Zoom Q2n - Video and Audio problems

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arst06d
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Zoom Q2n - Video and Audio problems

Post by arst06d » Sun Apr 29, 2018 4:25 pm

Hi

Just bought a Q2n on the back of reviews etc - nned it to record performances at my open mic music club.

Had the first outing the other day. Set video to 720-25 to test the file capacity of my 64GB class 10 Sandisk card, and audio set to 96k 24bit. Playback on the unit was fine, but when files were copies to pc running XUbuntu 17.10 video played fine but silent! However, in my video editing package Kdenlive I could hear the video so no probs. Subsequently read that I shouldn't use higher than 44.1k/16 bit. Not sure why - I want the best quality possible.

Anyway, this last time I was recording a full concert by a friend's band. Set the video to 1080-25 Video and the audio to 48k 24bit (before I read about restrictin to 44.1k). Playback on pc is impossible - choppy, stuttering, out of sync. tried various players inc VLC, Parole, SMPlayer, all the same, as in the video editing software.

Oddly enough, just playing the audio through Audacious is perfect.

What's going on and how do I fix it? I need to edit these video files - any way to convert to a format I can work with?

Also for future use - I want the best video and audio quality possible. What are the optimim settings? Why does the machine record something that cannot be manipulated afterward?

Thanks in advance.
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arst06d
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Re: Zoom Q2n - Video and Audio problems

Post by arst06d » Wed May 23, 2018 5:58 am

bump :D
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Re: Zoom Q2n - Video and Audio problems

Post by Wulfraed » Tue May 29, 2018 1:53 pm

arst06d wrote:
Sun Apr 29, 2018 4:25 pm
Subsequently read that I shouldn't use higher than 44.1k/16 bit. Not sure why - I want the best quality possible.
44.1kHz/16-bit is the standard for red-book audio CDs.

For video, however, the convention is 48kHz sample rate, as it divides evenly by all the common frame rates (24-cinema, 25-PAL, 30-NTSC, 50-PAL progressive, 60-NTSC progressive)
Anyway, this last time I was recording a full concert by a friend's band. Set the video to 1080-25 Video and the audio to 48k 24bit (before I read about restrictin to 44.1k). Playback on pc is impossible - choppy, stuttering, out of sync. tried various players inc VLC, Parole, SMPlayer, all the same, as in the video editing software.
So what are the specifications for the computer (Linux may not be the best choice as you are relying upon "free" CODECs rather than licensed CODECs; the CODECs may also not take advantage of the graphics card for off-loading processing). If the computer has a BluRay drive, how well does it play back a BD movie? (since you mention 1080, that implies high definition -- playing back a DVD won't prove anything as those are [NTSC 720x480; almost a quarter of the data of 1920x1080)

I haven't edited video in some years but use Vegas Pro (formerly Sony, now Magix... >$600 package). I used to transcode the HDV (miniDV tape) data to, as I recall, a MainConcept intermediate format. The intermediate was faster for editing (but needed a fast hard drive) as it "decompresses" 13GB/hour HDV to around 80-90GB/hour.
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arst06d
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Re: Zoom Q2n - Video and Audio problems

Post by arst06d » Wed May 30, 2018 3:29 am

Hi, thanks for the response.

I'm using a notebook running Xubuntu Linux 18.04, 8gb (maxed out) memory, SSD hard drive. Don't have a BlueRay drive. The editing package I use is Kdenlive, using ffmpeg.

So, you're recommending 1080p 25fps for video with 48k 24bit for audio?

Unfortunately, I cannot work with those files. I recorded the last session at 720p 44.1 16bit and I could work fine, but I sometimes have to zoom in on a part of the frame and naturally lose definition, hence requirement to record in as good a format as possible.

Since it's possibly a limitation with my hardware, I may look at online video editing - let their servers take the strain.
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Re: Zoom Q2n - Video and Audio problems

Post by still_fiddlin » Wed May 30, 2018 2:25 pm

How old is that notebook that it's maxed at 8GB? That's going to hurt at 1080, since you've more than doubled the bits to be manipulated.

I record video at 1080 for the same reason, i.e., I want, or sometimes have, to use cropping, and personally, in live club situations, 720p renders fine on YouTube, especially on small devices or even most TVs with reasonable upconvert capability. (Never tried it on a 4k TV, but then you shouldn't be using a Q2n if that's your target device.) But, I only try to edit video on my 16GB system. The 2010 notebook with 8GB (maxed per mfr spec, but folks have gone to 16 in it - I just don't trust the thermals of that configuration) is an exercise in frustration, though it can work with simple edits on smaller clips in simple software like iMovie.

Realistically, you should probably have even more than 16, but it works for me. 8 is going to be a problem unless the software has some really good optimizations going on. My 16GB system works because the software does a lot of optimization and proxying of the video, i.e., so it's not trying to do all of the changes that have been made "on the fly" while still being edited. Video editing, just like audio, is non-destructive, so when you make a change, that's simply done "real-time" and temporarily rendered while you're watching it go by and you're making the next edit. The application of all the edits in realtime to produce something that looks like the true-rendered final is very CPU and memory intensive. In short, HD video is not for the lightweight computer, or faint of wallet, IME/IMO.

Unless you are editing the audio separately, IMO, there's going to be no real audible difference going to a 44.1/16 but I'd stick with 48/24 because the extra headroom might prevent some clipping, depending on the audio record setting you are using.
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Re: Zoom Q2n - Video and Audio problems

Post by arst06d » Thu May 31, 2018 2:53 am

still_fiddlin wrote:
Wed May 30, 2018 2:25 pm
How old is that notebook that it's maxed at 8GB? That's going to hurt at 1080, since you've more than doubled the bits to be manipulated.
It's a Hannspree SN12E2, bought in late 2011

Just checked and it's actually maxed out at 4GB memory! No doubt that is the problem.
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Re: Zoom Q2n - Video and Audio problems

Post by still_fiddlin » Thu May 31, 2018 6:46 am

You need to get a better computer for HD video editing. More memory, faster, newer CPU and a fast disk all would help make what you're trying to do less frustrating. I wouldn't spend a nickel on trying to make that system go faster. Probably any old "standard" notebook in the past 10 years would be a better platform than that, because you could stuff a lot more memory in it, and easily upgrade the hard disk. I've got Ubuntu running on my 10 year old HP.
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