MediaInfo fails to read duplicate Vorbis Comment tags for opus audio codec tracks in matroska files

[Ironclad17]

Please refer to this closed mkvtoolnix issue. https://gitlab.com/mbunkus/mkvtoolnix/-/issues/3804#note_2381681793

While mediainfo does correctly identify both "Encoder" tags in the original opus file under "Encoded_Application", when the same tracks are read from a matroska file, it fails to identify the first tag.

[cjee21]

A sample file or steps to create such a file would help. I could not create a file with such tags using opus-tools and FFmpeg.

[cjee21]

Okay, if I manually add the additional tag using a file tagger this can be reproduced.

MediaInfo:

Audio
ID                                       : 1
Format                                   : Opus
Codec ID                                 : A_OPUS
Duration                                 : 988 ms
Bit rate                                 : 1 215 b/s
Channel(s)                               : 2 channels
Channel layout                           : L R
Sampling rate                            : 48.0 kHz
Frame rate                               : 50.616 FPS (948 SPF)
Compression mode                         : Lossy
Stream size                              : 150 Bytes (2%)
Writing library                          : Lavf61.7.100
Default                                  : Yes
Forced                                   : No

Trace:

1663    SimpleTag (54 bytes)
1663     Header (3 bytes)
1663      Name:                              10184 (0x27C8)
1665      Size:                              51 (0x33)
1666     TagName - ENCODER (10 bytes)
1666      Header (3 bytes)
1666       Name:                             1443 (0x05A3)
1668       Size:                             7 (0x07)
1669      Data:                              ENCODER
1670     TagString - opusenc from opus-tools 0.2-3-gf5f571b (41 bytes)
1670      Header (3 bytes)
1670       Name:                             1159 (0x0487)
1672       Size:                             38 (0x26)
1673      Data:                              opusenc from opus-tools 0.2-3-gf5f571b
1699    SimpleTag (28 bytes)
1699     Header (3 bytes)
1699      Name:                              10184 (0x27C8)
169B      Size:                              25 (0x19)
169C     TagName - ENCODER (10 bytes)
169C      Header (3 bytes)
169C       Name:                             1443 (0x05A3)
169E       Size:                             7 (0x07)
169F      Data:                              ENCODER
16A6     TagString - Lavf61.7.100 (15 bytes)
16A6      Header (3 bytes)
16A6       Name:                             1159 (0x0487)
16A8       Size:                             12 (0x0C)
16A9      Data:                              Lavf61.7.100

So MediaInfo did pick up the two tags but only the second one is shown. I am guessing the first was overwritten.