Subject: Re: [Cellar] ReferenceTimecode tracks in Matroska proposal

From: Kieran O Leary <[email-masked]>
Date: Mon, 28 Nov 2016 20:59:52 +0000

Hello all,

I'm wondering about the status of timecode within Matroska. Rereading the
thread, I really like Jerome's idea for (if I understand correctly)
remuxing preexisting timecode tracks within matroska,  such as a quicktime
tmcd track. I am not very knowledgeable about timecode so I would love to
hear what other archivists think,as well as what broadcast users/developers
think.

I see the lack of timecode support as being the last (imo) barrier to entry
for adopting Matroska in an archive.

The only files that I encounter seem to just store information about the
first frame, so if the timecode resets to zero on a tape, this isn't
reflected in the resulting file. It would be good to hear from users with
different types of timecode tracks as well,as my experience is relatively
limited.

Best,

Kieran

---

From: Jerome Martinez <[email-masked]>
Date: Mon, 28 Nov 2016 22:13:37 +0100

Le 28/11/2016 à 21:59, Kieran O Leary a écrit :
>
> Hello all,
>
> I'm wondering about the status of timecode within Matroska. Rereading 
> the thread, I really like Jerome's idea for (if I understand 
> correctly)  remuxing preexisting timecode tracks within matroska,  
> such as a quicktime tmcd track. I am not very knowledgeable about 
> timecode so I would love to hear what other archivists think,as well 
> as what broadcast users/developers think.
>

This is on my todo-list, sorry for the delay.

> I see the lack of timecode support as being the last (imo) barrier to 
> entry for adopting Matroska in an archive.
>
> The only files that I encounter seem to just store information about 
> the first frame, so if the timecode resets to zero on a tape, this 
> isn't reflected in the resulting file. It would be good to hear from 
> users with different types of timecode tracks as well,as my experience 
> is relatively limited.
>

It highly depends of the source of your encode. e.g.
- MOV may have both information about the first frame or information 
about all frames
- MXF can have a MXF timecode track (information about the first frame 
only), SDTI (information about all frames) or System Scheme (information 
about all frames), or ATC in VANC (information about all frames).
- GXF can have both information about the first frame or information 
about all frames.

All in their own formats :).
I'll try to find a good method for describing all of them.

Jérôme

---

From: Kieran O Leary <[email-masked]>
Date: Tue, 29 Nov 2016 10:32:31 +0000

Hi,

> This is on my todo-list, sorry for the delay.
Great to hear!

> - MOV may have both information about the first frame or information about
> all frames
> - GXF can have both information about the first frame or information about
> all frames.
>
Even better to hear :) I would assume that this would require some changes
to ffmpeg too as there is a generic warning at the moment when a user
attempts to include a data track in a Matroska file. https://github.com/
FFmpeg/FFmpeg/blob/master/libavformat/matroskaenc.c#L1271

Best,

Kieran.

---

From: "Peter B." <[email-masked]>
Date: Tue, 29 Nov 2016 16:18:01 +0100

> for adopting Matroska in an archive.

I'm also not really experienced with timecodes, but I can confirm
Kieran's suspicion.

Although I would say that most non-production archives don't have to
deal with timecode, institutions that *do* have tapes with timecode in
their collection told me they were limited (and therefore sticking) to
either MOV or MXF as container (for the time being).

Kind regards,
Pb