You can just use the on-camera microphone and fix it in post-production, right?

NO!

Audio is the most forgotten thing during a shoot. When shooting video, even professional TV shows and films capture crappy audio. It’s something that a lot of people consider inevitable. In a big production, a technique known as ADR, or Automatic Dialogue Replacement, is used for a lot of the character’s lines—Lord of The Rings apparently used 90% ADR! That’s a lot of rerecording voices after a shoot! On the other hand, filmmakers like Quentin Tarantino insist on getting great audio on set to avoid using ADR. Fortunately, with the right tools and some solid planning before you shoot, you can minimize the amount of audio hassle. If you’re really interested, here is a really informative article about capturing audio on reality TV shows.

Tools

To record audio, you’ve got lots of options. It’s like choosing between using your sister’s point-and-shoot 3 megapixel camera and a Canon 5DMkII. And if you really wanted it to turn out perfect (or as close as you can get), you’d pick a Leica S2 or Hasselblad H4D-40 megapixel medium format digital camera.

This is where we realize the built-in microphone isn’t going to cut it for quality audio. Let that sink in for a minute.

And that microphone that came with your camera (if it came with one, like the Sony Z7U or JVC HM100U) isn’t going to cut it for high quality audio either. Even if it looks pretty. A note before we continue: these kit microphones can work, and people make them work all-of-the-time. However, they’re a lot like the kit lens that comes with a Canon Rebel. It’s not bad, but it’s not much good either.

Picking a Microphone

The first step to getting quality audio is a good microphone. Good being defined as a microphone (or multiple microphones) that fit the requirements of the shooting you’ll be doing. Different types of microphones, categorized by use, include:

1. Shotgun microphones
2. Lavalier or lapel microphones
3. Handheld microphones

There are other types of mics, but these are the basics you’ll need to get good audio.

Shotgun microphones.

Shotgun microphones are designed for one purpose—to pick up audio at a distance. You see those commercials or live television shows with long microphones on boom poles? Those are shotgun microphones. They are created with a specific pickup pattern (how the microphone picks up audio), known as hypercardiod or shotgun. Take a look at the diagram below to illustrate pickup patterns.

Omnidirectional, Cardiod, Hypercardiod, and Shotgun pickup patterns

How are shotgun microphones used in productions? Where do you put them? Well, you can mount them on camera, but if you have a mattebox or other camera attachments, they probably aren’t going to fit. Your best bet for a shotgun microphone is to use a boom pole and have a friend come along and hold it. It doesn’t get bumped or pick up noise from the camera as easily either. If you’re doing an interview, you can mount the mic on a stationary stand because the person isn’t going to move.

Lavalier or lapel microphones.

These are small microphones, often clipped to a shirt. Extremely popular with TV news anchors and interviews, and used wirelessly for any large theatrical production (or your local church pastor). They often feature an omnidirectional pickup pattern, although are made with unidirectional and cardiod patterns as well.

Handheld microphones.

These often are used for ‘man-on-the-street’ interviews or for sideline interviews. The same type of mic is used on podiums everywhere. It typically features a unidirectional pickup pattern.

Other ways to characterize microphones.

Wired vs. Wireless

In some cases, particularly with lavalier microphones, the subject is moving, and it’s not convenient to run cables. Other times, the microphone is placed in the set, and a cable can’t be run without running through the camera’s shot. In both cases, a wireless transmitter is used. Wireless provides portability and flexibility, but also can bring RF interference from outside sources, causing hard-to-fix signal problems. If you can run wired mics without intruding into your shot or preventing movement, you should stick with wired mics. If wireless is the way to go, however, you can attach almost any microphone to a wireless kit and transmit it back to the camera. We carry the Sennheiser W2 Wireless Kit for this purpose.

Type of cartridge in the microphone.

The next differentiator in mics to consider is cartridge choice. The two major choices are dynamic and condenser (also known as capacitor) microphones.

Dynamic microphones

A dynamic mic is the exact opposite of a normal speaker. A speaker cone moves a magnet in response to incoming vibration, then the magnet moves along a coil and converts the vibration to electrical energy, which is sent as an electronic pulse to the camera/recorder. (A normal speaker moves the coil, vibrating the coil, making noise.) Dynamic microphones are simple and durable. The Shure SM58, a famous example of a dynamic mic, was used on tour with The Who, where lead singer Roger Daltrey would swing the mic around by the cable and smash it into cymbals. The mics would survive a few performances before needing to be replaced.

Condenser microphones

Condenser microphones, on the other hand, use a capacitor to pick up vibrations and convert it to electrical energy. These microphones are more sensitive then dynamic mics in general. Most lavalier mics use condenser cartridges.

Phantom power

It’s important to know if your mics need to be powered or not. Generally, condenser mics need to be powered, while dynamic microphones do not. Often, these microphones will have a battery compartment, but they can also receive phantom power, a 48V power source from the camera or recorder. Phantom power can harm a microphone if it is turned on, but the mic doesn’t need it.

Now, we’ve picked a microphone, how do we record the audio?

Professional video cameras include 2 XLR inputs, which each capture balanced, mono audio. Since there are 2 inputs, that gives you a stereo signal. Less expensive video cameras or dSLR’s offer a single, unbalanced, stereo input. A converter like the Beachtek DXA-5D allows you to convert 2 XLR inputs into a single stereo input for use with dSLR’s and smaller video cameras.

It’s all about quality.

How much background noise can you accept in your recordings? dSLR’s aren’t necessarily designed for video, and as a general rule, full size professional video cameras have better audio pickups with lower noise. Yet another option is an off-camera recorder like the Zoom H4N , which records either 2 XLR inputs, 2 headphone inputs, or can record with built-in microphones. Using an external recorder for audio is how it’s done, when you’re looking for the highest quality audio. Just like the difference between that cheapo 70-300 variable aperture zoom and a 70-200 f/2.8 lens, using an external recorder makes your recordings better. You can still get a good recording using the camera to record audio, but an external recorder makes it even better and cleaner.

Headphones

Don’t forget a pair of headphones. It’s critically important to be able to monitor sound as you’re shooting and also to do a sound check beforehand. Your standard headphones will work, but consider a pair designed for audio recording like the Sony MDR-7506’s. They provide open-ear, accurate, clear sound to check not only that the microphone is on, but also that it sounds good. Why open-ear? You want to be able to hear around you a little too… it’s bad news if the audio guy can’t hear a ‘watch out’ shouted in his direction.

Production time

You made it! You picked some microphones, and you’re getting ready to shoot. Where do you put the mics? We’re going to help with that (a little) too. Let’s look at a little example.

A simple setup.

You’re shooting a simple interview on a clean backdrop, filming with a built-in mic only, with one camera. The quick and easy way out. Just set the audio level and go.

Now, before you start recording, you need to set recording levels. Most cameras offer AGC, or Automatic Gain Control (on some cameras you can’t disable it). You don’t want this. What AGC does is guess the correct level based on the incoming signal. Great for when people are talking. But as soon as a pause in conversation comes up, it doesn’t hear anything, so pumps the level way up. Serious hissing and noise, plus when conversation starts again, it’s going to be really loud for the first second or so. Not good. Don’t use AGC. Ever. So, you need to set levels manually. How do you do that? Simple. You ask your talent to talk, engage them in conversation. While they’re rambling on and on, you set the level at about -20db. Ask them to speak loudly, and make sure it doesn’t go above around -3db. Ask them to speak softly, and make sure you can still clearly hear them over the fuzz.

If you set the levels too high, it peaks and you get super irritating and unfixable distortion. If you set them too low, you have to boost the level too much and the voice sounds thin and the background hiss and noise becomes a problem. Be careful and double check your sound check. If you have spare microphones you can use, wire them up to a secondary audio recorder (the second camera perhaps) and set the levels a little lower or higher than you set the primary. Then you’ve got another backup just in case. Too much audio recorded is a better problem to have than not enough. You’ll see that in future examples.

You can kick it up a notch in this simple setup, however. Just add a shotgun microphone on the camera to get better quality than the built-in mic (picture below). Easy and simple.

Now, for a more in-depth, higher quality, one man show (below, before audio setup).

Using 2 cameras on tripods, one for the traditional medium shot (your A camera), and one for close-ups and wide shots (B), you’ll be shooting solo today, with only an interviewer to ask the questions to your interviewees. You’re in a city, so wireless will be complicated because of all the other frequencies floating around, so you decide to shoot wired. Because you don’t have a dedicated audio person, you bring a music stand to hold a shotgun microphone (1) aimed at your interviewee. You also wire the person with a lavalier microphone (2). You decide to record audio on your first camera (A) because it’s a nice video camera and will record high quality audio without having to sync up an external recorder. You’re also recording audio on the B camera using the built-in mic, so that it’s easier to sync up the two cameras later (below).

The 2 microphones fit perfectly in the 2 XLR inputs of your A camera. When you’re in post-production, you’ll only use 1 of the mics, most likely the lavalier. We’re recording both to ensure you get decent levels, just in case one isn’t placed quite right. If you use both in post, you have to deal with a tricky little problem known as phase – cancelation or comb filtering. The two signals are slightly different because they were a different distance from the person, so… the audio is milliseconds delayed on one mic. This causes certain frequencies to either become louder or softer. It’s not a pleasant thing to deal with. Trust me. Just use one in post, and cut the other one in if the first one cuts out.

Yet, there’s a third option, recording externally and bringing a bigger crew. Two more crew members join. One holds a boom pole with a shotgun mic on it, and the second mans the audio recorder so you don’t have to record on camera and don’t have to worry about levels being correct all the time. Still keep your shotgun mic (and the second camera with the built-in for time sync) from before wired exactly the same. That becomes your backup, and the audio recordist (fancy term for the day) records the real audio on an external audio recorder like the Zoom H4n. It records the boom pole mounted shotgun mic, and a lapel mic. See below. Complicated, but it will get you extremely good audio (with a backup).

That’s it! Simple, right?

Your choice of which method of recording depends on budget, flexibility, and portability. If you’ve got the resources to hold boom poles and monitor and set levels externally, that’s an excellent option. If you’re out filming solo, you’re better off with an on-camera solution for mics and recording. Somewhere in the middle? You’ve got lots of options. Please feel free to send us an email if you’re not sure what to rent.

References

• http://www.articlesbase.com/advertising-articles/what-is-automated-dialog-replacement-984834.html
• http://www.thewho.net/whotabs/gear/pa/microphones.html

Note: This is a rather in-depth article about video compression. If you are new to video, you’ll want to read I’ve Shot Video, Now What? first.

When we started carrying the nanoFlash, Roger, our video challenged owner bought it because he was told it was great. When he read about it he became completely overwhelmed by the 762 different formats it would record to and from and demanded an explanation for just what the heck all that meant. Hence this article (which is written for video novices, like Roger). A photographer like Roger is used to working in only two formats: RAW, which has the maximum information the image contains, and JPG, which is compressed to a more convenient file size. As many photographers learning to shoot SLR video have found out, video is different: everything is compressed to one degree or another, but in an apparently bewildering array of methods and formats, each of which comes with their own cryptic codes and abbreviations.

What video compression is not

Compression is not the resolution of the video, but video resolution has a lot to do with how much information will need to be compressed. Common video formats are 720p, 1080i, or 1080p. The 720/1080 part is pretty straightforward, it simply refers to the number of pixels on the vertical scale of the image: 720 is a 1280×720 pixel image. 1080 is a 1920×1080 pixel image for each frame of video. That’s a big difference in the amount of information: a 720 frame has 921,600 pixels. A 1080 frame has just over 2 million pixels.

The i and p parts refer to whether the frame is interlaced or progressively scanned. To be (very, very) brief, progressively scanned is better, especially when there is a lot of motion in the image, but doesn’t make as much difference when objects in the image are fairly static. 1080p is the best of both worlds, but takes a lot of bandwidth to do (it’s overkill for web video or most television, for example). 720p and 1080i actually both take up roughly the same amount of bandwidth and are what are used for HD television as an example (some networks use 720p, some 1080i). 1080p generates significantly more data than either of the other two formats. That’s why many lower end cameras, storage devices, etc. can handle either 720p or 1080i, but not 1080p.

The other variable, that is not compression, but that does influence how much data must be compressed, is the FPS (frames per second) the camera records. Film cameras shoot at 24 FPS. Many, but not all, video cameras can shoot at 24 FPS for a ‘film-like’ look, but standard video is usually shot at 30 FPS. (Note: These standards refer to the US and a few other nations. There are other standards worldwide.) Some lower end cameras shoot at lower frame rates than these, and some high end cameras can shoot at much higher frame rates.

Obviously a 1080p image shot at 60 frames per second is going to generate a lot more data than a 720p image shot at 24 FPS. The bottom line, though, is video is generating a lot of information: 1 to 2 million pixels recorded 24 to 30 times a second, at 8 to 16 bits per pixel, plus audio is a lot of data to record. And, practically speaking, it has to be compressed somehow to make the file size manageable.

Compression and Bit rate

Simply put, bit rate (usually expressed as megabits per second, or Mb/s) is the amount of data recorded each second. After the camera (or computer) has done its compression thing, the file size will equal bitrate X seconds of video. If you dig around, you can often find the maximum bit rate that a camera, storage device, or processor handles. In theory, higher bit rate means more data is stored, which (assuming everything else is equal) means higher quality compression. But there are a lot of other variables.

Different cameras use different codecs (COmpression-DECompression algorithms) to compress the data. Your camera choice sets your choice of compression algorithm (more on this later), since different manufacturers have chosen different codecs. In general, compression algorithms are sorted into two general categories (this applies for audio and other data too, not just video) lossy and lossless. Lossless means that after decompression each pixel is exactly the same as the original, no data can be lost. There are no video cameras (other than a few amazingly expensive professional cameras) that record lossless.

Lossy compression isn’t an exact pixel-for-pixel match when uncompressed, but it offers much higher compression ratios than lossless compression. (The compression ratio is the size of the original video compared to the compressed video. Uncompressed video is 1:1. Lossy ratios can get very high— 1:200 compression isn’t unheard of for some heavily compressed video formats. The codecs used in video cameras offer better quality, but less dramatic compression ratios. More on the order of 1:50.) There are lots of different codecs in use today. The better codecs are usually newer and offer a higher compression ratio with similar quality image. For example, MPEG-4 gives a higher quality image than MPEG-2 at the same bit rate. Some high-end cameras, though, use less aggressive codecs with less compression to maintain the best possible image quality. In exchange for that, they require significantly higher bit rates to record their data.

How video compression works

There are two ways to compress the data in a video clip: Intra frame and inter frame. Intraframe compression takes each frame of the video and compresses it just like you would use JPEG to compress a still image (in fact one format, Motion JPEG, does exactly that). With intraframe compression every frame of the image is complete, although slightly compressed. This can be important if your video has lost a frame – since the frame before and after the lost frame are complete, not much damage is done. It’s also important when you cut and paste video clips – the video editing software needs a complete frame at the beginning and end of each transition. Intraframe compression, though, doesn’t really make the file size all that much smaller. Compression ratios of about 1:20 are about as good as it can do.

To really get more significant compression, video codecs also use interframe compression. The basic idea is simple. Video consists of multiple still frames, (anywhere from 24-60 per second typically). Interframe compression looks at each frame, compares it to the previous one, then stores only the data that has changed. Usually it doesn’t look at individual pixels, but rather at square blocks of pixels (less time consuming and resource intensive). But each frame in an interframe compressed video contains only the changed parts of the image.

But interframe compression brings a new problem: What happens when you’re sending this video to wherever (or importing it), and it skips a frame? If each frame is referencing the previous frame, you’re in trouble until the entire picture has changed. If you have a 3 minute clip of the same scenery, there would be a problem. And the same problem would occur, if you wanted to cut the scene halfway through that 3 minute clip: the frame at your transition wouldn’t be a complete frame, just a compression of the changes that occurred from the previous frame. And so on. The solution all interframe compression formats use is the key frame.

Key frames and long-GOP compression

Interframe compression codecs record a Key Frame every so often: a frame that contains the entire image data set, whether the scene has changed or not. The key frame is shot every x number of frames (usually 15) and that frame contains a complete image. The next group of frames (until the next key frame) is heavily compressed, containing only the changes from the previous key frame. Using this method, if you skip a frame, you only lose (at most) 15 frames before you’re good to go again (or until your next editing point). It’s still a relatively long time, but allows for a much smaller file size than intraframe compression alone. This key picture followed by several the compressed pictures until the next key frame is abbreviated GOP (group of pictures). Since there is a fairly long group of images grouped associated with each key frame, this is often referred to as long GOP compression.

A final note about frame skipping: it’s rare. In fact, it almost never happens when using quality equipment. Because of this, long-GOP encoding is usable and safe. Intraframe-only compression does protect against frame skips, but requires a lot more disk space (and a higher bit rate for the same quality image). Since video editing software can only cut at a key frame, some high quality video recording devices (like the nanoFlash that started this discussion) will record video with only intraframe compression (a half-second until the next key frame can be an eternity to a video editor), but the resulting files can get very, very large.

Luminance and Color Compression

Since the days when video was analog, luma (the black and white values) and chroma (the color) have been stored separately. Y’CbCr is how video is stored today, typically using a process known as chroma subsampling. Y’ (sometimes simplified to just Y) is the luma (grayscale) information. Cb and Cr each store a portion of the color information (like LAB color space in Photoshop, for you photographers).

We are less sensitive to color and very sensitive to the grayscale value of an image, so video cameras today discard some of the color information to further compress the video data. The proportions are usually shown as a ratio with 4, indicating no compression. Recording video at 4:4:4 would be ideal, but it takes up an enormous amount of space and isn’t feasible in most situations with today’s equipment. Top quality video formats, like XDCAM422 and DVCPRO HD, keeps twice as much Luma data as either color (Cb and CR) data in a ratio of 4:2:2. This reduces bit rate by 1/3 with very little image compromise. Other video formats such as HDV, AVCHD, MJPEG, and MPEG-2 (DVD quality) use even less chroma data, storing video at a ratio of 4:2:0. This may sound extreme, but DVD quality video is recorded at 4:2:0, so it is intentionally missing 3/4 of the color information originally present. Don’t we all think DVD is pretty high quality? Even Blu-ray is only keeping 1/2 of the color information, storing video at 4:2:2 chroma compression.

Many professional video cameras use a 4:2:0 ratio to keep the bit rate manageable when recording in camera. When absolute image quality is critical, however, these cameras (The Sony EX1 and EX3, for example) that internally record at 4:2:0 have HD-SDI output from the camera which can output a higher quality 4:2:2 signal, but will require an external recording device (like the nanoFlash that started this discussion).

Recorded Bitrates

Interframe compression algorithms record so many bits-per-second. Using a set bit rate stores the same amount of data for every second of video, regardless of how the frames change over that second. With a set bit rate you know exactly how large a 5 or 10 minute video file will be, since the bit rate is fixed. When we used film to record to (or MiniDV tape), the bit rate had to be constant, because the tape moved at a constant rate. DV footage, once digital, still records to tape at a fixed rate of 25Mbps. HDV, a descendent of DV that uses MPEG-2 compression, records at a fixed rate of 35Mbps.

Most cameras and codecs today, however, record using variable bit rates because it is more efficient. This changes the recording bit rate based on the amount of information change frame-to-frame. If it sees an almost identical previous frame, very little data will be encoded. However, if a large part of the frame is changing, there is much more data, and a higher bit rate will be recorded. The takeaway message, though, is that every recording device, whether in-camera or external, has a maximum bit rate it can handle. The various compression codecs have to provide final data at a bit rate that is acceptable to the recording device or bad things will happen: missed frames, jumping, etc.

HDV XDCAM AVCHD and every other codec

The terminology involved in the various codecs is beyond chaotic. To a video-outsider it’s incomprehensible, but we can try to clarify things a bit. Like most simplifications, what follows is a bit generalized in the interest of keeping it easy to follow. We’ve left out and ignored some arguable points that would easily lead to 4 more pages of clarification in an effort to make it readable. As a general overview, however, this is a pretty reasonable summary. First, we need to separate containers (sometimes called formats) from the underlying codecs. A container is a format that can use (or be used by) many different (but not all) codecs. AVI, Quicktime, RealMedia, DivX, and many other containers exist, but they are (with a few exceptions) not actual codecs.

There are several codecs in common use today, each following a set of standards developed by the Motion Picture Experts Group (MPEG), the ITU-T Video Coding Experts Group (VCEG), or the Joint Video Team (JVT) from both groups. These standards provide a lot of customizable options to the various camcorder and software manufacturers. Some cameras let you choose between two codecs, but most only offer one. The reason behind this? Different codecs require different processing algorithms to encode video. The processor in the camera (yes, cameras have processors very similar to computers) is designed so that it can handle the encoding for that specific codec. And the memory used to store the video is designed to handle the bit rate needed for decent quality video from that codec. Etc…

The most current families of standard codecs from MPEG and VCEG are combined as the H.264/AVC/MPEG-4 standards. H.264/MPEG-4 (also referred to as MP4 at times) allows for a much lower bit rate then previous codecs while still achieving excellent quality. It is used not only for video compression during recording, but also for compression after editing. Youtube, Blu-ray, and the iTunes Store all use H.264 for encoding video. AVCHD codecs are H.264 based codecs used in newer high end Sony and Panasonic cameras, but many other newer camcorders use H.264 based codecs.

Several other codecs remain in common use. Motion JPEG is used on many point-and-shoot video cameras and Nikon Video SLRs. It doesn’t compress nearly as much as H.264 codecs, but requires a lot less processing power and is particularly suitable for nonHD video and lower resolutions. The HDV and DVCAM family of codecs use largely MPEG-2 compression as does the XDCAM codec. These files aren’t usually as tightly compressed as H.264 codecs, although MPEG-2 Long-GOP comes close. These codecs are often found on high-end digital video cameras. The reason why they don’t use H.264? Depending on the source of information you read, this is because the files are easier to edit, or because the manufacturer had lots of chips made for these codecs and was going to use them. I suspect both reasons are true.

So basically each manufacturer chooses which of the standard codecs to implement in their camcorder. Well and good. However, they then modify it a bit, build the chip they’ll install in the camera to use their version and identify it with a cryptic set of initials in an apparent attempt to prevent anyone from understanding that their codec has anything in common with anyone else’s codec. Let’s look at one example. Sony and Panasonic jointly developed AVCHD (Advanced Video Codec High Definition) for their consumer camcorders, which is also used by Canon. AVCHD is MPEG-4 AVC/H.264 compliant so it can also get tagged with those initials. Panasonic tweaks AVCHD with some higher bitrates and markets this codec as AVCCAM in their professional cameras, or downgrades it to 720p recording only and calls that version AVCHD Lite. Sony calls their version NXCAM in their newest professional cameras (as opposed to the XDCAM, a different codec used in many of their current high end cameras). Canon and Panasonic use a High-Profile level 4.1 modification of the AVCHD codec in some cameras which allows a maximum bit rate capture of 24 Mbits/sec, while most camcorders using AVCHD capture a maximum bit rate of 17Mbits/sec. On the editing side, Adobe Premier required a third party plug-in to convert certain versions of AVCHD, but does fine with others, Final Cut Pro converted this format to Apple Intermediate Codec before editing was possible, and Vegas had no problems with the format at all.

Pretty confusing, huh? The takeaway message, with a lot of caveats, is that most codecs in higher level cameras are MPEG-4/H.264 compliant and fairly similar as to how effectively they compress video while maintaining quality. They may differ in offering 1080p (some don’t), in how high of a bit rate they can record (which, given similar codecs, is a fair estimate of image quality), how often they record a key frame (which may be user adjustable in-camera), and how easily your editing program can convert it into an editable format. There are a few common codecs that you’ll run across regularly that fall into several groups:

• DV/DVC/DVCPRO/DVCAM – largely legacy technology, but many HD/HDV systems are backwardly compatible with DV/DVC, and it is used in some high-end video and video broadcast cameras.
• HD/HDV – Used by Sony, Canon, JVC, and Sharp, originally designed for recording to tape. It uses MPEG-2 compression, 4:2:0 chroma sub-sampling, and writes with a constant bit rate. Used in many tape-based camcorders, but also some digital recorders.
• XDCAM – Designed by Sony, but also used by JVC, originally designed for recording to disc. (In some ways a container {see above} rather than just a codec as most cameras using XDCAM can also record in DVCAM or MPEG-2 variants.) Uses an MPEG-2 or MPEG-2 Long-GOP codec, 4:2:0 chroma subsampling, and writes in a variable bit rate to 35 Mbits/sec. However, the XDCAM HD422 version uses a 4:2:2 chroma subsampling profile and writes a maximum 50 Mbps rate.
• AVCHD – Sony (NXCAM), Panasonic (AVCCAM). Uses MPEG-4/H.264 compression, 4:2:0 chroma sub-sampling, and writes in a variable bit rate to 24 Mbps. Note: Some video editors need a third party plug-in to upsample certain AVCHD files to a usable format.
• Motion JPG – intraframe only compression, usually used in point-and-shoot video cameras, but also the Nikon D90 and Pentax K7. It is less efficient than other codecs, so usually image size or frame rate are limited.

Or if you’d rather see what some common camcorders and videoSLR cameras use:

Compare those bit rates to what an external recorder like the nanoFlash can record: 230Mbps.

Conclusion

What does all of this mean? In general, you want the highest bit rate, using the most efficient compression algorithm possible. MPEG-4/H.264 codecs probably produce the best quality/compression ratio. However, top-end professional editing may require a less lossy format, such as an MPEG-2 based codec with resulting larger file sizes to get the absolute best image quality. Some high end cameras will allow you to take the video feed directly out to an external device and record it at an even higher bit rate with less compression for critical footage. Hence an external recorder like the nanoFlash, provides higher bit rates (180Mbits/sec) and less compression than is possible in-camera. (A note of sensibility: the 230Mbps bit rate of the nanoFlash is excessive for use with your $300 handycam or even the Canon HV40. Your image isn’t going to improve beyond the quality of the camera.)

What you intend to do with the footage after recording is also important. Some of the higher compression codecs can be difficult to work with in a non-linear editor and require upcoding to an intermediate format (read: lots of processor power and hard drive space) for editing. Some of the simplest formats, like Motion JPEG, can be drag-and-drop edited in even the simplest programs. And less compressed, but larger files (or even uncompressed files in certain high-end devices) can be a dream to edit and provide the absolute best quality after processing.

Still have questions? Send them to support@lensrentals.com.

Mike Henry and Roger Cicala
January 2010
Lensrentals.com

References

• http://www.cameralabs.com/features/1080p_HD_video_comparison/GH1_vs_5D_Mark_II_vs_SX1_IS_vs_HX1.shtml
• http://www.luminous-landscape.com/reviews/cameras/gh1.shtml
• http://en.wikipedia.org/wiki/Comparison_of_video_codecs
• http://www.luminous-landscape.com/tutorials/video-primer.shtml
• http://www.videomaker.com/article/13754/
• http://en.wikipedia.org/wiki/Video_codecs
• http://en.wikipedia.org/wiki/HDV
• http://en.wikipedia.org/wiki/AVCHD
• http://www.animemusicvideos.org/guides/avtech/video3.htm

You’ve been using a dSLR with video capabilities, and you decided on your last shoot to take a little video for fun. Now what do you do with it?

With photos, you import them into iPhoto or Aperture or any number of programs, then you can bring them into Photoshop and edit to your heart’s content (unless you’re one of those people that sorts them in nested folders and then searches in an attempt to find the photos you actually took last week).

But video doesn’t work quite that easily. Oh, it’s also waaay bigger than the 4 – 40MB photos you’re used to. A DVD holds 4.7GB (4700MB). That’s 2 hours of SD resolution, decent quality video. Not high definition. Not uncompressed. Higher quality video ranges anywhere from 10GB per hour of video to over 100GB per hour of video. It’s very nice looking video.

Sidetrack: Image quality is affected by your choice of codec, but it’s not the only factor. The quality of the footage comes from a) the quality of the camera and lens; b) the codec chosen; c) the resolution of the footage; and d) the bitrate of the codec. Bitrate equals the amount of space the codec can use each second, measured in Megabits per second (Mbps). Back when digital tape was the only option, bitrate had to be constant (25 Mbps for DV and HDV footage). Today, with recording to things other than tape, bitrate can vary. Higher bitrate equals higher quality. End sidetrack.

Anyway, you could import it into iPhoto, or stick it in a folder on your hard drive somewhere (or buy another hard drive for it), but Photoshop doesn’t do video. Now what?

Share it

Burn it to DVD

You could take the raw footage and stick it on a DVD to show your friends. Easy to do with iDVD on a Mac, or on a PC with your DVD burning software of choice.

Upload it to a video sharing site

YouTube, Vimeo, lots of others (Flickr does video too). Just visit the site and click upload. Easy (assuming your internet connection can handle it). Then email the link to all of your photographer friends so they get jealous and start shooting video.

Edit it

Video editing software. Your options vary if you’re on a Mac or PC. Mac first: iMovie comes with your Mac, and it’s decent. Definitely usable for the basics. A step up from that is either Apple’s Final Cut Express or Adobe Premiere Pro. Above that, Apple’s full Final Cut Studio or Avid’s Media Composer (both are a little pricey for backyard video clips). On PC, Windows Movie Maker is ok for beginners. Above that, there are lots of options. Premiere Pro is available, as well as Avid Media Composer. There are also programs available from Pinnacle, Sony, CyberLink, Roxio, Corel, etc…

To start in video, I recommend the basics — either iMovie or Windows Movie Maker to start, and when you need the features and add-ons of a more robust software package, get one.

Codecs

Now, the next big issue with video: codecs. Depending on what camera you used, and what it was set to, you could have a ton of different codecs. Here are the basics: a codec is the format that the video was encoded in. And how it will be decoded. Think file format like JPG or RAW, but a little different (because one format can have many codecs!). For example, a DVD uses the MPEG-2 codec for video. Popular video codecs include MP4, divX, DV, and Theora.

Here are the codecs that some dSLRs and other video cameras use:

Canon 5D MkII, Canon 7D, Canon T1i — MP4
Nikon D90, D300s — Motion JPEG (in a .avi container)
Sony EX1, Z7U, JVC HM100 — XDCAM
Canon HG21 — AVCHD
Panasonic Micro 4/3 cameras — AVCHD, Motion JPEG
Olympus E-P1 — Motion JPEG

If your editing software of choice doesn’t recognize the video you’re trying to import, you’ll need to install the codec that your video is encoded in. Most computers will handle MP4 and Motion JPEG without any problems, but older computers might not recognize AVCHD. XDCAM is another beast, and will work on Mac and PC assuming the correct version of the codec is installed.

So, by this point you’ve imported your video into your editor of choice. Editing the video is different depending on the software, so we’re not going to talk about that today. However, when you export the finished product, you need to choose a codec then also. MP4 is your safest choice, with virtually universal compatibility and flexibility on file size.
Then you can burn the footage to DVD, upload it to YouTube, or whatever else!

I hope this helped explain working with video a little more. If you have questions or comments, feel free to contact us— support@lensrentals.com