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media: Add parsing for APP14 data segment in jpeg helpers

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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@nxp.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
This commit is contained in:
Mirela Rabulea 2021-03-11 01:28:49 +01:00 committed by Mauro Carvalho Chehab
parent b16ed1e660
commit b8035f7988
2 changed files with 61 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

42
drivers/media/v4l2-core/v4l2-jpeg.c
View File

@ -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)

20
include/media/v4l2-jpeg.h
View File

@ -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);