[libcamera-devel] [PATCH v2] android: jpeg: Split and pass the thumbnail planes to encoder

[Hirokazu Honda]

Hi Umang, thank you for the patch.

On Wed, Sep 8, 2021 at 6:50 PM Umang Jain <umang.jain at ideasonboard.com> wrote:
>
> After multi-planar support was introduced for jpeg encoding as well,
> EncoderLibJpeg::encode() expects a vector of planes as the source of
> framebuffer to be encoded. Currently, we are passing a contiguous buffer
> which is treated as only one plane (instead of two, as thumbnail is NV12).
>
> Hence, split the thumbnail data into respective planes according to NV12.
> This fixes a crash in encoding of thumbnails.
>
> Fixes: 894ca69f6043("android: jpeg: Support multi-planar buffers")
> Signed-off-by: Umang Jain <umang.jain at ideasonboard.com>
> ---
> Changes in v2:
> - Fix basic split logic error.
> - Add Jacopo's suggestion as a \todo since it's a superior method to fix
>   this.
> ---
>  src/android/jpeg/post_processor_jpeg.cpp | 18 ++++++++++++++----
>  1 file changed, 14 insertions(+), 4 deletions(-)
>
> diff --git a/src/android/jpeg/post_processor_jpeg.cpp b/src/android/jpeg/post_processor_jpeg.cpp
> index 68d74842..1bf507a4 100644
> --- a/src/android/jpeg/post_processor_jpeg.cpp
> +++ b/src/android/jpeg/post_processor_jpeg.cpp
> @@ -66,13 +66,23 @@ void PostProcessorJpeg::generateThumbnail(const FrameBuffer &source,
>         int ret = thumbnailEncoder_.configure(thCfg);
>
>         if (!rawThumbnail.empty() && !ret) {
> +               thumbnail->resize(rawThumbnail.size());
> +
>                 /*
> -                * \todo Avoid value-initialization of all elements of the
> -                * vector.

I think this comment should not be removed.

> +                * Split planes manually as the encoder expects a vector of
> +                * planes.
> +                *
> +                * \todo Pass a vector of planes directly to
> +                * Thumbnailer::createThumbnailer above and remove the manual
> +                * planes split from here.
>                  */
> -               thumbnail->resize(rawThumbnail.size());
> +               std::vector<Span<uint8_t>> thumbnailPlanes;
> +               unsigned int thumbnailSize = targetSize.height * targetSize.width;
> +               thumbnailPlanes.push_back({ rawThumbnail.data(), thumbnailSize });
> +               thumbnailPlanes.push_back({ rawThumbnail.data() + thumbnailSize,
> +                                           thumbnailSize / 2 });

Shall PixelFormatInfo::planeSize() be used?

With nits,
Reviewed-by: Hirokazu Honda <hiroh at chromium.org>

-Hiro
>
> -               int jpeg_size = thumbnailEncoder_.encode({ rawThumbnail },
> +               int jpeg_size = thumbnailEncoder_.encode(thumbnailPlanes,
>                                                          *thumbnail, {}, quality);
>                 thumbnail->resize(jpeg_size);
>
> --
> 2.31.0
>