Checking AV Properties - Basics

Peter Bubestinger-Steindl
(p.bubestinger @ AV-RD.com)

April 2022

Abstract

This is about technical properties of audiovisual files, how to identify and check/validate them.

The “Digital Video Trinity”

Structure

Tools

We’ll show these here:

  • VLC
  • MediaInfo

VLC

  • Great videoplayer
  • 99% chance you have it on the computer
  • Allows quick-check of tech-MD
    (Ctrl + J)
  • For all formats it can play!

Website: videolan.org/vlc

VLC

Very handy, but not the best for this job.

MediaInfo

“MediaInfo is a convenient unified display of the most relevant technical and tag data for video and audio files.”

Website: mediaarea.net/MediaInfo

MediaInfo

MediaInfo GUI

View ‘Easy’

  • General = container level
  • Video / Audio
  • Other

A/B comparison

(Only in view ‘Easy’)

  • Load more than 1 file:
    • Select multiple files
    • or drag/drop a whole folder
  • Scroll dropdown = switch between files

Excellent for a quick spotting of common/different values in a given set.

View ‘HTML’

View ‘HTML’

  • Nicer to read than view ‘Text’.
  • Identical content.

Machine Readable

(aka “parsable output formats”)

  • More suited for automated workflows.
  • Can be saved from GUI.
  • But: Usually commandline.

Machine Readable Output Formats

  • XML
  • JSON
  • CSV
  • EBUCore
  • PBCore
  • MPEG-7
  • FIMS
  • …

Report to File

  • Default:
    mediainfo myvideo.mkv > myvideo.mkv.mediainfo

  • XML Format (better):
    mediainfo --output=XML myvideo.mkv > myvideo.mkv.xml

Parsing Output

Built-in:
mediainfo --Inform="Audio;%Format%" myvideo.mkv

Using “xmlstarlet”:

xmlstarlet sel -t -m \
  "//_:media/_:track[@type='Audio']" \
  -c . -n \
  myvideo.xml`

Comments?

Questions?