Dirty video mixing

After the mid 90s boom in popularity glitch has become a critical part of contemporary popular esthetics. How to make Analog Video Glitches | Circuit Bending video discusses how to make unique analog “glitch” textures for your next video:

Karl Klomp‘s Dirty Video Mixer is one of the best known and wide used simple circuits for generating video gritch visuals.

Karl Klomp’s Dirty Video Mixer certainly gets about. It really is the easiest and most useful diy video project to get started with. here are some projects I found online…

This very simple circuit simply does analogue mixing of two composite video signals. If the video signals are synced together, it will mix them together quite OK. When the 1 kohm potentiometer is at one end, one video signal gets through as it is. When it is turned towards center, the video signal gets attenuated and some part of other video signal gets mixed in. There are also switches that allow to control which side of the potentiometer is connected to which video input.

This kind of simple video mixing can work as video fader from one source to another if the video signal is black&white composite video and the video sources are synced together. In case of color composite video this can work but is usually messy with the video color information handling.

In most cases the normal consumer video sources are not synced together, so we get a mix where the video signals are mixed together at “random” timing. This creates a sum of them, which is somewhat mess on the sync signals and color information. Typical CRT TV can somewhat decode something useful out of this mess, and you get the video glitch effects at certain settings and or useful video at all at some other settings. The colors in the video become messy because the color information coding of those two video signal is not in sync.

Please note that the mixing method used here is not in any way correct way to mix not synced video sources. It generates usually signal that does not usually match the official video standard (levels, sync timing and impedance) but in many cases get thing “close enough” that normal TV can show it.

Dirty Mixer example video:

If you want to see the result of mixing video sources out of sync, the “Dirty Video Mixer” is your new toy, and it will look like trying to watch the scrambled channels. :D

Karl Klomp Dirty Video Mixer Test 1

Karl Klomp Dirty Video Mixer demo

Hare is one video example of effects made with dirty video mixer and some other equipment. The source material was a VHS of video feedback (camera + monitor) through a circuit bent processor (dirty mixer) and a DVD of animated loops of diagonal lines created in Flash.

When I tested with my own Dirty video mixer circuit protype, I found one quite expected limitation of dirty video mixer: works usually work acceptably only with analog TVs.

If you have digital video equipment (flat TV, video projector, video processor deices) the results can be different looking glitches or missing video sync. Usually the results are somewhat different looking than with analog CRT display (not that nice). Not having anymore any large color CRT TV around limited the usability of this dirty video mixer.

More video links:

How to use the dirty VHS glitch video mixer

“Dirty Video Mixer” DIY Project

DIY dirty video mixer – crossfade test w/ audio input source

Dirty Mixer

Karl Klomp Dirty Video Mixer Test 1

How To Make A Dirty Video Mixer-Karl Klomp inspired schematic-Easy Beginner DIY A/V Circuit bending

Project pages:

Dirty Mixer based on design by Karl Klomp

https://www.reddit.com/r/electronics/comments/9asdb1/i_made_a_karl_klomp_dirty_video_mixer_with_audio/

Somewhat related projects:

https://www.reddit.com/r/CircuitBending/comments/92dtmt/dirty_video_colorizing_mixer/

http://www.waveguide.se/?article=bitmapped-video-interface

10 Comments

  1. Tomi Engdahl says:

    voyager of videoscapes: I create conceptually synesthetic artworks, that use both visual and aural glitch (or other noise) artifacts at the same time. These artifact
    http://videoscapes.blogspot.com/

    Reply
  2. Tomi Engdahl says:

    LZX VIDIOT, The beginning of a video modular synthesis journey
    https://www.youtube.com/watch?v=v9vJh0zvlXA

    The LZX INDUSTRIES VIDIOT, analog #Video Semi #Modular Synthesizer.
    This is the start of a long journey into understanding VIDEO Synthesis, which i know nothing about! so heres a video of me mashing knobs and making interesting things on the screen. I will be delving in deeper mark my words! i am working on a video for the LZX CADET DIY modular synthesiser range at the minute, and in that video im sure i will have a better idea of it all! BUT HERES THE BEGINNING OF THE JOURNEY!

    Stupid Me INSTRUMENTAL – Circuit Bent Green Screen VHS Video
    https://www.youtube.com/watch?v=OkFwPz56sjk

    A shout-out to the TACHYONS+ AND LZX VIDIOT which were. Both used in the making of this vid. Basically green screen dodgily keyed. Then put into multiple layers of conversion to TV through processors and re recording in etc. You’ll notice this version is not as “hi Def” as the other video that’s because the other video was partially merged with 4K footage underneath to give a sort of look that has the interlacing and odd analog stuff as well as a bit more definition.

    Reply
  3. Tomi Engdahl says:

    schele mixer
    https://gieskes.nl/visual-equipment/?file=schele-mixer

    this is a simple analog video mixer based on the lm1881 syncs eparator

    there is across fader cross dissolve 50 in the center and a fade effect with 3 settings

    the fade effect quickly charges a capacitor with the video signal and slowly discharges it back into the video signal

    selecting the filter will filter out the color information resulting in a black and white image

    because all video devices have slightly different video syncs peeds the selected video will standstill on the screen and the other video signal will scroll horizontally that is where the name schele comes from which is dutch for crosseyed

    it works byta king the sync of one of the two connected video signals and pushing it under the output video signal so blanking periods will partially beign ored making it not 100 percent valid video
    signal

    https://gieskes.nl/visual-equipment/?file=schele-mixer#p14

    Reply
  4. Tomi Engdahl says:

    8-input video switch Mark II
    http://www.vwlowen.co.uk/radio/videoswitch3/index.htm

    The heart of the video switching circuit is the MAX4312 integrated circuit from Maxim.

    Up to 8 composite video sources can be connected to the chip’s video input pins (pin 5 to pin 12). The Maxim data sheet shows each input terminated with a 75 ohm resistor but, in practice, I found these weren’t necessary

    Reply
  5. Tomi Engdahl says:

    High performance video mixer – find the right combination!
    https://www.elektormagazine.com/magazine/elektor-198199/44933

    Reply
  6. Tomi Engdahl says:

    MAKE Interview: DIY video mixers and more with Karl Klomp
    https://makezine.com/2008/04/26/make-interview-diy-video/

    “Dirt & Cheap Non-Sync Video Mixer. ” (Klomp, 2007)

    MAKE: The “Dirt & Cheap Non-Sync Video Mixer” requires no power and simply mixes two video signals into one using a 1K Ohm potentiometer knob, 3 RCA connectors, 2 switches, and a small enclosure. Why did you build this project and how well does it work in live performances?

    KK: I still dream about having a mini video mixer that can slide in your pocket. But after researching and trying to build a video mixer the official way (minimal video mixer http://karlklomp.nl/mda/other.html) I realized that the theory for a video mixer is complex and needs a lot of hardcore electronics background [that] I don’t have. Just to render my ideas, I took two signals and hooked them up with a [potentiometer]. After trying different pots, the 1 kOhm was working best. You can also use it as an unofficial video fader if you connect only one video signal. Out of fun and frustration I built this app. I don’t use this live because the aesthetics are not my style. This was more a joke than a serious attempt to build a useful live video tool. Still it can be useful and it’s become a standard option in the recent tools.

    Reply
  7. Tomi Engdahl says:

    On proper video mixing
    https://www.electro-tech-online.com/threads/video-mixer.13619/

    It’s very difficult because all the different video signals need to be syncronised together – professional equipment is designed to do this, and includes sync inputs. Historically TV studios had everything synced by a seperate sync generator, I don’t know if it’s still so?.

    Doing video mixing on domestic equipment is far more complicated, I suggest you buy a ready made unit!.

    Nigel is right. I used to design video synchronizers and time base correctors for a living. They are no doubt smaller now, due to integration, but they are still complex and must contain a megabyte or more of memory (which isn’t much, but controlling it isn’t simple). They also reqiure at least two phaselocked loops, an A/D, a D/A, filters, video amps, etc.

    PIP still requires that the inputs be synchronized. This is generally not the case unless you happen to be in a broadcast studio or a production facility. :cry:

    If anything PIP is probably harder to do, as you have no choice but to digitise the small picture in order to resize it, plus the sync problems are still there.

    Food for thought ???

    Some of my video cameras (cheap CCTV stuff) have synch inputs – in theory you can strip the synch pulses from an existing video signal and use them to drive the CCTV camera(s) – a cross-fade could then be achieved with a simple fader circuit ? (OK assuming synch pulses continued to maintain amplitude!).

    Reply

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