Video Screen Capture Best Practices


Towanda Jones
Instructional Support Specialist
Center for Support of Instruction
Published: November-December 2009

Category: » Tech-skills-software » Video

Introduction

Video screen capture, also commonly known as a screencast, is a digital recording of your computer screen which includes audio. Products such as Camtasia, CamStudio, SnagIt and Jing have allowed faculty to deliver new and engaging content in their online courses to benefit students.

Although video screen capture is relatively simple, it’s not just about clicking the Record button and capturing your computer screen. You must have some background knowledge about how audio and video are compressed. Otherwise, you could spend countless hours wondering why the audio is not syncing with the video, why video is not clear, or why your file size is so large.

This article discusses:

  • Selecting audio and video devices on your computer
  • How to obtain a high-quality video screen capture
  • How to configure audio and video input devices and compression
  • Starting the video screen capture
  • The importance of video compression

Selecting Audio and Video Devices

Before you start a video screen capture, make sure you have the correct audio and video devices selected on your computer. You can adjust these settings by going to your operating system’s control panel under sounds and devices. This is important because when you use the video screen capture software, the application detects what you have selected for your audio and video devices on your computer. If these devices are not set properly, you will run into problems later during your video screen capture. Once these devices are selected, you will also need to select them in the video screen capture software (discussed later in this article).

How to Obtain High-Quality Video Screen Capture

How do you obtain high-quality audio and video during a video screen capture and reduce the file size so that it is acceptable for the Web and/or your online classroom? You always want to produce your video screen capture at the highest quality in an uncompressed format before you output to another file format. This way, when you compress your video screen capture to an output file at a smaller file size, you are working from a high-quality file format and have less chance of losing quality. If your video screen capture software does not have an option to compress your video to a Web format, you will need to use separate video converter/encoder software to compress the video to a smaller file size.

Configure Audio and Video Input Devices and Compression

You will need to configure the settings for both audio and video input devices and compression in the video screen capture software. When capturing video from your computer screen, you must select in the video screen capture software what input devices you are using (just like you did in your computer’s control panel as mentioned earlier), and what codec (a program that encodes and decodes digital data) you want to use to compress both audio and video. Here are some steps to following when selecting your audio and video input devices and compression to ensure that your audio and video are captured at the highest quality in an uncompressed format:

  • If your audio is not recording, chances are that your computer's sound card does not allow internal recording.

Audio Input Device

  • Audio Device: Select the audio device you want to record from, i.e., computer sound card or USB device. Sound cards are best for recording good-quality audio.

  • Audio Input Source: Your audio capture device will vary depending on your sound card, i.e., microphone, rear input, stereo mix, etc. If you are recording from your sound card, select stereo mix.

Audio Compression

  • MS Video 1 is a standard audio codec on most computers, but the file size is large.
  • Pulse Code Modulation (PCM) is the uncompressed codec used for CDs.
  • The higher the sampling rate, the higher the bandwidth or frequency response.
  • A "hertz" (Hz) is the standard unit of frequency.
  • A "kilohertz" (KHz) is a unit of frequency equal to 1,000 hertz.
  • The higher the data rate, the large the file size, and the higher the quality.
  • Volume: Adjust the input volume which controls the overall volume of the input source.

  • Audio Format: Select the codec for audio compression, which compresses the audio to a digital format. Numerous audio codecs are available on the market. When in doubt, use the codec that comes with the product. An excellent audio codec for the Web is MPEG Layer-3. It produces a smaller file size and maintains good audio quality.

  • Sampling Rate: The sampling rate is the horizontal measure of wave samples per second and how often audio snapshots are taken. The more samples taken per second, the more the wave sample resembles the original. A good quality sampling rate would be 44.1 kHz. Here are three of the most common sampling rates:
    • Web = 22,000 Hz
    • CD = 44,000 Hz
    • Better Than CD Quality = 48,000 Hz
  • Bit Depth: Bit depth is the vertical measure of how much information is contained within a single audio sample or moment in time. To maintain high quality, choose at least 16 bit. Here are some typical settings for bit depth:
    • 8 bit - Low quality
    • 16 bit - Medium quality
    • 24 bit - High quality
  • Data Rate: Many applications will have a setting called “data rate.” Data rate is a measurement of how fast information can be downloaded. Select at least 128 kbs; you can always select a lower rate when you compress. Other typical settings for data rate are:
    • 56 kbs = Modem
    • 128 kbs = DSL
    • 256 kbs = Cable High Speed
    • 512 kbs = Broadband
  • Output Channels (Stereo and Mono): Mono is all the audio signals mixed together and routed through a single audio channel/speaker. Stereo has two independent audio channels—the right and left speakers. Unless you are recording from both speakers, select Mono.

Video Compression

  • FPS does not affect the clarity of the video, but it does affect the file size.
  • It's  best to give up video quality before you give up audio quality.
  • Screen Capture Codec Compressor: Select the codec for video compression, which compresses the video to a digital format. There are numerous video codecs on the market. Again, when in doubt, use the codec that comes with the product. Some common high-quality video codecs for the Web are H.264, On2VP6, and Sorenson.

  • Frames Per Second (FPS): FPS is the timing of the movements of the frames. The higher the FPS, the smoother the visual motion on the screen. A high-quality FPS would be at least 12–15 fps for the Web. Here are some typical settings for Web, film, and video:
    • Web = 12-15 fps
    • Film = 24 fps
    • Video = 30 fps

Start Video Screen Capture

  • Record and produce your video with consistent dimensions to keep the file size down and the quality high. The recommended screen resolution for videos on the Web is 240 x 320 pixels.  
  • Most users' Internet connections are modem (analog up to 56K), DSL, or high- speed broadband. Save your video in the format that you audience can view.

Before starting your video screen capture, keep in mind two important factors: (1) maintain consistent dimensions when capturing and compressing your video and (2) keep the length of your video to a maximum of 5 minutes. These considerations will reduce your file size and improve the quality of your video.

Once all the configurations for both audio and video input devices and compressions are set, the video screen capture can begin. Make sure you have enough RAM before you record; close all open programs on your computer before capturing the video to eliminate lag time. You may find that after you review your video screen capture, you will have to go back and make some adjustments to the compression settings to get the quality you desire. For example, the more compression you have set, the more loss of color accuracy you will see in your video. In cases such as these, you may have to do some adjusting with the data rate settings.

Compress Video Using Encoder/Converter

Unlike Camtasia, which has the ability to capture and produce video in a format ready for the Web and mobile devices, most video screen capturing products are known for producing incredibly large outputs files and have limited output formats and playback controls. Because of these limitations, video encoder/converter products such as AVS Video Converter, Windows Media Encoder or Adobe Media Encoder must be use to compress your video into a workable file format, i.e., .mpg, .mov, .flv, or .swf.

When you use a video encoder/converter to compress your video file, you will come across the same terminology as mentioned above. The same concepts for selecting audio and video input devices and compression will apply when compressing the file. Make sure you configure the compression in a format ready for the Web and where the quality is still good, but at a smaller file size.

Summary

The main ingredients for producing a high-quality video screen capture are an understanding of the basic concepts of audio and video input devices and compression. Terms such as bit depth, data rate, sampling rates, FPS, and codecs can be a bit confusing and overwhelming, especially if you do not have background experience in audio and video production. Each of these variables is critical to the quality of your audio and video whether you are producing a video screen capture or using video encoder/converter software. If you have a basic understanding of how these variables work, you will be able to produce high-quality videos for your online classroom.

Additional Resources

Video Screen Capture Software

Video Encoder/Converter Software

Articles

Tutorials

Acknowledgments

  • Laddie Odom (CSI), Technical Consultant
  • Garth Gerstein (CSI), Technical Consultant
  • Floyd Csir (CSI), Technical Consultant

About the Author(s)

Towanda Jones earned a BS in Information Systems Management (IFSM) from UMUC and has continued to expand her professional career in instructional development, Web 2.0, multimedia technologies such as Flash, video production, Web design and development, and podcasting.

Rating: Not yet rated



Comments

No comments posted.

Post a Comment / Vote

You must be logged and be a member of the UMUC community in order to comment.

If you have a guest account but are Faculty/Staff of UMUC please send an email to the DE Oracle Site Mananger so that your guest account can be updated.

If you don't have a log in, please register for a FREE account.