transcoding HD to 4k

[marcorocchini]

Hi

a cat here, please respect.

LWLibavVideoSource("temp.mkv")# HD source
Spline64Resize(3840,2160)
FrameRateConverterMix(50,1,output="flow")
QTGMC(InputType=1,EzDenoise=2.0,Preset="Super Fast",SubPel=4)
AssumeFPS(50)
Prefetch(8)

ffmpeg.exe -threads auto -y -i tempAVS2.avs -i tempAudio_PAIR1_ForFFmbc.wav -pix_fmt yuv420p -c:v libx264 -b:v 5000k -minrate 4000k -maxrate 10000k -bufsize 48000k -x264-params 8x8dct=1 -g 33 -bf 2 -crf 22 -rc-lookahead 32 -rc:v constqp -global_quality 23 -qp 5 -map 0:v -map 1:a -c:a aac -b:a 250k -ar 48000 -aspect 16:9 -r 50 OUTUHD3840x2160.MP4

this is my "intuitive" commandline, not verified

I wonder: when HD is bring to 4k is there particular parameter shoud be use during the ffmpeg encoding process?

[abolibibelot]

a cat here, please respect.

It's getting old, isn't it?

ffmpeg.exe -threads auto -y -i tempAVS2.avs -i tempAudio_PAIR1_ForFFmbc.wav -pix_fmt yuv420p -c:v libx264 -b:v 5000k -minrate 4000k -maxrate 10000k -bufsize 48000k -x264-params 8x8dct=1 -g 33 -bf 2 -crf 22 -rc-lookahead 32 -rc:v constqp -global_quality 23 -qp 5 -map 0:v -map 1:a -c:a aac -b:a 250k -ar 48000 -aspect 16:9 -r 50 OUTUHD3840x2160.MP4

Several things I'm not so sure about in that command, but one thing I'm pretty sure about is that it makes no sense to both use a -crf quality based parameter and specify average, minimum and maximum bitrates. The very purpose of -crf (Constant Rate Factor) is to circumvent the need to specify supposedly optimal bitrates but rather aim for an approximate level of quality preservation and let the encoder allocate the bitrate accordingly. Can't have your kibble and eat it too.
Not sure what the purpose of the 2x upscale is, either. Ditto the framerate conversion. Also why add “AssumeFPS(50)” after an explicit conversion to 50FPS.
There has to be a purpose, you claim to be a cat but you're not a porpoise.
If you defeat the purpose you might as well eat your own tail and stay alive to tell the tale.
My German teacher in high school used to play a recording, then simply say those four words: “Wo? Wer? Was? Wenn?” She forgot the most important: “Warum?” As a matter of fact, in our world, more often than not, as they said in Auschwitz: “Hier ist kein Warum” (as reported by Primo Levi in Se questo è un uomo). Yet “Warum?” / “Why?” / “Perché?” / “Pourquoi?” is the most important question, and the very last word in the last movie by Andrei Tarkowski, Offret. (The very last word in the last movie by Stanley Kubrick is “Fuck”, which has to be of equal importance, but it is not a question, and can't possibly have any bearing whatsoever when it comes to video conversion, unless I missed sumpting. Neither of those movies features any cat as far as I remember so you might find them of little interest.)

I wonder: when HD is bring to 4k

Brought.