[FFmpeg-devel] Development opportunity: LTC noise on files created from videotape source: filter idea

[Stephen McConnachie]

> It should be possible to implement a LTC decoder that turns a audio track into LTC binary data. If that succeeded and the data is valid then teh track would very likely have contained LTC.

I was hoping that would be achievable, thank you Michael. For context, this site has a pretty good explanation of LTC -  http://www.philrees.co.uk/articles/timecode.htm 

>Do i understand correctly that the tracks are LTC or normal audio not mixed?
>or are there tracks that mix audio and LTC and require seperation ?

Yes your understanding is accurate - the LTC and the other audio (Mix / FX) tracks are discrete, not mixed - and in the encoding to FFV1 MKV the LTC-derived stream is a discrete stream.

>I think there are several developers who could develop such filter.
>I could do it, Iam sure paul could do as well.

Thank you! Dave Rice explained that he had made a start on this idea, and asked me for samples of files with LTC-derived audio - I will send Dave samples, and come back to you if I need to explore other options too.

Cheers,
Stephen

-----Original Message-----
From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of Michael Niedermayer
Sent: 18 July 2022 18:14
To: FFmpeg development discussions and patches <ffmpeg-devel at ffmpeg.org>
Subject: Re: [FFmpeg-devel] Development opportunity: LTC noise on files created from videotape source: filter idea

Attention. This email originated outside the BFI. Please be extra vigilant when opening attachments or clicking links.
On Mon, Jul 18, 2022 at 09:53:14AM +0000, Stephen McConnachie wrote:
> Hi FFMPEG developers,
> 
> I have a proposal for a paid development opportunity to add a filter to FFMPEG.
> 
> I followed the advice on the FFMPEG Consulting page at https://ffmpeg.org/consulting.html and am emailing this list to try to identify if any of the FFMPEG developers may be able to take on a development commission.
> 
> Background: we are digitising high volumes of videotape carriers, and have identified a common case in some videotape formats where Linear Time Code from the tape carrier is present on audio stream 1 in the encoded file - manifesting as a continuous noise.
> 
> Idea: could a filter be developed in FFMPEG, based on example files we can provide, to identify the presence of an LTC-derived audio stream, and additionally identify which of the streams is the LTC stream.
> 
> If this filter idea sounds achievable, I would aim to identify which of the FFMPEG developers may be able to take on this work, and estimated costs and timeline.

It should be possible to implement a LTC decoder that turns a audio track into LTC binary data. If that succeeded and the data is valid then teh track would very likely have contained LTC.

Do i understand correctly that the tracks are LTC or normal audio not mixed?
or are there tracks that mix audio and LTC and require seperation ?

I think there are several developers who could develop such filter.
I could do it, Iam sure paul could do as well.

thx

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

"I am not trying to be anyone's saviour, I'm trying to think about the  future and not be sad" - Elon Musk



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