From cdcbedc65b942e006775fb105363a82b6eb2f91e Mon Sep 17 00:00:00 2001
From: Vicki Pfau <vi@endrift.com>
Date: Thu, 23 Jul 2020 21:55:05 -0700
Subject: [PATCH] FFmpeg: Backport and improve some API from medusa

---
 src/feature/ffmpeg/ffmpeg-encoder.c | 15 +++++++++++++--
 src/feature/ffmpeg/ffmpeg-encoder.h |  3 +++
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/src/feature/ffmpeg/ffmpeg-encoder.c b/src/feature/ffmpeg/ffmpeg-encoder.c
index 04501c901..948822b26 100644
--- a/src/feature/ffmpeg/ffmpeg-encoder.c
+++ b/src/feature/ffmpeg/ffmpeg-encoder.c
@@ -7,6 +7,7 @@
 
 #include <mgba/core/core.h>
 #include <mgba/gba/interface.h>
+#include <mgba-util/math.h>
 
 #include <libavcodec/version.h>
 #include <libavcodec/avcodec.h>
@@ -92,6 +93,7 @@ void FFmpegEncoderInit(struct FFmpegEncoder* encoder) {
 	encoder->source = NULL;
 	encoder->sink = NULL;
 	encoder->sinkFrame = NULL;
+	FFmpegEncoderSetInputFrameRate(encoder, VIDEO_TOTAL_LENGTH, GBA_ARM7TDMI_FREQUENCY);
 
 	int i;
 	for (i = 0; i < FFMPEG_FILTERS_MAX; ++i) {
@@ -363,8 +365,8 @@ bool FFmpegEncoderOpen(struct FFmpegEncoder* encoder, const char* outfile) {
 		encoder->video->bit_rate = encoder->videoBitrate;
 		encoder->video->width = encoder->width;
 		encoder->video->height = encoder->height;
-		encoder->video->time_base = (AVRational) { VIDEO_TOTAL_LENGTH * encoder->frameskip, GBA_ARM7TDMI_FREQUENCY };
-		encoder->video->framerate = (AVRational) { GBA_ARM7TDMI_FREQUENCY, VIDEO_TOTAL_LENGTH * encoder->frameskip };
+		encoder->video->time_base = (AVRational) { encoder->frameCycles * encoder->frameskip, encoder->cycles };
+		encoder->video->framerate = (AVRational) { encoder->cycles, encoder->frameCycles * encoder->frameskip };
 		encoder->videoStream->time_base = encoder->video->time_base;
 		encoder->videoStream->avg_frame_rate = encoder->video->framerate;
 		encoder->video->pix_fmt = encoder->pixFormat;
@@ -821,3 +823,12 @@ static void _ffmpegSetVideoDimensions(struct mAVStream* stream, unsigned width,
 	    encoder->videoFrame->width, encoder->videoFrame->height, encoder->videoFrame->format,
 	    SWS_POINT, 0, 0, 0);
 }
+
+void FFmpegEncoderSetInputFrameRate(struct FFmpegEncoder* encoder, int numerator, int denominator) {
+	reduceFraction(&numerator, &denominator);
+	encoder->frameCycles = numerator;
+	encoder->cycles = denominator;
+	if (encoder->video) {
+		encoder->video->framerate = (AVRational) { denominator, numerator * encoder->frameskip };
+	}
+}
\ No newline at end of file
diff --git a/src/feature/ffmpeg/ffmpeg-encoder.h b/src/feature/ffmpeg/ffmpeg-encoder.h
index 9c2366277..746e8c46e 100644
--- a/src/feature/ffmpeg/ffmpeg-encoder.h
+++ b/src/feature/ffmpeg/ffmpeg-encoder.h
@@ -78,6 +78,8 @@ struct FFmpegEncoder {
 	int height;
 	int iwidth;
 	int iheight;
+	int frameCycles;
+	int cycles;
 	int frameskip;
 	int skipResidue;
 	bool loop;
@@ -97,6 +99,7 @@ bool FFmpegEncoderSetAudio(struct FFmpegEncoder*, const char* acodec, unsigned a
 bool FFmpegEncoderSetVideo(struct FFmpegEncoder*, const char* vcodec, unsigned vbr, int frameskip);
 bool FFmpegEncoderSetContainer(struct FFmpegEncoder*, const char* container);
 void FFmpegEncoderSetDimensions(struct FFmpegEncoder*, int width, int height);
+void FFmpegEncoderSetInputFrameRate(struct FFmpegEncoder*, int numerator, int denominator);
 void FFmpegEncoderSetLooping(struct FFmpegEncoder*, bool loop);
 bool FFmpegEncoderVerifyContainer(struct FFmpegEncoder*);
 bool FFmpegEncoderOpen(struct FFmpegEncoder*, const char* outfile);