Add demo content selector for 1 kHz test tone option

Adds a selectbox in Demo mode UI to choose between program material and a 1 kHz test tone. Includes test tone WAV files at 16/24/48 kHz sample rates. The server detects and persists the demo content type based on the selected audio source files.

src/auracast/server/multicast_frontend.py

@@ -322,6 +322,17 @@ if audio_mode == "Demo":
         disabled=is_streaming,
         help="Select the demo stream configuration."
     )
+    demo_content_options = ["Program material", "1 kHz test tone"]
+    saved_demo_content = saved_settings.get('demo_content', 'Program material')
+    if saved_demo_content not in demo_content_options:
+        saved_demo_content = 'Program material'
+    demo_content = st.selectbox(
+        "Demo Content",
+        demo_content_options,
+        index=demo_content_options.index(saved_demo_content),
+        disabled=is_streaming,
+        help="Select whether demo streams use program audio files or a continuous 1 kHz test tone."
+    )
     # Stream password and flags (same as USB/AES67)
     saved_pwd = saved_settings.get('stream_password', '') or ''
     stream_passwort = st.text_input(
@@ -1508,9 +1519,13 @@ if start_stream:
         bigs1 = []
         for i in range(demo_cfg['streams']):
             cfg_cls, lang = lang_cfgs[i % len(lang_cfgs)]
+            if demo_content == "1 kHz test tone":
+                source_file = f'../testdata/test_tone_1k_{int(q["rate"]/1000)}kHz_mono.wav'
+            else:
+                source_file = f'../testdata/wave_particle_5min_{lang}_{int(q["rate"]/1000)}kHz_mono.wav'
             bigs1.append(cfg_cls(
                 code=(stream_passwort.strip() or None),
-                audio_source=f'file:../testdata/wave_particle_5min_{lang}_{int(q["rate"]/1000)}kHz_mono.wav',
+                audio_source=f'file:{source_file}',
                 iso_que_len=32,
                 sampling_frequency=q['rate'],
                 octets_per_frame=q['octets'],

src/auracast/server/multicast_server.py

@@ -528,6 +528,13 @@ async def init_radio(transport: str, conf: auracast_config.AuracastConfigGroup,
         demo_count = sum(1 for big in conf.bigs if isinstance(big.audio_source, str) and big.audio_source.startswith('file:'))
         demo_rate = int(conf.auracast_sampling_rate_hz or 0)
         demo_type = None
+        demo_sources = [
+            str(b.audio_source)
+            for b in conf.bigs
+            if isinstance(b.audio_source, str) and b.audio_source.startswith('file:')
+        ]
+        is_demo_tone = bool(demo_sources) and all('test_tone_1k_' in src for src in demo_sources)
+        demo_content = '1 kHz test tone' if is_demo_tone else 'Program material'
         if demo_count > 0 and demo_rate > 0:
             if demo_rate in (48000, 24000, 16000):
                 demo_type = f"{demo_count} × {demo_rate//1000}kHz"
@@ -554,8 +561,9 @@ async def init_radio(transport: str, conf: auracast_config.AuracastConfigGroup,
             'big_random_addresses': [getattr(big, 'random_address', DEFAULT_RANDOM_ADDRESS) for big in conf.bigs],
             'demo_total_streams': demo_count,
             'demo_stream_type': demo_type,
+            'demo_content': demo_content,
             'is_streaming': auto_started,
-            'demo_sources': [str(b.audio_source) for b in conf.bigs if isinstance(b.audio_source, str) and b.audio_source.startswith('file:')],
+            'demo_sources': demo_sources,
         }
         return mc, persisted
     except HTTPException: