randrianasulu at gmail.com
Tue Feb 12 21:51:17 CET 2019
В сообщении от Tuesday 12 February 2019 23:35:50 edouard chalaron написал(а):
> Hello all
> Raw video from machine visions can be handled like that
> ffmpeg -threads 4 -f rawvideo -pixel_format bgr24 -r 16 -video_size
> 2332x1752 -i reel02_dec -pix_fmt rgb24 -vcodec qtrle -r 16
> another example for 48 bits
> ffmpeg -threads 4 -f rawvideo -pixel_format bgr48 -video_size 2332x1404
> -i Reel3976_dec -pix_fmt rgb48 whatever_codec_one_wants_to_use
> I believe trying to incorporate it into Cinelerra is a bit pointless,
> if anything an export in TIFF files proves to work faster and Cinelerra
> is already equipped for that.
Point was to avoid huge intermediate files, I think, and save some time, too.
But well, ffmpeg apparently handles those files a bit wrongly - for example by
default it tries to stuff data into just rgb24 - probably ok for display, but
whole point of those huge raw files was additional color precision (and
avoidance of h264 artefacts).
So, I've taken the plunge and moved to RAW. I have hundreds of gigabytes
(seriously) of artifact-free footage recorded in the latest Magic Lantern MLV
(RAW v2) file format. Now what. How do I watch it?
The tools seem to be lagging a bit behind here. The start of most "workflow"
right now is to use the mlv2dng tool to create individual files for each raw
frame in the video in Adobe's widely understood DNG format.
If you have a Mac or Windows, those thousands of DNGS can then be imported
either into a tool like Adobe After Effects, or DaVinci Resolve (which
currently needs an NVIDIA GPU). Those allow fine control of colour mapping
(usually called "grading") and other effects using the full colur resolution,
before you finally convert the result into a compressed video.
If you're using Linux, like me, different options are needed. A not-so-quick but
dirty way to preview the video is to use a couple of commands like:
dcraw -T *.dng
ffmpeg -i %6d.tiff -vcodec mjpeg -r 25 -q:v 1 video.avi
This can still take a little while to churn through the images, and then ffmpeg
doesn't always seem to do a great job mapping the colour ranges. But it works.
Only don't forget to delete all the intermediate files afterwards otherwise you
will have quintupled your file space.
This approach quickly got tedious for me after working with more than a few
videos. What I really wanted was something that could just play all the raw
videos directly like any other video format, so I could decide which ones
deserved further editing.
--------------end of quote----
quote above talks about MLV files specifically
> Depending on the machine bgr24/48 may need to be rgb24/48. I use either
> of them depending on the camera I use
> Only if my assumption of the rawvideo concept is what we are talking
> about here !CheersEd
> On Tue, 2019-02-12 at 12:53 -0700, Phyllis Smith wrote:
> > This morning GG had time to look at this. (BTW, he is not much for
> > reading or writing email so I have to let him know and then type in
> > his response, so sometimes I do not get it all conveyed correctly).
> > When I initially read only a few of the 86 pages, I searched for some
> > download MLV examples and downloaded a couple from one place and then
> > 1 from where Andrew mentioned. Apparently ffmpeg can load them into
> > cinelerra and the Video compression in Info is rawvideo, but of
> > course they look awful as is (maybe a proper LUT would solve this?).
> > We also checked to see if "dcraw" of Dave Coffin handles this raw
> > format as that is his area of expertise and saw no reference on his
> > web site concerning Magic Lantern. But we still tried using
> > Cinelerra's probe order in Settings to see whether his included
> > program handled it. It did not.
> > Bottom line is that if there is ever a user who really needs to be
> > able to handle MLV files in cinelerra, gg could see about doing that
> > and will keep this in mind. gg/Phyllis
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