realtime flag for http urls

AGENTS.md

@@ -110,7 +110,7 @@ Frame output:
 
 - Maps `0:v:0`
 - Disables audio with `-an`
-- Applies `fps=<fps>,scale=w='min(<width>,iw)':h=-2:flags=bicubic:out_range=pc,format=yuvj420p`
+- Applies `fps=<fps>,scale=w='min(<width>,iw)':h=-2:flags=bicubic:out_range=pc,format=yuvj420p,realtime`
 - Encodes `mjpeg`
 - Uses `-pix_fmt yuvj420p`, `-color_range pc`, `-q:v <quality>`
 - Outputs `image2pipe` to either `pipe:1` or `pipe:3`

server/index.js

@@ -2798,6 +2798,7 @@ function buildFrameArgs(session, inputUrl, inputOptions) {
 }
 
 function buildInputArgs(inputUrl, { seekable = true, startTime = 0 } = {}) {
+  const isHttpInput = isHttpInputUrl(inputUrl);
   const args = [
     '-hide_banner',
     '-nostdin',
@@ -2806,7 +2807,7 @@ function buildInputArgs(inputUrl, { seekable = true, startTime = 0 } = {}) {
     '-nostats',
   ];
 
-  if (seekable) {
+  if (seekable && isHttpInput) {
     args.push('-seekable', startTime > 0 ? '1' : FFMPEG_INPUT_SEEKABLE);
   }
 
@@ -2814,7 +2815,7 @@ function buildInputArgs(inputUrl, { seekable = true, startTime = 0 } = {}) {
     args.push('-ss', formatFfmpegSeconds(startTime));
   }
 
-  if (FFMPEG_HTTP_RECONNECT && isHttpInputUrl(inputUrl)) {
+  if (FFMPEG_HTTP_RECONNECT && isHttpInput) {
     args.push(
       '-reconnect',
       '1',
@@ -2849,7 +2850,7 @@ function formatFfmpegSeconds(seconds) {
 
 function buildFrameOutputArgs(session, outputUrl) {
   const { fps, quality, width } = session.options;
-  const videoFilter = `fps=${fps},scale=w='min(${width},iw)':h=-2:flags=bicubic:out_range=pc,format=yuvj420p`;
+  const videoFilter = `fps=${fps},scale=w='min(${width},iw)':h=-2:flags=bicubic:out_range=pc,format=yuvj420p,realtime`;
 
   return [
     '-an',