Frequently Asked Questions

iStockvideo offers three file types, and several sizes of each. Here’s a quick breakdown.

WMV
If you are making a Powerpoint presentation or other PC based multi-media project, or just emailing a video to a friend, then a WMV version will be best suited for you. The size depends on how large you want the video to play while retaining detail. WMV does not scale up well without losing a lot of quality, so in most cases the larger size is preferable. Most PC’s can play WMV files automatically, but Macs require the free Windows Media Player from Microsoft, or a player from Flip 4 Mac to view them.

The WMV files are highly compressed using the Windows Media 9 codec and as such are fairly easy to transport on the web. The visual quality is similar to the MP4 version, but not as high as the Quicktime version.

MP4
For smaller multi-media presentations on a Mac, MP4 is probably a good choice. Like the WMV though, these files do not scale up well. Unless you know for sure that 320x180 pixels is large enough, it is best to go for the larger web size. Many newer PCs with video or multimedia software installed can play MP4 files, and all newer Macs as well.

MP4 files are highly compressed, using the H.624 codec and are fairly easy to transport on the web. The visual quality is similar to the WMV version, but not as high as the Quicktime version.

Quicktime
For projects that require editing of the video, combining the video with other elements such as text, music or graphics, or when you need a higher quality version from which to generate other formats like Adobe Flash, then Quicktime is for you. Quicktime is a file type that has broad acceptance across computing platforms.

The files are large, but hold a lot of visual information. In the case of Small Web and Big Web sizes, the files are compressed with the Photo JPEG codec. For files larger than Web, the Quicktime files may be Photo JPEG, Motion JPEG, DV, HDV, or DVCPro HD codecs, depending on what the contributor provided.

The largest size that you see is the original file as supplied by the contributor. As such, it is also the best quality technically, and can be used as source footage in editing systems while retaining that original quality.

For files that are offered in only PAL and NTSC, it can be a bit harder to tell the difference between them. You can usually tell by the contributor’s description, that is supposed to claim which clip was the original. If HD is offered along with PAL and NTSC (there are three frame view tabs at the top of the preview), then the largest HD size is the original.

The preview video is a proxy of the actual video. While we do our best to represent the file accurately, it compressed with Adobe Flash, and may look slightly lighter, darker, or more (or less) pixilated than the files offered for download. They should be used to evaluate the content rather than the technical quality. It accurately shows the flow and composition of the video.

iStockvideo inspects each and every video, and rejects clips that do not meet our technical or content standards.

Video does not scale up in size very well. The reason is that it is relatively low resolution to begin with. In fact, at around 72 pixels per inch, it is about the lowest we can go and still be convinced that we are not looking at dots. When we stretch it it starts to get real soft, real fast. It is always best to download the file size that best meets your needs.

Imagine that you are editing together some footage from your last great adventure, shot with your DV camera. Of course you didn’t shoot everything, so you find some perfect footage at iStock to compliment your shots. In this case, you want to download NTSC or PAL (depending on what you shot your material in). If you find HD content that fits your story better, you can use that, just crop and scale it down – it will still look great. However, downloading a big web version and scaling it up will create a scene in your project that will look very out of place. It will be fuzzy with muted colours, and possibly distorted as well. Small and Big Web look great… on the Web.

SD – This just means Standard Definition as opposed to High Definition or HD. NTSC and PAL are SD video frame sizes.

NTSC – This is the standard for SD television monitors in North America, Japan, South Korea, and parts of South America as well. It features a frame size of 720x480 or 720x486, and a frame rate of 29.97 frames per second. The pixels are non-square, since the format was designed before the advent of the personal computer.

PAL – This is featured in Europe, Africa, South America, Australia, and much of Asia. For simplicity, we have lumped another standard called SECAM in with PAL – they are pretty compatible, at least as far as digital video is concerned.

PAL (SECAM) features a frame size of 720x576 pixels, and a frame rate of 25 frames per second. The pixels are also non-square, but in a different orientation than NTSC.

HD – iStock offers two sizes of HD – 1280x720 and 1920x1080. These files originate from either HD capable cameras or computers. The 1280x720 size is commonly called 720p, the p designating that the picture is displayed as a progressive scan, as opposed to interlaced. This size is never interlaced. The 1920x1080 is often interlaced, especially when camera generated. When a 1080 clip is generated by a computer, it is almost always non-interlaced.

Where possible, we offer our HD clips in their original uploaded form; therefore they may be compressed with an HDV or DVCPro HD codec, both of which are non square pixel formats. Most contemporary video editing software will interpret these codecs correctly and display them in their proper size and proportions. They may also be compressed with Motion JPEG or Photo JPG, which are very large files, and are displayed as square pixels. This is most common in files generated by computer, such as animations.

If you have an HD television made in the last couple of years, it will likely be able to play both 1280x720 and 1920x1080 sizes.

Try posting a request in the video forum. If the shot is not too complicated, chances are you won’t have to wait long before the clip appears. Be specific so that contributors know what it is you want, such as length, format, frame rate etc. as well as the concept.