Decoders
********

Decoders are configured elements in FFmpeg which allow the decoding of multimedia streams.

When you configure your FFmpeg build, all the supported native decoders are enabled by default. Decoders requiring an external library must be enabled manually via the corresponding --enable-lib option. You can list all available decoders using the configure option --list-decoders.

You can disable all the decoders with the configure option --disable-decoders and selectively enable / disable single decoders with the options --enable-decoder=DECODER / --disable-decoder=DECODER.

The option -codecs of the ff* tools will display the list of enabled decoders.

Video Decoders
**************

A description of some of the currently available video decoders follows.

rawvideo
========

Raw video decoder.

This decoder decodes rawvideo streams.

Options
-------

top TOP_FIELD_FIRST
     Specify the assumed field type of the input video.

     -1
          the video is assumed to be progressive (default)

     0
          bottom-field-first is assumed

     1
          top-field-first is assumed

Audio Decoders
**************

ffwavesynth
===========

Internal wave synthetizer.

This decoder generates wave patterns according to predefined sequences. Its use is purely internal and the format of the data it accepts is not publicly documented.

Subtitles Decoders
******************

dvdsub
======

This codec decodes the bitmap subtitles used in DVDs; the same subtitles can also be found in VobSub file pairs and in some Matroska files.

Options
-------

palette
     Specify the global palette used by the bitmaps. When stored in VobSub, the palette is normally specified in the index file; in Matroska, the palette is stored in the codec extra-data in the same format as in VobSub. In DVDs, the palette is stored in the IFO file, and therefore not available when reading from dumped VOB files.

     The format for this option is a string containing 16 24-bits hexadecimal numbers (without 0x prefix) separated by comas, for example 0d00ee, ee450d, 101010, eaeaea, 0ce60b, ec14ed, ebff0b, 0d617a, 7b7b7b, d1d1d1, 7b2a0e, 0d950c, 0f007b, cf0dec, cfa80c, 7c127b.