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Author Topic: I actually went to a jazz club gig, after a year of staying home!  (Read 982 times)

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Offline Ozpeter

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I finally got some recording action after a year of staying home and doing very little with my world-largest collection of small audio and video devices.

I got to the gig with 5 minutes to spare, grabbed a table at the front, and plonked down a DJI Pocket 2 video camera (which has 4 mics in a surround configuration), a Sony A10 just using its own mics, and I wore a Sennheiser Ambeo binaural headset.  Each device was controlled from a separate phone, so there was a bit of a glow at the table.

Here's a short comparison recording from the three devices.  The sound switches from one to another every ten seconds or so.  You should be able to detect the changes.  They cycle round in the order DJI - Ambeo - Sony - DJI - Ambeo - Sony, etc etc.

I discovered that the DJI, which only has three level settings (high, medium, low), has an unadvertised compressor, which in the context of video isn't such a bad thing, but I had it set to medium, and low would have been better.  Still, for a consumer camera it's not that bad.  The Ambeo captures a little less room reflections, and the Sony less still, being just an XY pair.  The DJI can be set to something more like XY, which will be worth a try next time I get a chance.

The DJI seems to me to have a good bottom end but it's a bit less bright than the Ambeo.  The Sony is thinner than both but not a complete disaster - could benefit from a bit of low end EQ.

Just a bit of fun.  We need fun...

https://soundcloud.com/ozpeter/recordings-compared

Offline Gutbucket

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Re: I actually went to a jazz club gig, after a year of staying home!
« Reply #1 on: March 08, 2021, 10:30:14 AM »
Woo for return to jazz club activity!
(((finger-snap)))

Fun listen.  I'm using Samsung phone earphones so its probably not surprising the Ambeo headset recording translates most advantageously for me.

How does the DJI Pocket 2 handle mixdown from its native 4 mic surround configuration to stereo?  Is it done automatically, and if so does it provide options for the fold-down? ..or does it record two stereo pairs or four mono files and whatever mixdown method you choose to do separately, afterward?

musical volition > vibrations > voltages > numeric values > voltages > vibrations> virtual teleportation time-machine experience
Better recording made easy - >>Improved PAS table<< | Made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<< (note: This is a 1st draft, now several years old and in need of revision!  Stay tuned)

Offline illconditioned

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Re: I actually went to a jazz club gig, after a year of staying home!
« Reply #2 on: March 08, 2021, 04:42:31 PM »
Nice to see what a close up recording sounds like on the different devices.
I liked the camera.  Do you have details on this?

Please DO NOT mail me with tech questions.  I will try to answer in the forums when I get a chance.  Thanks.

Sample recordings at: http://www.soundmann.com.

Offline Fatah Ruark (aka MIKE B)

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Re: I actually went to a jazz club gig, after a year of staying home!
« Reply #3 on: March 08, 2021, 05:03:43 PM »
I'm pretty sure I liked the DJI source the best.

I was thinking of picking one of those up mostly to take vacation videos, but also for the occasional concert. I know it's not going to zoom well for concerts, but it would be nice to have some video on occasion.
||| MICS:  Beyer CK930 ~ DPA 4080 ~ Nevaton MCE400 ~ Countryman B3 ~ Sennheiser Ambeo Headset |||
||| CABLES: Kind Kables |||
||| PREAMPS: Naiant Tinybox | Naiant Littlebox | Naiant IPA | Church BB |||
||| DECKS: Sound Devices MixPre6 | Sony M10 | iPod Touch 32GB |||
||| PLAYBACK: Outlaw Audio RR2150 > Epos ELS8 |||
||| PHOTO: Sony a6000 | Sony 16-50 | Sony 55-210 | Rokinon 14mm | Rokinon 8mm |||
|||Concert History || LMA Recordings || Live YouTube |||

Offline Ozpeter

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Re: I actually went to a jazz club gig, after a year of staying home!
« Reply #4 on: March 08, 2021, 06:37:33 PM »
The Pocket 2 has options for mono or stereo, and for "front only", "front and back", and "all".  Cleverly, although the four mics are mounted in the handle of the camera, the references to "front" and "back" etc are in relation to the rotating gimbal head of the device.  So if the handle is pointing to the front but the gimbal head (with the lens) is pointing 90 degrees to the left, the soundfield is rotated to match the picture.  The result of all the processing is stored as a stereo file in AAC format as part of the mp4 video file, (you can't get at the individual channels) and is specified as follows -

Format                                   : AAC LC
Format/Info                              : Advanced Audio Codec Low Complexity
Codec ID                                 : mp4a-40-2
Bit rate mode                            : Constant
Bit rate                                 : 192 kb/s
Channel(s)                               : 2 channels
Channel layout                           : L R
Sampling rate                            : 48.0 kHz
Frame rate                               : 46.875 FPS (1024 SPF)
Compression mode                         : Lossy

This of course is well below the expectation of recordists here, but for the target audience for the device, it's probably par for the course.  I have put in a feature request for an option to save the audio in wave format, but I don't know whether that's feasible as a firmware update.  It would increase the file sizes of course, but from this 90 minute gig I came home with 54GB of files as it is - uncompressed audio wouldn't make a big percentage difference I would have thought.

The compression or limiting is not an option in the menus.  To be honest it wasn't until I compared it with the other recordings that I spotted its operation, but looking at the waveform, it's obvious.  My mistake was to have the level set too high so the signal was driven into the limiter more than it should have been.  But it was a totally run and gun thing, and next time I'll know.  Compression is better than distortion imho, but of course having neither is best!

Other mistakes were to use the device inside a 3rd party protective case, which is supposed to be transparent to the audio, but I should test that before assuming it's true.  And, in preparing the comparison samples, the AAC file from the Pocket 2 was put through an mp3 encoding stage, and I should know better!!

Generally though I think DJI have put a remarkable amount of thought into the audio side of this device - I'm unaware of anything that competes.  How they achieve the sound when the mics are closely spaced and peek out of pinholes I have no idea.  It's a bit like those modern warplanes which in theory can't fly, but due to fly-by-wire processing, they do.  Normally.

The Ambeo headset I rather like in terms of simplicty of use, and end result.  Getting the files off the iPhone is a bit of a pain, but that's the nature of the beast.  Compared with the Roland in-ears that I have, it's less susceptible to handling and cable noise, which is relevant when wearing such a device.  If I had the black version it would be a bit more low profile in appearance to the very white one I've got, but I think white is the only colour now readily and cheaply available.  Chief problem with any in-ear binaural mic is the need to keep your head still throughout the performance to avoid the stereo image swinging about.

The Sony A10 internals don't seem to have gained much good press here, but I've heard worse.  Personally I much prefer their stereo image compared with the M10 which I hated in that respect.  Closely spaced omni mics just don't work for stereo.  As a very compact run and gun device, it has a lot to recommend it.

For more info on the camera, 'Illconditioned', just search for "DJI Pocket 2" on YouTube - there's loads of stuff explaining its features, and showing samples of its use, though more or less nothing involving live acoustic (or semi acoustic) music, surprisingly.  I'm awaiting feedback from the duo I recorded and I may be able to post the finished video for public access, in which case I'll mention it here, for those who love bass and trombone duos.  (Actually I thought it worked rather well - and some of the items were acoustic guitar and trombone, with both players singing too - Something Completely Different!)

Offline Ozpeter

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Re: I actually went to a jazz club gig, after a year of staying home!
« Reply #5 on: March 08, 2021, 06:44:40 PM »
I'm pretty sure I liked the DJI source the best.

I was thinking of picking one of those up mostly to take vacation videos, but also for the occasional concert. I know it's not going to zoom well for concerts, but it would be nice to have some video on occasion.

I did the video in 4K and with manual exposure it handled the contrasty lighting reasonably well.  Then I cropped it in editing, and rendered in 1080p, and it came out quite well - better that than doing a digital zoom at the outset with no option to reconsider.  For concert use you can lock the gimbal to the direction of the stage and then you don't have to worry too much about keeping your hand dead still.  For this gig I used its (fixed) internal battery for part one, then attached a battery pack for part two as the battery was almost half gone by the interval.  Externally powered it can get quite warm though.

When listening to the DJI source on headphones, I immediately felt that it was what I'd heard with my own ears at the time, in terms of tonal balance and stereo image.  What you don't hear on the sample is the sound of applause coming from behind - it's close to binaural in that respect.

Offline Gutbucket

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Re: I actually went to a jazz club gig, after a year of staying home!
« Reply #6 on: March 09, 2021, 10:48:29 AM »
The Pocket 2 has options for mono or stereo, and for "front only", "front and back", and "all".  Cleverly, although the four mics are mounted in the handle of the camera, the references to "front" and "back" etc are in relation to the rotating gimbal head of the device.  So if the handle is pointing to the front but the gimbal head (with the lens) is pointing 90 degrees to the left, the soundfield is rotated to match the picture.  The result of all the processing is stored as a stereo file in AAC format as part of the mp4 video file[..]   How they achieve the sound when the mics are closely spaced and peek out of pinholes I have no idea.

I'd like to find out more about how the audio routing and processing is handled.  Sampling sound arrival from all horizontal cardinal directions then manipulating that to best fit a particular playback regime is my basic philosophical approach to recording. Please post if you find out more about what its doing in this regard.

Pin holes likely indicate the use of omni microphone elements. What is the orientation of the pin holes with respect to "front/back"? - are they located at each "corner" (Front Left / Front Right / Rear Left / Rear Right), or in the center of each "face" (Left / Center / Right / Back)?  I put "corner" and"face" in quotes because I realize that the area in where they are located may be cylindrical.

Quote
When listening to the DJI source on headphones, I immediately felt that it was what I'd heard with my own ears at the time, in terms of tonal balance and stereo image.  What you don't hear on the sample is the sound of applause coming from behind - it's close to binaural in that respect.

Presumably some type of differential processing is applied for certain modes, and what differentiates "stereo - front and back" from "stereo - all".  Did you record this using the "stereo - front and back mode"?


As an example of the tech being used, here's a DIY oriented device using DSP processing to achieve rudimentary beamforming, or steereable pickup pattern directional sensitivity by manipulating 7 MEMS omni elements arrayed on a circuit board- https://www.minidsp.com/products/usb-audio-interface/uma-8-16-usb-mic-array



musical volition > vibrations > voltages > numeric values > voltages > vibrations> virtual teleportation time-machine experience
Better recording made easy - >>Improved PAS table<< | Made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<< (note: This is a 1st draft, now several years old and in need of revision!  Stay tuned)

Offline illconditioned

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Re: I actually went to a jazz club gig, after a year of staying home!
« Reply #7 on: March 09, 2021, 11:13:52 PM »

As an example of the tech being used, here's a DIY oriented device using DSP processing to achieve rudimentary beamforming, or steereable pickup pattern directional sensitivity by manipulating 7 MEMS omni elements arrayed on a circuit board- https://www.minidsp.com/products/usb-audio-interface/uma-8-16-usb-mic-array
Very interesting device.
Also they sell "active crossover" devices that do take line level  input (RCA) and split each one to two channels.Inside is a programmable digital filter.
https://www.minidsp.com/products/minidsp-in-a-box/minidsp-2x4

Neat idea.

Please DO NOT mail me with tech questions.  I will try to answer in the forums when I get a chance.  Thanks.

Sample recordings at: http://www.soundmann.com.

Offline Ozpeter

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Re: I actually went to a jazz club gig, after a year of staying home!
« Reply #8 on: March 10, 2021, 01:09:25 AM »
Hopefully I have attached a diagram of the device, where "4" shows the position of 3 of the mics (back, left and right).  The front mic is on the remaining face at the same distance below the gimbal head as the side mics, but smack in the middle.

Here's a video in which I test and explain and demonstrate all the audio configuration options.  https://youtu.be/j2nZPGsBJtI

I appear to have made this video during a long no-haircuts lockdown period.  I apologise for appearing here in a scruffy condition.

I actually had to revisit that video to answer your very good question about the difference between "front and back" and "all" in stereo - it would appear that in stereo "front and back" mode the side mics have the upper frequencies rolled off, while in "all" mode, all four mics are fully in use.  Note also that there's a "zoom" mode, whereby the front mic is raised in level and some eq applied, it would appear.  It really is remarkable that they have gone to these lengths on such a device.

On my channel I have also explained other facets of this device - including using an H2N as an external mic - i'm sure you'll see them in the channel list, if you think they might be of interest.  Or, they might be deeply boring!

The jazz recording was in "all" stereo mode.  Perhaps this was not appropriate as it picks up maximum room reverberation, but it made the audience sound good!  As for the binaural aspect, I concede that there's a risk in suggestion being an element.  The proper test here would be to ask someone to identify with no picture showing whether sounds were coming from above, below, front or back.

Lastly, for completeness, here is a link to the case in which the device was buried for the jazz recording. It has holes drilled opposite the mics, but I have yet to properly test just what difference this makes to the audio.  One might assume that it doesn't help high frequencies much, but only a careful test would reveal that.

https://scottymakesstuff.com/collections/dji-pocket-2-accessories/products/dji-pocket-2-pro-creators-case

Hopefully I've provided an adequate explanation but do let me know if there's anything else I could mention.
« Last Edit: March 10, 2021, 01:20:13 AM by Ozpeter »

Offline Gutbucket

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Re: I actually went to a jazz club gig, after a year of staying home!
« Reply #9 on: March 10, 2021, 04:06:42 PM »
Thanks for the link above to your video, shaggy Peter.  Excellent demo of the audio modes on the DJI pocket 2.

As an example of the tech being used, here's a DIY oriented device using DSP processing to achieve rudimentary beamforming, or steereable pickup pattern directional sensitivity by manipulating 7 MEMS omni elements arrayed on a circuit board- https://www.minidsp.com/products/usb-audio-interface/uma-8-16-usb-mic-array
Very interesting device.
Also they sell "active crossover" devices that do take line level  input (RCA) and split each one to two channels.Inside is a programmable digital filter.
https://www.minidsp.com/products/minidsp-in-a-box/minidsp-2x4

Neat idea.

Those DSP boxes are popular for implementing active cross-overs in DIY speaker building, EQ'd subwoofer integration and the like.  I've yet to use one but am considering picking one up to play around with the available ambiophonic crosstalk-cancellation program, eliminating the need for the physical acoustic barrier otherwise required between a close-spaced stereo-dipole arrangement of speakers with about a 20-degree separation between them.  I played around with that using a large sheet of plywood a couple decades back and when implemented correctly it worked really well.  If the electronic crosstalk-cancellation routine works acceptably well, I may use a couple of these (one in front, another in back) in a long-time back-burner project of a portable multichannel surround playback system built into pop-up shade tent canopy, as it would simplify things and reduce the necessary speaker channel count.
« Last Edit: March 10, 2021, 04:08:27 PM by Gutbucket »
musical volition > vibrations > voltages > numeric values > voltages > vibrations> virtual teleportation time-machine experience
Better recording made easy - >>Improved PAS table<< | Made excellent- >>click here to download the Oddball Microphone Technique illustrated PDF booklet<< (note: This is a 1st draft, now several years old and in need of revision!  Stay tuned)

 

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