Add helpers for JPEG header parsing. They allow both scanning for marker segment positions and later parsing the segments individually, as required by s5p-jpeg, as well as parsing all headers in one go, as required by coda-vpu. The frame header is always parsed, as basically all decoders are interested in width, height, and number of components. For convenience, the JPEG chroma subsampling factors are decoded into a v4l2_jpeg_chroma_subsampling enum. Only baseline and extended sequential DCT encoded JPEGs with 8-bit or 12-bit precision with up to four components are supported. Signed-off-by: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx> --- Changes since v1: - Do not fail parsing for up to 4-component images. The driver must check the number of components. - Support SOF1 (extended sequential DCT) frame headers, 12-bit precision, and 16-bit quantization table elements. The driver must check precision and quantization table lengths. --- drivers/media/v4l2-core/Kconfig | 4 + drivers/media/v4l2-core/Makefile | 2 + drivers/media/v4l2-core/v4l2-jpeg.c | 632 ++++++++++++++++++++++++++++ include/media/v4l2-jpeg.h | 135 ++++++ 4 files changed, 773 insertions(+) create mode 100644 drivers/media/v4l2-core/v4l2-jpeg.c create mode 100644 include/media/v4l2-jpeg.h diff --git a/drivers/media/v4l2-core/Kconfig b/drivers/media/v4l2-core/Kconfig index 39e3fb30ba0b..89809ec24779 100644 --- a/drivers/media/v4l2-core/Kconfig +++ b/drivers/media/v4l2-core/Kconfig @@ -45,6 +45,10 @@ config VIDEO_PCI_SKELETON config VIDEO_TUNER tristate +# Used by drivers that need v4l2-jpeg.ko +config V4L2_JPEG_HELPER + tristate + # Used by drivers that need v4l2-mem2mem.ko config V4L2_MEM2MEM_DEV tristate diff --git a/drivers/media/v4l2-core/Makefile b/drivers/media/v4l2-core/Makefile index 786bd1ec4d1b..144564656d22 100644 --- a/drivers/media/v4l2-core/Makefile +++ b/drivers/media/v4l2-core/Makefile @@ -24,6 +24,8 @@ obj-$(CONFIG_V4L2_MEM2MEM_DEV) += v4l2-mem2mem.o obj-$(CONFIG_V4L2_FLASH_LED_CLASS) += v4l2-flash-led-class.o +obj-$(CONFIG_V4L2_JPEG_HELPER) += v4l2-jpeg.o + obj-$(CONFIG_VIDEOBUF_GEN) += videobuf-core.o obj-$(CONFIG_VIDEOBUF_DMA_SG) += videobuf-dma-sg.o obj-$(CONFIG_VIDEOBUF_DMA_CONTIG) += videobuf-dma-contig.o diff --git a/drivers/media/v4l2-core/v4l2-jpeg.c b/drivers/media/v4l2-core/v4l2-jpeg.c new file mode 100644 index 000000000000..8947fd95c6f1 --- /dev/null +++ b/drivers/media/v4l2-core/v4l2-jpeg.c @@ -0,0 +1,632 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * V4L2 JPEG header parser helpers. + * + * Copyright (C) 2019 Pengutronix, Philipp Zabel <kernel@xxxxxxxxxxxxxx> + * + * For reference, see JPEG ITU-T.81 (ISO/IEC 10918-1) [1] + * + * [1] https://www.w3.org/Graphics/JPEG/itu-t81.pdf + */ + +#include <asm/unaligned.h> +#include <linux/errno.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/types.h> +#include <media/v4l2-jpeg.h> + +MODULE_DESCRIPTION("V4L2 JPEG header parser helpers"); +MODULE_AUTHOR("Philipp Zabel <kernel@xxxxxxxxxxxxxx>"); +MODULE_LICENSE("GPL"); + +/* Table B.1 - Marker code assignments */ +#define SOF0 0xffc0 /* start of frame */ +#define SOF1 0xffc1 +#define SOF2 0xffc2 +#define SOF3 0xffc3 +#define SOF5 0xffc5 +#define SOF7 0xffc7 +#define JPG 0xffc8 /* extensions */ +#define SOF9 0xffc9 +#define SOF11 0xffcb +#define SOF13 0xffcd +#define SOF15 0xffcf +#define DHT 0xffc4 /* huffman table */ +#define DAC 0xffcc /* arithmetic coding conditioning */ +#define RST0 0xffd0 /* restart */ +#define RST7 0xffd7 +#define SOI 0xffd8 /* start of image */ +#define EOI 0xffd9 /* end of image */ +#define SOS 0xffda /* start of stream */ +#define DQT 0xffdb /* quantization table */ +#define DNL 0xffdc /* number of lines */ +#define DRI 0xffdd /* restart interval */ +#define DHP 0xffde /* hierarchical progression */ +#define EXP 0xffdf /* expand reference */ +#define APP0 0xffe0 /* application data */ +#define APP15 0xffef +#define JPG0 0xfff0 /* extensions */ +#define JPG13 0xfffd +#define COM 0xfffe /* comment */ +#define TEM 0xff01 /* temporary */ + +/** + * struct jpeg_stream - JPEG byte stream + * @curr: current position in stream + * @end: end position, after last byte + */ +struct jpeg_stream { + u8 *curr; + u8 *end; +}; + +/* returns a value that fits into u8, or negative error */ +static int jpeg_get_byte(struct jpeg_stream *stream) +{ + if (stream->curr >= stream->end) + return -EINVAL; + + return *stream->curr++; +} + +/* returns a value that fits into u16, or negative error */ +static int jpeg_get_word_be(struct jpeg_stream *stream) +{ + u16 word; + + if (stream->curr + sizeof(__be16) > stream->end) + return -EINVAL; + + word = get_unaligned_be16(stream->curr); + stream->curr += sizeof(__be16); + + return word; +} + +static int jpeg_skip(struct jpeg_stream *stream, size_t len) +{ + if (stream->curr + len > stream->end) + return -EINVAL; + + stream->curr += len; + + return 0; +} + +static int jpeg_next_marker(struct jpeg_stream *stream) +{ + int byte; + u16 marker = 0; + + while ((byte = jpeg_get_byte(stream)) >= 0) { + marker = (marker << 8) | byte; + /* skip stuffing bytes and REServed markers */ + if (marker == TEM || (marker > 0xffbf && marker < 0xffff)) + return marker; + } + + return byte; +} + +/* this does not advance the current position in the stream */ +static int jpeg_reference_segment(struct jpeg_stream *stream, + struct v4l2_jpeg_reference *segment) +{ + u16 len; + + if (stream->curr + sizeof(__be16) > stream->end) + return -EINVAL; + + len = get_unaligned_be16(stream->curr); + if (stream->curr + len > stream->end) + return -EINVAL; + + segment->start = stream->curr; + segment->length = len; + + return 0; +} + +static int v4l2_jpeg_decode_subsampling(u8 nf, u8 h_v) +{ + if (nf == 1) + return V4L2_JPEG_CHROMA_SUBSAMPLING_GRAY; + + /* no chroma subsampling for 4-component images */ + if (nf == 4 && h_v != 0x11) + return -EINVAL; + + switch (h_v) { + case 0x11: + return V4L2_JPEG_CHROMA_SUBSAMPLING_444; + case 0x21: + return V4L2_JPEG_CHROMA_SUBSAMPLING_422; + case 0x22: + return V4L2_JPEG_CHROMA_SUBSAMPLING_420; + case 0x41: + return V4L2_JPEG_CHROMA_SUBSAMPLING_411; + default: + return -EINVAL; + } +} + +static int jpeg_parse_frame_header(struct jpeg_stream *stream, u16 sof_marker, + struct v4l2_jpeg_frame_header *frame_header) +{ + int len = jpeg_get_word_be(stream); + + if (len < 0) + return len; + /* Lf = 8 + 3 * Nf, Nf >= 1 */ + if (len < 8 + 3) + return -EINVAL; + + if (frame_header) { + /* Table B.2 - Frame header parameter sizes and values */ + int p, y, x, nf; + int i; + + p = jpeg_get_byte(stream); + if (p < 0) + return p; + /* + * Baseline DCT only supports 8-bit precision. + * Extended sequential DCT also supports 12-bit precision. + */ + if (p != 8 && (p != 12 || sof_marker != SOF1)) + return -EINVAL; + + y = jpeg_get_word_be(stream); + if (y < 0) + return y; + if (y == 0) + return -EINVAL; + + x = jpeg_get_word_be(stream); + if (x < 0) + return x; + if (x == 0) + return -EINVAL; + + nf = jpeg_get_byte(stream); + if (nf < 0) + return nf; + /* + * The spec allows 1 <= Nf <= 255, but we only support up to 4 + * components. + */ + if (nf < 1 || nf > V4L2_JPEG_MAX_COMPONENTS) + return -EINVAL; + if (len != 8 + 3 * nf) + return -EINVAL; + + frame_header->precision = p; + frame_header->height = y; + frame_header->width = x; + frame_header->num_components = nf; + + for (i = 0; i < nf; i++) { + struct v4l2_jpeg_frame_component_spec *component; + int c, h_v, tq; + + c = jpeg_get_byte(stream); + if (c < 0) + return c; + + h_v = jpeg_get_byte(stream); + if (h_v < 0) + return h_v; + if (i == 0) { + int subs; + + subs = v4l2_jpeg_decode_subsampling(nf, h_v); + if (subs < 0) + return subs; + frame_header->subsampling = subs; + } else if (h_v != 0x11) { + /* all chroma sampling factors must be 1 */ + return -EINVAL; + } + + tq = jpeg_get_byte(stream); + if (tq < 0) + return tq; + + component = &frame_header->component[i]; + component->component_identifier = c; + component->horizontal_sampling_factor = + (h_v >> 4) & 0xf; + component->vertical_sampling_factor = h_v & 0xf; + component->quantization_table_selector = tq; + } + } else { + return jpeg_skip(stream, len - 2); + } + + return 0; +} + +static int jpeg_parse_scan_header(struct jpeg_stream *stream, + struct v4l2_jpeg_scan_header *scan_header) +{ + size_t skip; + int len = jpeg_get_word_be(stream); + + if (len < 0) + return len; + /* Ls = 8 + 3 * Ns, Ns >= 1 */ + if (len < 6 + 2) + return -EINVAL; + + if (scan_header) { + int ns; + int i; + + ns = jpeg_get_byte(stream); + if (ns < 0) + return ns; + if (ns < 1 || ns > 4 || len != 6 + 2 * ns) + return -EINVAL; + + scan_header->num_components = ns; + + for (i = 0; i < ns; i++) { + struct v4l2_jpeg_scan_component_spec *component; + int cs, td_ta; + + cs = jpeg_get_byte(stream); + if (cs < 0) + return cs; + + td_ta = jpeg_get_byte(stream); + if (td_ta < 0) + return td_ta; + + component = &scan_header->component[i]; + component->component_selector = cs; + component->dc_entropy_coding_table_selector = + (td_ta >> 4) & 0xf; + component->ac_entropy_coding_table_selector = + td_ta & 0xf; + } + + skip = 3; /* skip Ss, Se, Ah, and Al */ + } else { + skip = len - 2; + } + + return jpeg_skip(stream, skip); +} + +/* B.2.4.1 Quantization table-specification syntax */ +static int jpeg_parse_quantization_tables(struct jpeg_stream *stream, + u8 precision, + struct v4l2_jpeg_reference *tables) +{ + int len = jpeg_get_word_be(stream); + + if (len < 0) + return len; + /* Lq = 2 + n * 65 (for baseline DCT), n >= 1 */ + if (len < 2 + 65) + return -EINVAL; + + len -= 2; + while (len >= 65) { + u8 pq, tq, *qk; + int ret; + int pq_tq = jpeg_get_byte(stream); + + if (pq_tq < 0) + return pq_tq; + + /* quantization table element precision */ + pq = (pq_tq >> 4) & 0xf; + /* + * Only 8-bit Qk values for 8-bit sample precision. Extended + * sequential DCT with 12-bit sample precision also supports + * 16-bit Qk values. + */ + if (pq != 0 && (pq != 1 || precision != 12)) + return -EINVAL; + + /* quantization table destination identifier */ + tq = pq_tq & 0xf; + if (tq > 3) + return -EINVAL; + + /* quantization table element */ + qk = stream->curr; + ret = jpeg_skip(stream, pq ? 128 : 64); + if (ret < 0) + return -EINVAL; + + if (tables) { + tables[tq].start = qk; + tables[tq].length = pq ? 128 : 64; + } + + len -= pq ? 129 : 65; + } + + return 0; +} + +/* B.2.4.2 Huffman table-specification syntax */ +static int jpeg_parse_huffman_tables(struct jpeg_stream *stream, + struct v4l2_jpeg_reference *tables) +{ + int mt; + int len = jpeg_get_word_be(stream); + + if (len < 0) + return len; + /* Table B.5 - Huffman table specification parameter sizes and values */ + if (len < 2 + 17) + return -EINVAL; + + for (len -= 2; len >= 17; len -= 17 + mt) { + u8 tc, th, *table; + int tc_th = jpeg_get_byte(stream); + int i, ret; + + if (tc_th < 0) + return tc_th; + + /* table class - 0 = DC, 1 = AC */ + tc = (tc_th >> 4) & 0xf; + if (tc > 1) + return -EINVAL; + + /* huffman table destination identifier */ + th = tc_th & 0xf; + /* only two Huffman tables for baseline DCT */ + if (th > 1) + return -EINVAL; + + /* BITS - number of Huffman codes with length i */ + table = stream->curr; + mt = 0; + for (i = 0; i < 16; i++) { + int li; + + li = jpeg_get_byte(stream); + if (li < 0) + return li; + + mt += li; + } + /* HUFFVAL - values associated with each Huffman code */ + ret = jpeg_skip(stream, mt); + if (ret < 0) + return ret; + + if (tables) { + tables[(tc << 1) | th].start = table; + tables[(tc << 1) | th].length = stream->curr - table; + } + } + + return jpeg_skip(stream, len - 2); +} + +/* B.2.4.4 Restart interval definition syntax */ +static int jpeg_parse_restart_interval(struct jpeg_stream *stream, + u16 *restart_interval) +{ + int len = jpeg_get_word_be(stream); + int ri; + + if (len < 0) + return len; + if (len != 4) + return -EINVAL; + + ri = jpeg_get_word_be(stream); + if (ri < 0) + return ri; + + *restart_interval = ri; + + return 0; +} + +static int jpeg_skip_segment(struct jpeg_stream *stream) +{ + int len = jpeg_get_word_be(stream); + + if (len < 0) + return len; + if (len < 2) + return -EINVAL; + + return jpeg_skip(stream, len - 2); +} + +/** + * 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 + * + * The out->scan_header pointer must be initialized to NULL or point to a valid + * v4l2_jpeg_scan_header structure. The out->huffman_tables and + * out->quantization_tables pointers must be initialized to NULL or point to a + * valid array of 4 v4l2_jpeg_reference structures each. + * + * Returns 0 or negative error if parsing failed. + */ +int v4l2_jpeg_parse_header(void *buf, size_t len, struct v4l2_jpeg_header *out) +{ + struct jpeg_stream stream; + int marker; + int ret = 0; + + stream.curr = buf; + stream.end = stream.curr + len; + + out->num_dht = 0; + out->num_dqt = 0; + + /* the first marker must be SOI */ + marker = jpeg_next_marker(&stream); + if (marker < 0) + return marker; + if (marker != SOI) + return -EINVAL; + + /* loop through marker segments */ + while ((marker = jpeg_next_marker(&stream)) >= 0) { + switch (marker) { + /* baseline DCT, extended sequential DCT */ + case SOF0 ... SOF1: + ret = jpeg_reference_segment(&stream, &out->sof); + if (ret < 0) + return ret; + ret = jpeg_parse_frame_header(&stream, marker, + &out->frame); + break; + /* progressive, lossless */ + case SOF2 ... SOF3: + /* differential coding */ + case SOF5 ... SOF7: + /* arithmetic coding */ + case SOF9 ... SOF11: + case SOF13 ... SOF15: + case DAC: + case TEM: + return -EINVAL; + + case DHT: + ret = jpeg_reference_segment(&stream, + &out->dht[out->num_dht++ % 4]); + if (ret < 0) + return ret; + ret = jpeg_parse_huffman_tables(&stream, + out->huffman_tables); + break; + case DQT: + ret = jpeg_reference_segment(&stream, + &out->dqt[out->num_dqt++ % 4]); + if (ret < 0) + return ret; + ret = jpeg_parse_quantization_tables(&stream, + out->frame.precision, + out->quantization_tables); + break; + case DRI: + ret = jpeg_parse_restart_interval(&stream, + &out->restart_interval); + break; + + case SOS: + ret = jpeg_reference_segment(&stream, &out->sos); + if (ret < 0) + return ret; + ret = jpeg_parse_scan_header(&stream, out->scan); + /* + * stop parsing, the scan header marks the beginning of + * the entropy coded segment + */ + out->ecs_offset = stream.curr - (u8 *)buf; + return ret; + + /* markers without parameters */ + case RST0 ... RST7: /* restart */ + case SOI: /* start of image */ + case EOI: /* end of image */ + break; + + /* skip unknown or unsupported marker segments */ + default: + ret = jpeg_skip_segment(&stream); + break; + } + if (ret < 0) + return ret; + } + + return marker; +} +EXPORT_SYMBOL_GPL(v4l2_jpeg_parse_header); + +/** + * v4l2_jpeg_parse_frame_header - parse frame header + * @buf: address of the frame header, after the SOF0 marker + * @len: length of the frame header + * @frame_header: returns the parsed frame header + * + * Returns 0 or negative error if parsing failed. + */ +int v4l2_jpeg_parse_frame_header(void *buf, size_t len, + struct v4l2_jpeg_frame_header *frame_header) +{ + struct jpeg_stream stream; + + stream.curr = buf; + stream.end = stream.curr + len; + return jpeg_parse_frame_header(&stream, SOF0, frame_header); +} +EXPORT_SYMBOL_GPL(v4l2_jpeg_parse_frame_header); + +/** + * v4l2_jpeg_parse_scan_header - parse scan header + * @buf: address of the scan header, after the SOS marker + * @len: length of the scan header + * @scan_header: returns the parsed scan header + * + * Returns 0 or negative error if parsing failed. + */ +int v4l2_jpeg_parse_scan_header(void *buf, size_t len, + struct v4l2_jpeg_scan_header *scan_header) +{ + struct jpeg_stream stream; + + stream.curr = buf; + stream.end = stream.curr + len; + return jpeg_parse_scan_header(&stream, scan_header); +} +EXPORT_SYMBOL_GPL(v4l2_jpeg_parse_scan_header); + +/** + * v4l2_jpeg_parse_quantization_tables - parse quantization tables segment + * @buf: address of the quantization table segment, after the DQT marker + * @len: length of the quantization table segment + * @precision: sample precision (P) in bits per component + * @q_tables: returns four references into the buffer for the + * four possible quantization table destinations + * + * Returns 0 or negative error if parsing failed. + */ +int v4l2_jpeg_parse_quantization_tables(void *buf, size_t len, u8 precision, + struct v4l2_jpeg_reference *q_tables) +{ + struct jpeg_stream stream; + + stream.curr = buf; + stream.end = stream.curr + len; + return jpeg_parse_quantization_tables(&stream, precision, q_tables); +} +EXPORT_SYMBOL_GPL(v4l2_jpeg_parse_quantization_tables); + +/** + * v4l2_jpeg_parse_huffman_tables - parse huffman tables segment + * @buf: address of the Huffman table segment, after the DHT marker + * @len: length of the Huffman table segment + * @huffman_tables: returns four references into the buffer for the + * four possible Huffman table destinations, in + * the order DC0, DC1, AC0, AC1 + * + * Returns 0 or negative error if parsing failed. + */ +int v4l2_jpeg_parse_huffman_tables(void *buf, size_t len, + struct v4l2_jpeg_reference *huffman_tables) +{ + struct jpeg_stream stream; + + stream.curr = buf; + stream.end = stream.curr + len; + return jpeg_parse_huffman_tables(&stream, huffman_tables); +} +EXPORT_SYMBOL_GPL(v4l2_jpeg_parse_huffman_tables); diff --git a/include/media/v4l2-jpeg.h b/include/media/v4l2-jpeg.h new file mode 100644 index 000000000000..ddba2a56c321 --- /dev/null +++ b/include/media/v4l2-jpeg.h @@ -0,0 +1,135 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * V4L2 JPEG helpers header + * + * Copyright (C) 2019 Pengutronix, Philipp Zabel <kernel@xxxxxxxxxxxxxx> + * + * For reference, see JPEG ITU-T.81 (ISO/IEC 10918-1) + */ + +#ifndef _V4L2_JPEG_H +#define _V4L2_JPEG_H + +#include <linux/v4l2-controls.h> + +#define V4L2_JPEG_MAX_COMPONENTS 4 +#define V4L2_JPEG_MAX_TABLES 4 + +/** + * struct v4l2_jpeg_reference - reference into the JPEG buffer + * @start: pointer to the start of the referenced segment or table + * @length: size of the referenced segment or table + * + * Wnen referencing marker segments, start points right after the marker code, + * and length is the size of the segment parameters, excluding the marker code. + */ +struct v4l2_jpeg_reference { + u8 *start; + size_t length; +}; + +/* B.2.2 Frame header syntax */ + +/** + * struct v4l2_jpeg_frame_component_spec - frame component-specification + * @component_identifier: C[i] + * @horizontal_sampling_factor: H[i] + * @vertical_sampling_factor: V[i] + * @quantization_table_selector: quantization table destination selector Tq[i] + */ +struct v4l2_jpeg_frame_component_spec { + u8 component_identifier; + u8 horizontal_sampling_factor; + u8 vertical_sampling_factor; + u8 quantization_table_selector; +}; + +/** + * struct v4l2_jpeg_frame_header - JPEG frame header + * @height: Y + * @width: X + * @precision: P + * @num_components: Nf + * @component: component-specification, see v4l2_jpeg_frame_component_spec + * @subsampling: decoded subsampling from component-specification + */ +struct v4l2_jpeg_frame_header { + u16 height; + u16 width; + u8 precision; + u8 num_components; + struct v4l2_jpeg_frame_component_spec component[V4L2_JPEG_MAX_COMPONENTS]; + enum v4l2_jpeg_chroma_subsampling subsampling; +}; + +/* B.2.3 Scan header syntax */ + +/** + * struct v4l2_jpeg_scan_component_spec - scan component-specification + * @component_selector: Cs[j] + * @dc_entropy_coding_table_selector: Td[j] + * @ac_entropy_coding_table_selector: Ta[j] + */ +struct v4l2_jpeg_scan_component_spec { + u8 component_selector; + u8 dc_entropy_coding_table_selector; + u8 ac_entropy_coding_table_selector; +}; + +/** + * struct v4l2_jpeg_scan_header - JPEG scan header + * @num_components: Ns + * @component: component-specification, see v4l2_jpeg_scan_component_spec + */ +struct v4l2_jpeg_scan_header { + u8 num_components; /* Ns */ + struct v4l2_jpeg_scan_component_spec component[V4L2_JPEG_MAX_COMPONENTS]; + /* Ss, Se, Ah, and Al are not used by any driver */ +}; + +/** + * struct v4l2_jpeg_header - parsed JPEG header + * @sof: pointer to frame header and size + * @sos: pointer to scan header and size + * @dht: pointers to huffman tables and sizes + * @dqt: pointers to quantization tables and sizes + * @frame: parsed frame header + * @scan: pointer to parsed scan header, optional + * @quantization_tables: references to four quantization tables, optional + * @huffman_tables: references to four Huffman tables in DC0, DC1, AC0, AC1 + * order, 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. + */ +struct v4l2_jpeg_header { + struct v4l2_jpeg_reference sof; + struct v4l2_jpeg_reference sos; + unsigned int num_dht; + struct v4l2_jpeg_reference dht[V4L2_JPEG_MAX_TABLES]; + unsigned int num_dqt; + struct v4l2_jpeg_reference dqt[V4L2_JPEG_MAX_TABLES]; + + struct v4l2_jpeg_frame_header frame; + struct v4l2_jpeg_scan_header *scan; + struct v4l2_jpeg_reference *quantization_tables; + struct v4l2_jpeg_reference *huffman_tables; + u16 restart_interval; + size_t ecs_offset; +}; + +int v4l2_jpeg_parse_header(void *buf, size_t len, struct v4l2_jpeg_header *out); + +int v4l2_jpeg_parse_frame_header(void *buf, size_t len, + struct v4l2_jpeg_frame_header *frame_header); +int v4l2_jpeg_parse_scan_header(void *buf, size_t len, + struct v4l2_jpeg_scan_header *scan_header); +int v4l2_jpeg_parse_quantization_tables(void *buf, size_t len, u8 precision, + struct v4l2_jpeg_reference *q_tables); +int v4l2_jpeg_parse_huffman_tables(void *buf, size_t len, + struct v4l2_jpeg_reference *huffman_tables); + +#endif -- 2.20.1
