[libcamera-devel] [RFC PATCH 2/2] android: jpeg: Add a basic NV12 image thumbnailer
Kieran Bingham
kieran.bingham at ideasonboard.com
Wed Oct 21 12:55:22 CEST 2020
Hi Umang,
On 21/10/2020 11:51, Umang Jain wrote:
> Hi Kieran,
>
> Thanks for the comments.
>
> On 10/21/20 2:49 PM, Kieran Bingham wrote:
>> Hi Umang,
>>
>> 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?
>>> + 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
--
Kieran
More information about the libcamera-devel
mailing list