mp4 track names

[Drakul]

Hi all guys, i'm using vlc 1.1.2 and i noted that vlc doesn't show the name of the video/audio tracks of an mp4 container(neither in the track selection nor in the codec details) as it does with an mkv. In case of an mp4 container, vlc only shows the language type.
Is there a fix for this?

[Lotesdelere]

I second that, that would be nice

As you said, VLC can already do it for MKV so why not for MP4 as well ?

[Drakul]

Well, at least i think someone around here saw this post, so... i'm hoping for a fix, if possible.
bye

[Jean-Baptiste Kempf]

What atom?

[Drakul]

What atom?

If i'm not wrong, should be the hdlr atom for the tracks

[Jean-Baptiste Kempf]

which is the handler, not the name.

[Drakul]

Do you mean the atom at which hdlr belongs to?

[Lotesdelere]

which is the handler, not the name.

With a MP4 file muxed and tagged with MP4Box being compliant with the MPEG-4 Base Media ISOM standard where the video track is named "H.264/AVC Video" and the audio track is named "AAC LC Audio" we can get the following information:

That's from VLC messages log:

Code: Select all

mp4 debug: found Box: hdlr size 48 mp4 debug: read box: "hdlr" handler type vide name H.264/AVC Video mp4 debug: found Box: hdlr size 45 mp4 debug: read box: "hdlr" handler type soun name AAC LC Audio

And when using MP4v2 trunk-r355 tools:

That's from MP4file tool:

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type hdlr (moov.trak.mdia.hdlr) version = 0 (0x00) flags = 0 (0x000000) reserved1 = <4 bytes> 00 00 00 00 |....| handlerType = vide reserved2 = <12 bytes> 00 00 00 00 00 00 00 00 00 00 00 00 |............| name = H.264/AVC Video type hdlr (moov.trak.mdia.hdlr) version = 0 (0x00) flags = 0 (0x000000) reserved1 = <4 bytes> 00 00 00 00 |....| handlerType = soun reserved2 = <12 bytes> 00 00 00 00 00 00 00 00 00 00 00 00 |............| name = AAC LC Audio

That's from MP4track tool:

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track[0] id=1 type = video enabled = true inMovie = false inPreview = false layer = 0 alternateGroup = 0 volume = 0.0000 width = 480.00000000 height = 360.00000000 language = English handlerName = H.264/AVC Video userDataName = <absent> track[1] id=2 type = audio enabled = true inMovie = false inPreview = false layer = 0 alternateGroup = 0 volume = 1.0000 width = 0.00000000 height = 0.00000000 language = English handlerName = AAC LC Audio userDataName = <absent>

[Drakul]

I'm sorry, i can't tell you more detailed information because i don't know much of mp4 implementation, however, saying track names, i'm refering to those names that you set through mp4box (with the syntax -add video.h264:name=TrackName) while adding tracks before muxing. That 'TrackName' is written inside the component name field of the handler reference atom contained in the mdia atom(just after the mdhd atom). Various programs(like media info etc.) report that strings as video/audio name(or title, something like that).
It would be nice to show that name when you select a track in a mp4 with multiple tracks(like vlc does with mkv as i said).
It's not a real bug, but only a detail that could be useful for people(like me ) that handle mp4 files.