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Automatically orient JPEG image based on orientation flag, if present
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>
This commit is contained in:
Wayne McDougall
Jean-Baptiste Kempf
parent
c33cdace3b
commit
16b5785805
1
NEWS
1
NEWS
@ -67,6 +67,7 @@ Decoder:
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supporting H.263, H.264/MPEG-4 AVC, MPEG-4 Part 2, and DV depending on device
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and OS version
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* Support for the OggSpots video codec
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* JPEG images correctly oriented using embedded orientation tag, if present
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Demuxers:
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* Support HD-DVD .evo (H.264, VC-1, MPEG-2, PCM, AC-3, E-AC3, MLP, DTS)
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@ -1,7 +1,7 @@
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/*****************************************************************************
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* jpeg.c: jpeg decoder module making use of libjpeg.
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*****************************************************************************
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* Copyright (C) 2013-2014 VLC authors and VideoLAN
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* Copyright (C) 2013-2014,2016 VLC authors and VideoLAN
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*
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* Authors: Maxim Bublis <b@codemonkey.ru>
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*
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@ -181,6 +181,220 @@ static int OpenDecoder(vlc_object_t *p_this)
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return VLC_SUCCESS;
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}
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/*
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* The following two functions are used to return 16 and 32 bit values from
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* the EXIF tag structure. That structure is borrowed from TIFF files and may be
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* in big endian or little endian format. The endian parameter tells us which.
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* Case Little Endian EXIF tag / Little Endian machine
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* - just memcpy the tag structure into the value to return
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* Case Little Endian EXIF tag / Big Endian machine
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* - memcpy the tag structure into value, and bswap it
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* Case Little Endian EXIF tag / Big Endian machine
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* - memcpy the tag structure into value, and bswap it
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* Case Big Endian EXIF tag / Big Endian machine
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* - just memcpy the tag structure into the value to return
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*
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* While there are byte manipulation functions in vlc_common.h, none of them
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* address that format of the data supplied may be either big or little endian.
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*
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* The claim is made that this is the best way to do it. Can you do better?
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*/
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#define G_LITTLE_ENDIAN 1234
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#define G_BIG_ENDIAN 4321
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LOCAL( unsigned short )
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de_get16( void * ptr, uint endian ) {
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unsigned short val;
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memcpy( &val, ptr, sizeof( val ) );
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if ( endian == G_BIG_ENDIAN )
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{
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#ifndef WORDS_BIGENDIAN
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val = bswap16( val );
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#endif
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}
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else
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{
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#ifdef WORDS_BIGENDIAN
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val = bswap16( val );
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#endif
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}
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return val;
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}
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LOCAL( unsigned int )
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de_get32( void * ptr, uint endian ) {
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unsigned int val;
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memcpy( &val, ptr, sizeof( val ) );
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if ( endian == G_BIG_ENDIAN )
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{
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#ifndef WORDS_BIGENDIAN
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val = bswap32( val );
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#endif
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}
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else
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{
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#ifdef WORDS_BIGENDIAN
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val = bswap32( val );
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#endif
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}
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return val;
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}
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/*
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* Look through the meta data in the libjpeg decompress structure to determine
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* if an EXIF Orientation tag is present. If so return its value (1-8),
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* otherwise return 0
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*
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* This function is based on the function get_orientation in io-jpeg.c, part of
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* the GdkPixbuf library, licensed under LGPLv2+.
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* Copyright (C) 1999 Michael Zucchi, The Free Software Foundation
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*/
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LOCAL( int )
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jpeg_GetOrientation( j_decompress_ptr cinfo )
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{
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uint i; /* index into working buffer */
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ushort tag_type; /* endianed tag type extracted from tiff header */
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uint ret; /* Return value */
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uint offset; /* de-endianed offset in various situations */
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uint tags; /* number of tags in current ifd */
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uint type; /* de-endianed type of tag */
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uint count; /* de-endianed count of elements in a tag */
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uint tiff = 0; /* offset to active tiff header */
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uint endian = 0; /* detected endian of data */
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jpeg_saved_marker_ptr exif_marker; /* Location of the Exif APP1 marker */
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jpeg_saved_marker_ptr cmarker; /* Location to check for Exif APP1 marker */
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const char leth[] = { 0x49, 0x49, 0x2a, 0x00 }; /* Little endian TIFF header */
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const char beth[] = { 0x4d, 0x4d, 0x00, 0x2a }; /* Big endian TIFF header */
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#define EXIF_JPEG_MARKER 0xE1
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#define EXIF_IDENT_STRING "Exif\000\000"
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#define EXIF_ORIENT_TAGID 0x112
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/* check for Exif marker (also called the APP1 marker) */
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exif_marker = NULL;
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cmarker = cinfo->marker_list;
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while ( cmarker )
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{
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if ( cmarker->marker == EXIF_JPEG_MARKER )
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{
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/* The Exif APP1 marker should contain a unique
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identification string ("Exif\0\0"). Check for it. */
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if ( !memcmp( cmarker->data, EXIF_IDENT_STRING, 6 ) )
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{
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exif_marker = cmarker;
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}
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}
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cmarker = cmarker->next;
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}
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/* Did we find the Exif APP1 marker? */
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if ( exif_marker == NULL )
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return 0;
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/* Do we have enough data? */
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if ( exif_marker->data_length < 32 )
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return 0;
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/* Check for TIFF header and catch endianess */
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i = 0;
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/* Just skip data until TIFF header - it should be within 16 bytes from marker start.
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Normal structure relative to APP1 marker -
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0x0000: APP1 marker entry = 2 bytes
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0x0002: APP1 length entry = 2 bytes
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0x0004: Exif Identifier entry = 6 bytes
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0x000A: Start of TIFF header (Byte order entry) - 4 bytes
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- This is what we look for, to determine endianess.
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0x000E: 0th IFD offset pointer - 4 bytes
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exif_marker->data points to the first data after the APP1 marker
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and length entries, which is the exif identification string.
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The TIFF header should thus normally be found at i=6, below,
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and the pointer to IFD0 will be at 6+4 = 10.
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*/
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while ( i < 16 )
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{
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/* Little endian TIFF header */
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if ( memcmp( &exif_marker->data[i], leth, 4 ) == 0 )
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{
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endian = G_LITTLE_ENDIAN;
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}
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/* Big endian TIFF header */
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else
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if ( memcmp( &exif_marker->data[i], beth, 4 ) == 0 )
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{
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endian = G_BIG_ENDIAN;
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}
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/* Keep looking through buffer */
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else
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{
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i++;
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continue;
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}
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/* We have found either big or little endian TIFF header */
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tiff = i;
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break;
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}
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/* So did we find a TIFF header or did we just hit end of buffer? */
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if ( tiff == 0 )
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return 0;
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/* Read out the offset pointer to IFD0 */
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offset = de_get32( &exif_marker->data[i] + 4, endian );
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i = i + offset;
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/* Check that we still are within the buffer and can read the tag count */
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if ( ( i + 2 ) > exif_marker->data_length )
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return 0;
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/* Find out how many tags we have in IFD0. As per the TIFF spec, the first
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two bytes of the IFD contain a count of the number of tags. */
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tags = de_get16( &exif_marker->data[i], endian );
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i = i + 2;
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/* Check that we still have enough data for all tags to check. The tags
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are listed in consecutive 12-byte blocks. The tag ID, type, size, and
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a pointer to the actual value, are packed into these 12 byte entries. */
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if ( ( i + tags * 12 ) > exif_marker->data_length )
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return 0;
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/* Check through IFD0 for tags of interest */
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while ( tags-- )
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{
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tag_type = de_get16( &exif_marker->data[i], endian );
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/* Is this the orientation tag? */
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if ( tag_type == EXIF_ORIENT_TAGID )
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{
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type = de_get16( &exif_marker->data[i + 2], endian );
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count = de_get32( &exif_marker->data[i + 4], endian );
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/* Check that type and count fields are OK. The orientation field
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will consist of a single (count=1) 2-byte integer (type=3). */
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if ( type != 3 || count != 1 )
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return 0;
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/* Return the orientation value. Within the 12-byte block, the
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pointer to the actual data is at offset 8. */
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ret = de_get16( &exif_marker->data[i + 8], endian );
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return ( ret <= 8 ) ? ret : 0;
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}
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/* move the pointer to the next 12-byte tag field. */
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i = i + 12;
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}
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return 0; /* No EXIF Orientation tag found */
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}
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/*
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* This function must be fed with a complete compressed frame.
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*/
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@ -214,6 +428,7 @@ static picture_t *DecodeBlock(decoder_t *p_dec, block_t **pp_block)
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jpeg_create_decompress(&p_sys->p_jpeg);
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jpeg_mem_src(&p_sys->p_jpeg, p_block->p_buffer, p_block->i_buffer);
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jpeg_save_markers( &p_sys->p_jpeg, EXIF_JPEG_MARKER, 0xffff );
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jpeg_read_header(&p_sys->p_jpeg, TRUE);
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p_sys->p_jpeg.out_color_space = JCS_RGB;
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@ -230,6 +445,14 @@ static picture_t *DecodeBlock(decoder_t *p_dec, block_t **pp_block)
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p_dec->fmt_out.video.i_gmask = 0x0000ff00;
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p_dec->fmt_out.video.i_bmask = 0x00ff0000;
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int i_otag; /* Orientation tag has valid range of 1-8. 1 is normal orientation, 0 = unspecified = normal */
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i_otag = jpeg_GetOrientation( &p_sys->p_jpeg );
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if ( i_otag > 1 )
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{
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msg_Dbg( p_dec, "Jpeg orientation is %d", i_otag );
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p_dec->fmt_out.video.orientation = ORIENT_FROM_EXIF( i_otag );
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}
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/* Get a new picture */
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p_pic = decoder_NewPicture(p_dec);
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if (!p_pic)
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