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ODR-PadEnc is an encoder for Programme Associated Data (PAD) and includes support for:

  • MOT Slideshow (including catSLS), according to ETSI EN 301 234 and TS 101 499
  • DLS (including DL Plus), according to ETSI EN 300 401 and TS 102 980

To encode DLS and Slideshow data, the odr-padenc 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 tool with the -h option.

More information is available on the Opendigitalradio wiki

How to build


  • a C++11 compiler
  • ImageMagick MagickWand (optional, for MOT Slideshow), version 6 (legacy) or 7

To install MagickWand on Debian or Ubuntu:

sudo apt-get install libmagickwand-dev

To compile and install ODR-PadEnc:

sudo make install

ImageMagick and Debian Jessie/Ubuntu 16.04

Please note that Debian Jessie and Ubuntu 16.04 shipped a version of ImageMagick that was affected by two memory leaks (see #2, and also Ubuntu's #1671630 and #1680543). Hence ODR-PadEnc increasingly consumed memory until it crashed.

This has been fixed with the following package versions:

  • Debian Jessie: 8:
  • Ubuntu 16.04: 8:

Usage of MOT Slideshow and DLS

odr-padenc reads images from the specified folder, and generates the PAD data for the encoder. This is communicated through a socket to the encoder. It also reads DLS from a file, and includes this information in the PAD.

If ImageMagick is available

It can read all file formats supported by ImageMagick, and by default resizes them to 320x240 pixels, and compresses them as JPEG. If the input file is already a JPEG file of the correct size, and smaller than 50kB, it is sent without further compression. If the input file is a PNG that satisfies the same criteria, it is transmitted as PNG without any recompression.

RAW Format

If ImageMagick is not compiled in, or when enabled with the -R option, the images are not modified, and are transmitted as-is. Use this if you can guarantee that the generated files are smaller than 50kB and not larger than 320x240 pixels. Files whose name end in _PadEncRawMode.png or _PadEncRawMode.jpg will always be transmitted in RAW mode. It may be useful to apply optipng to any PNG file prior to transmission.

Supported Encoders

odr-audioenc and odr-sourcecompanion can insert the PAD data from odr-padenc into the bitstream.

This is an ongoing development. Only some PAD lengths are supported, please see odr-padenc's help.

ODR-PadEnc v2 is compatible with ODR-AudioEnc v2 and ODR-SourceCompanion v0.x, and uses a fifo to communicate between the tools.

ODR-PadEnc v3 replaced the fifo with a socket and is compatible with ODR-AudioEnc v3 and ODR-SourceCompanion v1.

Character Sets

When odr-padenc is launched with the default character set options, it assumes that the DLS text in the file is encoded in UTF-8, and will convert it according to the DAB standard to the Complete EBU Latin based repertoire character set encoding.

If you set the character set encoding to any other setting (except Complete EBU Latin based repertoire which needs no conversion), odr-padenc will abort, as it does not support any other conversion than from UTF-8 to Complete EBU Latin based repertoire.

You can however use the -C option to transmit the untouched DLS text. In this case, it is your responsibility to ensure the encoding is valid. For instance, if your data is already encoded in Complete EBU Latin based repertoire, you must specify both --charset=0 and --raw-dls.

Known Limitations

Some receivers are unable to decode slides larger than some size, even within the allowed size limit given in the specification.


This encoder was initially called mot-encoder and has been contributed by CSP.