[libcamera-devel] [PATCH v2 2/2] android: Fix generation of thumbnail for EXIF data

[Jacopo Mondi]

On Mon, Sep 13, 2021 at 04:08:05PM +0200, Jacopo Mondi wrote:
> Hi Umang,
>
> On Mon, Sep 13, 2021 at 09:31:10AM +0530, Umang Jain wrote:
> > Generation of thumbnail is not occuring currently because
> > ANDROID_JPEG_THUMBNAIL_SIZE is not set for request metadata passed
> > to PostProcessorJpeg::process(). This is a regression introduced in
> > 1264628d3c92("android: jpeg: Configure thumbnailer based on request
> > metadata").
>
> I see the issue, but I'm not sure those commit was wrong. I mean, what
> that commit does that itroduced a regression is:
>
> --- a/src/android/jpeg/post_processor_jpeg.cpp
> +++ b/src/android/jpeg/post_processor_jpeg.cpp
> +       ret = requestMetadata.getEntry(ANDROID_JPEG_THUMBNAIL_SIZE, &entry);
> +       if (ret) {
> +               const int32_t *data = entry.data.i32;
> +               Size thumbnailSize = { static_cast<uint32_t>(data[0]),
> +                                      static_cast<uint32_t>(data[1]) };
> +
> +               if (thumbnailSize != Size(0, 0)) {
> +                       std::vector<unsigned char> thumbnail;
> +                       generateThumbnail(source, thumbnailSize, &thumbnail);
> +                       if (!thumbnail.empty())
> +                               exif.setThumbnail(thumbnail, Exif::Compression::JPEG);
> +               }
> +
> +               resultMetadata->addEntry(ANDROID_JPEG_THUMBNAIL_SIZE, data, 2);
> +
> +               /* \todo Use this quality as a parameter to the encoder */
> +               ret = requestMetadata.getEntry(ANDROID_JPEG_THUMBNAIL_QUALITY, &entry);
> +               if (ret)
> +                       resultMetadata->addEntry(ANDROID_JPEG_THUMBNAIL_QUALITY,
> +                                                entry.data.u8, 1);
> +       }
>
>
> Which I read as: "If ANDROID_JPEG_THUMBNAIL_SIZE is not specified in
> the request's settings, do not populate it in result metadata".
>
> Is this correct in your opinion, or should we populate it regardless
> of the fact the tag was passed in ?
>
> >
> > The patch fixes this issue by setting ANDROID_JPEG_THUMBNAIL_SIZE in
> > the request metadata template populated by
> > CameraCapabilities::requestTemplatePreview(). The value for
> > ANDROID_JPEG_THUMBNAIL_SIZE is set to be the first non-zero size
> > reported by static metadata ANDROID_JPEG_AVAILABLE_THUMBNAIL_SIZES.
>
> Let's say just that this patch adds ANDROID_JPEG_THUMBNAIL_SIZE to the
> capture request template generated for the preview use case. I wonder
> if the JPEG thunbnail size should be part of the preview template now.
>
> >
> > Fixes: 1264628d3c92("android: jpeg: Configure thumbnailer based on request metadata")
> > Signed-off-by: Umang Jain <umang.jain at ideasonboard.com>
> > Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> > ---
> >  src/android/camera_capabilities.cpp | 14 ++++++++++++--
> >  1 file changed, 12 insertions(+), 2 deletions(-)
> >
> > diff --git a/src/android/camera_capabilities.cpp b/src/android/camera_capabilities.cpp
> > index e92bca42..76dddafd 100644
> > --- a/src/android/camera_capabilities.cpp
> > +++ b/src/android/camera_capabilities.cpp
> > @@ -1341,9 +1341,9 @@ std::unique_ptr<CameraMetadata> CameraCapabilities::requestTemplatePreview() con
> >  {
> >  	/*
> >  	 * \todo Keep this in sync with the actual number of entries.
> > -	 * Currently: 20 entries, 35 bytes
> > +	 * Currently: 21 entries, 37 bytes
> >  	 */
> > -	auto requestTemplate = std::make_unique<CameraMetadata>(21, 36);
> > +	auto requestTemplate = std::make_unique<CameraMetadata>(22, 38);
>
> Comment says 21, code says 22.
>
> It was there already as the comment was not aligned with the code, but
> since you're at it you could fix it
>
> >  	if (!requestTemplate->isValid()) {
> >  		return nullptr;
> >  	}
> > @@ -1364,6 +1364,16 @@ std::unique_ptr<CameraMetadata> CameraCapabilities::requestTemplatePreview() con
> >  	requestTemplate->addEntry(ANDROID_CONTROL_AE_TARGET_FPS_RANGE,
> >  				  entry.data.i32, 2);
> >
> > +	/*
> > +	 * Get thumbnail sizes from static metadata and add the first non-zero
> > +	 * size to the template.
> > +	 */
> > +	found = staticMetadata_->getEntry(ANDROID_JPEG_AVAILABLE_THUMBNAIL_SIZES,
> > +					  &entry);
> > +	ASSERT(found && entry.count >= 4);
> > +	requestTemplate->addEntry(ANDROID_JPEG_THUMBNAIL_SIZE,
> > +				  entry.data.i32 + 2, 2);
> > +
>
> If I were to be extra paranoid I would make sure we actually discard
> (0, 0). The code assumes the first two entries are (0, 0) which is
> fine as we populate it after all.
>
> If you don't want to
>
>         unsigned int j = 0;
>         while (j < entry.count / 2) {
>                 if (entry.data.i32[j] == 0 || entry.data.i32[j + 1] == 0) {
                          j += 2;

                          :)

>                         continue;
                  }
>
>                 requestTemplate->addEntry(ANDROID_JPEG_THUMBNAIL_SIZE,
>                                           entry.data.i32 + j, 2);
>         }
>
> Could you at least capture that we assume the first two entries are
> (0,0) ?
>
> Thanks
>    j
>
>
> >  	uint8_t aeMode = ANDROID_CONTROL_AE_MODE_ON;
> >  	requestTemplate->addEntry(ANDROID_CONTROL_AE_MODE, aeMode);
> >
> > --
> > 2.31.1
> >