AUDIO-VIDEO-MEDIA

AUDACITY (Windows, Mac, Linux)
An excellent audio recording and editing program. I use it for all my audio recording and processing - don't waste your money on commercial products.
The default file format is Audacity (suffix .aup) that is used for all editing functions, from which selections can be exported into several formats
such as mp3. Other nice features include:
(i) you can select a piece of background noise and subtract it from the entire file. For example, if one copies an LP to a file, this feature allows you to subtract
the noise of the lead-in from the entire LP and make it sound better than the original.
 (ii) there are several  (programmable) options such as click removal, equalization (with several pre-defined settings such as "am radio"), and setting
maximum amplitude for all files.  I have had satisfactory results using all default settings.  Audacity crashes occasionally
and I have found one silly quirk: when exporting to a format such as mp3 the file extension is not automatically ".mp3".
The homesite is HERE

GIMP (Gnu Image Manipulation Program).
This is probably a part of most Linux distributions. Evidently comparable with Photoshop in sophistication (I have only used its simplest features). Cheat Sheet HERE

VLC MEDIA PLAYER   (Windows, Linux)
Best of the bunch.