NCast Presentation Recorder Reference Manual
There are several tools which have been used to edit and manipulate MPEG-4 archive files: Quicktime Pro,
Adobe After Effects and Streamclip. There may be, and probably are, other tools as well, but these are
known to work.
The words "video editing" means different things to different people. Common tasks related to manipulating
archive files would include these different activities:
•
Reducing resolution and reducing the frame rate to downsize the file to smaller formats and smaller
bit rates so lower power PCs can successfully play them back.
•
Cleaning up a file by removing unneeded material at the beginning, end or in the middle of a file.
•
Converting archive files to another format (e.g. conversion to RealMedia or WindowsMedia formats).
•
More complex editing tasks such as adding titles, inserting other video sequences or material that
was not in the original presentation, selectively adding or deleting sequences or scenes from the
original file, rearranging the order of the presentation, adding fancier transitions or wipes, and
technical work such as fixing color balance.
•
Creation of DVDs, VCR tapes, CDs etc. from the original material.
Obviously this could be a long list and the above items are only representative.
The nature of MPEG-4 files (one keyframe - I frame followed by many differential frames - P, B frames) is
hard for a video editor to deal with directly. Any type of more complex edit would require conversion of the
archive files to an I-frame only format (Motion JPEG or DV format, for example) where differential frame
interpolation is no longer required.
Quicktime Pro, an inexpensive add-on to Quicktime player for both MACs and Windows, is suitable for taking
the original files and exporting them to a variety of other formats for further editing or simple playback in the
new format. It is not a video editor and should be used just for straight export of the original files to the new
format.
Adobe After Effects (available on PCs and MACs) is a high powered, full-featured video editor, which is very
popular with professional videographers and which can do almost any video editing or rendering task known
to man. It is, however, expensive in both cost and time-to-learn. This package can import the archive files
directly.
Squared 5 MPEG Streamclip is an application for editing Presentation Recorder MPEG-4 files, setting In/Out
points, and converting to different formats such as AVI and DV.
The archive files are at the ultra-high-end in terms of resolution and frame rate, and that processing times for
these files are not trivial, with rendering times often being 3 to 7 times real-time (one minute of material may
take three minutes to export, for example).
A high-powered PC is absolutely essential, with something like a 3 GHz. Pentium with 1.5 GB of RAM being
the required hardware. A 1 GHz laptop with 256 MB of memory will not do the job.
Customers should carefully assess what their target audience requirements are, and make recordings in
reduced resolution or reduced frame rates if a lot of down-conversion is contemplated. Keeping everything at
the highest resolution and highest frame rates will be very costly in terms of video-editing post processing.
NCast Corporation
Revision 1.1
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