Commit b8035f79 authored by Mirela Rabulea's avatar Mirela Rabulea Committed by Mauro Carvalho Chehab
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media: Add parsing for APP14 data segment in jpeg helpers 



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: default avatarMirela Rabulea <mirela.rabulea@nxp.com>
Reviewed-by: default avatarPhilipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: default avatarHans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+huawei@kernel.org>
parent b16ed1e6

drivers/media/v4l2-core/v4l2-jpeg.c

+41 −1
Original line number Diff line number Diff line
@@ -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
@@ -444,6 +445,39 @@ 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,

				 enum v4l2_jpeg_app14_tf *tf)

{

	int ret;

	int lp;

	int skip;



	lp = jpeg_get_word_be(stream);

	if (lp < 0)

		return lp;



	/* Check for "Adobe\0" in Ap1..6 */

	if (stream->curr + 6 > stream->end ||

	    strncmp(stream->curr, "Adobe\0", 6))

		return -EINVAL;



	/* get to Ap12 */

	ret = jpeg_skip(stream, 11);

	if (ret < 0)

		return ret;



	ret = jpeg_get_byte(stream);

	if (ret < 0)

		return ret;



	*tf = ret;



	/* skip the rest of the segment, this ensures at least it is complete */

	skip = lp - 2 - 11;

	return jpeg_skip(stream, skip);

}



/**

 * v4l2_jpeg_parse_header - locate marker segments and optionally parse headers

 * @buf: address of the JPEG buffer, should start with a SOI marker
@@ -476,6 +510,9 @@ 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 = V4L2_JPEG_APP14_TF_UNKNOWN;



	/* loop through marker segments */

	while ((marker = jpeg_next_marker(&stream)) >= 0) {

		switch (marker) {
@@ -519,7 +556,10 @@ 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:

			ret = jpeg_parse_app14_data(&stream,

						    &out->app14_tf);

			break;

		case SOS:

			ret = jpeg_reference_segment(&stream, &out->sos);

			if (ret < 0)

include/media/v4l2-jpeg.h

+20 −0
Original line number Diff line number Diff line
@@ -87,6 +87,24 @@ struct v4l2_jpeg_scan_header { 
	/* Ss, Se, Ah, and Al are not used by any driver */

};



/**

 * enum v4l2_jpeg_app14_tf - APP14 transform flag

 * 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:

 * @V4L2_JPEG_APP14_TF_CMYK_RGB: CMYK for images encoded with four components

 *                               RGB for images encoded with three components

 * @V4L2_JPEG_APP14_TF_YCBCR: an image encoded with three components using YCbCr

 * @V4L2_JPEG_APP14_TF_YCCK: an image encoded with four components using YCCK

 * @V4L2_JPEG_APP14_TF_UNKNOWN: indicate app14 is not present

 */

enum v4l2_jpeg_app14_tf {

	V4L2_JPEG_APP14_TF_CMYK_RGB	= 0,

	V4L2_JPEG_APP14_TF_YCBCR	= 1,

	V4L2_JPEG_APP14_TF_YCCK		= 2,

	V4L2_JPEG_APP14_TF_UNKNOWN	= -1,

};



/**

 * struct v4l2_jpeg_header - parsed JPEG header

 * @sof: pointer to frame header and size
@@ -102,6 +120,7 @@ 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
@@ -121,6 +140,7 @@ struct v4l2_jpeg_header { 
	struct v4l2_jpeg_reference *huffman_tables;

	u16 restart_interval;

	size_t ecs_offset;

	enum v4l2_jpeg_app14_tf app14_tf;

};



int v4l2_jpeg_parse_header(void *buf, size_t len, struct v4l2_jpeg_header *out);