From 68bacc07dce2a89d93e6b4130fa21ead4be44141 Mon Sep 17 00:00:00 2001
From: Michael Fabian 'Xaymar' Dirks <info@xaymar.com>
Date: Mon, 22 Jul 2019 14:00:28 +0200
Subject: [PATCH] encoders/generic: Fix NV12 support and improve copy
 performance

FFmpeg's swscale does not properly copy all planes when the pixel format is NV12, so instead we will handle cases where nothing actually changes and we just have to copy memory.
---
 source/encoders/generic.cpp | 52 ++++++++++++++++++++++++++++++++-----
 1 file changed, 45 insertions(+), 7 deletions(-)

diff --git a/source/encoders/generic.cpp b/source/encoders/generic.cpp
index f983172..22dff63 100644
--- a/source/encoders/generic.cpp
+++ b/source/encoders/generic.cpp
@@ -581,6 +581,36 @@ bool encoder::generic::get_extra_data(uint8_t** extra_data, size_t* size)
 	return true;
 }
 
+static inline void copy_data(encoder_frame* frame, AVFrame* vframe)
+{
+	int h_chroma_shift, v_chroma_shift;
+	av_pix_fmt_get_chroma_sub_sample(static_cast<AVPixelFormat>(vframe->format), &h_chroma_shift, &v_chroma_shift);
+
+	for (size_t idx = 0; (idx < MAX_AV_PLANES) && (idx < AV_NUM_DATA_POINTERS); idx++) {
+		if (!frame->data[idx] || !vframe->data[idx])
+			continue;
+
+		size_t plane_height = vframe->height >> (idx ? v_chroma_shift : 0);
+
+		if (static_cast<uint32_t>(vframe->linesize[idx]) == frame->linesize[idx]) {
+			std::memcpy(vframe->data[idx], frame->data[idx], frame->linesize[idx] * plane_height);
+		} else {
+			size_t ls_in  = frame->linesize[idx];
+			size_t ls_out = vframe->linesize[idx];
+			size_t bytes  = ls_in < ls_out ? ls_in : ls_out;
+
+			uint8_t* to   = vframe->data[idx];
+			uint8_t* from = frame->data[idx];
+
+			for (size_t y = 0; y < plane_height; y++) {
+				std::memcpy(to, from, bytes);
+				to += ls_out;
+				from += ls_in;
+			}
+		}
+	}
+}
+
 bool encoder::generic::video_encode(encoder_frame* frame, encoder_packet* packet, bool* received_packet)
 {
 	// Convert frame.
@@ -588,16 +618,24 @@ bool encoder::generic::video_encode(encoder_frame* frame, encoder_packet* packet
 	{
 		ScopeProfiler profile("convert");
 
+		vframe->height      = this->context->height;
+		vframe->format      = this->context->pix_fmt;
 		vframe->color_range = this->context->color_range;
 		vframe->colorspace  = this->context->colorspace;
 
-		int res =
-		    swscale.convert(reinterpret_cast<uint8_t**>(frame->data), reinterpret_cast<int*>(frame->linesize),
-		                    0, this->context->height, vframe->data, vframe->linesize);
-		if (res <= 0) {
-			PLOG_ERROR("Failed to convert frame: %s (%ld).", ffmpeg::tools::get_error_description(res),
-			           res);
-			return false;
+		if ((swscale.is_source_full_range() == swscale.is_target_full_range())
+		    && (swscale.get_source_colorspace() == swscale.get_target_colorspace())
+		    && (swscale.get_source_format() == swscale.get_target_format())) {
+			copy_data(frame, vframe.get());
+		} else {
+			int res = swscale.convert(reinterpret_cast<uint8_t**>(frame->data),
+			                          reinterpret_cast<int*>(frame->linesize), 0, this->context->height,
+			                          vframe->data, vframe->linesize);
+			if (res <= 0) {
+				PLOG_ERROR("Failed to convert frame: %s (%ld).",
+				           ffmpeg::tools::get_error_description(res), res);
+				return false;
+			}
 		}
 	}