Video Encoding and File Size
There are several variables that affect file size. This article provides tips and general guidelines to help maximize your video and audio quality while minimizing the file size. The items below all will affect the overall production size & quality.
As a general rule of thumb, producing the video in MP4/h.264 format often delivers the best quality with smallest file size. MP4 is especially popular for web-based delivery. (AVI, MOV, or WMV can sometimes be good choices for CD or DVD delivery.) The default output from Camtasia Studio is MP4.
Video Dimensions (in pixels)
Larger videos (in resolution) will dramatically increase file size. You may want to limit your video to no larger than 1280 pixels (width) by 720 (height). Don't record your entire screen unless it's really necessary, or consider using zoom and pan actions. This way you can scale the video down, but still focus the viewer's attention on a specific portion of the screen. Another tip is to reduce your screen resolution before recording your screen activity.
Video dimensions are set when you add video to the Timeline with the Production Settings or Editing Editing Dimensions box in Camtasia.
Amount of Movement in the video
The more movement in the video, the larger the file size will be. For example, recording some fairly static presentation slides will yield a smaller file size than recording some on-screen live video. If possible, try not to drag windows around and limit some of the fancy animations in PowerPoint for example. Using the MP4 video format will also help mitigate some of the file size issues associated with movement, as MP4 is highly efficient in this regard.
It is very rare that uncompressed audio is going to make an audible difference to your viewers. Therefore, you can reduce the file size dramatically by compressing the audio upon production. Unless you're featuring an orchestral masterpiece in your screencast, record mono audio, and after you're done editing, produce your video with compressed audio. Our default MP4 format uses AAC audio compression which has a good combination of sound quality and file size. You can learn more about audio at the end of this article.
The frame rate indicates how many frames per second are shown to the viewer. The custom production settings allow for between 1 and 30 frames per second (fps). The default is 30 fps and it is typically more than adequate for most Camtasia users. If you're recording something fairly static, like a PowerPoint presentation you can drop the fps down which will save you a bit of file size and go virtually unnoticed to your viewers. Frame rate is set in the Camtasia Recorder on Windows. You can also change the Frame Rate during the production process.
Recording Technology Used
On the Windows platform, there is a screen recorder called Fraps which is optimized for gaming. You may wish to use Fraps if you are recording a game, especially full screen, full motion, high framerate games.
Camtasia uses a new recording codec called TSC2 which works well for both screen activity and full-motion video.
Additional Information & Examples about Compressed and Uncompressed Audio
Camtasia records uncompressed audio because this is the best quality audio, and it can be edited without loss of quality. Upon producing your video, you will likely want to compress the audio.
By default, the Camtasia Recorder uses PCM uncompressed audio configured at 22.050 kHz, 16 bit mono. This audio configuration adds 44,100 bytes per second to the size of the file, or about 2.6MB per minute. This is the amount data that must be stored just for the audio portion of the original recording file.
This means that about 22,000 times per second the audio is sampled, and 2 bytes (16 bits) of information is saved. If this same audio configuration were set to stereo, the size of the audio would double, because 4 bytes instead of 2 would be saved 22,000 times per second.
It is recommended to avoid using stereo, especially for voice. Keep in mind that if you choose to use stereo, the file size of the audio will double.
Unless there is an overriding reason to not do so, always use good quality PCM uncompressed audio for the original recording and during the editing process. This will ensure that there is no loss of audio quality when the video is edited. When the editing process is completed, you will have a perfect, high quality master copy of your video from which you can make copies into other compressed audio formats.
Because compressing audio always degrades the quality of the audio, only compress the audio after editing is complete. Every time you edit the video the audio must be recompressed. Every time it's recompressed it loses more quality.
Compressing the audio can drastically reduce the overall size of the video. For example a 1 minute video with PCM uncompressed audio, 22.050kHz, 16 bit mono was 3.9MB. The same video using CCITT u-Law, 11.25kHz, 8 bit mono was 887KB.