From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail.kapsi.fi ([217.30.184.167]:51153 "EHLO mail.kapsi.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753314Ab3KKNkQ (ORCPT ); Mon, 11 Nov 2013 08:40:16 -0500 Message-ID: <5280DE3D.5040408@iki.fi> Date: Mon, 11 Nov 2013 15:40:13 +0200 From: Antti Palosaari MIME-Version: 1.0 To: Hans Verkuil CC: linux-media@vger.kernel.org Subject: Re: [PATCH RFC] libv4lconvert: SDR conversion from U8 to FLOAT References: <1384103776-4788-1-git-send-email-crope@iki.fi> <5280D83C.5060809@xs4all.nl> In-Reply-To: <5280D83C.5060809@xs4all.nl> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: On 11.11.2013 15:14, Hans Verkuil wrote: > On 11/10/2013 06:16 PM, Antti Palosaari wrote: >> Convert unsigned 8 to float 32 [-1 to +1], which is commonly >> used format for baseband signals. >> >> Signed-off-by: Antti Palosaari >> --- >> 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 */ > > I would prefer V4L2_PIX_FMT_SDR_FLOAT and _FMT_SDR_U8. > > That way it is clear that this format refers to - and should be interpreted as - an SDR format. > > Otherwise it looks fine to me (but it needs to be documented as well, of course). Thanks for the comments! What do you think is it OK to abuse/reuse pixelformat for radio signals? Basically the only one field needed is just that, whilst those image only fields (width/height) are not needed at all. Good point to reuse existing things as much as possible is that it does not bloat Kernel data structures etc. I am also going to make some tests to find out if actual float conversion is faster against pre-calculated LUT, in Kernel or in libv4lconvert and so. Worst scenario I have currently is Mirics ADC with 14-bit resolution => 16384 quantization levels => 32-bit float LUT will be 16384 * 4 = 65536 bytes. Wonder if that much big LUT is allowed to library - but maybe you could alloc() and populate LUT on the fly if needed. Or maybe native conversion is fast enough. regards Antti > > Regards, > > Hans > >> + >> /* >> * 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; >> > -- http://palosaari.fi/