This will never happen with any of the lower sampling rates. This happens only occassionally, I'd say a few times during an album.

My question to you fellas would be:

1. is it possible that lossless formats like FLAC stress the CPU more, enough to cause these interruptions with 24/192 FLAC?
2. would decompressing (for a lack of a better word) these FLAC files to WAV solve the problem?
3. Where and how can you monitor the CPU load of theBDP-1?

One other thing, has someone tried clocking the BDP-1 CPU to a higher frequency?

Cheers!
Antun

[JRace]

Where are the problem files located, USB drive, network?

[R. Daneel]

Where are the problem files located, USB drive, network?

Hi and thanks for your reply!

The files are on a USB flash drive. The drive is pretty quick so it should not be the problem.
I really dpn't know what the problem is.

Antun

[Krutsch]

In response to this question:

is it possible that lossless formats like FLAC stress the CPU more

... I definitely found that to be the case with Apple's ALAC (as noted in my original post). However, with FLAC (encoded with XLD from original CD rips), I find the CPU utilization much lower: 6-8%. Still higher than PCM (AIFF or WAV, which hovers at around 3%), but within the same order of magnitude.

I routinely play back 192/24 tracks and I've yet to hear even the smallest hiccup - the BDP-1 is amazing in that regard, with flawless, artifact-free playback.

I am using a G-Drive USB 7200 rpm portable drive, connected to a single USB port on the back of the BDP-1 with no external power.

[Krutsch]

The files are on a USB flash drive. The drive is pretty quick so it should not be the problem.

Maybe, but my USB HDD (the G-Drive) outperforms my flash drives (USB 3.0 Corsair - very fast, but in USB 2.0 mode they are slower).

Using the Manic Moose drive bench feature:

G-Drive: 14+ MB/s
Corsair Flash (512GB GS and 128GB): 11.5 MB/s

These numbers are fairly consistent across multiple test runs. That said, I've run 192/24 tracks off of all three drives without a problem.

[R. Daneel]

Hi!

Then this is worrying me!

Mine is running MM too and is connectect to the DAC with an AES/EBU cable. Perhaps that has something to do with it although I don't see how it would matter.

Does anyone have any ideas? The Bryston bunch?

[James Tanner]

Hi!

Then this is worrying me!

Mine is running MM too and is connectect to the DAC with an AES/EBU cable. Perhaps that has something to do with it although I don't see how it would matter.

Does anyone have any ideas? The Bryston bunch?

Sounds like a Chris Rice question Antun

I do not have any issues with 192 but I am using a Western Digital 1TB drive and a Seagate 1 TB drive on a BDP-2.

james

[R. Daneel]

Sounds like a Chris Rice question Antun

I do not have any issues with 192 but I am using a Western Digital 1TB drive and a Seagate 1 TB drive on a BDP-2.

james

Hi James!

Thanks for your reply!

I talked to Chris a few months ago and at that time, he assured me it would be fixed with the newer revision of firmware. It improved the situation but still, it happens. Just please be aware, we are talking about the BDP-1, not BDP-2.

It would be great if Chris would help! In addition, I will run all 192 files I have and report back if it has to do with the files themselves.

[James Tanner]

Hi James!

Thanks for your reply!

I talked to Chris a few months ago and at that time, he assured me it would be fixed with the newer revision of firmware. It improved the situation but still, it happens. Just please be aware, we are talking about the BDP-1, not BDP-2.

It would be great if Chris would help! In addition, I will run all 192 files I have and report back if it has to do with the files themselves.

OK I assume you have tried the 192 on different drives - have you tried a thumbdrive?  Just wondering if your current drive is using up the current available from the power supply and that is causing the problem at 192?

james

[R. Daneel]

OK I assume you have tried the 192 on different drives - have you tried a thumbdrive?  Just wondering if your current drive is using up the current available from the power supply and that is causing the problem at 192?

james

All of my drives are thumbdrives. I have a couple of different types rated at different speeds but it is the same with all of them.

Antun

[James Tanner]

All of my drives are thumbdrives. I have a couple of different types rated at different speeds but it is the same with all of them.

Antun

OK Thumbdrives use very little power so that is not the issue.

I will wait for Chris to comment.

james'

[R. Daneel]

OK Thumbdrives use very little power so that is not the issue.

I will wait for Chris to comment.

james'

Thank you!

Antun

[Mag]

Hi!

Then this is worrying me!

Mine is running MM too and is connectect to the DAC with an AES/EBU cable. Perhaps that has something to do with it although I don't see how it would matter.

Does anyone have any ideas? The Bryston bunch?

IMO it may be the conversion software. I had similar issues with cd years ago and switched the software program, which solved the glitches problem.

[R. Daneel]

IMO it may be the conversion software. I had similar issues with cd years ago and switched the software program, which solved the glitches problem.

Hi!

I know what you mean but that cannot be the problem. All of these files were purchased from online stores.

I have verified this happens on at least two albums:
- Channel Classics - Budapest festival orchestra - Stravinsky - Rite of Spring
- Chesky records - Dr. Chesky's ... binaural album

I am running further tests...

[JRace]

Hi and thanks for your reply!

The files are on a USB flash drive. The drive is pretty quick so it should not be the problem.
I really dpn't know what the problem is.

Antun

Shoudn't be....but it could be the problem

For troubleshooting purposes any chance you could move known problematic files to external powered hard drive, and or network drive?

[R. Daneel]

Shoudn't be....but it could be the problem

For troubleshooting purposes any chance you could move known problematic files to external powered hard drive, and or network drive?

I will try that!

[R. Daneel]

It didn't help. I need Chris' advice.

[unincognito]

Hi Guys,

A number of customers have called in about concerns in the past and quite recently.  The BDP in its default configuration, while not performing any additional tasks (updating database, building an album art database, etc) is capable of playing back flac and wav up to 352khz USB and 192khz over spdif.  This has been tested using a USB thumb drive formatted as fat32, wd mybook live and a wd mycloud as the source.

Fat32 will have the least amount of overhead in comparison to NTFS or hfs+.  Using a samba share (NAS), will have even less impact on the CPU.

I will say any additional reads/write operation during playback will cause interruptions.  While playing back the 192khz file of a song I was also upsampling the same song using Audacity on my computer to 352khz and noticed interruption in playback. 

I will also say some songs, one in perticular we use to include on the USB thumb drive sounds like it's not playing back correctly; but in fact it is.  Just the way the song was recorded, but this should be repeatable each time the song is played.

Hope the above helps