From 5f4c3b244d8a67205d3f66909638a22dbebd96ff Mon Sep 17 00:00:00 2001
From: Alexandre Beaulieu <alex@segfault.me>
Date: Sun, 24 Oct 2021 12:59:06 -0400
Subject: [PATCH 1/2] fix(359): Support fractional fps.

---
 pyrdp/convert/MP4EventHandler.py | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/pyrdp/convert/MP4EventHandler.py b/pyrdp/convert/MP4EventHandler.py
index fe19b9108..f0ae714a5 100644
--- a/pyrdp/convert/MP4EventHandler.py
+++ b/pyrdp/convert/MP4EventHandler.py
@@ -10,6 +10,7 @@
 from pyrdp.player.RenderingEventHandler import RenderingEventHandler
 
 import logging
+from math import floor
 
 import av
 import qimage2ndarray
@@ -38,7 +39,7 @@ def screen(self) -> QImage:
 
 class MP4EventHandler(RenderingEventHandler):
 
-    def __init__(self, filename: str, fps=30, progress=None):
+    def __init__(self, filename: str, fps=25, progress=None):
         """
         Construct an event handler that outputs to an Mp4 file.
 
@@ -57,16 +58,17 @@ def __init__(self, filename: str, fps=30, progress=None):
         #       we could probably batch the encoding of several frames and benefit from threads
         #       but trying this as-is lead to no gains
         #       (actually a degradation but that could be statistically irrelevant)
-        #self.stream.thread_count = 4
+        # self.stream.thread_count = 4
         self.stream.pix_fmt = 'yuv420p'
         self.progress = progress
         self.scale = False
         self.mouse = (0, 0)
         self.fps = fps
-        self.delta = 1000 // fps  # ms per frame
+        self.delta = 1000 / fps  # ms per frame
         self.log = logging.getLogger(__name__)
         self.log.info('Begin MP4 export to %s: %d FPS', filename, fps)
         self.timestamp = self.prevTimestamp = None
+        self.drift = 0  # Support non-integer frame rates.
 
         super().__init__(MP4Image())
 
@@ -84,8 +86,12 @@ def onPDUReceived(self, pdu: PlayerPDU):
             dt = self.delta
         else:
             dt = self.timestamp - self.prevTimestamp  # ms
-        nframes = (dt // self.delta)
-        if nframes > 0:
+
+        # Prevent drifting when fps doesn't perfectly divide a second.
+        nframes = (dt / self.delta) + self.drift
+        self.drift = nframes - floor(nframes)  # update drift.
+
+        if floor(nframes) > 0:  # Only take whole frames.
             for _ in range(nframes):
                 self.writeFrame()
             self.prevTimestamp = ts

From cd3892567b4f3ead1efbfe1a8d7453082d581531 Mon Sep 17 00:00:00 2001
From: Alexandre Beaulieu <alex@segfault.me>
Date: Sun, 24 Oct 2021 13:13:41 -0400
Subject: [PATCH 2/2] fix: render whole frames only.

---
 pyrdp/convert/MP4EventHandler.py | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/pyrdp/convert/MP4EventHandler.py b/pyrdp/convert/MP4EventHandler.py
index f0ae714a5..fd51a88ee 100644
--- a/pyrdp/convert/MP4EventHandler.py
+++ b/pyrdp/convert/MP4EventHandler.py
@@ -89,13 +89,14 @@ def onPDUReceived(self, pdu: PlayerPDU):
 
         # Prevent drifting when fps doesn't perfectly divide a second.
         nframes = (dt / self.delta) + self.drift
-        self.drift = nframes - floor(nframes)  # update drift.
+        nwhole = floor(nframes)
+        self.drift = nframes - nwhole  # update drift.
 
-        if floor(nframes) > 0:  # Only take whole frames.
-            for _ in range(nframes):
+        if nwhole > 0:  # Only take whole frames.
+            for _ in range(nwhole):
                 self.writeFrame()
             self.prevTimestamp = ts
-            self.log.debug('Rendered %d still frame(s)', nframes)
+            self.log.debug('Rendered %d still frame(s) Drift=%f', nwhole, self.drift)
 
     def cleanup(self):
         # Add one second worth of padding so that the video doesn't end too abruptly.