Arrays¶

Arrays can be specified by suffixing the tag name with a colon and the index number. e.g. wrt:1. Arrays are only implemented for string data.

Index values are relative, not absolute. There will never be an array with a empty slot.

Cover Images¶

There may be more than one cover image present. If there is more than one cover image, the subsequent cover images will display a tag name of covr:1 with the appropriate index value.

If there is a name associated with the cover image, the tag name will be displayed as covr:1:name using the appropriate index value.

The indexes are only used if there is already an existing cover image at that index. Setting a cover image at index 1 in a file with no cover image present will place the cover image at index 0.

Custom Tags¶

Custom tags are specified as ----:APP:tagname. To prevent the command line parser from recognizing a custom tag as an option, the end of option specifier -- must be added to the command line before the custom tag.

e.g. mp4tagcli sample.m4a -- ----:BDJ4:DANCE=Waltz

Displaying Tag Information¶

mp4tagcli filename

Running mp4tagcli without any arguments displays all tags and their values for filename. The duration is also displayed. Each tag is output as tag=value on a separate line.

mp4tagcli filename {-u|--duration}

Prints the duration of the MP4 file without any label.

mp4tagcli filename {-u|--asstream}

Processes the filename as a stream. This is purely for debugging purposes.

mp4tagcli filename {-d|--display} tag

Display tag and its value.

Setting Tags¶

mp4tagcli filename [--binary] [tag {|value|filename} ...]

Without any value specified, the tag is removed from the MP4 file.

If a value is specified for a tag, the tag is set to value.

For tags with associated binary data (e.g. cover images), the data for the tag is read from filename.

The --binary option is only used when setting a new tag with binary data. It is not necessary to use the --binary option with cover images or tags with existing binary data.

Multiple tags may be specified on the command line.

The --freespace option is used to specify the size of the free space box to create when the audio file is re-written.

Removing All Tags¶

mp4tagcli filename --clean

Removes all tags from the MP4 file.

Copying Tags¶

mp4tagcli {-f|--copyfrom} infile {-t|--copyto} outfile

Copies the tags from from infile to outfile. Any existing tags in outfile are completely removed.