GH5 - GH5 6K 10 bit 2X anamorphic transcoding - HELP!

buggz

buggz

Active member
- GH5 6K 2X anamorphic transcoding - HELP!

Hello,

I am trying to transcode GH5 6K 10 Bit - 2X anamorphic video, to something sane for the average person to playback.
VLC playback does not these files.
I'm guessing I need to transcode them to 1080P for the average TV to play them properly?
This should also be good for VLC playback, I would hope.

BTW, I am on a windoze PC, STILL Win7PRo, as I refuse to go to Win10.
I am also a hobbiest with a very stressful fultime job, so not much time to perform all of this properly.
Sigh, how I would love to to do this fulltime!

My biggest questions invove aspect ratio and rescalling.
Not really understanding this properly.

The excellent Mediainfo application reads the native files, MP4, as:
Format : MPEG-4
Format profile : Base Media / Version 2
Codec ID : mp42 (mp42/hvc1)
Bit rate : 192 Mb/s
Format : HEVC
Format/Info : High Efficiency Video Coding
Format profile : Main 10@L6@High
Codec ID : hvc1
Width : 4 992 pixels
Height : 3 744 pixels
Display aspect ratio : 4:3
Frame rate mode : Constant
Frame rate : 29.970 (30000/1001) FPS
Original frame rate : 59.940 (60000/1001) FPS
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 10 bits
Bits/(Pixel*Frame) : 0.343
Color range : Full
Color primaries : BT.709
Transfer characteristics : BT.709
Matrix coefficients : BT.709

I am using ffmpeg - ffmpeg-20170915-6743351-win64-static

ffmpeg.exe -threads 4 -i "F:\pics\GH5\2017-15Sept-homecoming\6K\copies\P1077002.MP4" -r 29.97 -vf "setdar=dar='2.666:1/1',scale=w=9984:h=3744,colormatrix=bt709:bt470bg" -c:v prores "F:\pics\GH5\2017-15Sept-homecoming\6K\copies\P1077002-transcode.mov"

Is this correct?
The thumbnail seems to be close.

I used the prores output as I wanted to try Davinci Resolve.
Though, I know I need to output 1080P to give to my family and friends.
 
buggz said:
I used the prores output as I wanted to try Davinci Resolve.
Click to expand...
Windows 7 is not supported by Resolve.
I would advice you upgrade to Windows 10 if you want to use Resolve. You are asking for problems if you use Resolve with Windows 7.

Why do you want to use a colormatrix conversion? There is no need, HD is Rec.709.
Also colormatrix conversions in ffmpeg might not be 10 bit safe for ProRes.

I would make sure you test your workflow because you start with full range and you will have to end with limited range, so you have to make sure nothing is clipped and instead gracefully brought in the the legal range.

I would not change the DAR, just keep it 1:1 and just resize the footage to the preferred horizontal size and calculate the vertical size.
 
Last edited:
Yeah, I think that is for Davinci Resolve V14

I am still using Studio V12.5 with my dongle under Win7Pro.
Guess I will be building yet another Linux box.
Though, that will have to wait until next year.
Sigh...

Cary Knoop said:
Windows 7 is not supported by Resolve.
I would advice you upgrade to Windows 10 if you want to use Resolve.
Click to expand...
 
FFMPEG is a pain to batch transcode. Just use Handbrake. It useses FFMPEG as it's transcoder. It has a ton of presets that will suit your need or create your own.
 
Simple transcode from GH5 "6K" 2X 4:3 anamorphic to 1920/1080 via ffmpeg:

D:\ffmpeg-20170915-6743351-win64-static\bin\ffmpeg -threads 4 -i P1077005.MP4 -r 29.97 -metadata copyright="© buggz - 2017" -vf scale=1920/1080,setsar=1/1,setdar=2.6667/1,colormatrix=bt709:bt470bg -pix_fmt yuv420p -c:v libx264 -c:a copy P1077005-ffmpegHD.mp4

I note that the audio in a GH5 "6K" video file is lossy recorded format, while a normal 4K audio file not lossy format recorded.
 
buggz said:
Simple transcode from GH5 "6K" 2X 4:3 anamorphic to 1920/1080 via ffmpeg:

D:\ffmpeg-20170915-6743351-win64-static\bin\ffmpeg -threads 4 -i P1077005.MP4 -r 29.97 -metadata copyright="© buggz - 2017" -vf scale=1920/1080,setsar=1/1,setdar=2.6667/1,colormatrix=bt709:bt470bg -pix_fmt yuv420p -c:v libx264 -c:a copy P1077005-ffmpegHD.mp4
Click to expand...
Again, why would you want to change the colormatrix and the DAR, there is no need for either.

You ask for help, you get it and then you ignore it.....
 
Shrug, not ignoring you, nor anyone else.
All I know, is this works for me.
As I understand from reading on the net, the colormatrix blurb is for other apps to read, and adjust as neccessary.
The DAR, I'm not understanding, but it keeps my aspect perpectives.
Again, I just a noob who is trying to maybe help others as I also learn.
All the other command lines I've tried do NOT keep the 2.6667 aspect ratio when scaled down from GH5 "6k", believe me, I've tried everyone's suggestions.

I'm a noob at all of this.
As I've said, I don't understand it all, especially the SAR and DAR verbiage, just trying different things and reporting to others my findings.
I actually found this on the net searching.
I also got the colormatrix=bt709:bt470bg -pix_fmt yuv420p blurbs from the net.
As I read and understand, the colormatrix=bt709:bt470bg blurb is for other apps to use, if they can use the information.
I haven't read about the -pix_fmt yuv420p blurb...
Though, the GH5 "6K" files, report:
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 10 bits
I'm guessing the -pix_fmt yuv420p blurb isn't needed?
 
Last edited:
buggz said:
As I've said, I don't understand it all, especially the SAR and DAR verbiage, just trying different things and reporting to others my findings.
I actually found this on the net searching.
I also got the colormatrix=bt709:bt470bg -pix_fmt yuv420p blurbs from the net.
As I read and understand, the colormatrix=bt709:bt470bg blurb is for other apps to use, if they can use the information.
Click to expand...
Just use the actual aspect ratio (after anamorphic adjustment) with a DAR and SAR of 1:1. With the colormatrix you use you are telling your video is Rec.601 which means that your colors will be off.

So again don't mess with the DAR or SAR just calculate the straight aspect ratio and do not use the colormatrix command.
Also if you want to maintain a 10 bit resolution you should not use yuv420p because that is an 8 bit pixel format.
 
You must log in or register to reply here.
Back
Top