[FFmpeg-user] Optimal method to capture both metadata and thumbnails for video files

[Pavan Kulkarni]

ffmpeg stand alone gives me metadata such as duration in its stdout.
But I also need at a minimum these three metadata : width, height, number
of streams.
These three are currently obtained through the metadata program which is
essentially using ffmpeg's public metadata API such as AVFormatContext,
AVStream etc.
Additionally, tt would be great if I can also get such metadata as :
file_size, modified_time (which I'm currently getting by reading the
filesystem data)
What I'm trying to achieve is to execute ffmpeg only once using the right
set of options such that I get all the above described metadata along with
the thumbnail in one go. I can then parse the output (read from stdout) and
then create my structure of metadata.
I also had another question: Are "rating" and "tag" metadata fields only
applicable to certain file formats?
Thanks in advance for all your inputs