Topic: Crazy glitching, skipping, drop outs... please help

[atxwolfattack]

hey everyone,

So i have been recording for about a year with a iRiver ihp-120, and i recently purchased another iRiver for soundboard recordings (the most recent iriver being a h-115, the 15 gig model). I have recorded about 4 soundboard recordings with it just fine, no problems at all, but a few nights ago, i taped a show and about 3 times during the recording there are these like 15 seconds of super glitching and drop outs. The rest of the recording is totally fine, but at those 3 random places, the recording starts jumping around and cutting out, and then it will cut back in but maybe like 5 or 10 seconds later and work fine for a while, until maybe 15 minutes later when it does it again.

Here is a sample recording so you can actually hear the problem. My main question is, does this sound like...

A) A recorder problem
B) A cable problem
C) A soundboard problem

Any help would be greatly appreciated, there is a long string of some good shows coming up, and if any one has any help, i would really appreciate it. Oh yeah also, after you listen to this sample, would the correct term for this problem be 'dropouts'? I am not exactly sure what dropouts sound like, but i am assuming thats what this problem is.

-Josh


SAMPLE

glitches1.wav

[dorrcoq]

My understanding is a dropout is where there is no sound at all

[atxwolfattack]

oh okay, well, i don't know what this is called then, it is not a dropout then, but its like it keep recording but cuts out part of the recording.

lets pretend this is a recording of someone singing a Beatles song....


"Blackbird singing in the dead of night. Take these broken wings and learn to fly"

this is what my recording has done....

"Blackbird singi dead of these broken win rn to fly"


So basically, for those 30 seconds or whatever, there are parts that seem to be deleted out of it, making a glitching sounding recording.

[rowjimmytour]

I think this is digi noise your getting and when this happen to me it was caused by a bad optical cable. Check your cable(s) and avoid toslink>mini adapters and the 45 degree adapters as will. How about the heat? Was it hot and muggy inside? This causes problems some times w/ my NJB3 but mostly out side in extreme heat(100+). Good luck and +t for your troubles because I had this shit happen at HSMF in '05 but luckly at the end.
Peace

[Brian Skalinder]

Sounds like skipping to me.  Breaks / jumps in audio, as opposed to digi-noise which I associate with non-musical artifacts like clicks, pops, static, etc.  Skipping could be caused by a cable if running digital-in.  If running analog-in sounds more likely a problem with the recording medium not keeping up with the ADC output.  Have you been able to duplicate in testing?

[atxwolfattack]

Okay, yeah, i was thinking it could be a cable thing, because i would say like maybe 5 times during the show i went over and picked up my iRiver to check and see how everything was (i get paranoid sometimes that my recorder stopped recording or the levels are going nuts) and it could have moved the cable and caused this effect i guess.

If so, i am a bit upset with my Kind Kable. It is just a mini to rca cable, and a month or two ago when Ed sent it to me, the left channel was dropping out like crazy, so i sent it back to him, and i just got it back again after he fixed that, and now this. Geez, i might have to just get my money back this time.

What do you think the best way to replicate this would be to try to figure out if the cable is the problem? I was thinking about just plugging my recorder with this cable into my audio receiver on my tv and record for a half hour with it or so, maybe move the cable around some, things like that?

Thanks for the help, any other help is greatly appreciated as well.

[atxwolfattack]

Sounds like skipping to me.  Breaks / jumps in audio, as opposed to digi-noise which I associate with non-musical artifacts like clicks, pops, static, etc.  Skipping could be caused by a cable if running digital-in.  If running analog-in sounds more likely a problem with the recording medium not keeping up with the ADC output.  Have you been able to duplicate in testing?

Hey Brian, actually, it is an analog Mini to RCA cable, so i guess it is not the cable. Could you elaborate more on this "more likely a problem with the recording medium not keeping up with the ADC output" possibility. Not to sound like a totally newbie, but what is the ADC output? I just got back in town today, so i have not had a chance to duplicate the problem in testing. Do you have any advice on ways i can duplicate it in testing to seclude the problem?

thanks, Josh



EDIT: I just realized ADC stands for Analog to Digital Converter, but would this still be a factor is i am just running straight from the soundboard into my iRiver's Line In?

[Brian Skalinder]

I doubt it's the analog cable - I've not heard problems like this from an analog cable.  Analog cables are more likely to introduce clicks, static, hums, etc.  Skipping is typically a digital-realm problem, IME.  To test:  set up your gear as you would in the field.  Record anything at all.  Record over and over again, seeing if the problem recurs.  If you picked up and handled the unit in the field when it happened, do the same during your testing - move the unit around, move cables around, etc.  See what happens.

The ADC output is the digitized form of the sound you're recording.  It sounds to me like the HDD didn't record the full stream from the ADC, like the actual recording of the ADC output to HDD was interrupted for some reason, hence the skipping.  I'd suspect a fragmented HDD first, vibration in the field with insufficient HDD padding or buffering (was there substantial bass or vibration at the show, or wherever the recorder was located within the venue?), and maybe last a bad HDD. 

Test first to try to duplicate.  Then defrag.  Test some more.  Then format.  Then test some more.  After that......depends on the results.

[atxwolfattack]

I doubt it's the analog cable - I've not heard problems like this from an analog cable.  Analog cables are more likely to introduce clicks, static, hums, etc.  Skipping is typically a digital-realm problem, IME.  To test:  set up your gear as you would in the field.  Record anything at all.  Record over and over again, seeing if the problem recurs.  If you picked up and handled the unit in the field when it happened, do the same during your testing - move the unit around, move cables around, etc.  See what happens.

The ADC output is the digitized form of the sound you're recording.  It sounds to me like the HDD didn't record the full stream from the ADC, like the actual recording of the ADC output to HDD was interrupted for some reason, hence the skipping.  I'd suspect a fragmented HDD first, vibration in the field with insufficient HDD padding or buffering (was there substantial bass or vibration at the show, or wherever the recorder was located within the venue?), and maybe last a bad HDD. 

Test first to try to duplicate.  Then defrag.  Test some more.  Then format.  Then test some more.  After that......depends on the results.

Thanks Brian, much appreciated. I will do some tests tomorrow and see what i come up with. One thing i was just thinking about, the iRiver ihp-120 has a 32mb buffer, while the 115 (with the problem) only has a 16mb buffer, could this have anything to do with the problem? I always thought this would only be a problem with audio playback speed.

Maybe installing the latest build of the rockbox firmware could possibly help?

[atxwolfattack]

Hmmm, well, i did some tests, first i recorded the audio from my tv for like 20 minutes, picked up my iRiver and moved it around a lot, shook it a good bit, definitely more than i did at the show that it messed up, and there were no skipping problems.

So i decided to do it for a longer period since the show it messed up on was about 40 minutes long. So what i did was i hooked up the recorder with the problems to my stereo, and then patched my good recorder to that so i could compare the waveforms without having to listen to the whole thing for skipping. After loading both 40 minute recordings, they lined up perfectly together, unlike the show the other night where one recording ended a minute or two earlier than the other one because of the skipping.

I guess it could have just been a fluke? I am not sure. I guess it would probably be wise to defrag it and maybe format it right?

[stantheman1976]

Are you sure it wasn't the soundboard itself?  I've had a similar experience before.  I was having major problems in one channel from a board I had never used before and it turned out the record out channel was bad.  If it's the same board you've used 3 times before then that's probably not your problem but it never hurts to check.

[atxwolfattack]

Are you sure it wasn't the soundboard itself?  I've had a similar experience before.  I was having major problems in one channel from a board I had never used before and it turned out the record out channel was bad.  If it's the same board you've used 3 times before then that's probably not your problem but it never hurts to check.

You know what, that might be the problem. I've used this recorder at other venues no problem, and it worked fine with my stereo receiver at home. The venue was pretty crappy, very small bar with a equality crappy board (and sound engineer). That might just be it.

Did you have a listen to the clip? Could such a skipping problem be created from a messed up 1/4" output from a soundboard, even thought maybe 90% of the rest of the recording is fine?

[George2]

Maybe the sound guy putting your recorder in pause every once in a file, just for kicks.

[H₂O]

Sound like to me you are dropping samples.  I have had this happen in the past with a USB sound card.  And as Brian says typically is caused when the recording mechanism can't keep up with the output of the digital sound stage.

On a PC I needed to disable any other application on the PC except the audio software to reduce this.  In the end I ditched USB and went to a PCI solution to completely eleminate this issue.

Could mean you need to defrag or reformat your hard drive.   Other than this I don't know the iRiver, so is there anything that could turn on during operation that would chew up CPU cycles?

[atxwolfattack]

Sound like to me you are dropping samples.  I have had this happen in the past with a USB sound card.  And as Brian says typically is caused when the recording mechanism can't keep up with the output of the digital sound stage.

On a PC I needed to disable any other application on the PC except the audio software to reduce this.  In the end I ditched USB and went to a PCI solution to completely eleminate this issue.

Could mean you need to defrag or reformat your hard drive.   Other than this I don't know the iRiver, so is there anything that could turn on during operation that would chew up CPU cycles?

yeah, i am going to probably reformat just to be safe. I know its has nothing to do with my computer, because i played it in my car and on headphones and it does the same thing in the same spot, so it was defintely something that happened during the recording of the show.

[jerryfreak]

this is a classic example of dropped samples, the most common digital recording error.

def. in the digital domain, if you were using the iriver as an AD its 100% on your end and not the sbd.

dropped samples are a result of the device not being able to keep up with the stream for a number of reaons, usually hardware/software buffering/overhead, or a slow fragmented disc.

I WILL NOT take a recorder into the field until ive tested it at home for dropped samples for at least 20+ hours.

easy to do with a sinewave that you can generate in soundforge. record this sinewave using your recorder and use soundforge to scan the resulting wav for glitches, they are super easy to spot

[atxwolfattack]

I missed that my topic had gone onto the 2nd page, haha. Well, i reformatted, and went and recorded about 3 hours of shows 2 nights ago and had no problems at all. Hopefully the problem doesn't come back, i am definitely scared of it happening again. Its so weird though, i recorded a few shows before and they were totally fine, then i went to that one where it dropped samples all over the place, during both bands i was recording. So then i recorded sound from my stereo for over an hour and had no problems. I reformated to be safe, then i went to another show, recorded for maybe 2 or 3 hours and it is fine.

Hopefully it was just a fluke, i just don't see why it would have happened so frequently that one night and not once again since then.

[stantheman1976]

Defragment often and you should be fine.