Audio Only Files

• 1). Click "Start," then "Computer." Browse to an audio file on the computer you want to covert or encode with a different codec or format. Double-click the file to open it in Windows Media Player or your default audio player program.
  
  
• 2). Determine the total length, in minutes and seconds, of the audio track by viewing the play bar. Record the length of the track in minutes and seconds. As an example, consider a WAV audio file that is 4 minutes and 31 seconds in length.
  
  
• 3). Multiply the number of whole minutes in the track to covert to seconds. Using the example, multiply 4 times 60. The result is 240 seconds. Add 240 to 31 arrive at the total run time of the track in seconds (271 seconds).
  
  
• 4). Select a bitrate you want to use for the new file. For instance, common bitrates for MP3 files are 64 kilobits (64,000 bits) per second, 128 kilobits (128,000 bits) per second and 256 kilobits (256,000 bits) per second. The higher the bit rate, the less the amount of loss in an MP3 file audio signal. 128 kilobits per second is a common bitrate setting and produces digital audio tracks comparable in quality to those of many commercial music CDs. For the sample calculation, use a 128-kilobit bitrate variable.
  
  
• 5). Multiply the total number of seconds times the desired bitrate (231 x 128,000) to obtain the total number of bits of the new audio file. The result is 29,568,000 bits. Divide the total number of bits by eight (29,568,000 / 8) to obtain the total number of byte. The result is 3,696,000 bytes. Therefore, the approximate files size of the sample audio file -- when converted to an MP3 file with a bitrate of 128 kilobits per second -- is 3.96 megabytes.
  
  

Video Files with Audio

• 1). Open Windows Explorer and find the video file to convert to a new format. Determine the total length of the video clip in minutes and seconds.
  
  
• 2). Multiply the number of whole minutes in the video times 60 to convert the minutes into seconds. Add leftover seconds to the result. As an example, use a video clip 5 minutes and 8 seconds in length. The total number of seconds in the example video file is 308.
  
  
• 3). Select a desired bitrate for both audio and video portions of a new file. Video conversion applications encode the audio and video portions of a file separately. Therefore, you must consider both bitrates in your equation to obtain an approximate file size. For the sample file, use an audio bitrate value of 128 kilobits per second. For the video portion, use a value of 1500 kilobits per second.
  
  
• 4). Add together the values of the desired audio and video bitrates for the new file (128,000 + 1,500,000). The result is 1,628,000 total bits per second.
  
  
• 5). Multiply the total bit per second value times the total number of seconds for the video clip (1,628,000 x 308). The result is 501,424,000 bits. Divide the total number of bits by eight (501,424,000 x 8). The result is 62,678,000. Therefore, 308-second video (five minutes and eight seconds) video that has an audio bitrate of 128 kilobits per second and a video bitrate of 1500 kilobits per second would have an approximate file size of 62.7 megabytes.