fourcc (LSB first, so "ABCD" -> ('D'<<24) + ('C'<<16) + ('B'<<8) + 'A').
This is used to work around some encoder bugs.
A demuxer should set this to what is stored in the field used to identify the codec.
If there are multiple such fields in a container then the demuxer should choose the one
which maximizes the information about the used codec.
If the codec tag field in a container is larger than 32 bits then the demuxer should
remap the longer ID to 32 bits with a table or other structure. Alternatively a new
extra_codec_tag + size could be added but for this a clear advantage must be demonstrated
first.
- encoding: Set by user, if not then the default based on codec_id will be used.
- decoding: Set by user, will be converted to uppercase by libavcodec during init.
fourcc (LSB first, so "ABCD" -> ('D'<<24) + ('C'<<16) + ('B'<<8) + 'A'). This is used to work around some encoder bugs. A demuxer should set this to what is stored in the field used to identify the codec. If there are multiple such fields in a container then the demuxer should choose the one which maximizes the information about the used codec. If the codec tag field in a container is larger than 32 bits then the demuxer should remap the longer ID to 32 bits with a table or other structure. Alternatively a new extra_codec_tag + size could be added but for this a clear advantage must be demonstrated first. - encoding: Set by user, if not then the default based on codec_id will be used. - decoding: Set by user, will be converted to uppercase by libavcodec during init.