From 5f6df6340126fe9694a156ade658eead86f79855 Mon Sep 17 00:00:00 2001
From: Developer-Ecosystem-Engineering
 <65677710+Developer-Ecosystem-Engineering@users.noreply.github.com>
Date: Thu, 2 Jun 2022 15:33:29 -0700
Subject: [PATCH] Buffers in pool may not always point at the Metal video
 compositors output

We received a report of black frames in an applications video content once it was encoded with NextLevel.

Investigation revealed a similar issue as https://github.com/NextLevel/NextLevelSessionExporter/issues/38.

It appears NextLevelSessionExporter is pulling buffers from the pool that was created, and sending those buffers back to the API. The  assumption a buffer pulled from that pool will contain the output of the Metal video compositor is not always correct.

This change will pass the pixelBuffer directly, or use the toBuffer if a renderHandler exists.
---
 Sources/NextLevelSessionExporter.swift | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/Sources/NextLevelSessionExporter.swift b/Sources/NextLevelSessionExporter.swift
index b56338f..0f55d7e 100644
--- a/Sources/NextLevelSessionExporter.swift
+++ b/Sources/NextLevelSessionExporter.swift
@@ -453,11 +453,21 @@ extension NextLevelSessionExporter {
                     let result = CVPixelBufferPoolCreatePixelBuffer(kCFAllocatorDefault, pixelBufferPool, &toRenderBuffer)
                     if result == kCVReturnSuccess {
                         if let toBuffer = toRenderBuffer {
-                            self._renderHandler?(pixelBuffer, self._lastSamplePresentationTime, toBuffer)
-                            if pixelBufferAdaptor.append(toBuffer, withPresentationTime:self._lastSamplePresentationTime) == false {
-                                error = true
+                            // if _renderHandler is nil, then we can save time by just passing pixelBuffer directly to pixelBufferAdaptor.append
+                            if (self._renderHandler == nil) {
+                                if pixelBufferAdaptor.append(pixelBuffer, withPresentationTime:self._lastSamplePresentationTime) == false {
+                                    error = true
+                                }
+                                handled = true
+                            }
+                            // otherwise, we need to call into _renderHandler to preprocess the frames
+                            else {
+                                self._renderHandler?(pixelBuffer, self._lastSamplePresentationTime, toBuffer)
+                                if pixelBufferAdaptor.append(toBuffer, withPresentationTime:self._lastSamplePresentationTime) == false {
+                                    error = true
+                                }
+                                handled = true
                             }
-                            handled = true
                         }
                     }
                 }