LTX 2.3 Fast: from 20 credits, 4K, audio
LTX 2.3 Fast starts at 20 credits, native audio, up to 4K, 6–20s. Use it for cheap 4K sound takes. Skip it when SKU must hold or the hero is dialogue.
LTX 2.3 Text to Video Fast starts at 20 credits, native audio, up to 4K, 6–20 seconds. The card is the minimum job: it bills per second, 4 credits at SD/HD and 13 at 4K. That is the cheap native-audio 4K row. Use it when the brief is a prompt, a soundtrack, and a 4K file you can afford to miss. Do not use it when the SKU must hold, or when the hero is a Veo-shaped dialogue close-up.
The catalog card: audio true, text-to-video, 6 / 8 / 10 / 12 / 14 / 16 / 18 / 20s, 4K, 20 credits. Description: generates a video directly from a text prompt at 1080p / 1440p / 2160p, 6–20s, with optional native audio generation. Optional in the description, true in the audio field. Write the sound. A mute prompt still comes back with a bed.
This is not a prompting-style essay. It is when the 4K row is the right bill, and when it is the wrong one.
What 20 credits actually buys
A T2V generate. No still required. Native audio on. Even-second durations from 6 through 20. Max output 4K. Fast in the name is latency, not silence, not a draft-only ghetto.
Twenty credits is the catalog sticker. It is lower than Flux 3 T2V at 34 credits (5–20s, native audio), Grok Imagine Video at 24 credits (720p, 6 / 10 / 15 / 20 / 30s, native audio), Kling 3 Turbo at 22 credits (silent, 1080p), and far below Veo 3.1 at 64 credits. Cheap is real. Cheap is not a SKU lock, not 4 seconds, not 30 seconds, not image-to-video.
Duration rules that bite:
- No 4s, no 5s, no 7s, no 9s. If the brief is a 5-second hook, this floor is wrong. Veo has 4s. Flux 3 has 5s. Turbo has 3s.
- No 30s. Seedance 2.5 and Grok Imagine Video have 30s at 720p. LTX Fast stops at 20s, like Flux 3 T2V, at 4K instead of Flux’s described 1080p ceiling.
- 20s of accidental radio is a long accidental radio. Write “no speech, room tone only” or write the line.
Resolution: 1080p / 1440p / 2160p listed in the description, 4K on the card. If the delivery is 720p social, you can still generate here and downscale, but you are buying a 4K-capable row to get native audio cheap, not because the feed needs 2160p, and the 4K band (13 credits a second) only bills if you pick it. If the insertion order says 4K, this row is one of the few native-audio 4K T2V bills that is not Veo’s 64 credits — with Veo’s 8-second ceiling as the trade you are not making.
Aspect on this family is the narrow pair, 16:9 and 9:16. Pick one. Do not expect 1:1.
Run it from the AI video generator. Inspect the quote before a 20s 4K click. The live quote is what charges. The sticker is 20.
When this is the right row
Volume 4K with sound, prompt-led. Hook tests, b-roll beds, location plates that do not have to match a JPEG. At SD/HD it is 4 credits a second, so you can miss; spend the 13 a second at 4K on the keeper.
20-second native audio when 4K matters more than family taste. Sora 2 T2V was 20s at 720p from 32 credits, API ending 24 September 2026. LTX Fast covers 6–20s at 4K at 13 credits a second with native audio. Flux 3 T2V covers 5–20s from 34 credits. Pick LTX Fast when the 4K-and-cheap constraint is the brief. Pick Flux 3 T2V when you want that family. Do not run both every time.
A talking line that fits 6–20s and does not need Veo’s close-up job. Native audio will speak if you write the line. That is enough for a lot of social. It is not the Veo 3.1 dialogue replacement for an 8-second 4K hero you will put in front of a buyer who asked for Veo.
A silent-feeling clip where you still want room tone. Write the room. Do not switch to Turbo unless you truly want audio false.
Caption anyway. Native audio does not play when the phone is mute. Captions for silent autoplay and add captions to video remain the finish.
When not to use it
SKU must hold. T2V invents the pack. There is no LTX Fast reference-to-video row. Use Seedance 2.0 (44 credits, 4–15s, 1080p, T2V+R2V, native audio) or Fast R2V (55 credits, was 78, 720p). A cheap 4K cousin of the bottle is an expensive way to fail review even though the sticker is 20.
Dialogue hero that is actually the Veo job. 4 / 6 / 8s, 4K, 64 credits, talking close-up, cinematic physics. LTX Fast can talk. It is not Veo 3.1. If the deck says Veo, run Veo. If the deck says “cheap 4K with a line,” LTX Fast.
You have an approved still. This row does not require an image and will not treat one as a contract. Use I2V / first-last / R2V on families that publish those categories.
You need 3–5 seconds. Floor is 6s. Turbo, Veo, Seedance, or Flux 3 (5s) depending on audio.
You need 30 seconds. Wrong ceiling.
You are editing an existing take. This is T2V, not edit-video. Wan 2.7 edit and Omni Flash Edit are edit rows.
You wanted silent look-dev. Turbo, 22 credits, audio false, 1080p. LTX Fast will spend the generate making a soundtrack. That is waste if you will mute it.
Do not treat Fast as a preview discount that you later “upgrade in place.” A second generate on Veo or Seedance is a new identity. Promote the idea, not the frames, unless you are on an I2V path with a still grabbed from the LTX file.
How to brief it so 20 credits is honest
One action. One camera. Sound written. Duration even. Ratio 16:9 or 9:16.
If you came from Sora 20s drafts, cut the prompt in half. Twenty seconds of four plot points is four failed points. If you came from Veo 8s, you may lengthen — 10 / 12 / 14 are legal here — but only if the extra seconds are camera travel, not extra slogans.
Do not write “4K cinematic filmic masterpiece.” The row already has a 4K ceiling. Write the room and the verb.
If Article 50 applies, label photoreal output at first exposure. Cheap does not mean unmarked. The Article 50 disclosure template is the text.
When the brief is prompt-plus-sound-plus-4K, run LTX 2.3 Fast from Versely.
FAQ
Is LTX 2.3 Fast really 4 credits at 4K with native audio?
Not at 4K. The published card is 20 credits, audio true, up to 4K, 6–20s even ticks, text-to-video. The rate is 4 credits a second at SD/HD and 13 at 4K. Read the live quote before you generate.
Why not use it for every Sora replacement?
Sora SKU work needs a still-contract family. Sora talking heroes that are 4 / 6 / 8s 4K belong on Veo 3.1. Sora silent drafts belong on Kling 3 Turbo. LTX Fast is the cheap native-audio 4K T2V band, 6–20s.
Can I lock a product JPEG on this row?
Not as a published I2V/R2V contract. This slug is text-to-video. For a pack that must hold, Seedance 2.0 / Fast R2V, Veo R2V, or another reference row.