From fa9888f83ee2fcdd12167de79db9bac83e3cf3f6 Mon Sep 17 00:00:00 2001
From: Julian Vollmer <julianvollmer@gmail.com>
Date: Mon, 18 May 2026 18:19:34 +0200
Subject: [PATCH] Reduce audio stream latency

- fflags nobuffer + flags low_delay: ffmpeg Input-Buffer deaktiviert
- frame_duration 20ms + page_duration 20ms: kleinste Ogg-Pages
- flush_packets 1: sofortiges Schreiben nach jedem Frame
- HTTP Header no-cache + X-Accel-Buffering no: kein Proxy/Flask-Buffering

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
---
 app/main.py | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/app/main.py b/app/main.py
index b21091e..b92055c 100644
--- a/app/main.py
+++ b/app/main.py
@@ -115,12 +115,18 @@ AUDIO_SAMPLERATE = 16000
 def generate_audio():
     cmd = [
         "ffmpeg",
+        "-fflags", "nobuffer",
+        "-flags", "low_delay",
         "-f", "alsa",
+        "-thread_queue_size", "128",
         "-i", AUDIO_DEVICE,
         "-ar", str(AUDIO_SAMPLERATE),
         "-ac", "1",
         "-c:a", "libopus",
         "-b:a", "24k",
+        "-frame_duration", "20",
+        "-page_duration", "20000",
+        "-flush_packets", "1",
         "-f", "ogg",
         "-",
     ]
@@ -142,6 +148,10 @@ def audio():
     return Response(
         generate_audio(),
         mimetype="audio/ogg; codecs=opus",
+        headers={
+            "Cache-Control": "no-cache, no-store",
+            "X-Accel-Buffering": "no",
+        },
     )