[libcamera-devel] [RFC PATCH 2/2] android: jpeg: Add a basic NV12 image thumbnailer
Laurent Pinchart
laurent.pinchart at ideasonboard.com
Thu Dec 10 08:45:32 CET 2020
Hi Tomasz,
On Thu, Dec 10, 2020 at 02:32:39PM +0900, Tomasz Figa wrote:
> On Tue, Oct 27, 2020 at 10:04 AM Laurent Pinchart wrote:
> > On Mon, Oct 26, 2020 at 04:29:20PM +0900, Hirokazu Honda wrote:
> >> On Fri, Oct 23, 2020 at 5:39 PM Kieran Bingham wrote:
> >>> On 23/10/2020 04:59, Laurent Pinchart wrote:
> >>>> On Fri, Oct 23, 2020 at 09:37:09AM +0900, Hirokazu Honda wrote:
> >>>>> On Thu, Oct 22, 2020 at 11:00 PM Laurent Pinchart wrote:
> >>>>>> On Thu, Oct 22, 2020 at 08:42:01PM +0900, Hirokazu Honda wrote:
> >>>>>>> Hi Umang,
> >>>>>>> Thanks for the work. I couldn't have time to review these today and
> >>>>>>> will review tomorrow.
> >>>>>>> In my understanding, the thumbnail class is basically to scale frames
> >>>>>>> to the given destination.
> >>>>>>> Can we generalize it as PostProcessor interface so that we will be
> >>>>>>> able to make use of it for down-scaling regardless of whether jpeg
> >>>>>>> encoding is required.
> >>>>>>> It will be necessary when Android HAL adaptation layer has to output
> >>>>>>> multiple different NV12 streams while the native camera can produce a
> >>>>>>> single NV12 stream simultaneously.
> >>>>>>
> >>>>>> One point to consider is that the thumbnailer is a down-scaler using a
> >>>>>> nearest-neighbour algorithm. It's good enough for thumbnails, but will
> >>>>>> lead to awful quality when scaling streams. For that, I think we need a
> >>>>>> better scaler implementation, and we could then replace the thumbnailer
> >>>>>> class with it.
> >>>>>
> >>>>> We can select nearest-neighbor and bilinear algorithms in
> >>>>> libyuv::NV12Scale with the filtering mode argument[1].
> >>>>> We may want to specify the scale algorithm on a class construction.
> >>>>> I would use libyuv here for better performance and less buggy (+ less
> >>>>> lines to be reviewed).
> >>>>> What do you'all think?
> >>>>
> >>>> We have considered libyuv early on, and I think it's an interesting
> >>>> option moving forward. The reason we have decided to go for a minimal
> >>>> scaler implementation to create JPEG thumbnails is to avoid adding an
> >>>> external dependency that isn't packaged by distributions. This allows us
> >>>> to finalize JPEG thumbnail support without delay, and decide on the
> >>>> longer term solution separately.
> >>>>
> >>>> It would be very nice if Google could work with distributions to package
> >>>> libyuv. I'd like to avoid including a copy of libyuv in libcamera.
> >>>
> >>> Lack of packaging is a big factor here. If it's not available we can't
> >>> use it ;-)
> >>
> >> Thanks. That is fair enough.
> >>
> >>> However I looked into this briefly yesterday, - we could use a meson
> >>> wrap. But I don't know how that will affect us distributing packages, as
> >>> then we also have to distribute libyuv.
> >>>
> >>> Or perhaps the meson wrap would link statically.
> >>
> >> Can we download libyuv somewhere in libcamera, e.g. //third_party,
> >> during meson config if it is necessary?
> >> The code under //third_party is ignored by .gitignore, i.e., is not a
> >> part of libcamera tree.
> >> We may want to maintain a commit hash to be checked out in the libcamera tree.
> >
> > As Kieran mentioned, we could use a meson wrap, and link statically to
> > libyuv. If we rely on a particular commit of libyuv then I think we
> > could as well copy the source code in the libcamera repository, to avoid
> > depending on an internet connection at meson config time. I'm however
> > not sure what issues we would encounter on the way. libyuv is integrated
> > with the Chromium code base, but looking, for instance, at the buildroot
> > package, it seems fairly easy to compile it standalone. We may need to
> > add support for the meson build system though.
>
> If the alternative is to implement the conversion routines ourselves,
> I guess it's not any better than just forking libyuv permanently and
> possibly submitting any relevant changes back there to avoid diverging
> too much, especially given that libyuv has a proven and very well
> optimized implementation.
I agree with you.
> Regardless of that, I'll check internally if we can do anything to
> make it easier to use outside of Chromium.
That would be great, I think it would benefit way more projects than
just libcamera.
> > As a conclusion, I think we'll need to figure out how we can use libyuv,
> > but not as a prerequisite for the JPEG thumbnail work. The best option
> > would be if Google maintained libyuv as a standalone library and worked
> > on getting it packaged in distributions :-)
> >
> >>>> One last comment to provide all the design background. We have also
> >>>> considered creating a format conversion library in libcamera, to gather
> >>>> code from various projects that exist out there. There's format
> >>>> conversion in libv4l2, in raw2rgbpnm, in projects such as ffmpeg, and of
> >>>> course in libyuv. I would be great if that could be consolidated and
> >>>> packaged, but that's a big task in itself.
> >>>
> >>> And that's the bigger picture. This should be consolidated. And that
> >>> consolidated library should support more than yuv ;-)
> >>>
> >>> Given it would be a software format convertor, and scaler, and ideally
> >>> with hardware acceleration support where possible, I think that quickly
> >>> becomes libisp - and the feature creep will ... creep in ;-)
> >>>
> >>>>> [1] https://chromium.googlesource.com/libyuv/libyuv/+/refs/heads/master/include/libyuv/scale.h#148
> >>>>>
> >>>>>>> On Wed, Oct 21, 2020 at 8:09 PM Kieran Bingham wrote:
> >>>>>>>> On 21/10/2020 12:03, Umang Jain wrote:
> >>>>>>>>> On 10/21/20 4:25 PM, Kieran Bingham wrote:
> >>>>>>>>>> On 21/10/2020 11:51, Umang Jain wrote:
> >>>>>>>>>>> On 10/21/20 2:49 PM, Kieran Bingham wrote:
> >>>>>>>>>>>> On 21/10/2020 09:08, Umang Jain wrote:
> >>>>>>>>>>>>> Add a basic image thumbnailer for NV12 frames being captured.
> >>>>>>>>>>>>> It shall generate a thumbnail image to be embedded as a part of
> >>>>>>>>>>>>> EXIF metadata of the frame. The output of the thumbnail will still
> >>>>>>>>>>>>> be NV12.
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> Signed-off-by: Umang Jain <email at uajain.com>
> >>>>>>>>>>>>> ---
> >>>>>>>>>>>>> src/android/jpeg/post_processor_jpeg.cpp | 39 +++++++++
> >>>>>>>>>>>>> src/android/jpeg/post_processor_jpeg.h | 3 +
> >>>>>>>>>>>>> src/android/jpeg/thumbnailer.cpp | 100 +++++++++++++++++++++++
> >>>>>>>>>>>>> src/android/jpeg/thumbnailer.h | 40 +++++++++
> >>>>>>>>>>>>> src/android/meson.build | 1 +
> >>>>>>>>>>>>> 5 files changed, 183 insertions(+)
> >>>>>>>>>>>>> create mode 100644 src/android/jpeg/thumbnailer.cpp
> >>>>>>>>>>>>> create mode 100644 src/android/jpeg/thumbnailer.h
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> diff --git a/src/android/jpeg/post_processor_jpeg.cpp
> >>>>>>>>>>>>> b/src/android/jpeg/post_processor_jpeg.cpp
> >>>>>>>>>>>>> index 9d452b7..f5f1f78 100644
> >>>>>>>>>>>>> --- a/src/android/jpeg/post_processor_jpeg.cpp
> >>>>>>>>>>>>> +++ b/src/android/jpeg/post_processor_jpeg.cpp
> >>>>>>>>>>>>> @@ -11,6 +11,7 @@
> >>>>>>>>>>>>> #include "../camera_metadata.h"
> >>>>>>>>>>>>> #include "encoder_libjpeg.h"
> >>>>>>>>>>>>> #include "exif.h"
> >>>>>>>>>>>>> +#include "thumbnailer.h"
> >>>>>>>>>>>>> #include <libcamera/formats.h>
> >>>>>>>>>>>>> @@ -44,6 +45,32 @@ int PostProcessorJpeg::configure(const StreamConfiguration &inCfg,
> >>>>>>>>>>>>> return encoder_->configure(inCfg);
> >>>>>>>>>>>>> }
> >>>>>>>>>>>>> +void PostProcessorJpeg::generateThumbnail(const libcamera::Span<uint8_t> &source,
> >>>>>>>>>>>>> + std::vector<unsigned char> &thumbnail)
> >>>>>>>>>>>>> +{
> >>>>>>>>>>>>> + libcamera::Span<uint8_t> destination;
> >>>>>>>>>>>>> + Thumbnailer thumbnailer;
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> + thumbnailer.configure(streamSize_, formats::NV12);
> >>>>>>>>>>>>> + libcamera::Size targetSize = thumbnailer.computeThumbnailSize();
> >>>>>>>>>>>>> + thumbnailer.scaleBuffer(source, thumbnail);
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> + if (thumbnail.data()) {
> >>>>>>>>>>>>> + StreamConfiguration thumbnailCfg;
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> + std::unique_ptr<EncoderLibJpeg> encoder =
> >>>>>>>>>>>>> + std::make_unique<EncoderLibJpeg>();
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> + thumbnailCfg.pixelFormat = formats::NV12;
> >>>>>>>>>>>>> + thumbnailCfg.size = targetSize;
> >>>>>>>>>>>>> + encoder->configure(thumbnailCfg);
> >>>>>>>>>>>>
> >>>>>>>>>>>> thumbnail.capacity() might be quite low here.
> >>>>>>>>>>>> We need to make sure the vector is big enough at this point, you might
> >>>>>>>>>>>> need to do something like:
> >>>>>>>>>>>>
> >>>>>>>>>>>> thumbnail.resize(targetSize.width * targetSize.height * 4);
> >>>>>>>>>>>
> >>>>>>>>>>> I am not sure I follow. This is compressing the thumbnail part right? So
> >>>>>>>>>>> thumbnail is the "source" for the encoder here (Please refer to
> >>>>>>>>>>> ->encode() below) and why would we resize the source(i.e. 'thumbnail')?
> >>>>>>>>>>
> >>>>>>>>>> Ugh, sorry - tired eyes indeed. Yes, please ignore those comments.
> >>>>>>>>>>
> >>>>>>>>>>>> Really we should obtain that size from the encoder. I thought we had a
> >>>>>>>>>>>> helper to do that already, but it seems we don't.
> >>>>>>>>>>>> We could/should add Encoder::maxOutput(); which would ask the encoder
> >>>>>>>>>>>> "For your given configuration, what is the maximum number of bytes you
> >>>>>>>>>>>> might output".
> >>>>>>>>>>>>
> >>>>>>>>>>>> Then of course we'd do:
> >>>>>>>>>>>> thumbnail.resize(encoder.maxOutput());
> >>>>>>>>>>>>
> >>>>>>>>>>>>
> >>>>>>>>>>>>> + int jpeg_size = encoder->encode({ thumbnail.data(), thumbnail.capacity() },
> >>>>>>>>>>>>> + destination, { });
> >>>>>>>>>>>
> >>>>>>>>>>> As said above, thumbnail is the source here. The compressed thumbnail
> >>>>>>>>>>> output is carried in destination. And, destination is a local span<>
> >>>>>>>>>>> here. Does it makes sense?
> >>>>>>>>>>
> >>>>>>>>>> Yes, I had mixed up source and destination I'm sorry.
> >>>>>>>>>>
> >>>>>>>>>> So who/where is allocating the destination?
> >>>>>>>>>
> >>>>>>>>> Ah, that's a good question and I think I just found a bug. I currently
> >>>>>>>>> pass on a locally allocated Span<> 'destination' to the encoder. But
> >>>>>>>>> there is no explicit allocation here. I think I need to point / create
> >>>>>>>>> the Span with the output size / bytes and then pass to the encode().
> >>>>>>>>
> >>>>>>>> :-) Ok - then please apply all of my earlier comments to that part
> >>>>>>>> instead. ;-)
> >>>>>>>>
> >>>>>>>> We certainly need somewhere to store the compressed image, to be able to
> >>>>>>>> pass it into the exif :-D
> >>>>>>>>
> >>>>>>>>>>>>> + LOG(JPEG, Info) << "Thumbnail compress returned "
> >>>>>>>>>>>>> + << jpeg_size << " bytes";
> >>>>>>>>>>>>
> >>>>>>>>>>>> And I presume we could then do an:
> >>>>>>>>>>>> thumbnail.resize(jpeg_size);
> >>>>>>>>>>>>
> >>>>>>>>>>>> here to update the thumbnail with the correct size. I'd be weary of the
> >>>>>>>>>>>> resize operations doing lots of re-allocations though, so perhaps we
> >>>>>>>>>>>> want to minimize that. But lets get to something that works first
> >>>>>>>>>>>> before worrying about optimising.
> >>>>>>>>>>>>
> >>>>>>>>>>>>> + }
> >>>>>>>>>>>>> +}
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> int PostProcessorJpeg::process(const libcamera::FrameBuffer *source,
> >>>>>>>>>>>>> const libcamera::Span<uint8_t> &destination,
> >>>>>>>>>>>>> CameraMetadata *metadata)
> >>>>>>>>>>>>> @@ -73,6 +100,18 @@ int PostProcessorJpeg::process(const
> >>>>>>>>>>>>> libcamera::FrameBuffer *source,
> >>>>>>>>>>>>> return jpeg_size;
> >>>>>>>>>>>>> }
> >>>>>>>>>>>>> + std::vector<unsigned char> thumbnail;
> >>>>>>>>>>>>
> >>>>>>>>>>>> You need to resize this somewhere.
> >>>>>>>>>>>> Edit: Now seen a better place above ;-)
> >>>>>>>>>>>
> >>>>>>>>>>> The thumbnail vector just gets resized in Thumbnailer::scaleBuffer(). :)
> >>>>>>>>>>> We just pass in to the thumbnailer, while keeping its ownership in
> >>>>>>>>>>> PostProcessorJpeg.
> >>>>>>>>>>>
> >>>>>>>>>>>>> + generateThumbnail(destination, thumbnail);
> >>>>>>>>>>>>> + /*
> >>>>>>>>>>>>> + * \todo: Write the compressed thumbnail to a file for inspection.
> >>>>>>>>>>>>> + * (I) Check if we can still write the thumbnail to EXIF here.
> >>>>>>>>>>>>> + * If not, we might need to move the thumbnailer logic to encoder.
> >>>>>>>>>>>>> + * And if we do that, first we need to make sure we get can
> >>>>>>>>>>>>> + * compressed data written to destination first before calling
> >>>>>>>>>>>>> + * jpeg_finish_compress operation somehow. Thumbnailing will
> >>>>>>>>>>>>> + * only occur if we have compressed data available first.
> >>>>>>>>>>>>> + */
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> /*
> >>>>>>>>>>>>> * Fill in the JPEG blob header.
> >>>>>>>>>>>>> *
> >>>>>>>>>>>>> diff --git a/src/android/jpeg/post_processor_jpeg.h
> >>>>>>>>>>>>> b/src/android/jpeg/post_processor_jpeg.h
> >>>>>>>>>>>>> index 62c8650..05601ee 100644
> >>>>>>>>>>>>> --- a/src/android/jpeg/post_processor_jpeg.h
> >>>>>>>>>>>>> +++ b/src/android/jpeg/post_processor_jpeg.h
> >>>>>>>>>>>>> @@ -28,6 +28,9 @@ public:
> >>>>>>>>>>>>> CameraMetadata *metadata) override;
> >>>>>>>>>>>>> private:
> >>>>>>>>>>>>> + void generateThumbnail(const libcamera::Span<uint8_t> &source,
> >>>>>>>>>>>>> + std::vector<unsigned char> &thumbnail);
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> CameraDevice *cameraDevice_;
> >>>>>>>>>>>>> std::unique_ptr<Encoder> encoder_;
> >>>>>>>>>>>>> libcamera::Size streamSize_;
> >>>>>>>>>>>>> diff --git a/src/android/jpeg/thumbnailer.cpp
> >>>>>>>>>>>>> b/src/android/jpeg/thumbnailer.cpp
> >>>>>>>>>>>>> new file mode 100644
> >>>>>>>>>>>>> index 0000000..3163576
> >>>>>>>>>>>>> --- /dev/null
> >>>>>>>>>>>>> +++ b/src/android/jpeg/thumbnailer.cpp
> >>>>>>>>>>>>> @@ -0,0 +1,100 @@
> >>>>>>>>>>>>> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> >>>>>>>>>>>>> +/*
> >>>>>>>>>>>>> + * Copyright (C) 2020, Google Inc.
> >>>>>>>>>>>>> + *
> >>>>>>>>>>>>> + * thumbnailer.cpp - Basic image thumbnailer from NV12
> >>>>>>>>>>>>> + */
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> +#include "thumbnailer.h"
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> +#include <libcamera/formats.h>
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> +#include "libcamera/internal/file.h"
> >>>>>>>>>>>>> +#include "libcamera/internal/log.h"
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> +using namespace libcamera;
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> +LOG_DEFINE_CATEGORY(Thumbnailer)
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> +Thumbnailer::Thumbnailer()
> >>>>>>>>>>>>> + : validConfiguration_(false)
> >>>>>>>>>>>>> +{
> >>>>>>>>>>>>> +}
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> +void Thumbnailer::configure(const Size &sourceSize, PixelFormat pixelFormat)
> >>>>>>>>>>>>> +{
> >>>>>>>>>>>>> + sourceSize_ = sourceSize;
> >>>>>>>>>>>>> + pixelFormat_ = pixelFormat;
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> + if (pixelFormat_ != formats::NV12) {
> >>>>>>>>>>>>> + LOG (Thumbnailer, Error) << "Failed to configure: Pixel Format "
> >>>>>>>>>>>>> + << pixelFormat_.toString() << " unsupported.";
> >>>>>>>>>>>>> + return;
> >>>>>>>>>>>>> + }
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> + validConfiguration_ = true;
> >>>>>>>>>>>>> +}
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> +/*
> >>>>>>>>>>>>> + * The Exif specification recommends the width of the thumbnail to be a
> >>>>>>>>>>>>> + * mutiple of 16 (section 4.8.1). Hence, compute the corresponding height
> >>>>>>>>>>>>> + * keeping the aspect ratio same as of the source.
> >>>>>>>>>>>>> + */
> >>>>>>>>>>>>> +Size Thumbnailer::computeThumbnailSize()
> >>>>>>>>>>>>> +{
> >>>>>>>>>>>>> + unsigned int targetHeight;
> >>>>>>>>>>>>> + unsigned int targetWidth = 160;
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> + targetHeight = targetWidth * sourceSize_.height / sourceSize_.width;
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> + if (targetHeight & 1)
> >>>>>>>>>>>>> + targetHeight++;
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> + return Size(targetWidth, targetHeight);
> >>>>>>>>>>>>> +}
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> +void
> >>>>>>>>>>>>> +Thumbnailer::scaleBuffer(const libcamera::Span<uint8_t> &source,
> >>>>>>>>>>>>> + std::vector<unsigned char> &destination)
> >>>>>>>>>>>>> +{
> >>>>>>>>>>>>> + if (!validConfiguration_) {
> >>>>>>>>>>>>> + LOG(Thumbnailer, Error) << "config is unconfigured or invalid.";
> >>>>>>>>>>>>> + return;
> >>>>>>>>>>>>> + }
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> + targetSize_ = computeThumbnailSize();
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> + const unsigned int sw = sourceSize_.width;
> >>>>>>>>>>>>> + const unsigned int sh = sourceSize_.height;
> >>>>>>>>>>>>> + const unsigned int tw = targetSize_.width;
> >>>>>>>>>>>>> + const unsigned int th = targetSize_.height;
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> + /* Image scaling block implementing nearest-neighbour algorithm. */
> >>>>>>>>>>>>> + unsigned char *src = static_cast<unsigned char *>(source.data());
> >>>>>>>>>>>>> + unsigned char *src_c = src + sh * sw;
> >>>>>>>>>>>>> + unsigned char *src_cb, *src_cr;
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> + size_t dstSize = (th * tw) + ((th/2) * tw);
> >>>>>>>>>>>>> + destination.reserve(dstSize);
> >>>>>>>>>>>>> + unsigned char *dst = destination.data();
> >>>>>>>>>>>>> + unsigned char *dst_c = dst + th * tw;
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> + for (unsigned int y = 0; y < th; y+=2) {
> >>>>>>>>>>>>> + unsigned int sourceY = (sh*y + th/2) / th;
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> + src_cb = src_c + (sourceY/2) * sw + 0;
> >>>>>>>>>>>>> + src_cr = src_c + (sourceY/2) * sw + 1;
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> + for (unsigned int x = 0; x < tw; x+=2) {
> >>>>>>>>>>>>> + unsigned int sourceX = (sw*x + tw/2) / tw;
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> + dst[y * tw + x] = src[sw * sourceY + sourceX];
> >>>>>>>>>>>>> + dst[(y+1) * tw + x] = src[sw * (sourceY+1) + sourceX];
> >>>>>>>>>>>>> + dst[y * tw + (x+1)] = src[sw * sourceY + (sourceX+1)];
> >>>>>>>>>>>>> + dst[(y+1) * tw + (x+1)] = src[sw * (sourceY+1) + (sourceX+1)];
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> + dst_c[(y/2) * tw + x + 0] = src_cb[(sourceX/2) * 2];
> >>>>>>>>>>>>> + dst_c[(y/2) * tw + x + 1] = src_cr[(sourceX/2) * 2];
> >>>>>>>>>>>>> + }
> >>>>>>>>>>>>> + }
> >>>>>>>>>>>>> +}
> >>>>>>>>>>>>> diff --git a/src/android/jpeg/thumbnailer.h
> >>>>>>>>>>>>> b/src/android/jpeg/thumbnailer.h
> >>>>>>>>>>>>> new file mode 100644
> >>>>>>>>>>>>> index 0000000..bab9855
> >>>>>>>>>>>>> --- /dev/null
> >>>>>>>>>>>>> +++ b/src/android/jpeg/thumbnailer.h
> >>>>>>>>>>>>> @@ -0,0 +1,40 @@
> >>>>>>>>>>>>> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> >>>>>>>>>>>>> +/*
> >>>>>>>>>>>>> + * Copyright (C) 2020, Google Inc.
> >>>>>>>>>>>>> + *
> >>>>>>>>>>>>> + * thumbnailer.h - Basic image thumbnailer from NV12
> >>>>>>>>>>>>> + */
> >>>>>>>>>>>>> +#ifndef __ANDROID_JPEG_THUMBNAILER_H__
> >>>>>>>>>>>>> +#define __ANDROID_JPEG_THUMBNAILER_H__
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> +#include <libcamera/geometry.h>
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> +#include "libcamera/internal/buffer.h"
> >>>>>>>>>>>>> +#include "libcamera/internal/formats.h"
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> +class Thumbnailer
> >>>>>>>>>>>>> +{
> >>>>>>>>>>>>> +public:
> >>>>>>>>>>>>> + Thumbnailer();
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> + void configure(const libcamera::Size &sourceSize,
> >>>>>>>>>>>>> + libcamera::PixelFormat pixelFormat);
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> + /*
> >>>>>>>>>>>>> + * \todo: Discuss if we can return targetSize_ via configure() or
> >>>>>>>>>>>>> + * scaleBuffer(). We need targetSize_ to re-encode the scaled
> >>>>>>>>>>>>> buffer
> >>>>>>>>>>>>> + * via encoder in PostProcssorJpeg::writeThumbnail().
> >>>>>>>>>>>>> + */
> >>>>>>>>>>>>> + libcamera::Size computeThumbnailSize();
> >>>>>>>>>>>>> + void scaleBuffer(const libcamera::Span<uint8_t> &source,
> >>>>>>>>>>>>> + std::vector<unsigned char> &dest);
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> +private:
> >>>>>>>>>>>>> + libcamera::PixelFormat pixelFormat_;
> >>>>>>>>>>>>> + libcamera::Size sourceSize_;
> >>>>>>>>>>>>> + libcamera::Size targetSize_;
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> + bool validConfiguration_;
> >>>>>>>>>>>>> +};
> >>>>>>>>>>>>> +
> >>>>>>>>>>>>> +#endif /* __ANDROID_JPEG_THUMBNAILER_H__ */
> >>>>>>>>>>>>> diff --git a/src/android/meson.build b/src/android/meson.build
> >>>>>>>>>>>>> index 5a01bea..3905e2f 100644
> >>>>>>>>>>>>> --- a/src/android/meson.build
> >>>>>>>>>>>>> +++ b/src/android/meson.build
> >>>>>>>>>>>>> @@ -25,6 +25,7 @@ android_hal_sources = files([
> >>>>>>>>>>>>> 'jpeg/encoder_libjpeg.cpp',
> >>>>>>>>>>>>> 'jpeg/exif.cpp',
> >>>>>>>>>>>>> 'jpeg/post_processor_jpeg.cpp',
> >>>>>>>>>>>>> + 'jpeg/thumbnailer.cpp',
> >>>>>>>>>>>>> ])
> >>>>>>>>>>>>> android_camera_metadata_sources = files([
> >>>>>>>>>>>>>
--
Regards,
Laurent Pinchart
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