[HN Gopher] Video playback on low-end MS-DOS machines
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Video playback on low-end MS-DOS machines
Author : zdw
Score : 61 points
Date : 2024-01-01 05:01 UTC (1 days ago)
(HTM) web link (scalibq.wordpress.com)
(TXT) w3m dump (scalibq.wordpress.com)
| reaperducer wrote:
| The Atari 2600 says, "Hold my beer."
|
| https://forums.atariage.com/topic/318978-movie-cart/
| mrguyorama wrote:
| >It uses a 16mips pic (64hz 4-cycle) driving 1K of an 8k dual
| port ram.
|
| This is much closer to the "Reverse Emulation" of the NES that
| https://www.youtube.com/watch?v=ar9WRwCiSr0 did than playing a
| movie on the actual device. Using the original hardware as
| nothing more than an RF output interface is clearly not the
| same work, though just like in the reverse emulation of the
| NES, it is still a neat thing.
|
| The reason video on original IBM 5150s is so neat to most
| people is that it could have reasonably been done in it's
| heyday if we could take knowledge and algorithms back in time,
| which the reverse emulation versions could not.
| reaperducer wrote:
| It was common, especially in the later days of the 2600, for
| cartridges to include helper circuitry including RAM and even
| sound chips.
| adhoc32 wrote:
| so, it's full screen compiled sprites.
| Scali wrote:
| Yes, combined with streaming the data from disk in realtime,
| and playing the audio over the PC speaker in this case, bit-
| banged. Given the limited performance of both the HDD system
| and the CGA adapter, the most important thing the compiler has
| to do is to stay within the budget of HDD and CGA resources.
| kierank wrote:
| > It is impossible for the audio to drift ahead of or behind the
| video, regardless of the video framerate or audio samplerate.
|
| How is this "impossible" if the video clock and audio clock are
| on different physical devices?
| Scali wrote:
| The video clock (I assume you mean pixel clock) isn't relevant.
| The synchronization of video and audio happens on a per-frame
| basis. And since the frames are clocked out on the audio-clock,
| there cannot be any drift.
| Scali wrote:
| Having said that, the CGA card does not actually have its own
| clock. It takes the NTSC base frequency of 14.31818 MHz from
| the OSC-pin of the ISA bus. On early PCs, such as the IBM
| 5150/5160, the CPU frequency is also derived from this same
| base clock (which is why you get the oddly specific speed of
| 4.77 MHz).
| bazza97 wrote:
| Love how people are still pushing old hardware. These are also
| two excellent demo's on the XT:
|
| Area 5150 https://youtu.be/fWDxdoRTZPc?feature=shared
|
| 8088 MPH https://youtu.be/yHXx3orN35Y?feature=shared
| qingcharles wrote:
| Same guy, I think.
| mmastrac wrote:
| > And indeed, I found that it set a period of 1 instead of a
| period of 1.
|
| I assume this should be ...
|
| > And indeed, I found that it set a period of 1 instead of a
| period of 0.
| Scali wrote:
| Yes, thanks! Fixed the original text.
| bdcravens wrote:
| I had a 486DX - if I wanted to play an MP3, I had to exit out of
| everything and run only the DOS player.
| qingcharles wrote:
| On my 486 I don't remember being able to play MP3s in realtime.
| I remember having to convert a 3MB MP3 to a 50MB WAV that took
| up my whole HDD just to play it.
| Minor49er wrote:
| Ken Silverman, creator of the BUILD Engine, made MP3PC.exe
| that's still hosted on his Utilities page. I'm pretty sure I
| used this on a 486 years ago and was surprised at how well it
| worked, though it apparently is picky about MP3 encodings.
| From the description:
|
| > MP3PC.EXE (73,483 bytes): Got no sound card? MP3PC plays
| MP3 files through your PC speaker! For some reason I like to
| make programs work through the PC speaker. Some people still
| don't know that it's possible to play real sounds through it.
| Unfortunately, you must run this in pure DOS mode for it to
| work.
|
| His Utilities page can be found at:
| http://advsys.net/ken/utils.htm
| starik36 wrote:
| Wow, I just learned that he is also the author of PNGOut.
| AnotherGoodName wrote:
| There were entire games, eg. star control 2, that played
| sample audio through the PC speaker. It included voice
| sample in parts (eg. The pkunk swear words).
| Scali wrote:
| It was actually patented by Access Software, under the
| name of RealSound.
| https://en.wikipedia.org/wiki/RealSound
| HPsquared wrote:
| 16 FPS video and audio on a Commodore 64 demo. Very, very highly
| compressed and optimized data and algorithm:
|
| https://m.youtube.com/watch?t=12m55s&v=yW5v93P-gBw&feature=y...
|
| EDIT: and some details on the audio encoding method, might as
| well start here:
| https://m.youtube.com/watch?t=11m55s&v=yW5v93P-gBw&feature=y...
| qingcharles wrote:
| That's actually really good.
| qingcharles wrote:
| This is awesome. I tried doing this in the early 90s by breaking
| down video frames into averaged color triangle polygons and then
| using the renderer I had to draw them. It worked fine, but
| obviously best on large swathes of flat color like cartoons where
| it would create the smallest number of vertices and the largest
| runs of bytes.
|
| Somewhere on Usenet there is a post of mine about running it on
| my 286, but I just wasted an hour trying to find it.
| gmueckl wrote:
| This seems very similar to how the cinematic platformer Another
| World (1991, also known as Out of This World) was doing its
| elaborate full screen animation sequences, although the
| animations were rotoscoped rather than generated by an
| automatic encoder.
| EvanAnderson wrote:
| re: decomposing video to triangles - That makes me think of
| State of the Art[0] and Nine Fingers[1], though I don't
| actually know how they worked.
|
| [0] https://www.pouet.net/prod.php?which=99
|
| [1] https://www.pouet.net/prod.php?which=100
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