From: Mirela Rabulea <[email protected]> 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 <[email protected]> --- drivers/media/v4l2-core/v4l2-jpeg.c | 39 +++++++++++++++++++++++++++-- include/media/v4l2-jpeg.h | 16 ++++++++++-- 2 files changed, 51 insertions(+), 4 deletions(-) diff --git a/drivers/media/v4l2-core/v4l2-jpeg.c b/drivers/media/v4l2-core/v4l2-jpeg.c index 8947fd95c6f1..a8198f98c158 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 +445,35 @@ 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, + struct v4l2_jpeg_app14_data *app14) +{ + int Lp; + int skip; + int tf; + + if (!app14) + return 0; /* do not parse */ + + Lp = jpeg_get_word_be(stream); + if (Lp < 0) + return Lp; + app14->len = Lp; + + /* get to Ap12 */ + jpeg_skip(stream, 11); + tf = jpeg_get_byte(stream); + if (tf < 0) + return tf; + app14->transform_flag = tf; + + skip = Lp - 2 - 11; + return jpeg_skip(stream, skip); +} + /** - * 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 +504,10 @@ 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 */ + if (out->app14) + out->app14->len = -1; + /* loop through marker segments */ while ((marker = jpeg_next_marker(&stream)) >= 0) { switch (marker) { @@ -519,7 +551,10 @@ 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); + 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..2b02d89f20b4 100644 --- a/include/media/v4l2-jpeg.h +++ b/include/media/v4l2-jpeg.h @@ -87,6 +87,16 @@ struct v4l2_jpeg_scan_header { /* Ss, Se, Ah, and Al are not used by any driver */ }; +/** + * struct v4l2_jpeg_app14_data - APP14 data segment + * @len: Lp application data segment length, becomes -1 if APP14 is not present + * @transform_flag: Ap12 byte for color encoding + */ +struct v4l2_jpeg_app14_data { + u16 len; + u8 transform_flag; +}; + /** * struct v4l2_jpeg_header - parsed JPEG header * @sof: pointer to frame header and size @@ -98,12 +108,13 @@ struct v4l2_jpeg_scan_header { * @quantization_tables: references to four quantization tables, optional * @huffman_tables: references to four Huffman tables in DC0, DC1, AC0, AC1 * order, optional + * @app14: pointer to app14 data, optional * @restart_interval: number of MCU per restart interval, Ri * @ecs_offset: buffer offset in bytes to the entropy coded segment * * 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, huffman_tables and app14 pointers must be initialized + * to NULL or point at valid memory. */ struct v4l2_jpeg_header { struct v4l2_jpeg_reference sof; @@ -117,6 +128,7 @@ struct v4l2_jpeg_header { struct v4l2_jpeg_scan_header *scan; struct v4l2_jpeg_reference *quantization_tables; struct v4l2_jpeg_reference *huffman_tables; + struct v4l2_jpeg_app14_data *app14; u16 restart_interval; size_t ecs_offset; }; -- 2.17.1
