VideoHelp Forum

Our website is made possible by displaying online advertisements to our visitors. Consider supporting us by disable your adblocker or Try ConvertXtoDVD and convert all your movies to DVD. Free trial ! :)
+ Reply to Thread
Results 1 to 5 of 5
Thread
  1. 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"
    Quote Quote  
  2. 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.
    Last edited by smrpix; 11th Apr 2019 at 09:47.
    Quote Quote  
  3. Originally Posted by smrpix View Post
    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
    Quote Quote  
  4. You could try

    ffmpeg -i input -vf scale=-1:480 -preset slow -crf 33 -c:a aac -b:a 128k output
    Quote Quote  
  5. 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.
    Image Attached Thumbnails Click image for larger version

Name:	Source.png
Views:	20
Size:	1.63 MB
ID:	49478  

    Click image for larger version

Name:	Resized.png
Views:	16
Size:	1.33 MB
ID:	49479  

    Last edited by hello_hello; 28th Jun 2019 at 07:43.
    Quote Quote  



Similar Threads