video mixer

[gliptitude]

i want to build a video mixer. i have very very little experience with electronics. i'm currently working on a guitar stompbox for practice and to learn, and i plan on finishing that up pretty guickly, after the rest of the parts come in the mail. it would definitely be easier (and maybe even cheaper) to just buy a video mixer, but i want to make one.

i want it to be able to transition/combine at least two video and live broadcast signals on a regular television.

how difficult would this be? where can i start? what do i need to learn about? does this or could/should this include some conversion to digital signals to render effects?

thank you for your time.

 

[Nigel Goodwin]

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!.

 

[Roff]

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.

 

[gliptitude]

"video mixer"

("g" is sometimes "cue" b/c "cue" key is jammed)

thanks for these replies. the video mixer is way advanced for me. so let me rephrase and repropose my idea at a simpler level.

how hard would it be to build a portable console to generate the "picture in picture" function on a regular tv, switching between two or three inputed video signals?

such devices already exist, for example:

**broken link removed**

(see halfway down the page: "PICTURE IN PICTURE WITH REMOTE, ... /REF:LEK-PIP-1")

this model looks pretty sophisticated and mine may be relatively crude, with no remote and only one location for the PIP frame. would this be egually difficult and reguire complicated sychronization? is it possable to simplify the process by converting between analogue and digital signals?

 

[Roff]

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:

 

[Nigel Goodwin]

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.

The unit you listed in the link looks very reasonably priced, and the basic function is what costs the money - not the simple 'add-ons' like remote control.

 

[gliptitude]

thank you for your help electronics gods.

i definitely won't be buying a PIP device except if it will assist me in building one.

one of the electronics books i've been reading says a television is so sophisticated that if it were not mass produced so effectively it would be a $5000 instrument. i guess that is the realm of technology i would be dealing with. probably way outside of the amateur realm. :?

at some undocumented moment in my research i think i came accross a project for converting analogue signals to digital. in and of itself, is this relatively acheivable with video signals? could i get that far and, as a preliminary project, mix the signals and render the effect with a computer? is synchronization as difficult with digital signals?

 

[Nigel Goodwin]

thank you for your help electronics gods.

i definitely won't be buying a PIP device except if it will assist me in building one.

one of the electronics books i've been reading says a television is so sophisticated that if it were not mass produced so effectively it would be a $5000 instrument. i guess that is the realm of technology i would be dealing with. probably way outside of the amateur realm. :?

A TV probably isn't too hard too build, certainly an easier amateur project than a video mixer or PIP unit. However, it would cost considerably more than buying one - unless you could get most of the parts second hand, or even better completely free!.

at some undocumented moment in my research i think i came accross a project for converting analogue signals to digital. in and of itself, is this relatively acheivable with video signals? could i get that far and, as a preliminary project, mix the signals and render the effect with a computer? is synchronization as difficult with digital signals?

You can get TV input cards for computers, this is certainly by far the cheapest option - building your own very high speed A2D would cost more, and you would have to write the entire software from scratch. Even better, you can get multiple input ones (four inputs) for security systems, these will display four small pictures for you.

 

[gliptitude]

my ultimate goal is a compact self-contained PIP device. this goal is unchanging as i personally have no need for PIP in my daily life. i would rather not go into detail about the reasoning behind the project, but it has to do with a patent i would eventually like to file.

i am a little farther along now having participated in this forum, but no one has said anything about digital vs. analogue, which has been a part of all of my posts. now i know that i can input video signals to my computer with a TV input card. but does digital technology have anything to do with my ultimate goal?

:shock: Does converting to digital simplify the synchronization process? :shock:

it seems like PIP is a kind of an accessory function, and not really vital to the high end television. clearly the manufacturers can create this function easily enouph. why can't i? does a PIP eguiped tv have components inside that could be removed and adapted to form a free standing PIP device? if so, this too would only be a preliminary project, but...

thank you for you posts.

 

[gliptitude]

A TV probably isn't too hard too build, certainly an easier amateur project than a video mixer or PIP unit. However, it would cost considerably more than buying one - unless you could get most of the parts second hand, or even better completely free!.

hmmm. maybe i will try a tv first. it would be utterly thrilling to see a tv i built myself light up with a live broadcast (or taped). a primative, LED looking tv like the ones i've seen in museums, would be even more thrilling! i'm obviously not prepared to complete the PIP device. it is still what i am working towards, but i would rather a couple gratifying interem projects along the way, in order to learn, than weeks, months...years of failure and tedium with an excessive project.

if i bust up a (working) 20 year old tv can i get many of the parts for a DIY tv?

 

[Nigel Goodwin]

if i bust up a (working) 20 year old tv can i get many of the parts for a DIY tv?

Old TV's are by far the best source, they don't have the large scale integration of the newer sets. You're probably better off going back even further though, to when TV's were of modular construction.

 

[Nigel Goodwin]

my ultimate goal is a compact self-contained PIP device. this goal is unchanging as i personally have no need for PIP in my daily life. i would rather not go into detail about the reasoning behind the project, but it has to do with a patent i would eventually like to file.

i am a little farther along now having participated in this forum, but no one has said anything about digital vs. analogue, which has been a part of all of my posts. now i know that i can input video signals to my computer with a TV input card. but does digital technology have anything to do with my ultimate goal?

:shock: Does converting to digital simplify the synchronization process? :shock:

In a nutshell, YES!.

You can probably implement it using massive surfacemount chips, designed for the purpose - but you have to arrange for all the support circuitry, plus suitable micro-processor/controller control.

Obviously this all requires large quantities of information on the devices, as these are usually fairly obscure it could be difficult to find?.

 

[mechie]

Other video ideas ?

As a way of getting your head around some of the concepts in video how about building some sort of toy that outputs video ...
**broken link removed**

Or ... if you want to synchronise something to an existing video signal I'm sure I saw a PIC microcontroller project that stuck a simple digital clock display in a corner of a TV picture (or onto a CCTV image or whatever ...)
**broken link removed**
http://www.brouhaha.com/~eric/pic/pictock.html
http://alternatezone.com/electronics/vcg.htm
A long way from PiP but it lets you see some principles in action ?

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!).

 

[gliptitude]

LED television

thanks for the great suggestions mechie!

the link to rickard's gaming projects was awesome. the LED display for his "virtual game system" was particularly interesting to me.

do you (or anyone else) know any projects similar to this mechanical LED display? can something like this display a broadcast?

 

[gliptitude]

i was not finding much for diy tv's until i started reading about the earliest televisions. one of the methods was called "baird", i think after the inventor, and a search for "baird television project" turned up lots of projects.

has anyone done one of these or know what can be done with one? this is getting off track for me, but it is fascinating.

 

[Nigel Goodwin]

i was not finding much for diy tv's until i started reading about the earliest televisions. one of the methods was called "baird", i think after the inventor, and a search for "baird television project" turned up lots of projects.

has anyone done one of these or know what can be done with one? this is getting off track for me, but it is fascinating.

The Baird system was a mechanically scanned system, used in the UK, it worked along side an electronically scanned version (on alternate days) before WW2.