Hertz Overload by RETREAM [web]
HERTZ OVERLOAD MANUAL -------------------------------------------------------------------------------- END-USER AGREEMENT DEFINITIONS - In this agreement: "Software" refers to any and all files constituting the demo Hertz Overload and its accessory data. RIGHTS AND RESTRICTIONS - You can: make copies of the Software; distribute unmodified copies of the Software. You cannot: distribute modified copies of the Software; use (any part of) the Software for a profit. DISCLAIMER - THE SOFTWARE IS PROVIDED "AS-IS", WITHOUT ANY WARRANTY. TO THE FULLEST EXTENT ALLOWED BY LAW, THE AUTHOR CANNOT BE HELD LIABLE FOR ANY DAMAGE ARISING OUT OF THE (INABILITY OF MAKING) USE OF IT. USE AT YOUR OWN RISK. GOVERNING LAW AND JURISDICTION - This agreement shall be governed by the laws of the country of residence of the author at the time of the dispute. The author reserves the right to appoint the venue for the dispute. EPILEPSY WARNING - Some people are susceptible to epileptic seizures when exposed to certain flashing lights or light patterns, and they may even be unaware of it. The Software may cause problems to such people. Who experiences blurred vision, dizziness, disorientation, loss of consciousness, twitches, involuntary movements, convulsions while playing/watching the Software must stop doing so immediately and receive the due medical assistance. -------------------------------------------------------------------------------- GETTING STARTED Hertz Overload requires: * Amiga computer * AGA chipset * ~1.8 MB of RAM * ~56 MB of storage space * PAL-capable display * stereo loudspeakers To start Hertz Overload, run its executable from either shell or Workbench. To quit Hertz Overload, press the right mouse button anytime (if not done, Hertz Overload returns to AmigaOS automatically at the end). During the loading of files or the streaming of music, you might need to keep the button pressed for a short while. If the device Hertz Overload is installed on is not fast enough to stream the music, audio stuttering might happen or, in the worst case, the machine might freeze. Allocating many buffers with AddBuffers might have adverse effects. A stock Amiga 1200 with AmigaOS 3.1, able to trasfer blocks from a CompactFlash card at a rate of about 1 MB/s, can run Hertz Overload from it just fine (even after booting without startup-sequence, with as little as 10 buffers, and without running any additional software). Note for emulators: due to the high and odd audio frequency, emulators will have a hard time reproducing the audio exactly; the settings to use depend what the emulator offers and on how it operates; as a general guideline, the output rate should be set to a high value starting from at least 141876 Hz; also, emulators should emulate the Paula timings exactly. -------------------------------------------------------------------------------- OVERVIEW Hertz Overload is a demo that focuses on delivering very high quality music on AGA Amigas, including base machines equipped with just a mass storage device (which is needed to stream the huge amount of audio data). "Very high quality translates" to: 2 true stereo channels, 14 bit resolution and 70937.9 Hz sample rate. While the first two parameters are common on the Amiga, the third one is not: it is widely known that the Paula chip can play samples at almost 29 or 58 kHz in normal or doublescan screenmodes, respectively, but frequencies above those are at least unusual. It is also common knowledge that Paula supports higher frequencies when, instead of fetching the samples from the CHIP RAM through its DMA channels, it passively receives them from the CPU - and that is what happens in Hertz Overload. Such playback method is extremely CPU intensive, as it requires the CPU to feed Paula with samples regularly and frequently; therefore, it has been rarely (or maybe never?) used. Hertz Overload pushes things further as it also streams the samples from disk and, at the same time, displays and scrolls graphics - and manages to do so also on unexpanded machines. -------------------------------------------------------------------------------- TECHNICAL DETAILS The visual side of Hertz Overload is very lightweight and is handled by stock machines without effort. In fact, it is programmed with AMOS Professional and RETREAM's own ALS library. The initial music and the sound effects are normal tracker modules, played by means of the AMOS Professional P61 Extension (this was made necessary by the fact that AMOS Professional's Track Play command does not support or execute correctly the EDx command; maybe this could be worked around by reworking the music module using a speed of 1 tick, but it would be basically a useless exercise). The streaming music part (graphics scrolling included) is executed entirely by highly optimized assembly code (which disables AMOS Professional altogether so that it does not get in the way). -------------------------------------------------------------------------------- BACKSTORY The music track "Prockressions" was written while fiddling with the RETREAM guitar after it got fixed and overhauled. It was not made for Hertz Overload, but rather Hertz Overload was made to find a use for it. Thinking of a way to let others enjoy the music brought the idea of making an Amiga production, which immediately suggested the creation of a CPU-based player to achieve a sufficiently high quality. In the past, I had never tried CPU-based audio playback, but a quick experiment showed that it was doable and quite easy. That led to the development of a set of tools that process and play WAVE files. They also proved that the Amiga can reach remarkably high frequencies (much beyond 70937.9 Hz), which pushed me in another direction: making something more artistic than a player, and that simply meant... a demo! Hertz Overload was being made for no specific demoparty. When it was almost finished (May 21st, 2024), I decided to check out which demoparties were about to come and found out that the 68k Inside 2024 was only a days away! It looked like I could meet the deadline (May 25th) easily, but, of course, on the last day all that could go wrong went wrong, so I could not make all the little changes and additions that I had planned - but those may come in the future. -------------------------------------------------------------------------------- CREDITS Created by Simone Bevilacqua AMOS Professional P61 Extension by Chris Hodges The Player 6.1A by Jarno Paananen Testing by John Scolieri -------------------------------------------------------------------------------- rev. 20240527 www.retream.com/Hertz_Overload contact@retream.com (c) 2024 RETREAM
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