Note: this recognizer runs on a web server, the video file will be uploaded using HTTP.
How to use the Key Frame Extractor from within ELAN
The Key Frame Extractor recognizer by the Fraunhofer Heinrich Hertz
Institute HHI allows you to generate a set of snapshots from a video
to get an overview of the contents.
- Input: A video in FFMPEG supported format (most
common formats are supported) and a tier indicating which
timespans should be considered as structure of the video.
- Settings:
- JPEG quality lets you adjust JPEG size, lower values
produce smaller image files but lower image quality.
- Logging level can be used to adjust log verbosity.
- Keyframe type lets you select either lossless PNG or
lossy JPEG compression for the generated image files.
- Name type gives a choice between different styles of
output picture file names.
- Image size offers the possibility to reduce resolution
of the generated picture files, for example half width and
height, often sufficient to get an overview.
- Pic name template is a text (!) parameter giving you
the possibility to adjust image file naming somewhat.
- Output: A zip archive file containing the generated
video snapshot image files and optionally annotation tiers with
metadata such as the corresponding image file name for each
timespan.
AVATecH and AUVIS compatible recognizers have the following
categories of settings, input and output elements:
- input media: ELAN automatically uses the first suitable media
file of your current annotation session, but you can change
that to other supported files belonging to the session. Very
few recognizers expect multiple input media files or extra
input files in 'timeseries' or recognizer-specific formats.
- input tiers: Some recognizers need input in the form of an
annotation tier, for example to select timespans of interest.
For some recognizers, the input is expected to be the output
of another recognizer. This gives you a chance to edit and
correct data - often simply tiers - between the two steps.
- numerical input: Recognizers can be configurable by
numerical 'knobs'. ELAN can show those as slider or field.
Recognizers often work well enough with defaults already.
- choice input: Recognizers can give you the option
to select settings from a pre-defined list. An example can
be 'verbose/normal/silent' messages or 'high/low' sensitivity.
ELAN shows drop down selectors here. In special cases, a
recognizer can also have 'any text' configuration items.
- output: Recognizers often produce one or more annotation
tiers. ELAN will offer to add those to your annotation
session as new tiers. It is also possible for recognizers
to output timeseries (which ELAN can show as curves) or
even audio, video or other files. Most recognizers only
produce zero or more tiers (plus log messages) as output.
It is often possible to selectively skip some output steps.
- log: You can open a window showing general messages from
the recognizer, tagged by type (e.g. DEBUG, INFO, WARN,
ERROR, RESULT or PROGRESS). Messages of higher priority
also update the processing status display, so they can
be seen directly without having to review the log text.
- basic or advanced recognizer settings: ELAN gives you
the choice to either hide or show 'advanced' settings. Default
values will be used for those settings which are hidden.
Your default ELAN configuration invokes a
CLAM
REST
web service wrapper on catalog.clarin.eu to have your files analyzed.
In other words, your media files and, if applicable, input tiers will
be uploaded for processing and ELAN will process the downloaded (tier
or other) results as if you had done the processing locally. For use
in situations where a web service can not be used (too large files or
no internet available) you can also request a copy of the recognizer
for local installation on Linux or Windows, protected by USB dongle.
For this and for general support with the use of this recognizer,
please contact auvis@mpi.nl or use
the ELAN and AUVIS forums on the website of
The Language Archive.
CLAM, ELAN and the client-side recognizer proxy are free open source
software under the
GNU
General Public License - however, some of the recognizers can be
propietary closed source software. Licenses for academic use are
available on request. Use of the web services is free at the moment,
but may be limited to the academic community if it becomes necessary.