[vlc-devel] [PATCH] Automatically orient JPEG image based on orientation flag, if set
Wayne McDougall
waynemcdougall at gmail.com
Sun Apr 17 22:06:53 CEST 2016
Please find an update patch:
[PATCH] Automatically orient JPEG images using orientation tag, if present
Addressed:
Rémi's ORIENT_FROM_EXIF - although I think the values supplied are in
reverse order
Jean-Baptiste's var_InheritBool
Comments added to address...
Jean-Baptiste's question as to whether it needs to be optional. I think
yes it does.
Jean-Baptiste's suggestion to use existing big/little endian functions. I
don't think they apply
because JPEG's tags can come in either format.
---
modules/codec/jpeg.c | 239
++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 235 insertions(+), 4 deletions(-)
diff --git a/modules/codec/jpeg.c b/modules/codec/jpeg.c
index 0e3ae9d..d540365 100644
--- a/modules/codec/jpeg.c
+++ b/modules/codec/jpeg.c
@@ -1,7 +1,7 @@
/*****************************************************************************
* jpeg.c: jpeg decoder module making use of libjpeg.
*****************************************************************************
- * Copyright (C) 2013-2014 VLC authors and VideoLAN
+ * Copyright (C) 2013-2014,2016 VLC authors and VideoLAN
*
* Authors: Maxim Bublis <b at codemonkey.ru>
*
@@ -50,6 +50,22 @@
#define ENC_QUALITY_LONGTEXT N_( "Quality level " \
"for encoding (this can enlarge or reduce
output image size)." )
+#define DEC_CFG_PREFIX "jpeg-"
+#define DEC_AUTOORIENT_TEXT N_( "Automatic Orientation" )
+#define DEC_AUTOORIENT_LONGTEXT N_( "Automatic rotation based on EXIF
orientation tag." )
+
+const char leth[] = {
+ 0x49, 0x49, 0x2a, 0x00
+}; // Little endian TIFF
header
+const char beth[] = {
+ 0x4d, 0x4d, 0x00, 0x2a
+}; // Big endian TIFF header
+
+#define G_LITTLE_ENDIAN 1234
+#define G_BIG_ENDIAN 4321
+
+#define EXIF_JPEG_MARKER 0xE1
+#define EXIF_IDENT_STRING "Exif\000\000"
/*
* jpeg common descriptor
@@ -107,6 +123,13 @@ set_description( N_( "JPEG image decoder" ) )
set_capability( "decoder", 1000 )
set_callbacks( OpenDecoder, CloseDecoder )
add_shortcut( "jpeg" )
+/*
+ * Some JPEG get transformed to a normal orientation without resetting
+ * embedded orientation tag to reflect that.
+ * Allow disabling of autoorientation in case we have to work with such
images.
+*/
+add_bool( DEC_CFG_PREFIX "autoorient", true,
+ DEC_AUTOORIENT_TEXT, DEC_AUTOORIENT_LONGTEXT, true )
/* encoder submodule */
add_submodule()
@@ -178,6 +201,201 @@ static int OpenDecoder ( vlc_object_t * p_this )
return VLC_SUCCESS;
}
+/* The EXIF headers in JPEG are based on TIFF and so
+ * may be in big endian or little endian format. We may be on a
+ * big endian machine or little endian machine.
+ * The following functions swap our 2 and 4 byte pairs, depending
+ * on which of the 4 possibilities we are dealing with.
+ * endian parameter tells us the source format, and WORDS_BIGENDIAN
+ * tells us how the machine we are running on stores that source
+ * format.
+*/
+
+LOCAL( unsigned short )
+de_get16( void * ptr, uint endian ) {
+ unsigned short val;
+
+ memcpy( &val, ptr, sizeof( val ) );
+ if ( endian == G_BIG_ENDIAN )
+ {
+ #ifndef WORDS_BIGENDIAN
+ val = bswap16( val );
+ #endif
+ }
+ else
+ {
+ #ifdef WORDS_BIGENDIAN
+ val = bswap16( val );
+ #endif
+ }
+ return val;
+}
+
+LOCAL( unsigned int )
+de_get32( void * ptr, uint endian ) {
+ unsigned int val;
+
+ memcpy( &val, ptr, sizeof( val ) );
+ if ( endian == G_BIG_ENDIAN )
+ {
+ #ifndef WORDS_BIGENDIAN
+ val = bswap32( val );
+ #endif
+ }
+ else
+ {
+ #ifdef WORDS_BIGENDIAN
+ val = bswap32( val );
+ #endif
+ }
+ return val;
+}
+
+/* jpeg_GetOrientation function based on code from GdkPixbuf library -
JPEG image loader
+ *
http://src.gnu-darwin.org/ports/x11-toolkits/gtk20/work/gtk+-2.12.3/gdk-pixbuf/io-jpeg.c
+ *
+ * Copyright (C) 1999 Michael Zucchi
+ * Copyright (C) 1999 The Free Software Foundation
+ */
+
+LOCAL( int )
+jpeg_GetOrientation( j_decompress_ptr cinfo ) {
+ /* This function looks through the meta data in the libjpeg decompress
structure to
+ determine if an EXIF Orientation tag is present and if so return
its value (1-8).
+ If no EXIF Orientation tag is found, 1 (normal orientation) is
returned. */
+
+ uint i; /* index into working buffer */
+ ushort tag_type; /* endianed tag type extracted from tiff
header */
+ uint ret; /* Return value */
+ uint offset; /* de-endianed offset in various situations
*/
+ uint tags; /* number of tags in current ifd */
+ uint type; /* de-endianed type of tag */
+ uint count; /* de-endianed count of elements in a tag */
+ uint tiff = 0; /* offset to active tiff header */
+ uint endian = 0; /* detected endian of data */
+
+ jpeg_saved_marker_ptr exif_marker; /* Location of the Exif APP1
marker */
+ jpeg_saved_marker_ptr cmarker; /* Location to check for Exif
APP1 marker */
+
+ /* check for Exif marker (also called the APP1 marker) */
+ exif_marker = NULL;
+ cmarker = cinfo->marker_list;
+
+ while ( cmarker )
+ {
+ if ( cmarker->marker == EXIF_JPEG_MARKER )
+ {
+ /* The Exif APP1 marker should contain a unique
+ identification string ("Exif\0\0"). Check for it. */
+ if ( !memcmp( cmarker->data, EXIF_IDENT_STRING, 6 ) )
+ {
+ exif_marker = cmarker;
+ }
+ }
+ cmarker = cmarker->next;
+ }
+
+ /* Did we find the Exif APP1 marker? */
+ if ( exif_marker == NULL )
+ return 1;
+
+ /* Do we have enough data? */
+ if ( exif_marker->data_length < 32 )
+ return 1;
+
+ /* Check for TIFF header and catch endianess */
+ i = 0;
+
+ /* Just skip data until TIFF header - it should be within 16 bytes
from marker start.
+ Normal structure relative to APP1 marker -
+ 0x0000: APP1 marker entry = 2 bytes
+ 0x0002: APP1 length entry = 2 bytes
+ 0x0004: Exif Identifier entry = 6 bytes
+ 0x000A: Start of TIFF header (Byte order entry) - 4 bytes
+ - This is what we look for, to determine endianess.
+ 0x000E: 0th IFD offset pointer - 4 bytes
+
+ exif_marker->data points to the first data after the APP1
marker
+ and length entries, which is the exif identification string.
+ The TIFF header should thus normally be found at i=6, below,
+ and the pointer to IFD0 will be at 6+4 = 10.
+ */
+
+ while ( i < 16 )
+ {
+ /* Little endian TIFF header */
+ if ( memcmp( &exif_marker->data[i], leth, 4 ) == 0 )
+ {
+ endian = G_LITTLE_ENDIAN;
+ }
+ /* Big endian TIFF header */
+ else
+ if ( memcmp( &exif_marker->data[i], beth, 4 ) == 0 )
+ {
+ endian = G_BIG_ENDIAN;
+ }
+ /* Keep looking through buffer */
+ else
+ {
+ i++;
+ continue;
+ }
+ /* We have found either big or little endian TIFF header */
+ tiff = i;
+ break;
+ }
+
+ /* So did we find a TIFF header or did we just hit end of buffer? */
+ if ( tiff == 0 )
+ return 1;
+
+ /* Read out the offset pointer to IFD0 */
+ offset = de_get32( &exif_marker->data[i] + 4, endian );
+ i = i + offset;
+
+ /* Check that we still are within the buffer and can read the tag
count */
+
+ if ( ( i + 2 ) > exif_marker->data_length )
+ return 1;
+
+ /* Find out how many tags we have in IFD0. As per the TIFF spec, the
first
+ two bytes of the IFD contain a count of the number of tags. */
+ tags = de_get16( &exif_marker->data[i], endian );
+ i = i + 2;
+
+ /* Check that we still have enough data for all tags to check. The tags
+ are listed in consecutive 12-byte blocks. The tag ID, type, size,
and
+ a pointer to the actual value, are packed into these 12 byte
entries. */
+ if ( ( i + tags * 12 ) > exif_marker->data_length )
+ return 1;
+
+ /* Check through IFD0 for tags of interest */
+ while ( tags-- )
+ {
+ tag_type = de_get16( &exif_marker->data[i], endian );
+ /* Is this the orientation tag? */
+ if ( tag_type == 0x112 )
+ {
+ type = de_get16( &exif_marker->data[i + 2], endian );
+ count = de_get32( &exif_marker->data[i + 4], endian );
+
+ /* Check that type and count fields are OK. The orientation
field
+ will consist of a single (count=1) 2-byte integer (type=3).
*/
+ if ( type != 3 || count != 1 )
+ return 1;
+
+ /* Return the orientation value. Within the 12-byte block, the
+ pointer to the actual data is at offset 8. */
+ ret = de_get16( &exif_marker->data[i + 8], endian );
+ return ( ret <= 8 && ret > 0 ) ? ret : 1;
+ }
+ /* move the pointer to the next 12-byte tag field. */
+ i = i + 12;
+ }
+
+ return 1; /* No EXIF Orientation tag found */
+}
+
/*
* This function must be fed with a complete compressed frame.
*/
@@ -186,8 +404,8 @@ static picture_t * DecodeBlock ( decoder_t * p_dec,
block_t * * pp_block )
decoder_sys_t * p_sys = p_dec->p_sys;
block_t * p_block;
picture_t * p_pic = 0;
-
JSAMPARRAY p_row_pointers = NULL;
+ bool b_autoorient;
if ( !pp_block || !*pp_block )
{
@@ -211,8 +429,14 @@ static picture_t * DecodeBlock ( decoder_t * p_dec,
block_t * * pp_block )
jpeg_create_decompress( &p_sys->p_jpeg );
jpeg_mem_src( &p_sys->p_jpeg, p_block->p_buffer, p_block->i_buffer );
- jpeg_read_header( &p_sys->p_jpeg, TRUE );
+ b_autoorient = var_InheritBool( p_dec, "jpeg-autoorient" );
+ if ( b_autoorient )
+ {
+ jpeg_save_markers( &p_sys->p_jpeg, EXIF_JPEG_MARKER, 0xffff );
+ }
+
+ jpeg_read_header( &p_sys->p_jpeg, TRUE );
p_sys->p_jpeg.out_color_space = JCS_RGB;
jpeg_start_decompress( &p_sys->p_jpeg );
@@ -226,6 +450,14 @@ static picture_t * DecodeBlock ( decoder_t * p_dec,
block_t * * pp_block )
p_dec->fmt_out.video.i_rmask = 0x000000ff;
p_dec->fmt_out.video.i_gmask = 0x0000ff00;
p_dec->fmt_out.video.i_bmask = 0x00ff0000;
+ if ( b_autoorient )
+ {
+ /*
+ * Orientation tag has valid range of 1-8. We force to 1 if
undefined - 1 = normal orientation
+ * It seems as if ORIENT_FROM_EXIF in vlc_es.h has values in
reverse order so pass in ( 9 - Orientation tag )
+ */
+ p_dec->fmt_out.video.orientation = ORIENT_FROM_EXIF( 9 -
jpeg_GetOrientation( &p_sys->p_jpeg ) );
+ }
/* Get a new picture */
p_pic = decoder_NewPicture( p_dec );
@@ -265,7 +497,6 @@ static picture_t * DecodeBlock ( decoder_t * p_dec,
block_t * * pp_block )
jpeg_destroy_decompress( &p_sys->p_jpeg );
free( p_row_pointers );
-
block_Release( p_block );
return NULL;
}
--
2.7.4
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