Using JoltCracker

Jolt reads Minecraft's tick counter off the hunger bar and the hearts in a video and reports where the counter and the video clock disagree: cuts, lag, a second game window. This guide covers the window, how the hearts and the hunger bar give the tick away, typing jolts in by hand, the graphics card decoding, and what to do when something goes wrong.

Starting it

Jolt is one file, jolt.exe. Put it in a folder of its own, it keeps the tools it downloads next to itself.

• Double click it and the window opens. A console window shows for a moment first.
• Drop a video file on jolt.exe and the window opens with that video filled in. Files can also be dropped on the open window.
• From a terminal it works too: jolt VIDEO_OR_LINK [options]. The options are at the end of this guide.

The first scan needs ffmpeg. If it is not on the PC, Jolt says so, asks, and downloads it (about 115 MB). The first YouTube or Twitch link also needs yt-dlp and Deno, fetched the same way. Nothing has to be installed by hand.

Windows may show "Windows protected your PC" the first time, because the exe is not signed. Click More info, then Run anyway.

If you open Jolt from inside the zip without unzipping it, it runs from a temp folder that Windows cleans up later. A box says so and offers to put Jolt in Downloads\Jolt and start it from there, so ffmpeg, downloaded videos and updates stay. Open it from that folder next time.

Updates

Which version you have is at the bottom right of the window and at the bottom of every report.

When a newer version is out, Jolt says so when it starts and asks whether to update:

• OK: Jolt downloads the new version, puts it in the place of the one you have and starts again. It takes a few seconds, there is nothing to do by hand, and your settings stay.
• Cancel: nothing changes. A yellow line at the bottom left of the window stays, click it whenever you want the update.

Jolt only replaces itself with a build that carries my signature, and only after that build has started once on your PC. If the update does not work, the Jolt you have is still there and still works. It says why (J12) and opens the download page, where you can get the new version by hand.

Linux and Mac update the same way. Linux needs curl and unzip installed, and replaces the AppImage file you started. A Mac replaces the program inside Jolt.app. Either way the file has to be in a folder you can write to, so keep Jolt.app in Applications and not on the downloaded disk image.

In a terminal, jolt --update does the same and jolt --version says which version it is.

Videos that show more than one player's screen

An edited video often cuts to another player's screen. When that player's game is drawn at another size, their hunger bar sits in another place. From version 2.2 Jolt finds every hunger bar in a video and reads them all, which adds a few seconds to a scan.

Each screen counts as its own game. A cut to another player shows in the report as "Another screen, game N" under game changes, not as missing footage, and the footer of the report says where each screen's bar is and which game is on which screen. What Jolt finds on the main screen is the same with or without other screens in the video.

Two players whose games are drawn at the same size share a bar. Jolt then tells them apart by their counters. If you give the bar's place yourself (x, y, scale), only that bar is read.

The window

Under More settings:

Manual, beside Scan at the top, is for typing jolts in by hand (see below). Start runs the scan and turns into Stop while it runs. Open report opens the last report. Check this PC, top right, tests everything Jolt needs.

The line under the buttons says what Jolt is doing and how long it has been at it. Its square is yellow while a scan runs, green for a video with no cuts, red for cuts or a problem. The box at the bottom shows what the scan prints.

Hearts, the hunger bar and jolts

Minecraft draws its HUD with random numbers that it takes from the game's tick counter. The counter starts at 0 when the game opens and goes up 20 times a second. The way the icons shake on a tick is the same every time that tick comes round, so Jolt can work back from the shake to the tick. That shake is a jolt, and working back from jolts to the tick is jolt cracking.

Two rows of the HUD jolt:

• The hunger bar, once saturation has run out. It jolts on one tick at a time, on ticks that are a multiple of food level × 3 + 1: every 61 ticks with a full bar, more often as it empties. Each shank goes up a pixel, stays, or goes down a pixel.
• The hearts, at 2 hearts or less. They jolt on every tick, and each heart drops a pixel or stays. At low health the hearts take their random numbers before the hunger bar does, so the hunger bar jolts differently then.

For about a second after damage or healing the hearts blink white. From version 2.3 Jolt reads them through the blinking too. In a dark place the empty hearts can be too faint to make out. From version 2.5 Jolt then follows the hearts it can see from one tick to the next, even a single one. A heart that Regeneration lifts hides its own jolt.

Ten hearts make only 1,024 patterns and ten shanks 59,049, while a day of play is 1,728,000 ticks. One jolt fits many ticks, so Jolt pins the tick down with the jolts around it and the time between them.

Typing jolts in by hand

The scan reads the jolts by itself, but some it misses: a bar that is too small or blurry, an odd texture pack, a frame the encoder smeared. Those you can read off the video yourself.

1. Click Manual at the top of the window.
2. Pick Hunger bar jolts or Heart jolts.
3. Open the video in a player that steps one frame at a time. Find a frame where the row is jolted and compare each icon with where it sits on a frame where the row is still.
4. Type the code in Jolt codes and press Crack.

A code is one mark per icon, left to right as on screen:

A hunger code starts with the food level in half shanks, a full bar is 20. Put H after it when the player had 2 hearts or less on that frame. Then the ten shanks: 18H -000+0--+0.

A heart code is the ten hearts of the bottom row alone: 0--------0. Give a heart that Regeneration lifted a ?.

In front of a code can go @ and the video time it shows at, like @1:08.25 or @68.25, right to a tenth of a second. Codes go in the order the video shows them, with spaces between. A code with no time is the tick right after the one before it, which is what you see when you step frames until the icons move. Once any code has a time, the first one needs a time too.

How many codes it takes:

• Hunger bar: one code with its food level often leaves a handful of ticks in 24 hours. A second jolt with its time almost always leaves one: @0.10 20 +--+000-++ @3.17 20 -0+++0+--+
• Hearts: one code is never enough. Low hearts jolt on every tick, so type three ticks in a row: 0--------0 -00-0--0-0 0-0000-0-0

What comes back:

2 hunger jolt codes, looked up over 24 hours of game uptime

Cracked, one tick fits. Game uptime at the first code:
  0:05:11.10 (6222 ticks), video began at 0:05:11.00

• Cracked in green: one tick fits. The log says how long the game had been open at the first code, and when that code has a time, how long it had been open when the video began.
• N ticks fit: up to twenty are listed. Read another jolt, add it and press Crack again. A fit that says "with 1 absorption heart" only works if the player had absorption hearts, those come last.
• No tick fits in red: most often one mark is read wrong, or the food level or the H. It can also be a game that was open longer than Longest game uptime, which manual mode uses as well.

Graphics cards

Decoding the video is nearly all of the time a scan takes. Jolt decodes on the processor and lets each graphics card decode a share next to it:

• NVIDIA: through CUDA. If that does not work on the PC, through Direct3D 11.
• Intel: through Direct3D 11, with the chip cutting the hunger bar's strip out of each frame itself so only that comes back. A whole frame comes back from an Intel chip at about a third of the speed it decodes. If that does not work, through Direct3D 11 alone.
• AMD and anything else: through Direct3D 11.

Before a card is let into a scan it decodes two seconds that the processor decodes too. It is used only if its frames are the same, byte for byte. A card that fails that, hangs, or stops part way is left out and the processor does its share. So a card can make a scan faster but cannot change what it finds.

The log says what happened:

  AMD Radeon RX 7700 XT is decoding too (d3d11va)
  decoded by the CPU 66%, AMD Radeon RX 7700 XT 25%, Intel(R) UHD Graphics 770 10%

A processor already decodes H.264 very fast, so on a strong one the cards add little. A weaker processor, or a video in AV1 or HEVC, gains more. To switch the cards off, untick Use the graphics card.

When something goes wrong

Jolt says what went wrong, what to do about it, and gives a code. Ctrl+C copies a whole message box as text, which is the best thing to send when asking for help.

Check this PC lists Windows, the processor, every tool with its version, the graphics cards with their drivers and whether each can decode, and ends with what needs putting right. With a video file in the Video box it also says whether that video can be read and whether the hunger bar is found.

Lines in the log that are not errors:

• X is left out of the decoding: ... A card did not pass its trial. The scan goes on without it.
• X stopped at 0:18:37, the CPU reads on from there A card decoder died part way. Nothing is lost.
• ffmpeg stopped at 0:04:55, starting it again there ffmpeg died and was started again on the same frame. Nothing is lost.
• no tick within 24 hours of the game starting, looking up to 168 hours: 20 or more jolts were seen and none fits, so the game was most likely open longer than the longest game uptime. Jolt matches them again from what it already read, which takes seconds and no second scan.
• N seen, 0 matched to a tick, with a hint under it: even that found nothing. Either the game was open for over a week, then read the video again with a higher number like 600, or these are not real jolts.

Command line

usage: jolt                                   opens the window
       jolt VIDEO_OR_YOUTUBE_LINK [options]
       jolt --render RESULT.json [--html FILE]
       jolt --check [VIDEO]
       jolt --update
       jolt --hunger CODES | --hearts CODES
  --render FILE     redraw the report page from a result saved with --json, without reading any video
  --check           test what Jolt needs on this PC and say what is wrong, with a video also that video
  --update          get the newest Jolt from splosh.icu and put it in the place of this one
  --version         say which Jolt this is
  --hunger CODES    crack hunger bar jolts typed in by hand, like "18H -000+0--+0"
  --hearts CODES    the same for heart jolts, ticks in a row, like "0--------0 -00-0--0-0 0-0000-0-0"
  --start TIME      video time to start reading at, like 1:08
  --end TIME        video time to stop reading at
  --bar X,Y,SCALE   hunger bar position when it is not found automatically
  --max-hours N     longest game uptime to consider (default 24)
  --thorough        decode every frame, even where no bar that could jolt is in sight
  --jobs N          how many stretches of the video to decode at once on the CPU
  --gpu on|off      whether graphics cards take a share of the decoding (default on)
  --html FILE       where to write the report page (default: next to the video)
  --open            open the report page in the browser when done
  --json FILE       also write the raw result to this file
  --videos DIR      where videos fetched from YouTube are kept (default: videos)
  --delete-download delete the video fetched from a link once the report is written, never a file given
  --ytdlp "ARGS"    extra arguments for yt-dlp, like --cookies-from-browser firefox