[PATCH RFC] libv4lconvert: SDR conversion from U8 to FLOAT

[Antti Palosaari <crope@xxxxxx>]

Convert unsigned 8 to float 32 [-1 to +1], which is commonly
used format for baseband signals.

Signed-off-by: Antti Palosaari <crope@xxxxxx>
---
 contrib/freebsd/include/linux/videodev2.h |  4 ++++
 include/linux/videodev2.h                 |  4 ++++
 lib/libv4lconvert/libv4lconvert.c         | 29 ++++++++++++++++++++++++++++-
 3 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/contrib/freebsd/include/linux/videodev2.h b/contrib/freebsd/include/linux/videodev2.h
index 1fcfaeb..8829400 100644
--- a/contrib/freebsd/include/linux/videodev2.h
+++ b/contrib/freebsd/include/linux/videodev2.h
@@ -465,6 +465,10 @@ struct v4l2_pix_format {
 #define V4L2_PIX_FMT_SE401      v4l2_fourcc('S', '4', '0', '1') /* se401 janggu compressed rgb */
 #define V4L2_PIX_FMT_S5C_UYVY_JPG v4l2_fourcc('S', '5', 'C', 'I') /* S5C73M3 interleaved UYVY/JPEG */
 
+/* SDR */
+#define V4L2_PIX_FMT_FLOAT    v4l2_fourcc('D', 'F', '3', '2') /* float 32-bit */
+#define V4L2_PIX_FMT_U8       v4l2_fourcc('D', 'U', '0', '8') /* unsigned 8-bit */
+
 /*
  *	F O R M A T   E N U M E R A T I O N
  */
diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
index 437f1b0..14299a6 100644
--- a/include/linux/videodev2.h
+++ b/include/linux/videodev2.h
@@ -431,6 +431,10 @@ struct v4l2_pix_format {
 #define V4L2_PIX_FMT_SE401      v4l2_fourcc('S', '4', '0', '1') /* se401 janggu compressed rgb */
 #define V4L2_PIX_FMT_S5C_UYVY_JPG v4l2_fourcc('S', '5', 'C', 'I') /* S5C73M3 interleaved UYVY/JPEG */
 
+/* SDR */
+#define V4L2_PIX_FMT_FLOAT    v4l2_fourcc('D', 'F', '3', '2') /* float 32-bit */
+#define V4L2_PIX_FMT_U8       v4l2_fourcc('D', 'U', '0', '8') /* unsigned 8-bit */
+
 /*
  *	F O R M A T   E N U M E R A T I O N
  */
diff --git a/lib/libv4lconvert/libv4lconvert.c b/lib/libv4lconvert/libv4lconvert.c
index e2afc27..38c9125 100644
--- a/lib/libv4lconvert/libv4lconvert.c
+++ b/lib/libv4lconvert/libv4lconvert.c
@@ -78,7 +78,8 @@ static void v4lconvert_get_framesizes(struct v4lconvert_data *data,
 	{ V4L2_PIX_FMT_RGB24,		24,	 1,	 5,	0 }, \
 	{ V4L2_PIX_FMT_BGR24,		24,	 1,	 5,	0 }, \
 	{ V4L2_PIX_FMT_YUV420,		12,	 6,	 1,	0 }, \
-	{ V4L2_PIX_FMT_YVU420,		12,	 6,	 1,	0 }
+	{ V4L2_PIX_FMT_YVU420,		12,	 6,	 1,	0 }, \
+	{ V4L2_PIX_FMT_FLOAT,		 0,	 0,	 0,	0 }
 
 static const struct v4lconvert_pixfmt supported_src_pixfmts[] = {
 	SUPPORTED_DST_PIXFMTS,
@@ -131,6 +132,8 @@ static const struct v4lconvert_pixfmt supported_src_pixfmts[] = {
 	{ V4L2_PIX_FMT_Y6,		 8,	20,	20,	0 },
 	{ V4L2_PIX_FMT_Y10BPACK,	10,	20,	20,	0 },
 	{ V4L2_PIX_FMT_Y16,		16,	20,	20,	0 },
+	/* SDR formats */
+	{ V4L2_PIX_FMT_U8,		0,	0,	0,	0 },
 };
 
 static const struct v4lconvert_pixfmt supported_dst_pixfmts[] = {
@@ -1281,6 +1284,25 @@ static int v4lconvert_convert_pixfmt(struct v4lconvert_data *data,
 		}
 		break;
 
+	/* SDR */
+	case V4L2_PIX_FMT_U8:
+		switch (dest_pix_fmt) {
+		case V4L2_PIX_FMT_FLOAT:
+			{
+				/* 8-bit unsigned to 32-bit float */
+				unsigned int i;
+				float ftmp;
+				for (i = 0; i < src_size; i++) {
+					ftmp = *src++;
+					ftmp -= 127.5;
+					ftmp /= 127.5;
+					memcpy(dest, &ftmp, 4);
+					dest += 4;
+				}
+			}
+		}
+		break;
+
 	default:
 		V4LCONVERT_ERR("Unknown src format in conversion\n");
 		errno = EINVAL;
@@ -1349,6 +1371,11 @@ int v4lconvert_convert(struct v4lconvert_data *data,
 		temp_needed =
 			my_src_fmt.fmt.pix.width * my_src_fmt.fmt.pix.height * 3 / 2;
 		break;
+	/* SDR */
+	case V4L2_PIX_FMT_FLOAT:
+		dest_needed = src_size * 4; /* 8-bit to 32-bit */
+		temp_needed = dest_needed;
+		break;
 	default:
 		V4LCONVERT_ERR("Unknown dest format in conversion\n");
 		errno = EINVAL;
-- 
1.8.4.2

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