[FFmpeg-devel] [RFC PATCH] libavcodec/jpeg2000_parser: Add jpeg2000 parser
gautamramk at gmail.com
gautamramk at gmail.com
Sat Apr 18 22:30:02 EEST 2020
From: Gautam Ramakrishnan <gautamramk at gmail.com>
I have attempted to write a JPEG2000 Parser. Need
help on testing the code and some tips on how to
document this code. The variable names are also
a bit hard to understand. Would appreciate some
tips. The sample from #7445 seems to get decoded
now.
---
libavcodec/Makefile | 1 +
libavcodec/jpeg2000_parser.c | 148 +++++++++++++++++++++++++++++++++++
libavcodec/parsers.c | 1 +
3 files changed, 150 insertions(+)
create mode 100644 libavcodec/jpeg2000_parser.c
diff --git a/libavcodec/Makefile b/libavcodec/Makefile
index 88944d9a3a..dedd7a0429 100644
--- a/libavcodec/Makefile
+++ b/libavcodec/Makefile
@@ -1062,6 +1062,7 @@ OBJS-$(CONFIG_H261_PARSER) += h261_parser.o
OBJS-$(CONFIG_H263_PARSER) += h263_parser.o
OBJS-$(CONFIG_H264_PARSER) += h264_parser.o h264_sei.o h264data.o
OBJS-$(CONFIG_HEVC_PARSER) += hevc_parser.o hevc_data.o
+OBJS-$(CONFIG_JPEG2000_PARSER) += jpeg2000_parser.o
OBJS-$(CONFIG_MJPEG_PARSER) += mjpeg_parser.o
OBJS-$(CONFIG_MLP_PARSER) += mlp_parse.o mlp_parser.o mlp.o
OBJS-$(CONFIG_MPEG4VIDEO_PARSER) += mpeg4video_parser.o h263.o \
diff --git a/libavcodec/jpeg2000_parser.c b/libavcodec/jpeg2000_parser.c
new file mode 100644
index 0000000000..e172c5a9c9
--- /dev/null
+++ b/libavcodec/jpeg2000_parser.c
@@ -0,0 +1,148 @@
+/*
+ * JPEG2000 parser
+ * Copyright (c) 2000, 2001 Fabrice Bellard
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * JPEG2000 parser.
+ */
+
+#include "parser.h"
+
+typedef struct JPEG2000ParserContext{
+ ParseContext pc;
+ uint64_t bytes_read;
+ uint64_t fheader_state;
+ uint8_t fheader_read;
+ uint8_t frame_type; // 1 if file, 2 if codestream
+ uint8_t reading_file_header;
+ uint8_t skipped_codestream;
+ uint8_t codestream_frame_end;
+}JPEG2000ParserContext;
+
+static inline void reset_context(JPEG2000ParserContext *m)
+{
+ ParseContext *pc = &m->pc;
+
+ pc->frame_start_found= 0;
+ pc->state = 0;
+ m->bytes_read = 0;
+ m->frame_type = 0;
+ m->skipped_codestream = 0;
+ m->fheader_read = 0;
+ m->fheader_state = 0;
+ m->reading_file_header = 0;
+ m->codestream_frame_end = 0;
+}
+/**
+ * Find the end of the current frame in the bitstream.
+ * @return the position of the first byte of the next frame, or -1
+ */
+static int find_frame_end(JPEG2000ParserContext *m, const uint8_t *buf, int buf_size)
+{
+ ParseContext *pc= &m->pc;
+ int i;
+ uint32_t state;
+ state= pc->state;
+
+ if (buf_size == 0) {
+ return 0;
+ }
+
+ for (i = 0; i < buf_size; i++) {
+ state = state << 8 | buf[i];
+ m->bytes_read++;
+ if (m->codestream_frame_end) {
+ reset_context(m);
+ return i;
+ }
+ if (m->reading_file_header) {
+ m->fheader_state = m->fheader_state << 8 | buf[i];
+ m->fheader_read++;
+ if (m->fheader_read == 8) {
+ if (m->fheader_state == 0x6A5020200D0A870A) {
+ if (pc->frame_start_found) {
+ pc->frame_start_found = 0;
+ reset_context(m);
+ return i - 11;
+ } else {
+ pc->frame_start_found = 1;
+ m->frame_type = 1;
+ }
+ }
+ m->reading_file_header = 0;
+ m->fheader_read = 0;
+ }
+ }
+ if (state == 0x0000000C && m->bytes_read >= 3) {
+ m->reading_file_header = 1;
+ } else if ((state & 0xFFFF) == 0xFF4F) {
+ if (!pc->frame_start_found) {
+ pc->frame_start_found = 1;
+ m->frame_type = 2;
+ } else if (pc->frame_start_found && m->frame_type == 1 && m->skipped_codestream) {
+ reset_context(m);
+ return i - 1;
+ }
+ } else if ((state & 0xFFFF) == 0xFFD9) {
+ if (pc->frame_start_found && m->frame_type == 1) {
+ m->skipped_codestream = 1;
+ } else if (pc->frame_start_found && m->frame_type == 2) {
+ m->codestream_frame_end = 1;
+ }
+ }
+ }
+
+ pc->state= state;
+ return END_NOT_FOUND;
+}
+
+static int jpeg2000_parse(AVCodecParserContext *s,
+ AVCodecContext *avctx,
+ const uint8_t **poutbuf, int *poutbuf_size,
+ const uint8_t *buf, int buf_size)
+{
+ JPEG2000ParserContext *m = s->priv_data;
+ ParseContext *pc = &m->pc;
+ int next;
+
+ if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){
+ next= buf_size;
+ }else{
+ next= find_frame_end(m, buf, buf_size);
+
+ if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
+ *poutbuf = NULL;
+ *poutbuf_size = 0;
+ return buf_size;
+ }
+ }
+
+ *poutbuf = buf;
+ *poutbuf_size = buf_size;
+ return next;
+}
+
+AVCodecParser ff_jpeg2000_parser = {
+ .codec_ids = { AV_CODEC_ID_JPEG2000 },
+ .priv_data_size = sizeof(JPEG2000ParserContext),
+ .parser_parse = jpeg2000_parse,
+ .parser_close = ff_parse_close,
+};
\ No newline at end of file
diff --git a/libavcodec/parsers.c b/libavcodec/parsers.c
index 9fbf182594..7d75cea830 100644
--- a/libavcodec/parsers.c
+++ b/libavcodec/parsers.c
@@ -48,6 +48,7 @@ extern AVCodecParser ff_h261_parser;
extern AVCodecParser ff_h263_parser;
extern AVCodecParser ff_h264_parser;
extern AVCodecParser ff_hevc_parser;
+extern AVCodecParser ff_jpeg2000_parser;
extern AVCodecParser ff_mjpeg_parser;
extern AVCodecParser ff_mlp_parser;
extern AVCodecParser ff_mpeg4video_parser;
--
2.17.1
More information about the ffmpeg-devel
mailing list