How to Compress and Convert 1080 to 480p with Intact Quality

[mindphasar]

My goal is to reduce the size of this file to 480p resolution with Intact Quality

This is the information obtained from mediainfo

# MediaInfo

Format : MPEG-4
Format profile : Base Media
Codec ID : isom (isom/iso2/avc1/mp41)
File size : 15.1 GiB
Duration : 7 h 30 min
Overall bit rate : 4 796 kb/s
Writing application : Lavf58.26.101

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L4
Format settings : CABAC / 1 Ref Frames
Format settings, CABAC : Yes
Format settings, RefFrames : 1 frame
Format settings, GOP : M=1, N=12
Codec ID : avc1
Codec ID/Info : Advanced Video Coding
Duration : 7 h 30 min
Bit rate : 4 672 kb/s
Width : 1 920 pixels
Height : 1 080 pixels
Display aspect ratio : 16:9
Frame rate mode : Variable
Frame rate : 22.450 FPS
Minimum frame rate : 0.047 FPS
Maximum frame rate : 25.000 FPS
Original frame rate : 23.976 (24000/1001) FPS
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.100
Stream size : 14.7 GiB (97%)
Codec configuration box : avcC

Audio
ID : 2
Format : AAC LC
Format/Info : Advanced Audio Codec Low Complexity
Codec ID : mp4a-40-2
Duration : 7 h 30 min
Bit rate mode : Constant
Bit rate : 118 kb/s
Channel(s) : 2 channels
Channel layout : L R
Sampling rate : 44.1 kHz
Frame rate : 43.066 FPS (1024 SPF)
Compression mode : Lossy
Stream size : 379 MiB (2%)
Default : Yes
Alternate group : 1

Are these two solutions good ?

ffmpeg.exe -i "15GB.mp4" -s 720x480 -aspect 16:9 -an -pix_fmt yuv420p -f yuv4mpegpipe - | x264.exe --demuxer y4m --crf 20.0 --preset veryslow --tune film --bluray-compat --vbv-maxrate 8000 --vbv-bufsize 8000 --level 3.2 --keyint 30 --open-gop --colorprim "smpte170m" --transfer "smpte170m" --colormatrix "smpte170m" --sar 40:33 --output "15GB.x264.mkv" -

ffmpeg.exe -i "15GB.x264mp4" -c:a ac3 -b:a 192k -ar 48000 "raw_audio.ac3"

mkvmerge.exe --output "15GB.7hous.x264.mkv" --language 0:und ^"^(^" 15GB.x264.mkv ^"^)^" --language 0:und ^"^(^" raw_audio.ac3 ^"^)^" --track-order 0:0,1:0


OR

for %%a in ("15GB.*") do ffmpeg -i "%%a" -preset veryslow -tune film -profile high -level 32 -g 30 -r 30000/1001 -flags +ilme+ildct -pix_fmt yuv420p -filter_complex scale=interl=1,fieldorder=tff,setsar=sar=40/33 -refs 10 -x264-params crf=20 -x264opts bluray-compat=1:vbv-bufsize=30000:vbv-maxrate=40000lices=4pen-gop=1:force-cfr=1:colorprim=smpte170m:colormatrix=smpte170m:tr ansfer=smpte170m -acodec -c:a ac3 -b:a 192k -s 720x480 -aspect 16:9 "%%~na.x264.veryslow.20.Level.32.mp4"

[smrpix]

You literally cannot throw away more than 85% of your image and maintain "intact quality." Try encoding short samples at your settings and see if they are acceptable for your purposes.

[mindphasar]

You literally cannot throw away more than 75% of your image and maintain "intact quality." Try encoding short samples at your settings and see if they are acceptable for your purposes.

Thank you for the information

[4kblurayguru]

You could try

ffmpeg -i input -vf scale=-1:480 -preset slow -crf 33 -c:a aac -b:a 128k output

[hello_hello]

For funzies, a screenshot of a 1080p source, and another after it'd been resized to NTSC DVD resolution (with borders) and then resized back to 1080p for playback.

I used the following script for Avisynth.

FFMS2("E:\Video.mkv", threads=1)
CropResize(720,480, Borders=true, OutDAR=16.0/9.0, Resizer="ResampleHQ")
CropResize(1920,800, AutoC=True, OutDAR=0, Resizer="Spline36Resize")

I'm not making any claims about the source being riddled with detail, but it gives you some idea of the blurring you can expect to introduce (the screenshots are probably best case scenario). It's not too bad considering how much the resolution was reduced.

Then there's whatever the re-encoding does, according to the encoder settings and how much bitrate you let it have etc.