From 4ea659d569d596791bc6bf3f15d8ee9eea20b672 Mon Sep 17 00:00:00 2001
From: Chocobozzz <me@florianbigard.com>
Date: Wed, 29 May 2024 08:56:53 +0200
Subject: [PATCH] Handle videos with FPS < 1

---
 packages/ffmpeg/src/ffmpeg-images.ts                |  2 +-
 .../transcoding/video-transcoding-fps.model.ts      | 13 +++++++++++--
 server/core/helpers/ffmpeg/framerate.ts             | 12 +++++++-----
 server/core/initializers/constants.ts               |  5 +++--
 4 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/packages/ffmpeg/src/ffmpeg-images.ts b/packages/ffmpeg/src/ffmpeg-images.ts
index 52076de54..b34e22f5e 100644
--- a/packages/ffmpeg/src/ffmpeg-images.ts
+++ b/packages/ffmpeg/src/ffmpeg-images.ts
@@ -120,7 +120,7 @@ export class FFmpegImage {
 
     const filter = [
       // Fix "t" variable with some videos
-      `setpts=N/round(FRAME_RATE)/TB`,
+      `setpts='N/FRAME_RATE/TB'`,
       // First frame or the time difference between the last and the current frame is enough for our sprite interval
       `select='isnan(prev_selected_t)+gte(t-prev_selected_t,${options.sprites.duration})'`,
       `scale=${sprites.size.width}:${sprites.size.height}`,
diff --git a/packages/models/src/videos/transcoding/video-transcoding-fps.model.ts b/packages/models/src/videos/transcoding/video-transcoding-fps.model.ts
index 9a330ac94..c0a44c5d1 100644
--- a/packages/models/src/videos/transcoding/video-transcoding-fps.model.ts
+++ b/packages/models/src/videos/transcoding/video-transcoding-fps.model.ts
@@ -1,9 +1,18 @@
 export type VideoTranscodingFPS = {
-  MIN: number
+  // Refuse videos with FPS below this limit
+  HARD_MIN: number
+  // Cap FPS to this min value
+  SOFT_MIN: number
+
   STANDARD: number[]
   HD_STANDARD: number[]
+
   AUDIO_MERGE: number
+
   AVERAGE: number
-  MAX: number
+
+  // Cap FPS to this max value
+  SOFT_MAX: number
+
   KEEP_ORIGIN_FPS_RESOLUTION_MIN: number
 }
diff --git a/server/core/helpers/ffmpeg/framerate.ts b/server/core/helpers/ffmpeg/framerate.ts
index 8aef6f021..7d06cd3b1 100644
--- a/server/core/helpers/ffmpeg/framerate.ts
+++ b/server/core/helpers/ffmpeg/framerate.ts
@@ -18,13 +18,15 @@ export function computeOutputFPS (options: {
     fps = getClosestFramerateStandard({ fps, type: 'STANDARD' })
   }
 
-  // Hard FPS limits
-  if (fps > VIDEO_TRANSCODING_FPS.MAX) fps = getClosestFramerateStandard({ fps, type: 'HD_STANDARD' })
-
-  if (fps < VIDEO_TRANSCODING_FPS.MIN) {
-    throw new Error(`Cannot compute FPS because ${fps} is lower than our minimum value ${VIDEO_TRANSCODING_FPS.MIN}`)
+  if (fps < VIDEO_TRANSCODING_FPS.HARD_MIN) {
+    throw new Error(`Cannot compute FPS because ${fps} is lower than our minimum value ${VIDEO_TRANSCODING_FPS.HARD_MIN}`)
   }
 
+  // Cap min FPS
+  if (fps < VIDEO_TRANSCODING_FPS.SOFT_MIN) fps = VIDEO_TRANSCODING_FPS.SOFT_MIN
+  // Cap max FPS
+  if (fps > VIDEO_TRANSCODING_FPS.SOFT_MAX) fps = getClosestFramerateStandard({ fps, type: 'HD_STANDARD' })
+
   return fps
 }
 
diff --git a/server/core/initializers/constants.ts b/server/core/initializers/constants.ts
index a3a0b4951..4b6eecadc 100644
--- a/server/core/initializers/constants.ts
+++ b/server/core/initializers/constants.ts
@@ -513,12 +513,13 @@ const MAX_LOCAL_VIEWER_WATCH_SECTIONS = 100
 let CONTACT_FORM_LIFETIME = 60000 * 60 // 1 hour
 
 const VIDEO_TRANSCODING_FPS: VideoTranscodingFPS = {
-  MIN: 1,
+  HARD_MIN: 0.1,
+  SOFT_MIN: 1,
   STANDARD: [ 24, 25, 30 ],
   HD_STANDARD: [ 50, 60 ],
   AUDIO_MERGE: 25,
   AVERAGE: 30,
-  MAX: 60,
+  SOFT_MAX: 60,
   KEEP_ORIGIN_FPS_RESOLUTION_MIN: 720 // We keep the original FPS on high resolutions (720 minimum)
 }