Sunday, October 23, 2016

Reasons for Owning a Gravis Ultrasound - Sound Quality Comparisons

It is an unfortunate fact of PC retro gaming that the Gravis Ultrasound cards are very expensive to buy off the second-hand market and the auction sites.  You may ask why should I want one, my Sound Blaster and my Roland does the trick for me.

For most games, you would be correct, the GUS is not especially impressive.  Some games, like anything using the DOOM engine, mix all the digital audio in software and then send the result to the sound card.  This eliminates one of the most important advantages of the GUS, mixing multiple streams in hardware at reasonable bit-sizes and frequencies.  In this instance, the GUS is no better than a Sound Blaster 16.  In benchmarks, it is actually worse than a SB16.

But for other games, the GUS can have a distinct advantage.  In these games, all audio, music, speech and sound effects, is digitally generated and mixed.  The Sound Blasters must mix this audio in software, but the GUS mixes it in hardware.  The result is always a higher quality sound from the GUS than an SB, even if the SB is a Pro, 16 or AWE model.

Sunday, October 16, 2016

Video Potpourri II

Sometimes, one needs to discuss related subjects that do not by themselves warrant a full blog entry.  Hence the video potpourri series, in which I can talk about aspects of display technology.

I.  Composite Artifact Color Emulation

Composite artifact color emulation has been around for a long time.  Unfortunately, in many cases it just isn't very good at trying to replicate the look of a composite monitor.  Simple schemes just assign a color arbitrarily to a group of two or four monochrome pixels.  Mainline SVN DOSBox tries to simulate CGA composite color as if it were a VGA mode.  The colors are reasonably accurate to the real IBM CGA cards, but the text color fringing is rather blocky.  There are custom builds that use filtering and 16-bit color to give a more subtle impression of the composite color, but it still looks much, much cleaner than the real image.  You can obtain a custom build with better composite color emulation here :

Monday, October 3, 2016

Restoring the Fluid Look to Analog Video

As we all know theatrical sound film releases are typically projected at 24 or 25 frames per second.  Film is a progressive medium where each film frame captures an image at a discrete point in time.  However, film must be developed before it can be exhibited and must handled by experienced technicians, making it a costly medium in which to produce artistic works.  To reduce flicker, a shutter in the camera would open or close twice for each frame.

Prior to the advent of television, celluloid film was the only commercial means to display visual moving images.  However, the introduction of wholly-electronic television broadcast and receiver systems meant a massive change.  TV broadcast cameras were able to achieve acceptable image quality by broadcasting images in an interlaced format.  A broadcast camera and a TV tube display images in a set number of lines, and the electron scanning beam inside the tube scans or displays each line sequentially, then returns and draws the next line.  (Think of a typewriter.)  When it gets to the bottom of the tube, it returns to the top of the tube and draws the next set of lines.

In order to allow the electron beam sufficient time to draw all the lines, interlacing was used.  In an interlaced format, "frames" become "fields". A field only captures the odd or the even lines of the TV camera lens.  After all the odd lines in the first field are captured, then all the even lines of the second field are captured.  In the NTSC countries, 59.94 color fields (formerly 60 fields for B&W NTSC) are captured each second.  In PAL and SECAM countries, 50 fields are captured each second.  When this is broadcast to a TV screen, the fields are displayed as they are captured.  The high number of displayed fields avoids flicker on the TV screen.

Saturday, October 1, 2016

Nintendo Mini Mania Redux - The Classic Mini Family Computer

Nintendo has released another retro-themed surprise.  Back in July, Nintendo announced the NES Classic Edition/NES Mini, an emulation box containing 30 classic NES games.  Here is the original trailer for it :  I discussed it here :

Yesterday, Nintendo announced a Famicom version for the Japanese market.  Like the NES Mini, the "Classic Mini Family Computer" is a miniature replica of a Famicom with a power and a reset button.  It also has 30 games and will cost 5,980 Yen, which is close to the NES Mini's $59.99 price.  It is going to be released on the same day as the NES Mini, November 11, 2016.  While the official trailer is in Japanese, the visuals are self-explanatory :