Initial ID-LoRA support for LTX2

comfy/ldm/lightricks/av_model.py

@@ -681,7 +681,34 @@ class LTXAVModel(LTXVModel):
         additional_args["has_spatial_mask"] = has_spatial_mask
 
         ax, a_latent_coords = self.a_patchifier.patchify(ax)
+
+        # Inject reference audio for ID-LoRA in-context conditioning
+        ref_audio = kwargs.get("ref_audio", None)
+        ref_audio_seq_len = 0
+        if ref_audio is not None:
+            ref_tokens = ref_audio["tokens"].to(dtype=ax.dtype, device=ax.device)
+            if ref_tokens.shape[0] < ax.shape[0]:
+                ref_tokens = ref_tokens.expand(ax.shape[0], -1, -1)
+            ref_audio_seq_len = ref_tokens.shape[1]
+            B = ax.shape[0]
+
+            # Compute negative temporal positions matching ID-LoRA convention:
+            # offset by -(end_of_last_token + time_per_latent) so reference ends just before t=0
+            p = self.a_patchifier
+            tpl = p.hop_length * p.audio_latent_downsample_factor / p.sample_rate
+            ref_start = p._get_audio_latent_time_in_sec(0, ref_audio_seq_len, torch.float32, ax.device)
+            ref_end = p._get_audio_latent_time_in_sec(1, ref_audio_seq_len + 1, torch.float32, ax.device)
+            time_offset = ref_end[-1].item() + tpl
+            ref_start = (ref_start - time_offset).unsqueeze(0).expand(B, -1).unsqueeze(1)
+            ref_end = (ref_end - time_offset).unsqueeze(0).expand(B, -1).unsqueeze(1)
+            ref_pos = torch.stack([ref_start, ref_end], dim=-1) if p.start_end else ref_start
+
+            ax = torch.cat([ref_tokens, ax], dim=1)
+            a_latent_coords = torch.cat([ref_pos.to(a_latent_coords), a_latent_coords], dim=2)
+
         ax = self.audio_patchify_proj(ax)
+        additional_args["ref_audio_seq_len"] = ref_audio_seq_len
+        additional_args["total_audio_seq_len"] = ax.shape[1]
 
         # additional_args.update({"av_orig_shape": list(x.shape)})
         return [vx, ax], [v_pixel_coords, a_latent_coords], additional_args
@@ -721,6 +748,16 @@ class LTXAVModel(LTXVModel):
 
         # Prepare audio timestep
         a_timestep = kwargs.get("a_timestep")
+        ref_audio_seq_len = kwargs.get("ref_audio_seq_len", 0)
+        if ref_audio_seq_len > 0 and a_timestep is not None:
+            # Reference tokens must have timestep=0 (clean conditioning, as during training).
+            # Expand scalar/1D timestep to per-token so ref=0 and target=sigma.
+            target_len = kwargs.get("total_audio_seq_len", 0) - ref_audio_seq_len
+            if a_timestep.dim() <= 1:
+                a_timestep = a_timestep.view(-1, 1).expand(batch_size, target_len)
+            ref_ts = torch.zeros(batch_size, ref_audio_seq_len, *a_timestep.shape[2:],
+                                 device=a_timestep.device, dtype=a_timestep.dtype)
+            a_timestep = torch.cat([ref_ts, a_timestep], dim=1)
         if a_timestep is not None:
             a_timestep_scaled = a_timestep * self.timestep_scale_multiplier
             a_timestep_flat = a_timestep_scaled.flatten()
@@ -955,6 +992,13 @@ class LTXAVModel(LTXVModel):
         v_embedded_timestep = embedded_timestep[0]
         a_embedded_timestep = embedded_timestep[1]
 
+        # Trim reference audio tokens before unpatchification
+        ref_audio_seq_len = kwargs.get("ref_audio_seq_len", 0)
+        if ref_audio_seq_len > 0:
+            ax = ax[:, ref_audio_seq_len:]
+            if a_embedded_timestep.shape[1] > 1:
+                a_embedded_timestep = a_embedded_timestep[:, ref_audio_seq_len:]
+
         # Expand compressed video timestep if needed
         if isinstance(v_embedded_timestep, CompressedTimestep):
             v_embedded_timestep = v_embedded_timestep.expand()

comfy/model_base.py

@@ -1053,6 +1053,10 @@ class LTXAV(BaseModel):
         if guide_attention_entries is not None:
             out['guide_attention_entries'] = comfy.conds.CONDConstant(guide_attention_entries)
 
+        ref_audio = kwargs.get("ref_audio", None)
+        if ref_audio is not None:
+            out['ref_audio'] = comfy.conds.CONDConstant(ref_audio)
+
         return out
 
     def process_timestep(self, timestep, x, denoise_mask=None, audio_denoise_mask=None, **kwargs):

comfy_extras/nodes_lt.py

@@ -3,6 +3,7 @@ import node_helpers
 import torch
 import comfy.model_management
 import comfy.model_sampling
+import comfy.samplers
 import comfy.utils
 import math
 import numpy as np
@@ -682,6 +683,84 @@ class LTXVSeparateAVLatent(io.ComfyNode):
         return io.NodeOutput(video_latent, audio_latent)
 
 
+class LTXVReferenceAudio(io.ComfyNode):
+    @classmethod
+    def define_schema(cls) -> io.Schema:
+        return io.Schema(
+            node_id="LTXVReferenceAudio",
+            display_name="LTXV Reference Audio (ID-LoRA)",
+            category="conditioning/audio",
+            description="Set reference audio for ID-LoRA speaker identity transfer. Encodes a reference audio clip into the conditioning and optionally patches the model with identity guidance (extra forward pass without reference, amplifying the speaker identity effect).",
+            inputs=[
+                io.Model.Input("model"),
+                io.Conditioning.Input("positive"),
+                io.Conditioning.Input("negative"),
+                io.Audio.Input("reference_audio", tooltip="Reference audio clip whose speaker identity to transfer. ~5 seconds recommended (training duration). Shorter or longer clips may degrade voice identity transfer."),
+                io.Vae.Input(id="audio_vae", display_name="Audio VAE", tooltip="LTXV Audio VAE for encoding."),
+                io.Float.Input("identity_guidance_scale", default=3.0, min=0.0, max=100.0, step=0.01, round=0.01, tooltip="Strength of identity guidance. Runs an extra forward pass without reference each step to amplify speaker identity. Set to 0 to disable (no extra pass)."),
+                io.Float.Input("start_percent", default=0.0, min=0.0, max=1.0, step=0.001, advanced=True, tooltip="Start of the sigma range where identity guidance is active."),
+                io.Float.Input("end_percent", default=1.0, min=0.0, max=1.0, step=0.001, advanced=True, tooltip="End of the sigma range where identity guidance is active."),
+            ],
+            outputs=[
+                io.Model.Output(),
+                io.Conditioning.Output(display_name="positive"),
+                io.Conditioning.Output(display_name="negative"),
+            ],
+        )
+
+    @classmethod
+    def execute(cls, model, positive, negative, reference_audio, audio_vae, identity_guidance_scale, start_percent, end_percent) -> io.NodeOutput:
+        # Encode reference audio to latents and patchify
+        audio_latents = audio_vae.encode(reference_audio)
+        b, c, t, f = audio_latents.shape
+        ref_tokens = audio_latents.permute(0, 2, 1, 3).reshape(b, t, c * f)
+        ref_audio = {"tokens": ref_tokens}
+
+        positive = node_helpers.conditioning_set_values(positive, {"ref_audio": ref_audio})
+        negative = node_helpers.conditioning_set_values(negative, {"ref_audio": ref_audio})
+
+        # Patch model with identity guidance
+        m = model.clone()
+        scale = identity_guidance_scale
+        model_sampling = m.get_model_object("model_sampling")
+        sigma_start = model_sampling.percent_to_sigma(start_percent)
+        sigma_end = model_sampling.percent_to_sigma(end_percent)
+
+        def post_cfg_function(args):
+            if scale == 0:
+                return args["denoised"]
+
+            sigma = args["sigma"]
+            sigma_ = sigma[0].item()
+            if sigma_ > sigma_start or sigma_ < sigma_end:
+                return args["denoised"]
+
+            cond_pred = args["cond_denoised"]
+            cond = args["cond"]
+            cfg_result = args["denoised"]
+            model_options = args["model_options"].copy()
+            x = args["input"]
+
+            # Strip ref_audio from conditioning for the no-reference pass
+            noref_cond = []
+            for entry in cond:
+                new_entry = entry.copy()
+                mc = new_entry.get("model_conds", {}).copy()
+                mc.pop("ref_audio", None)
+                new_entry["model_conds"] = mc
+                noref_cond.append(new_entry)
+
+            (pred_noref,) = comfy.samplers.calc_cond_batch(
+                args["model"], [noref_cond], x, sigma, model_options
+            )
+
+            return cfg_result + (cond_pred - pred_noref) * scale
+
+        m.set_model_sampler_post_cfg_function(post_cfg_function)
+
+        return io.NodeOutput(m, positive, negative)
+
+
 class LtxvExtension(ComfyExtension):
     @override
     async def get_node_list(self) -> list[type[io.ComfyNode]]:
@@ -697,6 +776,7 @@ class LtxvExtension(ComfyExtension):
             LTXVCropGuides,
             LTXVConcatAVLatent,
             LTXVSeparateAVLatent,
+            LTXVReferenceAudio,
         ]