FFMPEG attach file as metadata

Question

I have a set of images which I want to convert to a video using ffmpeg. The following command works perfectly fine:

ffmpeg -y -i frames/%06d.png -c:v huffyuv -pi         


        

Answer 1

You need to specify your stream properly

Example:

ffmpeg -y -i frames/%06d.png -c:v huffyuv -pix_fmt rgb24 -attach mybinaryfile \
-metadata:s:t mimetype=application/octet-stream testout.mkv

This command will set the metadata for all attachment (t) streams (s). If you have more than one attachment, and the metadata are different, then you will have to be more specific, such as:

-metadata:s:t:0 mimetype=text/plain \
-metadata:s:t:1 mimetype=application/gzip

This will set the metadata for the first attachment as mimetype=text/plain, and the second as mimetype=application/gzip. Remember that the stream index starts at 0, so the first steam is labeled 0.

What was wrong with your command

Using -metadata:s:2 (which appears to have been copied verbatim from the documentation) sets the metadata for the third stream, regardless of stream type (because no specifier is present), but your output only contained two streams.

Attachment: None

You may see something like this:

Output #0, matroska, to 'output.mkv':
...
    Stream #0:1: Attachment: none
    Metadata:
      filename        : 2ceb-1916-56bb-3e10
      mimetype        : application/octet-stream

Attachment: none does not mean that there is no attachment, but that there is no format associated with it, so it can be ignored.

Also see

Stream specifiers and the ffmpeg documentation on -attach, -metadata, and -map_metadata for more details.