Friday, 24 May 2013

Gopro HERO3 Characteristics

EXIF

Make = GoPro
Model = Hero3-Black Edition
Focal Length = 2.77mm
Exposure = 1/xx sec at ƒ/2.8

Focus Distance

It's a bit tough to figure out the center-of-focus distance with no filters attached, so I used various close-up filters, and calculated the no-filter focus distance from those.

Answer: 35"

Specific results:
  • +1 filter (+1 diopter) - hard to tell -- long.
  • +2 = roughly 16".  Pretty sharp at 24"
  • +4 = 8.5".  Quite sharp from 6" to 10", and not bad 5" to 12".
  • +10 = 5".  Quite sharp 4" to 6", and not too horrible 2" to 10"
I used the +4 result of 8.5", or 22cm.  If +4 is 22cm, +0 is 22*4=88cm.  So the focus distance with a +0 filter (i.e. no filter) ought to be 88cm, or about 35".

I shot the test photos in pretty low light conditions, so they're somewhat noisy.  I might re-try in better light some day.

Wednesday, 22 May 2013

Software List

Here's a list of free and/or open-source software I use for working with videos:

I also use some commercial software
  • Corel VideoStudio Ultra (X5 at the moment)
  • Adobe Photoshop Lightroom

What VirtualDub is good for

VirtualDub is good for cutting, format conversion and various kinds of effects.  Many filters are available for it, to do simple and also complex things to your videos.

It can be made to import almost any kind of video file (using AviSynth as an import engine in extreme cases), but it can only write AVI files.  You get your choice of compression, and you can add codecs for additional compression formats.

VirtualDub plugins and extras



What Avidemux is good for

My main use for this program is initial processing of MP4 files from the GoPro HERO3, and cutting scenes from those files:

  • Load an MP4 into Avidemux
  • Drag additional files in, to append them.  The GoPro breaks your video into <4GB chunks
  • Change the "Output Format" setting to "MP4 Muxer", then save -- you wind up with a pixel-for-pixel (i.e. lossless) combined video file (can be tens of GB)
  • Find some action.  Just before the action, press "[" to set the start of the clip.  Just after the action, press "]" to set the end of the clip.  Then save.  It will save only that section, pixel-for-pixel, in the same format as the original file.

What AviSynth is good for

It's a scripting language that's made for processing video files.  You can go absolutely nuts with it, but there's no user interface or anything, so you need some scripting skill.  Once you have a script, you drag it on to any program that uses Video For Windows (VirtualDub, for example), and that program sees the processed file(s) rather than a raw file.

For example, you can re-size a video on import to VirtualDub, or change its frame-rate, or make each frame the difference between two frames, etc.

It can also write data files.  You can, for example, get it to create a file saying "the difference between frame N and frame N-1 is this much", for every frame in your video.

What Audacity is good for

Audacity does just about anything you can imagine with audio.  A typical workflow might be:

  • Load your video(s) in AviDemux
  • Set the audio output format (MP3, for example)
  • Do Audio / Save as (saving whatever.mp3, for example)
  • Leave AviDemux open... you'll come back to it later
  • Load that file in Audacity
  • Mess with it
  • Save it to an audio file
  • Back in AviDemux, Audio / Select Track.  Enable "Track 2" and drop down its "Track 0..." box.  Select "...Add audio track".  It lets you pick your sound file.  Then you can enable the original track, the processed track, or both.  The "Filters" button for each track lets you adjust relative volumes, etc.
You can also leave out the merge-back step, and use Audacity to find things in your audio file, so you can then in AviDemux use control-T to go to that location in the video file.  For example, if you're trying to get some footage of a bird chirping, you can dump the audio to Audacity, high-pass filter it, and look for bumps in the displayed waveforms.  Then you can preview just the bumps, and quickly find the point in the video where the bird chirped.  Same deal for vehicles driving/flying by, guns being fired, drunken friends doing cannonballs, or whatever.

What Corel VideoStudio Ultra is good for

VideoStudio (used to be a ULead product) is a full-featured non-linear video editing program.  It does basically everything, but it's not necessarily the most efficient tool for a particular job.  For example, it doesn't seem to know how to cut scenes from a video and save them without transcoding.

The idea is that you drag in a bunch of clips, apply transitions, filters, effects, overlays, titles, narration, etc., then write a video file or DVD/BluRay with the finished product.

What Adobe Photoshop Lightroom is good for

Lightroom is mainly a photo organizer and raw processor.  It can also organize videos, and do some limited processing on them.