MP4 Name Truncation Issue

[LeeThompson]

Originally I thought this was a mp4box (GPAC) issue (see https://github.com/gpac/gpac/issues/1416) but after working with them I've found it's a mediainfo issue.

I should stress is this a cosmetic issue and the file's metadata is fine.

The issue is this, sometimes (roughly 1 in 200) mediainfo truncates the first character of an MP4 (ISO) container track so if you've named the track "Commentary with Director Guy" it will show "ommentary with Director Guy". This occurs in all view modes.

hex view of mp4 file:

000ABA30  00 00 00 00 00 00 00 00 00 00 04 7B 8C 6D 64 69    ...........{Œmdi
000ABA40  61 00 00 00 20 6D 64 68 64 00 00 00 00 DB 8E AB    a... mdhd....ێ«
000ABA50  8B DB 8E AB 8C 00 00 BB 80 03 EE 44 00 15 C7 00    ‹ÛŽ«Œ..»€.îD..Ç.
000ABA60  00 00 00 00 65 68 64 6C 72 00 00 00 00 00 00 00    ....ehdlr.......
000ABA70  00 73 6F 75 6E 00 00 00 00 00 00 00 00 00 00 00    .soun...........
000ABA80  00 43 6F 6D 6D 65 6E 74 61 72 79 20 77 69 74 68    .Commentary with
000ABA90  20 4A 61 63 6B 73 6F 6E 20 50 75 62 6C 69 63 6B     Jackson Publick
000ABAA0  2C 20 44 6F 63 20 48 61 6D 6D 65 72 20 61 6E 64    , Doc Hammer and
000ABAB0  20 41 63 74 6F 72 20 4A 61 6D 65 73 20 55 72 62     Actor James Urb
000ABAC0  61 6E 69 61 6B 00 00 04 7A FF 6D 69 6E 66 00 00    aniak...zÿminf..

Mediainfo (20.08) output:

Audio #3
ID/String                        : 4
Format/String                    : AAC LC
Format/Info                      : Advanced Audio Codec Low Complexity
CodecID                          : mp4a-40-2
Duration/String                  : 22 min 53 s
BitRate_Mode/String              : Variable
BitRate/String                   : 160 kb/s
BitRate_Maximum/String           : 165 kb/s
Channel(s)/String                : 2 channels
ChannelLayout                    : L R
SamplingRate/String              : 48.0 kHz
FrameRate/String                 : 46.875 FPS (1024 SPF)
Compression_Mode/String          : Lossy
StreamSize/String                : 26.2 MiB (10%)
Title                            : ommentary with Jackson Publick, Doc Hammer and Actor James Urbaniak
Language/String                  : English
Encoded_Date                     : UTC 2020-09-21 19:12:11
Tagged_Date                      : UTC 2020-09-21 20:31:49

[ksarnelli]

Any update on this? I've been noticing this a lot too.

[JeromeMartinez]

I have an idea about what it is, please share a file demonstrating this issue.