Posted by: recordingsofnature | June 26, 2015

All night field recording in the forest, 22.6.2015

This is my first all night field recording with my tree ears microphones. It is captured June 22-23, 2015 approximately at the same spot in Brøndbyskoven as last recording. Basically, I started the recorder at 10 in the evening  and came back and stopped it at 6 next morning.

This forest is full of singing birds in the day, but I have often wondered what it would be like in middle of the night. I think there is something almost terrifying about a dark deserted forest in the latest hours. Here, around Midsummer, it is even said it is the time when trolls and elves are most active.

And to get a view of this, I think ears are much more effective in the night than a camera…

Night recording in Brøndbyskoven

The recording just started at 22:20. It was a calm night with no wind and only a tiny bit of passing rain.

The recording starts at 22:20 and ends around 6:00 in the morning.

Listen in Headphones. The recording volume is little low, especially during the night, so you might need to turn the volume up at that point.

panoramic view of the recording site in Brøndbyskoven June 2015

360 degrees panoramic view from the recording site at 6 am. Brøndbyskoven June 2015. Stitched with Hugin.

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Posted by: recordingsofnature | June 23, 2015

Green Midsummer forest, June 21, 2015

This is a nature recording of forest ambiance from Brøndbyskoven, June 21, 2015, around noon. It is captured close to previous recording location from March. Oh, now the forest is now just so fresh, dense, and green from top to bottom.

Brøndbyskoven at its greenest

Brøndbyskoven at its greenest

It is a common saying in Denmark, that the birds will stop singing after Midsummer, Sct. Hans. However, this year, the summer is delayed due to very cold weather in May and June, and it appears the birds are still very active and loud.

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Posted by: recordingsofnature | May 21, 2015

Field recording 5 am Valby parken, May 12th 2015

This is a nature recording at 5 am in Valby parken, May 12th 2015. This spot is a relatively desolated area located near the water and just 6 km south of Copenhagen centre.
The morning was a calm, moderately warm and moist with wet grass. At 5 it was just getting light, and birds were very active. During the recording you can also hear the motorway across the water and the city waking up slowly. Recording setup 5 o'clock

 

Panorama view of the recording site

Panorama view of the recording site (composed with Hugin free software)

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Posted by: recordingsofnature | April 23, 2015

Tree ears recording at Vestvolden April 20th 2015

This is a nature recording from a sunny day at Vestvolden  (near Husum S-train station and Kagsmosen) in Copenhagen April 20th, 2015.
Bushes and trees by Vestvolden, april 2015

Spring is very fresh now. Leafs are unfolding and things are really starting to grow.

360 degree panorama of the recording site

360 degree panorama of the recording site (large image 12MB)

The 25 minutes unattended recording is captured with my tree ears setup, now with updated ear geometries to better match my own ears.

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A nature recording from Brøndbyskoven on the first sunny spring morning, March 8th 2015. The weather forecast had predicted temperatures approaching 10C, however in the morning hours around 9, it felt windy and not very warm.

IMG_3784This forest located in the suburb of Copenhagen and is almost surrounded by motorways. On this morning only very few natural sounds were audible; a few tweets and hissing leaves. The all dominating sound was man-made and came from the motorway, -that is even for an early Sunday morning.
This forest would be completely different place if  the traffic noise was absent. It is easy to imaging how a constant, 24-7 background noise disturbs and stresses birds and animals. It simply makes it difficult to communicate over distances. Likely the birds will try to sing louder (and more harshly) in order to break though the background noise.

It is my clear experience from audio recordings in nature, that traffic noise, followed by air traffic, are by far the dominating man-made sounds. In this context, noise from wind turbines are exceeded by magnitudes, yet still wind turbines at desolate locations are yet another noise source that adds up in the total picture. Anyway wind turbines should not be a problem near busy roads since the noise is simply downed by the cars.

360 degrees panorama from the recording site

360 degrees panorama from the recording site. Forward direction of the recording corresponds to the center of the image. Location: 55.647841, 12.436417

With this field recording I am testings and comparing 4 different recording setups. It is my plan with a new binaural setup, one day, to be able to add an extra layer realism into the nature recordings. As by now, it has not really succeeded yet.

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1. Standard nature recording setup

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Posted by: recordingsofnature | November 22, 2014

Tree-Ears microphone setup

This is a demonstration of an another variant of the binaural microphone setup presented in the last post. This concept could well be called something like a tree-ears microphone setup. I think it can be useful for many types of nature recordings including for remote unattended recording stations. Furthermore, It should have potential for good sound capturing, being easy to install and stay relatively compact and unnoticed.

Tree ears setup

Basically, the mechanical parts of this prototype are just the same as used in the previous post. Only now, the two sides are strapped on to a suitable sized tree trunk. Clearly, there is no room for the Earthworks microphones, so I’m using a smaller custom made microphone setup based on the Primo 172 capsules.

Below is a test recording with the setup, directly connected to the microphone inputs of the Microtrack II recorder. It is captured in Ballerup, Denmark November 5th 2014 at sunset – same location as previous post,  just 10 minutes after.

Being the first raw take with the setup, only post processed with a low frequency (<30Hz) rumble filter, I think the sound is surprisingly good and with a low noise floor (apart from wind noise). This is also surprising taking into account that this is a set of low cost of the microphones which can be bought for ~£25.

Details about the setup are in the following.

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Posted by: recordingsofnature | November 12, 2014

Binaural nature recording and setup

My personal aim with nature recordings is to just capture the nature, the weather, the seasons, the situation as it is out there. I hope to let the listener experience and get a sensation of a particular spot and time through photos and especially  sound. Let it be a little trip and a break away from the daily restless digital information rush. A few minutes where you will only use your ears and imagination. Sit with closed eyes, or look at the photos from the take.

IMG_3300

This recording is a first experiment with a new binaural recording setup, where the microphones listens through a pair of plastic human ears. The binaural recording setup imitates the human head including the outer ears, so when listening in headphones, the sound that is feed into your ear canal is captured directly under the same conditions as when you actually hear. Hereby the sound experience has a chance of becoming very realistic with respect to stereo perspective and frequency response.

Headphones are needed, as binaural recordings are not well reproduced using speakers. The recording is made November 9th 2014 in Ballerup, Denmark near Sømosen and DTU ballerup campus. The last hour before getting dark.  Not much is happening. Hissing leafs, air planes and a constant traffic dominates the soundscape. Approx. 10C which is mild.  Apart form that, the autumn is just full of subtle sounds.

IMG_3329 view of the recording setup Read More…

With this investigation I hope to bring a view into how various low-level image sampling and related processes, including pixel binning, pixel skipping and Bayer demosaic algorithms, affect the image quality particularly with respect to the appearance of aliasing and Moiré.

The focus here is DSLR video systems, which typically use quality compromising methods to reduce the computational load when  scaling down of the multi-MP sensors designed for still images. As the pixel count of those sensors increases the down-scaling becomes more demanding and computational heavy.

While newer DSLR cameras seem to have come a long way solving this problem, aliasing is still a main problem for many digital cameras, and it is not an easy tassk to find information on what underlying processes are. Having this information is crucial for the design of optical antialiasing filters (low pass filters)  matching the various  DSLR video cameras.

In this (rather long) article I will present simulation results from a range of different pixel binning, pixel skipping and demosaic schemes (btw. chroma subsampling no included) in order to see the effect on image quality and to see if it is possible to replicate the observed aliasing and Moiré of the Nikon d5100 best. This may also be used to evaluate the sampling method of other cameras, when using the same video test and compare with the simulation results. Read More…

Posted by: recordingsofnature | August 26, 2014

Effect of pixel fill factor on aliasing and Moiré

This is an investigations of how the pixel fill factor in the image sampling process influences aliasing and Moiré. It is here done by use of a sampling simulation (terated as simple mono chromatic – no Bayer filters etc.)  just to illustrate the fundamental aspects.

The low pass filtering is an essential part of any image sampling process, serving to eliminate any high frequency component that cannot be reproduced with the given sampling rate and resolution. Any frequency detail above half the sampling rate (Fs/2= the Nyquist rate) will be reproduced as mirrored and aliased frequency artifacts, only contributing with artifacts and noise to the sampled image.

 

Test chart with indication of locations of the harmonics of the Nyquist frequency

Test chart with indication of locations of the harmonics of the Nyquist frequency= Fs/2 of the sampled image. The original high resolution chart found here.

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Posted by: recordingsofnature | February 27, 2014

Simple test to evaluate DSLR video aliasing and Moiré performance

[Updated article…]

Aliasing and Moire issues are heavily discussed topics for DSLR HD video, however the performance evaluations remain very subjective and are typically based on random Youtube or Vimeo videos. Adding to this, camera manufactures hardly disclose any details about the related actual sensor level pixel processing.

This is an alternative method to determine /characterize the aliasing and Moire performance of a DSLR video. Basically, the method is a scanning for critical line densities which produce interferences/resonances in the image. Knowing this will give hints on what is going on at the low level sampling process, reveling the effective vertical and horizontal resolutions. This will also provide information on the requirements for an optical antialising filter, ie. the blur diameter needed, to eliminate the aliasing artifacts.

The test is demonstrated in the videos:

The Test

The test is basically 2 fine line patterns (stacks of 600 lines), one vertical and one horizontal. To carry out the test, simply record a video of the test patterns while zooming in and out.  In this way, the sensor is  scanned for line densities with critical interferences/resonance.  A subsequent analysis of the video will readily provide precise respective line density values. (Bear in mind that this line pattern is designed to be a worst case scenario for provoking Moire patterns)

The line patterns can be printed from this document:  600 lines – line width 0.5.pdf , -alternative line widths are available here: 600 lines – line width 0.2.pdf and  600 lines – line width 1.0.pdf

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