LTX 2.5 Fast vs Grok Imagine 1.5 Lite: Which Should You Use?

TL;DR

• Need a controllable audio switch and 12 durations? Use LTX 2.5 Fast (ltx-2.5-fast/text-to-video, $0.043/s at 720p, $0.086 at 1080P). Need built-in sound and any integer duration 1–15? Use Grok Imagine 1.5 Lite (grok-imagine-1.5-lite/text-to-video, 480P $0.029, 720P $0.043, 1080P $0.2).
• The hardest number: 720p is priced the same at $0.043/s; 1080P forks — LTX at $0.086 versus Grok Lite at $0.2 (~2.3×).
• Both are live on HiAPI: the LTX page and the Grok Lite page, one shared /v1/tasks, 200 free credits on signup.

At a glance

HiAPI current prices, checked October 23, 2026. Pay for successful clips; failures refund.

Same prompt, both models, real clips

Both pairs run 720p, 5 s, 16:9 ($0.215 a clip on each side).

Pair A: sneaker ad

Product commercial: a white running sneaker drops onto wet asphalt in slow motion, water splashes outward, dramatic rim light, bass hit sound

Left: ltx-2.5-fast/text-to-video, 720p, 5 s, 16:9, 1280×720, audio (default on). Right: grok-imagine-1.5-lite/text-to-video, 720P, 5 s, 16:9, $0.215. Same prompt, one render each; Grok Lite's sound is built in — check the clip.

Pair A: both deliver slow-motion drop, splash, and rim light; LTX generates audio by default while Grok Lite's track rides along. Composition and shoe detail diverge — judge from the clips.

Pair B: alpine lake flyover

Sweeping cinematic aerial drone shot gliding low over a glacial turquoise alpine lake at sunrise. Pine forests cling to steep granite shoulders, morning mist curls off the still water and drifts between the trees, and golden light spills over snow-capped peaks as the camera slowly rises to reveal a winding river valley. Crisp natural detail, rich greens and deep blues, realistic motion. Soft wind rustling pine needles, distant birdsong, and gentle flowing water over stones.

Left: ltx-2.5-fast/text-to-video, 720p, 5 s, 16:9, $0.215. Right: grok-imagine-1.5-lite/text-to-video, 720P, 5 s, 16:9, $0.215. Same prompt, one render each.

Pair B: both complete the "skim the lake, rise to the valley" camera design; mist and peaks get their own readings, and the three named sounds generate each in its own way.

Choosing by scenario

• Vertical short-video delivery: both work (same 9:16, same price).
• Ads you'll score yourself: LTX — mute with generate_audio for clean footage at no extra cost.
• Spoken lines and dialogue: Grok Lite — write the line into the prompt and the track arrives.
• Budget draft rounds: Grok Lite has 480P ($0.029/s); LTX starts at 720p.
• 1080P finals: LTX at $0.086/s is far cheaper (Grok Lite $0.2/s).
• Odd durations (7 s, 9 s): only Grok Lite takes them; LTX enumerates.

Switching cost: change model and one field

{
  "model": "ltx-2.5-fast/text-to-video",
  "input": {
    "prompt": "Product commercial: a white running sneaker drops onto wet asphalt in slow motion, water splashes outward, dramatic rim light, bass hit sound",
    "resolution": "720p",
    "duration": 5,
    "aspect_ratio": "16:9",
    "generate_audio": true
  }
}

{
  "model": "grok-imagine-1.5-lite/text-to-video",
  "input": {
    "prompt": "Product commercial: a white running sneaker drops onto wet asphalt in slow motion, water splashes outward, dramatic rim light, bass hit sound",
    "resolution": "720p",
    "duration": 5,
    "aspect_ratio": "16:9"
  }
}

Grok Lite has no generate_audio field (sound is built in); everything else is identical.

FAQ

• Yes, 720p costs the same: $0.043/s — $0.215 for 5 seconds on both.
• Yes, 1080P diverges: $0.086/s (LTX) versus $0.2/s (Grok Lite) — $0.57 apart on a 5-second clip.
• Yes, only LTX can mute; Grok Lite's sound is part of the picture.
• Yes, both refund failures.

Next: run the sneaker prompt on both LTX and Grok Lite and compare their camera language; full pricing is in the LTX pricing page and the Grok Lite pricing page.