FDK-AAC-DABplus

The fdk-aad-dabplus package contains several tools that use the standalone library of the Fraunhofer FDK AAC code from Android, patched for 960-transform to do DAB+ broadcast encoding.

The main tool is dabplus-enc, which can encode from a file or pipe source or ALSA soundcard, and encode to a ZeroMQ output compatible with ODR-DabMux, to a file or to standard output. The ALSA input supports experimental sound card clock drift compensation, that can compensate for imprecise sound card clocks.

dabplus-enc includes experimental support for DAB MOT Slideshow and DLS, written by CSP http://rd.csp.it.

To encode DLS and Slideshow data, the mot-encoder tool reads images from a folder and DLS text from a file, and generates the PAD data for the encoder.

For detailed usage, see the usage screen of the different tools.

Its development is public : http://github.com/Opendigitalradio/fdk-aac-dabplus

Installation

Prerequisites

The fdk-aac-dabplus package depends on libfec, boost-thread, boost-system, alsa and ZeroMQ. For instructions on how to install these, please see ODR-DabMux#Prerequisites

The mot-encoder needs ImageMagick's magick_wand to be able to resize pictures.

Building

See https://github.com/Opendigitalradio/fdk-aac-dabplus#how-to-build

Usage

Several usage scenarios are shown in https://github.com/Opendigitalradio/fdk-aac-dabplus#how-to-use

Problem solving

In the case you are using ZeroMQ between the encoder and odr-dabmux, and you see errors that the size of the data is wrong, then the configured bitrate in the mux probably doesn't correspond to the bitrate given to the encoder. Make sure they are identical.

If you are using a pipe between the encoder and odr-dabmux, and you see a lot of errors like this:

<2> ERROR: Incomplete DAB+ frame! 136 != 360
<5> reach end of file -> rewinding
<2> ERROR: Can't rewind file
<6> ETI frame number: 228

Then the stream has to be buffered before giving it to muxer, this additional buffer installed between encoder and fifo. To calculate proper block size for mbuffer ("-s" parameter), the table below may be used:

DAB+ Stream bitrate, kbps	Block size, bytes
16	240
24	360
32	480
48	720
56	840
64	960
72	1080
128	1920
160	2400

In example above, for stream with bitrate 24 kbps, mbuffer size set to 360 bytes. This trick helping to solve problem.

Historical notes

The encoders were renamed at version 0.2.0. The aac-enc testing program disappeared, but its code is still in src/. The aac-enc-dabplus and aac-enc-dabplus-zmq were renamed to dabplus-enc-file and dabplus-enc-file-zmq. dabplus-enc-alsa-zmq appeared in v0.2.0.

In v0.2.2, dabplus-enc-file-zmq received support for output to file and pipe, making dabplus-enc-file obsolete, which has therefore been removed.

In v0.4.0, lots of code redundancy between different encoder variants has been merged into dabplus-enc. The old tools dabplus-enc-file-zmq, dabplus-enc-alsa-zmq and all this have been replaced by a single encoder.

Some of the encode- scripts available in the mmbtools-aux repository might still make use of the old names.