Popping/noise in Chillout stream?

[Apoch]

For the past week or so I've been getting some nasty pops and glitches in the Chillout channel; I haven't been able to find any pattern (e.g. splatter due to volume levels etc.) but it is very consistent and seriously disrupting my listening. Most commonly there is a slight click at random intervals, around 5 seconds or so; every now and then a more severe glitch will occur which noticeably disrupts the tempo of the music.

I've gone through the stickies on popping and noise, including several external tips/references for WinAmp (I'm using the latest build, 5.3, released 2006-09-26, with the Oct.10 update patch applied on top for good luck) and nothing has affected the problem. Local MP3 playback and other formats (CD, WMA, WAV, AAC, MOD, etc.) are all unaffected, as are other streams on DI. Chillout seems to be the only channel afflicted with this problem. The MP3 streams at both 192k and 128k exhibit the noise, as do the AAC+ streams at both 64k and 32k. I haven't been able to get the WMA streams working, probably because I dislike WMP and am too lazy to sort out the DRM garbage from WMP11


Is anyone else hearing this, or am I just going insane?

[Apoch]

It just occurred to me to check the network for this; I have no idea why the problem only shows up on Chillout since it appears that traffic routes across the same hops for most (all?) of the channels, but there's a definite latency problem three or four hops out on Comcast's Atlanta area backbone.

Looks like all I can do is grit my teeth and hope someone clears up the network... :s Although since it's been several days God only knows what Comcast is doing.

[Ari]

Apoch, is this in any particular part of the track? At beginning, the end. or randomly allo over in the middle?

[Apoch]

It's definitely most noticeable at the begin/end of tracks; but it does seem to go on constantly. It's certainly easiest to hear when the volume levels are low (which rules out splattering somewhere in my sound system).

I've also tried a second computer and sound system on the same network, and it also gets the same noise; that would be consistent with a network issue somewhere. The local network seems clean, though.

[Entranced]

You are sure you are not hearing vinyl "groove noise" there? We were just discussing this the other day during the live show. Increasingly the latest crop of DJs, clubkids and other electronic music fanatics have been raised 100% digital and don't even know what vinyl sounds like when they hear it!

My guess is that Chillout remixes have generally lower levels than other genres, thus the pops and such are more noticeable than on the House or Trance channels.

(PS: Network latency cannot cause sound problems on MP3 / AAC+ streams because they come to you by TCP, which does not "drop" packets! So if you have latency on MP3 / AAC+ the streams will begin buffering instead. UDP can "drop" packets on WMA and affect sound, often less disruptively than continuous buffering though. However, you are not using WMA.)

[Apoch]

I know what vinyl sounds like - this is definitely not it. It's also consistent across every track. (I know this is a little too subjective and vague to really be useful, but vinyl has a sort of natural and pleasing feel, even for fairly rough needle jarring. This is a very mechanical and electronic sounding pop, like you get when messing with cables on a live amp.)

Good to know that TCP is used - I'd just assumed it was done over UDP, not sure why. That does indeed rule out network latency.

[Entranced]

Originally Posted by Apoch

Good to know that TCP is used - I'd just assumed it was done over UDP, not sure why. That does indeed rule out network latency.

Right, MP3 and AAC+ streams only come by TCP. WMA gets delivered by TCP if your MyDI.fm->Preferences->Windows Media Protocol Tweak is set to HTTP, OR by UDP if MyDI.fm->Preferences->Windows Media Protocol Tweak is set to MMS.

(So users on Wi-Fi or cellphone or satellite networks will probably get best performance using the 64k or 128k Premium WMAs, with MyDI.fm->Preferences->Windows Media Protocol Tweak set to MMS.)

Anyway we are back to "square one" with your Chillout channel only popping, since it isn't latency and it isn't groove noise.

[Apoch]

OK, I'm going to get anal about this :-)

So far I've controlled for the following variables, each with no discernible effect on the noise:
- Sound card driver versions (tried 3)
- Master volume levels, software amplification levels, and external amp levels
- Listening to the Ambient channel for similar levels in the tracks (no noise noticed aside from "correct" groove noise, effects, etc.)
- Local playback of tracks with similar levels (no noise)
- Local playback of known matching tracks (e.g. Cardamar/Marco Torrance CDs), on multiple systems (no noise)
- Switching from front-panel output to direct output on sound card (noise still present)

Variables I still need to control for:
- Final presentation of audio (swapping speakers and headphones)
- Preamp, amp, and decoder in second audio system that has this problem
- Double-check on my 3 available systems to see if all exhibit the noise

It'll take a while, but at least it's enjoyable drudgery... should have some additional info in the next day or so.

[James (Jiimz)]

Hey Apoch,
Sorry to hear of your troubles. I've been listening to the Chillout stream all morning and everything seems fine here.
Are you familiar with 'wget'?
I spoke with our sound engineer who suggested you capture a sample of the stream using wget (as opposed to other methods). This way we'll be able to hear and analyse the raw data before it hits any sound devices.
If you'd like, please feel free to contact me via PM so I can assist you with wget capture.

[Ari]

Final presentation of audio (swapping speakers and headphones)

try checking that one first

[Apoch]

OK, here's what I've got:
- Effect is still present when rendering through speakers and my usual listening headphones
- Nicer speakers/headphones definitely bring up the visibility of the glitches
- Running the audio through my preamp/decoder masks the noise slightly; in this case the noise is only audible when levels are fairly low overall
- Activating 5.1 upmixing on the decoder almost totally obliterates the noise unless levels are near silent (e.g. between tracks)
- By far the most troubled setup is running direct from my PC's line out to my noise reducing headphones, with noise reduction turned on (which, unfortunately, happens to be how I work, which covers about 90% of my listening time)
- The noise seems to be around 75-80% of the peak level of the stream; i.e. not as loud as if a cable were getting tweaked on my physical end, but a very, very similar sound.

Just to be extra sure, I've played back local MP3s, CDs, and several other audio formats, as well as the Ambient channel which seems to have comparable volume levels overall - the problem remains constrained to the Chillout channel.

To recap: I've now tested 4 different final presentation methods (nice speakers, crap speakers, nice headphones, crap headphones) and the noise is audible to some extent in each. This is also consistent across 3 different machines so I doubt it's a sound hardware problem.


I'll work on setting up a capture for your tech guys. To be safe I'd like to do a packet capture as well just on the off-chance Winamp itself is handling the stream communication differently than wget would - is Ethereal's dump format okay with your engineer?

[Ari]

Apoch: go for it

[Ari]

Apoch: I am sorry let me restate. While I don't care too much if you use ethereal in this case, it won't help us find anything. So I don't recommend that.

I was told by our main sound guy that if you can use wget to rip the stream to a file, that's the most accurate way he could check and see if he hears the glitches in that, and maybe guess where they're coming from based on what we hear here.

[Apoch]

I was just setting up to do a rip and now I swear to God I'm hearing two tracks playing at the same time... either I've totally lost my mind, or something's borked here...

I can confirm that – I am hearing two tracks playing simultaneously on Chillout, regardless of the stream chosen (Public or Premium).

[James (Jiimz)]

Originally Posted by Apoch

something's borked here...

Indeed it was. That was fixed earlier.

[misan]

Originally Posted by James (Jiimz)

Indeed it was. That was fixed earlier.

hey you changed your username !!

[Apoch]

I don't want to jump the gun here, but it sounds like the noise/popping is gone - I can't be totally sure yet as it did have a tendency to clear up for short periods before, but after ~14 minutes of listening I haven't heard anything.

I also hate to leave the issue hanging open but I'm about to make a 6 week business trip and won't be able to poke at this any more until I get back :s

[Apoch]

Well, I'm happy to report that it seems to have cleared up following the doubled-track fix. After 270 minutes of continuous listening, I haven't heard anything remotely as severe as what was going on before. The only artifact I caught was an occasional skip or pop when changing tracks, but it's rarely distracting.


So who knows what was going on, but it seems to have quit.