feat: generation options for infer.py, and split out training deps

infer.py could only render a random example from examples/input_params:
there was no way to pass your own prompt, lyrics, duration or seed, so
using it for anything specific meant writing a separate script. Add
--prompt, --lyrics/--lyrics_file, --duration, --steps, --guidance_scale,
--scheduler, --cfg_type, --omega_scale, --seed and --format alongside the
existing runtime flags. Without --prompt the old random-example behaviour
is kept, so existing invocations are unaffected.

Also move the training-only packages out of the default install.
datasets, pytorch_lightning, matplotlib, tensorboard and tensorboardX are
imported by trainer.py and convert2hf_dataset.py, never on the inference
path, but every user was installing them — and datasets==3.4.1 is a hard
pin that drags constraints onto huggingface-hub. They now live in
requirements-train.txt behind the existing (previously ineffective)
"train" extra: pip install -e ".[train]".

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

infer.py

@@ -48,7 +48,66 @@ def sample_data(json_data):
 )
 @click.option("--device_id", type=int, default=0, help="Device ID to use")
 @click.option("--output_path", type=str, default=None, help="Path to save the output")
-def main(checkpoint_path, bf16, torch_compile, cpu_offload, overlapped_decode, device_id, output_path):
+# --- generation parameters -------------------------------------------------
+# Without --prompt the script keeps its original behaviour and generates from a
+# random example in examples/input_params.
+@click.option(
+    "--prompt",
+    type=str,
+    default=None,
+    help="Style tags or description, comma separated. If omitted, a random example is used.",
+)
+@click.option("--lyrics", type=str, default=None, help="Lyrics, with [verse]/[chorus] tags.")
+@click.option(
+    "--lyrics_file",
+    type=click.Path(exists=True, dir_okay=False),
+    default=None,
+    help="Read lyrics from a UTF-8 file. Takes precedence over --lyrics.",
+)
+@click.option("--duration", type=float, default=60.0, help="Audio duration in seconds (-1 for random).")
+@click.option("--steps", type=int, default=60, help="Number of inference steps.")
+@click.option("--guidance_scale", type=float, default=15.0, help="Guidance scale.")
+@click.option(
+    "--scheduler",
+    type=click.Choice(["euler", "heun", "pingpong"]),
+    default="euler",
+    help="Scheduler type.",
+)
+@click.option(
+    "--cfg_type",
+    type=click.Choice(["cfg", "apg", "cfg_star"]),
+    default="apg",
+    help="CFG type. apg is recommended.",
+)
+@click.option("--omega_scale", type=float, default=10.0, help="Granularity scale.")
+@click.option("--seed", type=str, default=None, help="Manual seeds, comma separated. Random if omitted.")
+@click.option(
+    "--format",
+    "audio_format",
+    type=click.Choice(["wav", "mp3", "ogg", "flac"]),
+    default="wav",
+    help="Output audio format.",
+)
+def main(
+    checkpoint_path,
+    bf16,
+    torch_compile,
+    cpu_offload,
+    overlapped_decode,
+    device_id,
+    output_path,
+    prompt,
+    lyrics,
+    lyrics_file,
+    duration,
+    steps,
+    guidance_scale,
+    scheduler,
+    cfg_type,
+    omega_scale,
+    seed,
+    audio_format,
+):
     os.environ["CUDA_VISIBLE_DEVICES"] = str(device_id)
 
     model_demo = ACEStepPipeline(
@@ -58,44 +117,70 @@ def main(checkpoint_path, bf16, torch_compile, cpu_offload, overlapped_decode, d
         cpu_offload=cpu_offload,
         overlapped_decode=overlapped_decode
     )
-    print(model_demo)
 
-    data_sampler = DataSampler()
+    if lyrics_file is not None:
+        with open(lyrics_file, "r", encoding="utf-8") as f:
+            lyrics = f.read()
 
-    json_data = data_sampler.sample()
-    json_data = sample_data(json_data)
-    print(json_data)
+    if prompt is None:
+        # No prompt given: keep the original behaviour and use a random example.
+        data_sampler = DataSampler()
+        json_data = data_sampler.sample()
+        (
+            audio_duration,
+            prompt,
+            sampled_lyrics,
+            infer_step,
+            sampled_guidance_scale,
+            scheduler_type,
+            sampled_cfg_type,
+            sampled_omega_scale,
+            manual_seeds,
+            guidance_interval,
+            guidance_interval_decay,
+            min_guidance_scale,
+            use_erg_tag,
+            use_erg_lyric,
+            use_erg_diffusion,
+            oss_steps,
+            guidance_scale_text,
+            guidance_scale_lyric,
+        ) = sample_data(json_data)
+        # Explicit options still win over the sampled example.
+        lyrics = lyrics if lyrics is not None else sampled_lyrics
+        manual_seeds = seed if seed is not None else manual_seeds
+    else:
+        audio_duration = duration
+        lyrics = lyrics if lyrics is not None else "[instrumental]"
+        infer_step = steps
+        sampled_guidance_scale = guidance_scale
+        scheduler_type = scheduler
+        sampled_cfg_type = cfg_type
+        sampled_omega_scale = omega_scale
+        manual_seeds = seed
+        guidance_interval = 0.5
+        guidance_interval_decay = 0.0
+        min_guidance_scale = 3.0
+        use_erg_tag = True
+        use_erg_lyric = True
+        use_erg_diffusion = True
+        oss_steps = None
+        guidance_scale_text = 0.0
+        guidance_scale_lyric = 0.0
 
-    (
-        audio_duration,
-        prompt,
-        lyrics,
-        infer_step,
-        guidance_scale,
-        scheduler_type,
-        cfg_type,
-        omega_scale,
-        manual_seeds,
-        guidance_interval,
-        guidance_interval_decay,
-        min_guidance_scale,
-        use_erg_tag,
-        use_erg_lyric,
-        use_erg_diffusion,
-        oss_steps,
-        guidance_scale_text,
-        guidance_scale_lyric,
-    ) = json_data
+    click.echo(f"prompt: {prompt}")
+    click.echo(f"duration: {audio_duration}s, steps: {infer_step}, seeds: {manual_seeds}")
 
     model_demo(
+        format=audio_format,
         audio_duration=audio_duration,
         prompt=prompt,
         lyrics=lyrics,
         infer_step=infer_step,
-        guidance_scale=guidance_scale,
+        guidance_scale=sampled_guidance_scale,
         scheduler_type=scheduler_type,
-        cfg_type=cfg_type,
-        omega_scale=omega_scale,
+        cfg_type=sampled_cfg_type,
+        omega_scale=sampled_omega_scale,
         manual_seeds=manual_seeds,
         guidance_interval=guidance_interval,
         guidance_interval_decay=guidance_interval_decay,