Question on CineForm CFHD with FFmpeg

[zabalex]

Hello team,

In my career I often work with various formats per clients' requests, and I normally have plenty of material available online on how to work those formats, mainly from ffmpeg documentation. But this time, I really am at a loss. Ffmpeg has only development references to this code from a few years ago, and nothing on usage material.

I've managed to pad my ffmpeg arguments to produce reasonably matching video format to what they requested in a sample, however, encoding their sample by simply using my parameters, I get bitrate from 248mb/s to 404mb/s, consequently, 593Mb file of 20 seconds jumps to 1Gb.
Most other parameters I've mapped more or less alright.

I came up with the following arguments to my ffmpeg run:

Code: Select all

ffmpeg -i <INPUTFILE.mov> <MY-FILTER> -vcodec cfhd -pix_fmt gbrap12le -field_order progressive -b:v 245699679 -framerate 29.97 -maxrate 245699679 -minrate 245699679 -map_metadata 0 <OUTPUTFILE.mov> 

Here goes the screenshot of json extracted dump of mediainfo from the source video:

Screen Shot 2021-10-26 at 9.49.17 PM.png (61.02 KiB) Viewed 3499 times

I appreciate any help, suggestion where I could go from here. Thanks a lot

[emcodem]

Hey @zabalex

hehe, i see you are still not using ffastrans but just throw ffmpeg user related questions here... this causes @admin to raise at least one eyebrown. Are you aware that the place to solve these kind of questions is the ffmpeg user group chat on libera? Did you try to post your question there?
So i tried your command but it was too hard to compare my mediainfo results with your original file's one as you posted a screenshot of some random program interpreting the mediainfo json instead of the original output, the number of potential differnces was just like huge.

So here is my advice for future questions like this (which you hopefully first try to solve on the ffmpeg user chat), is to make clear what exactly is your problem, e.g. you want to have the same framerate, bitrate, whatever

P.S. personally i'd never work with a propreitary codec at all, so don't expect too much deep interest from me here...

[zabalex]

Thank you Emcodem so much for your reply. Honestly I didn't know about Libera, I'm going to check it out right now.
To clarify my original question, I would like to have my output bitrate match as close as possible to the input one, but I get over 50% increase.

Another thing is, I think since about 2018 this CineForm codec went opensource, and some broadcasters, at least the one I'm working with today, consider this as a master format.

Anyway, I apologize if I was out of place asking this question here, I would like to adopt ffastrans, but the Windows-only environment is my stopping point.

[emcodem]

no worries, lemme know if you need help regarding the ffmpeg-user chat. It can be tedious, sometime you need to hang around a little and re-ask your question every hour or such hehe But usually i come to a result with the help of the guys there.

Another thing is, I think since about 2018 this CineForm codec went opensource, and some broadcasters, at least the one I'm working with today, consider this as a master format.

Ah yeah, i forgot about that... well done, they even have a SMPTE registration