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Saturday, September 23 2017 @ 02:25 AM CDT

PCs and Encoders

Previous: Internet Connections - Next: Lighting

The encoder is where video meets the internet. The output of all video cameras is simply not something that works over the internet by default. The internet for the most part can't handle the full amount of information the camera can produce, and the format of the information - interlaced frames of analog voltages in the case of composite video cameras, and long strings of large binary numbers in the case of digital cameras - simply doesn't directly translate into something the internet can deal with today.

The encoder translates the video (and audio) into bits and bytes, then compresses these bits and bytes to fit through the fairly minimal network upload bandwidth the typical end-user internet connection has. Along the way, the image and sound will lose some (maybe a lot) of its quality, but in the end it will represent your chosen subject pretty well, all things considered.

Here's how they do their job, and how to tell which might be best for your critter camera.


Encoders break down into two distinct types:

  • Encoder equipped PC
  • Specific purpose (embedded) encoder

You'll find examples of both for cameras that have no specific IP output.

To the right, you see the original PC encoder and archive systems at the Hornby eagle nest site.

The "IP Camera" is simply a camera with the embedded encoder built-in and pre-wired (and matched) to the camera. In the example of the Axis cameras we're so fond of, you can purchase the encoder they use as a separate box (the Axis 7401 encoder) or as multiple in one box, and use your choice of camera with it. There are other similar units for industrial security systems that are not directly useful for live streaming at this time, but we continue to hope and "strongly suggest" to manufacturers that they consider opening their proprietary systems to our use.

Where the camera is separate from the encoding PC-style computer the typical setup today is to use USB, Firewire or separate video capture card with an appropriate software driver that allows the encoding software to talk to the camera video and audio streams. With USB and Firewire cameras there may be audio in with the video and no separate microphone is needed (but can be plugged in if you wish) and with a capture card, the card may or may not have an audio port. For audio the capture software will typically allow use of the PC’s normal audio microphone or line-in input.

The encoding software we use for composite video cameras the most at this time is Adobe’s Flash Video Encoder version 3.0, (3.1 is now available but some of our other software does not yet work with it) available for free download from the Adobe site.

You may also use software provided by the specific internet streaming video distribution company too, as that software will typically also allow you to use any camera you can hook to the PC – and some will allow you to switch between cameras and do other things too – see the Production section for more.

The Encoder PC

If your camera requires a separate encoder, you should not normally use your desktop PC as the encoder for your long-term wildlife camera.

You should instead use a separate computer for the simple reason that most people tend to have to reboot their desktop computer every once in a while, whereas the encoder computer can end up running for months on end without reboot. Yes, it is possible to get a Windows computer to run for long periods of time without reboot.

For a typical composite video, USB or Firewire camera using the Adobe flash encoder software, the PC can be almost any Windows XP box with a CPU faster than 1.5 GHz and at least 512 Megs of RAM. At this time we strongly suggest Window XP rather than the newer operating systems because it is simpler to set up and “just works”. Vista and Windows 7 impose some (in our opinion) strange requirements on the hardware and software that are neither relevant nor conducive to long-term unattended operation. We expect that over time these limitations will be discovered and somehow worked around, but in the mean time if you are going to do unattended encoding and have to use Windows, use XP.

If you’re going to do fancy multi-camera mixes and other “production” things you might need a faster machine with more RAM. Chances are that in this case you’ll use one of the newer versions of Windows – version 7 is probably best. Note that at the time I’m writing this (late 2010) I don’t recommend using the 64 bit version of Windows unless you are absolutely sure that everything you are using has a 64 bit driver available and all works together. By all means, test it, but be prepared to fall back to the 32 bit version. This can have consequences if you have/need a lot of RAM as some of the production programs do with multi-camera setups, but at least things will work.

It is possible to use some of the faster netbook-class machines as an encoder if the camera system will plug into it. They don’t typically have a card-slot for a capture card but USB capture devices will work on them.

Another alternative is to get PC-104 (4” square CPU cards with all on one) boards with Atom and/or Pentium class processors on them that use less power and take up less space than a desktop PC, or even a netbook (they have no screen and less RAM). We’re experimenting with one such board that will do some capture for archive (running Linux) and control of peripherals such as our fuel cell and some lights, all on less than 8 watts of power.

When setting up the encoder PC I tend to run them “headless”, meaning no monitor, keyboard, mouse. In many cases they are in remote locations, even if in the same house. To do this you may need to tell the BIOS to ignore keyboard errors (as in, there isn’t one) when booting. Most BIOS settings also have a way to tell the computer to reboot whenever the power comes on so in the event of a power outage (like last Saturday night at the Sidney site during a wind storm – a place where there isn’t anybody around all weekend) the machine simply starts itself up after the outage. Depending on the encoder software you run you may also have to remotely log on and restart that software, but at least you don’t have to visit and push the power button.

The best setups simply start and run as soon as power is applied to them.

Video Capture

USB and Firewire cameras digitize the video and present it to the PC as digital video. Composite cameras need a video capture/digitization unit to do the same thing.

Video capture units come in both internal card format and external USB (or Firewire) types. Which you use is up to you, and the market is changing almost daily as new units come out for Hi-definition capture and to deal with new standards for things like TV capture.

We’ve used units from Hauppauge, Pinnacle, Osprey, ATI, and many others. In general, if the unit is compatible with Windows Media Encoder and/or Adobe Flash Encoder, then it should work just fine for whatever you are doing. You’ll likely need to install specific drivers for the unit, and may need to run a setup program that selects the input you need (some have TV tuners as well as composite video/S-video inputs) and may need some sort of cable adapter to fit the unit to your camera or cable extension.

Some units have their own audio input as well. In a dedicated encoding computer this may not be necessary as you are unlikely to have additional microphones or other input devices already plugged into the computer. In other cases the software supplied with the card will multiplex this audio directly to a container format such as MP4 for archiving to file if this is what you’re using the unit for. Remember, if you really want hi-res archives, you’ll probably need to use a second encoder as running both a live stream and file capture on the same unit is problematic.

If the capture unit does not have its own audio input it likely to be useful only for encoding to live stream as this means it will need to bring in the audio from the PC’s sound card/motherboard – and the hard work of encoding and multiplexing will be done under the control of the PC’s CPU instead of a dedicated chip on the interface unit.

Cabling

In general you’ll want to use cables that will reach directly from the camera to the PC with as few connectors as possible. See Overcoming Distance for cable length maximums.

If you are not handy with putting connectors on a cable yourself, then you’ll likely have to deal with adapting the camera to the long cable, then that long cable to the video capture unit. If you can, purchase or specify for custom build that the long cable have BNC (bayonet) or F (screw) type connectors on each end as these provide a positive locked connection. (BNC is a “bayonet” style typically used for radio antennas and F is a screw-on style typically used for cable vision)

The alternative is the typical RCA-type friction connectors found on audio/video patch cables. These are prone to coming undone and can cause problems in the long term.

All of these connectors are “coaxial” in nature by design, meaning they are best used for cable that has a central conductor surrounded by an insulator, then a braided or solid metal shield that acts as the ground and protects the signal on the center conductor from interference.

It is also possible to run either audio or video over twisted cable for some distances. How far will vary depending upon the types of electrical interference you have in your particular area. In general the use of twisted cable should not be for lengths much over a hundred feet or so. We’ve used things like 18 gauge rubber power cable for underwater cameras for example. The 3 conductor cable allows power on one lead, ground on a second, and video on the third (ground for the video on the same conductor as ground for the power). The video will lose definition as the length increases since the high-frequency signals are the first to drop out. Color will degrade, then disappear – then the image will lose gray tones and edge definition.

Do not under any circumstances use cable with power connectors still on it - at some point in the future, someone will mistake this for an extension cord and plug it into something and blow out (maybe cause fire) your encoder!

IP Cameras

Of all the cameras I’ve tried to use with our live wildlife streaming, IP cameras have given me the most headaches. The reason for this is that for the most part they are designed to work with specific monitoring software for industrial security applications, not stream to the internet. The software is typically from the same company that makes the camera, and the whole system is designed to lock the user into the company’s product line in some fashion. (Mid 2011 - this is changing - I'll post an update soon on some new cameras with facility to stream directly to the likes of Ustream.TV or Livestream.TV)

The problem is usually not just controlling or setting up the camera. The problem is getting the encoded video that they put out to be compatible with the standards of the internet distribution systems now (and in the future) available. Today this means FLASH video, tomorrow it might be something else.

You see, encoding video is a very complex problem. Because of this, companies that do it really well patent their methods and want license fees from those who want to view the video or distribute it. Even companies that don’t do it all that well want to play this game because it locks their customers into their product line. The software they distribute typically has a limited number of people that it supports (due to licensing) and there are no options for increasing this at any reasonable cost. This is all well and good when you’re only talking about one or two viewers wanting to see a security camera stream, but when you have the whole world wanting to to view streams the license model breaks down badly.

The answer in most cases is to re-encode the video, receiving it once (with a licensed viewer/decode facility) and re-encoding it with something that is either freely licensed (like the Adobe encoder) or totally free (like the open source encoder, Theora, and Google’s newly opened VP8 on WebM) and then sending that video out to the distribution facility.

In cases where you, as an operator of a single camera from your home, can sit in front of your PC and work the process using some of the available streaming production software this is only expensive ($400+ at the moment but by the time you read this it will likely be less) – but it can still be a pain.

For me, working remotely to many sites where cameras of all manner must run unattended for days and months at a time, it is just plain annoying. In fact in some instances it has proven completely impossible.

At this point in time I personally know only of two IP camera/computer set ups that work, and from the point of view of getting out to a FLASH distribution content distribution facility, even they don’t work all that well.

What it comes down to at this time is that there is a small selection of cameras that can be set up to go directly to some re-distribution internet services if special setup is allowed and followed, but in general for now you should stay away from IP cameras when you’re planning on doing wildlife video live to the internet unless you can use one of the techniques from the Production section. Again, I’ll spend some time on the specific setups in the next book on the professional aspects of this industry.

There is one way that an IP camera can be used fairly easily, and that is if it can also be connected via a video-out connector to a separate encoder PC. We have successfully used this setup to allow us to use the IP facilities for controlling the PTZ camera and bypass the IP for the video to the net. It takes extra wiring but is worth it. In some cases the raw video output is hidden behind a plate on the camera body and needs some work with tools to expose it.

The other way to use an IP camera involves “grabbing” its video from the screen of a PC and re-encoding it via production software on the PC – and having that re-encoded video be “pushed” to the distribution system. See the Production section for examples of this.

In addition, Axis has created a utility they provide for free which makes their IP cameras look as if they are directly connected to a PC running Windows – and available to some encoder software programs. They specifically state it is for Windows Media Encoder – but we’ve found it also works with many other programs, including some of the producer programs for the video distributors.

Tag: encoder pc capture audio video flash adobe connectors f-connector archive

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