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

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

[Stephen McConnachie]

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.

All the best,
Stephen

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

[Michael Niedermayer]

[-- Attachment #1.1: Type: text/plain, Size: 1723 bytes --]

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

[Paul B Mahol]

On Mon, Jul 18, 2022 at 7:14 PM Michael Niedermayer <michael@niedermayer.cc>
wrote:

> 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.
>

Perhaps it there are clear specifications I could.


>
> 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
>
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel@ffmpeg.org
> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>
> To unsubscribe, visit link above, or email
> ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".
>
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Re: [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@ffmpeg.org> On Behalf Of Michael Niedermayer
Sent: 18 July 2022 18:14
To: FFmpeg development discussions and patches <ffmpeg-devel@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



The British Film Institute is governed by Royal Charter and is a charity registered in England and Wales number 287780. The contents of this e-mail are confidential and may be legally privileged. If you are not the intended recipient, kindly notify the sender that you have received this message in error and immediately delete it. Unless you are the intended recipient, you may not forward this e-mail to anybody, nor make any use of its contents.

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