[flac-dev] A couple of questions about channel mapping

lvqcl lvqcl.mail at gmail.com
Thu Jul 16 14:52:28 PDT 2015


1) It seems that some programs (eac3to) write the value of
WAVEFORMATEXTENSIBLE_CHANNEL_MASK tag with uppercase 'x' (e.g. 0X3)
(see <http://forum.doom9.org/showthread.php?p=1728852#post1728852>)

Also, from MediaInfo changelog <https://mediaarea.net/MediaInfo/ChangeLog>:
Version 0.7.74, 2015-05-25
x VorbisComment: WAVEFORMATEXTENSIBLE_CHANNEL_MASK "0X" ("x" in uppercase) is accepted now

In flac we have:
     if(strncmp(p, "=0x", 3))
         return false;
so it's case-sensitive. Should it be changed to case-insensitive FLAC__STRNCASECMP?



2) Previously flac accepted mono files with 0x0001 channel mask; mono files
with correct value (0x0004 = front center) were rejected without --channel-map=none option.
(see <http://sourceforge.net/p/flac/feature-requests/96/>)

It was fixed, but now flac accepts mono files with three different channel masks:
0x0001 (FL), 0x0002 (FR), 0x0004 (FC).

Should flac reject the first two masks when there's no --channel-map=none option?


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