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libmpg123: check for ID3v2.4 update tags and replace old ID3v2 data otherwise

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This finally enables proper operation on concatenated files appearing as
one big stream with multiple embedded ID3v2 tags. The mode of actually
updating exiting data instead of replacing it has been tested by me before
this commit, but will lay dormant now until someone presents a file that
actually features an ID3v2.4 update tag.

There are parts of the spec that are just theoretical. I even looked at
a competing implementaton in taglib and didn't notice any extended header
parsing besides skipping it. So I guess hardly anyone ever bothered
implementing that part of the spec.



git-svn-id: svn://scm.orgis.org/mpg123/trunk@4609 35dc7657-300d-0410-a2e5-dc2837fedb53
This commit is contained in:
thor
2020-03-14 14:38:18 +00:00
parent 464d3b592b
commit bc28e60fe8
2 changed files with 73 additions and 6 deletions
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9
NEWS
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@@ -128,6 +128,15 @@ TODO: Make libout123 and/or mpg123 use that to convert on the fly. Optionally?
without feeding input, which was disabled by mistake. The use of
mpg123_read() (instead of mpg123_decode_frame()) with mpg123_open()
was broken in feederless builds since those were fixed in version 1.15.
-- Fix ID3v2 parser logic for multiple ID3v2 tags being encountered in one
stream. New tags replace old data instead of appending to it when the
extended header update flag is not set (ID3v2.4). Update tags only
replace data that shall be unique. So far, I have never seen an update
tag in the wild, so the check for the flag is untested. The mechanism
of replacing parts of existing tag data has been tested, though.
Note that the updated libmpg123 also avoids a growing ID3 data structure
when repeatedly seeking back to the beginning in a file with disabled
seek index.
1.25.13
-------

70
src/libmpg123/id3.c
View File

@@ -845,9 +845,11 @@ int store_id3v2( mpg123_handle *fr
int parse_new_id3(mpg123_handle *fr, unsigned long first4bytes)
{
#define UNSYNC_FLAG 128
#define EXTHEAD_FLAG 64
#define EXTHEAD_FLAG 64 /* ID3v2.3+ */
#define COMPRESS_FLAG 64 /* ID3v2.2 */
#define EXP_FLAG 32
#define FOOTER_FLAG 16
#define EXT_UPDATE_FLAG 64 /* ID3v2.4 only: extended header update flag */
#define UNKNOWN_FLAGS 15 /* 00001111*/
unsigned char buf[6];
unsigned long length=0;
@@ -931,6 +933,14 @@ int parse_new_id3(mpg123_handle *fr, unsigned long first4bytes)
, major, flags );
skiptag = 1;
}
// Standard says that compressed tags should be ignored as there isn't an agreed
// compressoion scheme.
if(major == 2 && flags & COMPRESS_FLAG)
{
if(NOQUIET)
warning("ID3v2: ignoring compressed ID3v2.2 tag");
skiptag = 1;
}
if(length < 10)
{
if(NOQUIET)
@@ -949,6 +959,9 @@ int parse_new_id3(mpg123_handle *fr, unsigned long first4bytes)
#ifndef NO_ID3V2
if(skiptag)
{
if(VERBOSE3)
fprintf(stderr, "Note: skipped tag clearing possibly existing ID3v2 data");
reset_id3(fr); // Old data is invalid.
#endif
if(!storetag && (ret2=fr->rd->skip_bytes(fr,length+footlen))<0)
ret=ret2;
@@ -957,30 +970,62 @@ int parse_new_id3(mpg123_handle *fr, unsigned long first4bytes)
else
{
unsigned char* tagdata = fr->id3v2_raw+10;
fr->id3v2.version = major;
/* try to interpret that beast */
debug("ID3v2: analysing frames...");
if(length > 0)
{
unsigned char extflags = 0;
unsigned long tagpos = 0;
/* bytes of frame title and of framesize value */
unsigned int head_part = fr->id3v2.version > 2 ? 4 : 3;
unsigned int flag_part = fr->id3v2.version > 2 ? 2 : 0;
unsigned int head_part = major > 2 ? 4 : 3;
unsigned int flag_part = major > 2 ? 2 : 0;
/* The amount of bytes that are unconditionally read for each frame: */
/* ID, size, flags. */
unsigned int framebegin = head_part+head_part+flag_part;
debug1("ID3v2: have read at all %lu bytes for the tag now", (unsigned long)length+6);
if(flags & EXTHEAD_FLAG)
{
debug("ID3v2: skipping extended header");
debug("ID3v2: extended header");
if(!bytes_to_long(tagdata, tagpos) || tagpos >= length)
{
ret = 0;
if(NOQUIET)
error4( "Bad (non-synchsafe/too large) tag offset:"
error4( "Bad (non-synchsafe/too large) tag offset from extended header:"
"0x%02x%02x%02x%02x"
, tagdata[0], tagdata[1], tagdata[2], tagdata[3] );
} else if(tagpos < 6)
{
ret = 0;
if(NOQUIET)
merror("Extended header too small (%lu).", tagpos);
}
if(major == 3)
{
tagpos += 4; // The size itself is not included.
if(tagpos >= length)
{
ret = 0;
if(NOQUIET)
error("Too much extended v2.3 header.");
}
} else if(ret) // v2.4 and at least got my 6 bytes of ext header
{
// Only v4 knows update frames, check for that.
// Need to step back. Header is 4 bytes length, one byte flag size,
// one byte flags. Flag size has to be 1!
if(tagdata[4] == 1 && tagdata[5] & EXT_UPDATE_FLAG)
{
if(VERBOSE3)
fprintf(stderr, "Note: ID3v2.4 update tag\n");
extflags |= EXT_UPDATE_FLAG;
}
}
}
if(!(extflags & EXT_UPDATE_FLAG))
{
if(VERBOSE3)
fprintf(stderr, "Note: non-update tag replacing existing ID3v2 data\n");
reset_id3(fr);
}
if(ret > 0)
{
@@ -988,6 +1033,7 @@ int parse_new_id3(mpg123_handle *fr, unsigned long first4bytes)
unsigned long framesize;
unsigned long fflags; /* need 16 bits, actually */
id[4] = 0;
fr->id3v2.version = major;
/* Pos now advanced after ext head, now a frame has to follow. */
/* Note: tagpos <= length, which is 28 bit integer, so both */
/* far away from overflow for adding known small values. */
@@ -1182,7 +1228,17 @@ int parse_new_id3(mpg123_handle *fr, unsigned long first4bytes)
else break;
#undef KNOWN_FRAMES
}
} else
{
if(VERBOSE3)
fprintf(stderr, "Note: faulty ID3v2 tag still clearing old data\n");
reset_id3(fr);
}
} else // No new data, but still there was a tag that invalidates old data.
{
if(VERBOSE3)
fprintf(stderr, "Note: empty ID3v2 clearing old data\n");
reset_id3(fr);
}
tagparse_cleanup:
/* Get rid of stored raw data that should not be kept. */
@@ -1197,8 +1253,10 @@ tagparse_cleanup:
return ret;
#undef UNSYNC_FLAG
#undef EXTHEAD_FLAG
#undef COMPRESS_FLAG
#undef EXP_FLAG
#undef FOOTER_FLAG
#undef EXT_UPDATE_FLAG
#undef UNKOWN_FLAGS
}