Beyond Linux® From Scratch (systemd Edition) - Version r12.3-79

Chapter 42. Multimedia Libraries and Drivers

faac-1.31.1

Introduction to faac

The faac application is an encoder for a lossy sound compression scheme specified in MPEG-2 Part 7 and MPEG-4 Part 3 standards and known as Advanced Audio Coding (AAC). This encoder is useful for producing files that can be played back on an iPod. Moreover, the iPod does not understand other sound compression schemes used in video files.

[Note]

Note

Development versions of BLFS may not build or run some packages properly if LFS or dependencies have been updated since the most recent stable versions of the books.

Package Information

[Note]

Note

On GitHub we've forked the upstream repository into our own lfs-book namespace and recreated a tag for the release. This is done to ensure the downloaded tarball file name to be correct and consistent (i.e. it shouldn't change when using the browser instead of a tool like wget). Our tag and the upstream release tag are on the same commit, so we've not introduced any change to the tarball content except the name of its top-level directory (that Git does not track).

Installation of faac

Install faac by running the following commands: 

./bootstrap                                &&
./configure --prefix=/usr --disable-static &&
make

This package does not come with a test suite. However, basic functionality can be tested by encoding a sample WAV file (the sample file is installed by the alsa-utils-1.2.13 package: 

./frontend/faac -o Front_Left.mp4 /usr/share/sounds/alsa/Front_Left.wav

Then, decode the result using the faad program from the FAAD2-2.11.2 package and play back the decoded file (requires the aplay program from the alsa-utils-1.2.13 package: 

faad Front_Left.mp4
aplay Front_Left.wav

aplay should identify the file as Signed 16 bit Little Endian, Rate 48000 Hz, Stereo, and you should hear the words “front left.”

Now, as the root user: 

make install

Command Explanations

--disable-static: This switch prevents installation of static versions of the libraries.

Other AAC encoders

The quality of faac is not up to par with the best AAC encoders currently available. Also, it only supports AAC and not High Efficiency AAC (also known as aacPlus), which provides better quality at low bitrates by means of using the “spectral band replication” technology. One example of an alternative program for producing AAC and HE-AAC streams is:

  • 3GPP Enhanced aacPlus general audio codec: available in the source form, can encode only HE-AAC up to 48 kbps out of the box, but the maximum bitrate can be changed by editing the tuning table in the FloatFR_sbrenclib/src/sbr_main.c file.

Note, however, that the iPod supports only the Low Complexity AAC profile, which is the default in faac, but is completely unavailable in the 3GPP encoder.

Contents

Installed Program: faac
Installed Libraries: libfaac.so and libmp4v2.so
Installed Directories: None

Short Descriptions

faac

is a command-line AAC encoder

libfaac.so

contains functions for encoding AAC streams

libmp4v2.so

contains functions for creating and manipulating MP4 files