From b380beba6d74efa1c3747065fb1091f60c230d6b Mon Sep 17 00:00:00 2001
From: gudvinr <gudvinr+github@gmail.com>
Date: Sat, 8 Mar 2025 21:01:49 +0300
Subject: [PATCH] Add GREY pixelformat (#171)

Fixes #170

Monochrome cameras send only Y component of YUV image
---
 src/libs/capture.c                   |  1 +
 src/libs/frame.c                     |  1 +
 src/ustreamer/encoders/cpu/encoder.c | 33 ++++++++++++++++++++++++++++
 3 files changed, 35 insertions(+)

diff --git a/src/libs/capture.c b/src/libs/capture.c
index 139b589..ef12d76 100644
--- a/src/libs/capture.c
+++ b/src/libs/capture.c
@@ -69,6 +69,7 @@ static const struct {
 	{"UYVY",	V4L2_PIX_FMT_UYVY},
 	{"YUV420",	V4L2_PIX_FMT_YUV420},
 	{"YVU420",	V4L2_PIX_FMT_YVU420},
+	{"GREY",	V4L2_PIX_FMT_GREY},
 	{"RGB565",	V4L2_PIX_FMT_RGB565},
 	{"RGB24",	V4L2_PIX_FMT_RGB24},
 	{"BGR24",	V4L2_PIX_FMT_BGR24},
diff --git a/src/libs/frame.c b/src/libs/frame.c
index b24735c..0636d0c 100644
--- a/src/libs/frame.c
+++ b/src/libs/frame.c
@@ -84,6 +84,7 @@ uint us_frame_get_padding(const us_frame_s *frame) {
 	switch (frame->format) {
 		case V4L2_PIX_FMT_YUV420:
 		case V4L2_PIX_FMT_YVU420:
+		case V4L2_PIX_FMT_GREY:
 			bytes_per_pixel = 1;
 			break;
 
diff --git a/src/ustreamer/encoders/cpu/encoder.c b/src/ustreamer/encoders/cpu/encoder.c
index f116b27..1ea6229 100644
--- a/src/ustreamer/encoders/cpu/encoder.c
+++ b/src/ustreamer/encoders/cpu/encoder.c
@@ -39,6 +39,7 @@ static void _jpeg_set_dest_frame(j_compress_ptr jpeg, us_frame_s *frame);
 
 static void _jpeg_write_scanlines_yuv(struct jpeg_compress_struct *jpeg, const us_frame_s *frame);
 static void _jpeg_write_scanlines_yuv_planar(struct jpeg_compress_struct *jpeg, const us_frame_s *frame);
+static void _jpeg_write_scanlines_grey(struct jpeg_compress_struct *jpeg, const us_frame_s *frame);
 static void _jpeg_write_scanlines_rgb565(struct jpeg_compress_struct *jpeg, const us_frame_s *frame);
 static void _jpeg_write_scanlines_rgb24(struct jpeg_compress_struct *jpeg, const us_frame_s *frame);
 #ifndef JCS_EXTENSIONS
@@ -75,6 +76,10 @@ void us_cpu_encoder_compress(const us_frame_s *src, us_frame_s *dest, uint quali
 		case V4L2_PIX_FMT_YVU420:
 			jpeg.in_color_space = JCS_YCbCr;
 			break;
+		case V4L2_PIX_FMT_GREY:
+			jpeg.input_components = 1;
+			jpeg.in_color_space = JCS_GRAYSCALE;
+			break;
 #		ifdef JCS_EXTENSIONS
 		case V4L2_PIX_FMT_BGR24:
 			jpeg.in_color_space = JCS_EXT_BGR;
@@ -102,6 +107,10 @@ void us_cpu_encoder_compress(const us_frame_s *src, us_frame_s *dest, uint quali
 		case V4L2_PIX_FMT_YVU420:
 			_jpeg_write_scanlines_yuv_planar(&jpeg, src);
 			break;
+		
+		case V4L2_PIX_FMT_GREY:
+			_jpeg_write_scanlines_grey(&jpeg, src);
+			break;
 
 		case V4L2_PIX_FMT_RGB565:
 			_jpeg_write_scanlines_rgb565(&jpeg, src);
@@ -249,6 +258,30 @@ static void _jpeg_write_scanlines_yuv_planar(struct jpeg_compress_struct *jpeg,
 	free(line_buf);
 }
 
+static void _jpeg_write_scanlines_grey(struct jpeg_compress_struct *jpeg, const us_frame_s *frame) {
+	u8 *line_buf;
+	US_CALLOC(line_buf, frame->width);
+
+	const uint padding = us_frame_get_padding(frame);
+	const u8 *data = frame->data;
+
+	while (jpeg->next_scanline < frame->height) {
+		u8 *ptr = line_buf;
+
+		for (uint x = 0; x < frame->width; ++x) {
+			ptr[0] = data[x];
+			ptr += 1;
+		}
+
+		data += frame->width + padding;
+
+		JSAMPROW scanlines[1] = {line_buf};
+		jpeg_write_scanlines(jpeg, scanlines, 1);
+	}
+
+	free(line_buf);
+}
+
 static void _jpeg_write_scanlines_rgb565(struct jpeg_compress_struct *jpeg, const us_frame_s *frame) {
 	u8 *line_buf;
 	US_CALLOC(line_buf, frame->width * 3);