DOCUMENT:Q118591  22-DEC-1999  [powerpt]
TITLE   :Calculating the Disk Space Required for an AVI File
PRODUCT :Microsoft PowerPoint for Windows
PROD/VER:WINDOWS:1.0,1.1
OPER/SYS:
KEYWORDS:

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The information in this article applies to:

 - Microsoft Video for Windows, versions 1.0, 1.1 
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SUMMARY
=======

This article provides information about how to calculate the hard disk space
required for digitized video and audio.

MORE INFORMATION
================

To calculate the disk space required for an AVI file, use the formulas below to
determine the disk space required for captured uncompressed video and audio.

Video
-----

The following two equations are used to determine the total disk space required
for capturing raw, uncompressed video with no audio:

1. Transfer rate (bytes/minute) = (frame height [pixels] * frame width [pixels]
   * frame rate [frames/second] * 60 [sec/min] * color depth [bits/pixel]) / 8
   (byte/bits)

   NOTE: The frame height in pixels multiplied by the frame width in pixels
   yields pixels per frame. The color depth could be 8 bits per pixel, 16 bits
   per pixel or 24 bits per pixel.

2. Disk space (bytes) = transfer rate (bytes/minutes) * length of captured video
   (minutes)

Audio
-----

To calculate the hard disk space required for captured audio, use the following
two equations:

1. Transfer rate (bytes/minute) = (sampling rate [kilohertz] * 1000 * sample
   size [bits] * 60 [sec/min] * 1, or 2 if in stereo) / 8 (byte/bits)

   NOTE: The sampling rate is multiplied by 1000 to convert the value to hertz.
   If the audio track is in stereo, multiply the equation by two.

2. Disk space (bytes) = transfer rate (bytes/minute) * length of captured audio
   (minutes)

Video and Audio
---------------

Combining the above equations provides a quick way to calculate disk space
required for both audio and video; this is specified in the following equation:

Total disk space required for an uncompressed AVI sequence = ([frame height *
frame width * frame rate] + [sampling rate * 1000 * sample size * 1, or 2 if in
stereo] * 60 [sec/min] * color depth * length of captured video) / 8
(byte/bits)

NOTE: If the audio is in stereo, multiply the audio transfer rate by two. This
information can be used to find the space required on a hard disk as well as a
CD-ROM.

Additional query words: 1.00 1.10 vfw transfer rate disk space avi

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Keywords          :  
Technology        : kbVideoSearch kbVideo100 kbVideo110
Version           : WINDOWS:1.0,1.1

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