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Marantz NA7004 & Hi-Res FLAC
26-11-2018, 19:24
Post: #1
Marantz NA7004 & Hi-Res FLAC
I have an issue which seems to be caused by the interaction between the latest version of MinimServer and my DMR, the Marantz NA7004.

Setup:

- MinimServer v0.8.5.2 update 126
- Windows 7 Enterprise SP1
- Marantz NA7004 (latest firmware)

Problem:

When playing high resolution FLAC files, at the very end of the track, there is a short burst of noise, like a "whoosh" or a fragment of white noise.

Observations:

- This is definitely an artifact. Checked the files w/ an audio editor, and the last few seconds are digital silence.

- It only happens w/ hi-rez FLACs (24/96 and up). It does NOT happen w/ "regular" (16/44.1) FLACs.

- It did NOT happen w/ my previous version of MinimServer (v0.8.4).

- It does NOT happen w/ a different server (Asset UPnP R6.1beta).

- It DOES happen w/ different controllers, including the player's built-in controls.

- It does NOT happen w/ some other players (Shanling DR2.1; various apps on iPad; Kodi on macOS).

Interpretations:

(1) The problem is not caused by controllers.

(2) It is not a simple issue, e.g., "the player is the problem" (no problem w/ Asset or MinimServer 0.8.4); or "the server is the problem" (no problem w/ other players). There must be some interaction between the NA7004's firmware and something new in MinimServer v0.8.5 which causes it.


Any suggestions on how to fix this, or what else to check or test?

Alternatively, any advice about downgrading to MinimServer 0.8.4? (I prefer MinimServer over Asset UPnP.)

TIA.
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26-11-2018, 20:40 (This post was last modified: 26-11-2018 20:40 by simoncn.)
Post: #2
RE: Marantz NA7004 & Hi-Res FLAC
Does this happen when you play a single track or only when one track is played after another?

MinimServer 0.8.4 is no longer supported and no downgrade path is available. I would like to help you solve this problem but I can only do this on MinimServer 0.8.5.

Are you doing transcoding using MinimStreamer?

If you remove update 126 in the Packages tab (downgrade to the original release of MinimServer 0.8.5), does the problem still occur?
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27-11-2018, 23:58
Post: #3
RE: Marantz NA7004 & Hi-Res FLAC
(26-11-2018 20:40)simoncn Wrote:  Does this happen when you play a single track or only when one track is played after another?
Thanks for replying.

Both.

(26-11-2018 20:40)simoncn Wrote:  Are you doing transcoding using MinimStreamer?
No. No transcoding -- unless there's some default MinimServer setting I don't know about.

(26-11-2018 20:40)simoncn Wrote:  If you remove update 126 in the Packages tab […], does the problem still occur?
Yes.

More details. The problem doesn't occur with all hi-res FLACs, only with some of them. I don't know what the difference is between those which do and those which don't. However, the issue is consistent within an album, i.e., either all tracks in an album do it, or none does it.

I took two 24/96 FLACs and did a little more testing.

- Removed all tags (MinimServer listed the tracks as "[untagged]"). No difference.

- Converted FLAC to WAV, streamed WAV. The problem did NOT occur with WAV files.

- Converted WAV back to FLAC using xACT. (I suppose it's possible -- but hardly likely -- that the original encoder also used xACT. My version of xACT uses flac v1.3.2.) The problem DID occur again.
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28-11-2018, 08:12
Post: #4
RE: Marantz NA7004 & Hi-Res FLAC
I wonder whether the issue is related to the compression level used by the FLAC encoder. Can you try converting the WAV file that you used in your test to FLAC using compression level 0 and also using compression level 5 and check whether both of these compression levels show the problem?
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28-11-2018, 19:36
Post: #5
RE: Marantz NA7004 & Hi-Res FLAC
(28-11-2018 08:12)simoncn Wrote:  Can you try converting the WAV file that you used in your test to FLAC using compression level 0 and also using compression level 5 and check whether both of these compression levels show the problem?
My default is set to encode at level 8, and that's what I used for the test I mentioned.

As you suggested, I encoded the WAV files again, at levels from 0 to 7. Levels 0 to 2 did NOT show the problem. Levels 3 and up DID show the problem.
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28-11-2018, 23:08
Post: #6
RE: Marantz NA7004 & Hi-Res FLAC
OK, this is conclusive. If you are sure you are not transcoding using MinimStreamer, the problem is caused by a fault in the Marantz FLAC decoder. It is not a fault in MinimServer because MinimServer sends the exact bytes from the FLAC file without looking at the encoding (unless you are transcoding). If I recall correctly, decompressing levels 3 and above requires floating point arithmetic whereas decompressing levels 2 and below doesn't. The Marantz processor might not have native floating-point capability and this would require it to process floating-point calculations in software. This could mean that decompressing a hi-res file using floating-point arithmetic is overloading the capabilities of the Marantz processor.
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29-11-2018, 03:51
Post: #7
RE: Marantz NA7004 & Hi-Res FLAC
(28-11-2018 23:08)simoncn Wrote:  If you are sure you are not transcoding using MinimStreamer
Are there any default settings for transcoding I may not be aware of? I do not set my servers to transcode. MinimStreamer shows up in the "Available packages" but not in the "Installed packages", so it's definitely not installed.

(28-11-2018 23:08)simoncn Wrote:  [...] If I recall correctly, decompressing levels 3 and above requires floating point arithmetic [...] This could mean that decompressing a hi-res file using floating-point arithmetic is overloading the capabilities of the Marantz processor.
I've no idea what CPU the NA7004 has, so no idea if it has or hasn't an FPU. But this proposition doesn't answer the following questions.

(1) Why does the problem occur only in some hi-res FLACs, and not in all? I re-encoded myself to level 8 a couple of FLACs which did not exhibit this problem, and it still wasn't there.

(2) Why doesn't the problem occur when the same files are served by Asset?

and, most importantly,

(3) Why didn't the problem occur with MinimServer v0.8.4?
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29-11-2018, 09:58
Post: #8
RE: Marantz NA7004 & Hi-Res FLAC
As MinimStreamer is not installed, you are definitely not doing transcoding.

Regarding 1), there might be some interaction between the audio data in the file and the more aggressive compression performed by level 3 and above. For each level, FLAC has a number of alternative compression strategies and it compresses each block of audio data using the strategy that produces the smallest size. Depending on what is in the data, different strategies might be used for different files.

Regarding 2), are you sure Asset is not doing any transcoding? Another possible explanation is that the timing of sending data blocks from server to renderer is different with Asset and MinimServer and this different timing could be triggering the Marantz issue.

Regarding 3), I don't understand this as when you removed update 126 from 0.8.5, this should have been equivalent to going back to 0.8.4 update 114 (the last update to 0.8.4). Are you sure you didn't have transcoding enabled when you were using MinimServer 0.8.4?

The next step for diagnosing the problem would be for you to produce a debug log when the problem occurs. I will PM you with instructions for this.
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02-12-2018, 19:37
Post: #9
RE: Marantz NA7004 & Hi-Res FLAC
Thanks to Simon's testing, we now have some idea of what's going on.

In my OP I wrote, "Checked the files w/ an audio editor, and the last few seconds are digital silence."

It turns out that I was quite wrong. Within the digital silence there was a short segment of very low amplitude audio (normally completely inaudible). Amplify it by cca 120dB, and that's the noise I was hearing.

The definitive test was that the same issue occurred when playing on the NA7004 the same file from an attached USB drive, rather than from the network.

Consequently, it would appear that, when the Marantz NA7004 plays a high resolution FLAC file encoded at compression level 3 or higher, it amplifies the final digital silence by roughly 120dB.

Why this happens, we don't know. Nor do we know why it doesn't happen when the file is served by Asset. (Simon suggests it's an audio data timing issue.)

However, as the file served by MinimServer plays exactly as the same file stored on a local USB drive, the problem is clearly with the NA7004, rather than MinimServer.

What to do about it? For me, the solution is to edit every file that displays this issue and silence that audio segment. (Is it a defect? The product of a bug? Or maybe a digital watermark or copyright indicator? At any rate, I don't think it should be there.) Not perhaps the ideal solution, but good enough to live with.

Thanks again to Simon for helping with this issue.
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05-12-2018, 04:55 (This post was last modified: 05-12-2018 04:56 by Rasmussen.)
Post: #10
RE: Marantz NA7004 & Hi-Res FLAC
...And... it turns out that Simon was right all along.

We now know why Asset wasn't triggering the NA7004 bug. Because it was, after all, transcoding.

I thought it wasn't because I had misinterpreted Asset's audio streaming setting. It turns out that Asset's "as is" means that a FLAC file can be streamed as FLAC, LPCM, or WAV, the choice being made by the player or perhaps the control point. One has to choose "as is single" to stream FLAC as FLAC and nothing else. Once that is done, Asset triggers the NA7004 bug as reliably as Minim.
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