Specifications

7
Tools or test materials provided as part of the deliverables may be used only for internal testing and development of the Licensed
Product and not for any other purpose. Tools or test materials may not be used as part of the Licensed Product itself or provided to or
used by any third party other than for the test development of the Licensed Product.
Software Libraries
For real-time or le-based applications, the Dolby Professional Loudness Metering software is delivered in the form of a reentrant
software library and sample code. The software library must not be modied; however, the sample code that is supplied as part of
the licensed software package may be modied, rewritten, or redesigned as needed to suit the system, subject to any limitations
contained in the deliverables.
The sample application illustrates how to call the loudness subroutine by using the application programming interface (API). The user
interface is via command-line options or the graphical user interface (GUI); loudness parameters are specied on the command line
or in the GUI. Although the sample-application code may be used as is for certain platforms (such as a PC or a Unix
®
platform–based
workstation), Licensees may wish to customize certain aspects of the audio I/O and user interface.
Table 1 shows the mean performance gures using a measurement mode of ITU-R BS.1770-2 plus Dialogue Intelligence for a ve-
minute, 5.1-channel input le. The Dolby Professional Loudness Metering Code User’s Guide for Intel Processors provides more-detailed
performance gures. Also, the user should keep in mind that these performance gures are estimates only and may dier based on
the platform, operating system, and state of that system (for example, if other tasks are running and so on). The performance gures
are also exclusive of any le I/O or other system functions.
Table 1 Typical Performance with a Five-Minute, 5.1-Channel Input File
Platform Operating System CPU Execution Time
(Seconds)
Number of Times
Faster than Real Time
Equivalent MHz
Intel IA-32 Windows 7 32-bit 2.93 GHz Intel Core™ i7 with
4GB RAM
3.7 81 36.1
Mac OS
®
X 10.6.6
2.0 GHz Intel Core 2 Duo with
2 GB RAM
7.74 39 51.6
Ubuntu
®
Linux
8.46 35 56.4
Intel 64 Windows 7 64-bit 7.73 39 51.6
Mac OS X 10.6.6 7.07 42 47.1
Ubuntu Linux 7.69 39 51.3
I/O Interfaces and Files
The loudness-estimation library is responsible for estimating the loudness of an audio le or stream. Currently, loudness estimation is
performed only with audio in PCM format. Hence, any coded audio source les and/or streams must be decoded prior to calling the process.
The following information is for I/O interfaces and les.
• For real-time applications, AES3 inputs and outputs are highly recommended: AES-3id-2001, AES3-2003, IEC 60958-4 (2003-05),
and IEC 60958-3 (2003-01).
• For le-based applications, PCM or WAV le format with embedded metadata is required. Please refer to the Dolby Audio Metadata
WAVE Chunk: An Extension to the WAVE File Format document for more information. Modication of metadata within the Dolby
audio metadata WAVE chunk of a WAV le as a result of using the loudness-estimation library is allowed only in le-based
applications.