[Cin] Cinelerra CV direct copy feature demo

[Andrew Randrianasulu]

ср, 2 нояб. 2022 г., 17:59 Terje J. Hanssen <terjejhanssen at gmail.com>:

>
> On Fri Oct 28 02:35:53 CEST 2022, Andrew Randrianasulu wrote:
>
>
> Recorded with Cin-GG :-)
>
> https://youtu.be/7pXG5cnjckQ
> 5min or so ....
>
>
> I put in an extract of section 20.5 of the CinCV manual here:
> http://cinelerra-cv.wikidot.com/cincv-manual-en:rendering-files
>
> Most of the time you will want to bring in the rendered output and fine
> tune the timing on the timeline. Also some file formats like MPEG can not
> be direct copied. Because of this, the jobs are left in individual files.
>
> You can load these by creating a new track and specifying concatenate to
> existing tracks in the load dialog. Files which support direct copy can be
> concatenated into a single file by rendering to the same file format with
> renderfarm disabled. Also to get direct copy, the track dimensions, output
> dimensions, and asset dimensions must be equal.
>
> MPEG files or files which do not support direct copy have to be
> concatenated with a command line utility. MPEG files can be concatenated
> with cat.
>
> By reading the parallell email thread "[Cin] fileexr/fileppm direct copy
> support", I wonder if this isn't equivalent to some other NLE's "Smart
> Rendering" or "by-pass re-encode/compression when possible"?
>


partially, but sadly not (yet) smart enough for dealing with non-i-only
files ...

there was interesting piece of code potentially decompressing anything
ffmpeg can decode in fileyuv in CinCV, but this need some encoding
counterpart and also more info passing  between assets, edits and
renderer....


https://github.com/cinelerra-cv-team/cinelerra-cv/commit/0ff51f4c53e17ff33701e8cc1096de33a87313b9


  If so it would be fine to get this dealed with in the CinGG manual ....?
>



CinGG as for now accelerates _image sequences_ in this way, due to our
de/muxer moved from dedicated libquicktime-based filemov.c into more
complete but complex ffmpeg.c's libavformat de/muxer.


so, no hdv copy in this mode yet (at least automatic)
May be you can rig avidemux or ffprobe for noting hdv keyframes and set
cuts in cin on those boundaries, but this is time-consuming....

https://forum.blackmagicdesign.com/viewtopic.php?f=21&t=157600
> https://www.kevinmonahan.net/?p=88
>


thanks for links, will look into them.

>
>
> And maybe also another CinGG theme "HDV on a Blu-ray without re-encode" as
> discussed earlier, is related and needs some manual update?
>
> https://cinelerra-gg.org/download/CinelerraGG_Manual/HDV_on_Blu_ray_Disc_Without.html
> https://www.mail-archive.com/cin@lists.cinelerra-gg.org/msg03520.html
>

As far as I understand problem for mpeg like codecs  you must re-encode not
just frames you altered, but also frames between your cut and codec-defined
input keyframes, and this kind of info simply not wired inside cinelerra
.... I'll try to download ffprobe-based I-frames finder as prototyped by
Bill long time ago and play with its output as guidance for cutting mpeg2
like streams


but just for unexpected side of video decoding at some time Natron
apparently had weird reordering problem on reading mp4 files, probably due
to in-decoder reordering ...some fun (eh) to code for ...

https://github.com/NatronGitHub/Natron/issues/555


>
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