Hi Philipp,
any thoughts on the jpeg helpers related patches from this patch set
(7,8,9,10)?
Thanks,
Mirela
On Thu, 2020-11-12 at 05:05 +0200, Mirela Rabulea (OSS) wrote:
> From: Mirela Rabulea <mirela.rabulea@xxxxxxx>
>
> According to Rec. ITU-T T.872 (06/2012) 6.5.3
> APP14 segment is for color encoding, it contains a transform flag,
> which
> may have values of 0, 1 and 2 and are interpreted as follows:
> 0 - CMYK for images that are encoded with four components
> - RGB for images that are encoded with three components
> 1 - An image encoded with three components using YCbCr colour
> encoding.
> 2 - An image encoded with four components using YCCK colour encoding.
>
> This is used in imx-jpeg decoder, to distinguish between
> YUV444 and RGB24.
>
> Signed-off-by: Mirela Rabulea <mirela.rabulea@xxxxxxx>
> ---
> Changes in v5:
> This was patch 8 in previous version
> Replaced a struct for app14 data with just an int, since the
> transform flag is the only meaningfull information from this segment
>
> drivers/media/v4l2-core/v4l2-jpeg.c | 39
> +++++++++++++++++++++++++++--
> include/media/v4l2-jpeg.h | 6 +++--
> 2 files changed, 41 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/media/v4l2-core/v4l2-jpeg.c
> b/drivers/media/v4l2-core/v4l2-jpeg.c
> index 8947fd95c6f1..3181ce544f79 100644
> --- a/drivers/media/v4l2-core/v4l2-jpeg.c
> +++ b/drivers/media/v4l2-core/v4l2-jpeg.c
> @@ -45,6 +45,7 @@ MODULE_LICENSE("GPL");
> #define DHP 0xffde /* hierarchical progression */
> #define EXP 0xffdf /* expand reference */
> #define APP0 0xffe0 /* application data */
> +#define APP14 0xffee /* application data for colour
> encoding */
> #define APP15 0xffef
> #define JPG0 0xfff0 /* extensions */
> #define JPG13 0xfffd
> @@ -444,8 +445,37 @@ static int jpeg_skip_segment(struct jpeg_stream
> *stream)
> return jpeg_skip(stream, len - 2);
> }
>
> +/* Rec. ITU-T T.872 (06/2012) 6.5.3 */
> +static int jpeg_parse_app14_data(struct jpeg_stream *stream)
> +{
> + int ret;
> + int Lp;
> + int skip;
> + int tf;
> +
> + Lp = jpeg_get_word_be(stream);
> + if (Lp < 0)
> + return Lp;
> +
> + /* get to Ap12 */
> + ret = jpeg_skip(stream, 11);
> + if (ret < 0)
> + return -EINVAL;
> +
> + tf = jpeg_get_byte(stream);
> + if (tf < 0)
> + return tf;
> +
> + skip = Lp - 2 - 11;
> + ret = jpeg_skip(stream, skip);
> + if (ret < 0)
> + return -EINVAL;
> + else
> + return tf;
> +}
> +
> /**
> - * jpeg_parse_header - locate marker segments and optionally parse
> headers
> + * v4l2_jpeg_parse_header - locate marker segments and optionally
> parse headers
> * @buf: address of the JPEG buffer, should start with a SOI marker
> * @len: length of the JPEG buffer
> * @out: returns marker segment positions and optionally parsed
> headers
> @@ -476,6 +506,9 @@ int v4l2_jpeg_parse_header(void *buf, size_t len,
> struct v4l2_jpeg_header *out)
> if (marker != SOI)
> return -EINVAL;
>
> + /* init value to signal if this marker is not present */
> + out->app14_tf = -EINVAL;
> +
> /* loop through marker segments */
> while ((marker = jpeg_next_marker(&stream)) >= 0) {
> switch (marker) {
> @@ -519,7 +552,9 @@ int v4l2_jpeg_parse_header(void *buf, size_t len,
> struct v4l2_jpeg_header *out)
> ret = jpeg_parse_restart_interval(&stream,
> &out-
> >restart_interval);
> break;
> -
> + case APP14:
> + out->app14_tf = jpeg_parse_app14_data(&stream);
> + break;
> case SOS:
> ret = jpeg_reference_segment(&stream, &out-
> >sos);
> if (ret < 0)
> diff --git a/include/media/v4l2-jpeg.h b/include/media/v4l2-jpeg.h
> index ddba2a56c321..008e0476d928 100644
> --- a/include/media/v4l2-jpeg.h
> +++ b/include/media/v4l2-jpeg.h
> @@ -100,10 +100,11 @@ struct v4l2_jpeg_scan_header {
> * order, optional
> * @restart_interval: number of MCU per restart interval, Ri
> * @ecs_offset: buffer offset in bytes to the entropy coded segment
> + * @app14_tf: transform flag from app14 data
> *
> * When this structure is passed to v4l2_jpeg_parse_header, the
> optional scan,
> - * quantization_tables, and huffman_tables pointers must be
> initialized to NULL
> - * or point at valid memory.
> + * quantization_tables and huffman_tables pointers must be
> initialized
> + * to NULL or point at valid memory.
> */
> struct v4l2_jpeg_header {
> struct v4l2_jpeg_reference sof;
> @@ -119,6 +120,7 @@ struct v4l2_jpeg_header {
> struct v4l2_jpeg_reference *huffman_tables;
> u16 restart_interval;
> size_t ecs_offset;
> + int app14_tf;
> };
>
> int v4l2_jpeg_parse_header(void *buf, size_t len, struct
> v4l2_jpeg_header *out);
