Uncompressed recording time in track-hours, Record time, Pcm audio – Sound Devices 744T User Manual
Page 46: Audio data rate = bit depth x sampling frequency
744T User Guide and Technical Information
40
v. 2.67
Features and specifications are subject to change. Visit www.sounddevices.com for the latest documentation.
• data rate - calculated from the sampling rate and bit depth for non-compressed audio and by
bit rate for data compressed audio. Data rate determines how big the data “container” is for the
audio signal (see the calculation below for determining PCM audio).
• storage capacity - typically expressed in GB
Uncompressed Recording Time in Track-Hours
Data Rate (bit depth/sampling rate), one track
16/44.1
(5.05 MB/min)
16/48
(5.49 MB/min)
24/48
(8.24 MB/min)
24/96
(16.5 MB/min)
24/192
(33.0 MB/min)
Stora
g
e in GB
(1000 MB = 1 GB)
1
3.3
3.1
2:
1
0.5
2
6.7
6.2
4.1
2
1
4
13.5
12.4
8:2
4.1
2
8
27
24.8
16.5
8.2
4.1
16
54
49.7
33.1
16.5
8.2
40
135.1
124.3
82.8
41.4
20.7
60
202.7
186.5
124.2
62.1
31
80
270.3
248.7
165.7
82.8
41.4
100
338
310.8
207.1
103.5
51.7
160
540.7
497.38
331.38
165.4
82.8
The chart above shows recording time available with the 744T. Time is expressed in hours per track
(track-hours) at the specified data rate supported by the 744T. If recording two tracks, divide the
track hours figure by two. Similarly for four-track recording, divide track-hours by four. Note that
the 744T supports additional sampling rate / bit depth combinations, however, only the most com-
mon are included below.
Record Time
The chart shows that when recording 24-bit/48 kHz audio to a 40 GB hard drive the maximum
amount of recording time available roughly 330 track-hours. If recording a stereo two-track file, this
yields 115 stereo hours of record time.
Note that most storage media now quote capacity in GB using SI units, where 1000 megabytes equals one
gigabyte.
PCM Audio
Uncompressed digital audio is expressed numerically by two measurements, bit depth and sampling
frequency, such as 16-bit/48 kHz. These two numbers are used to compute the data rate of uncom-
pressed audio.
Audio Data Rate = Bit Depth x Sampling Frequency
In the example below the data rate of a single 16-bit/48 kHz audio stream is computed in megabytes
per minute. Division by 1,048,576 converts from bits to megabits. Division by 8 converts from mega-
bits to megabytes; multiply by 60 converts seconds to minutes.
(((16 x 48000) / 1,048,576) / 8) x 60 = 5.49 MB/min