[libcamera-devel] [RFC PATCH 2/2] android: jpeg: Add a basic NV12 image thumbnailer
Laurent Pinchart
laurent.pinchart at ideasonboard.com
Thu Oct 22 15:59:14 CEST 2020
Hi Hiro-san,
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.
> 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
> >
> > --
> > Kieran
> >
> >
> > >>>>> + 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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