# Comparison

# Vapoursynth-Preview

# Setup

  1. Install Python 3.10

    • During installation tick Add Python 3.10 to PATH.
  2. Install Git

    • Optionally type git version in your terminal to verify Git was installed.
  3. Install Vapoursynth

  4. Before we install vs-preview, we need to install the following dependencies:

    To install LSMASHSource, download LSMASHSource and open it. Inside the zip, open the x64 folder, copy LSMASHSource.dll and paste it in %appdata%\VapourSynth\plugins64

    To install the rest of the plugins, run the following commands in your terminal:

    vsrepo.py install libp2p sub placebo dovi_library
    pip install git+https://github.com/OpusGang/awsmfunc.git
  5. Install vs-preview:

    pip install -U git+https://github.com/Irrational-Encoding-Wizardry/vs-preview.git
  6. Create a new file called comp.vpy.

  7. Open comp.vpy with a text editor such as notepad++ and paste the following, edit as required and save it:

    import vapoursynth as vs
    from vapoursynth import core
    from awsmfunc import FrameInfo
    ## Hold shift and right click your file, select copy as path and paste it here
    clip1 = core.lsmas.LWLibavSource(r"C:\Paste\File\Path\Here.mkv")
    clip2 = core.lsmas.LWLibavSource(r"C:\Paste\File\Path\Here.mkv")
    clip3 = core.lsmas.LWLibavSource(r"C:\Paste\File\Path\Here.mkv")
    ## Name of the source, uncomment as needed depending on how many sources you're comparing
    source1 = "FirstSourceName"
    source2 = "SecondSourceName"
    source3 = "ThirdSourceName"
     ## Sets the content as either progressive (0) or interlaced (1/2), required for progressive content tagged as interlaced
    ##clip1 = core.std.SetFieldBased(clip1, 0)
    ##clip2 = core.std.SetFieldBased(clip2, 1)
    ##clip3 = core.std.SetFieldBased(clip3, 2)
    ## Convert clip to 16bit (Only for filters that need it such as tonemapping and gamma fixing)
    ##clip1 = core.resize.Bicubic(clip1, format=vs.YUV444P16)
    ##clip2 = core.resize.Bicubic(clip2, format=vs.YUV444P16)
    ##clip3 = core.resize.Bicubic(clip3, format=vs.YUV444P16)
    ## Uncomment and edit values as needed if clips need cropping (Black letterboxing) [16 BIT REQUIRED FOR ODD NUMBERS]
    ##clip1 = core.std.Crop(clip1, left=240, right=240, top=0, bottom=0)
    ##clip2 = core.std.Crop(clip2, left=0, right=0, top=276, bottom=276)
    ##clip3 = core.std.Crop(clip3, left=0, right=0, top=21, bottom=21)
    ## Uncomment and edit values as needed if you need to upscale your clips
    ## Always scale to the highest resolution
    ##clip1 = core.resize.Spline36(clip1, 1920, 1080)
    ##clip2 = core.resize.Spline36(clip2, 1920, 1080)
    ##clip3 = core.resize.Spline36(clip3, 3840, 2160)
    ## Uncomment and edit values as needed if you need to trim your clips (Calculate the frame difference and enter the number here)
    ##clip1 = clip1[0:]
    ##clip2 = clip2[24:]
    ##clip3 = clip3[0:]
    ## Change fps to match other sources, only needed when the previewer doesn't automatically keep them in sync
    ##clip1 = core.std.AssumeFPS(clip1, fpsnum=24000, fpsden=1001)
    ##clip2 = core.std.AssumeFPS(clip2, fpsnum=25000, fpsden=1000)
    ##clip3 = core.std.AssumeFPS(clip3, fpsnum=24000, fpsden=1000)
    ## Tonemapping (For HDR/DV content only), src_csp=1 is for HDR, src_csp=3 is for DV [16 BIT REQUIRED]
    ##clip1 = core.placebo.Tonemap(clip1, dynamic_peak_detection=1, tone_mapping_function=2, tone_mapping_mode=1, src_csp=1, dst_csp=0, gamut_mode=0, use_dovi=1)
    ##clip2 = core.placebo.Tonemap(clip2, dynamic_peak_detection=1, tone_mapping_function=2, tone_mapping_mode=1, src_csp=3, dst_csp=0, gamut_mode=0, use_dovi=1)
    ##clip3 = core.placebo.Tonemap(clip3, dynamic_peak_detection=1, tone_mapping_function=2, tone_mapping_mode=1, src_csp=1, dst_csp=0, gamut_mode=0, use_dovi=1, dst_max=120)
    ##Set DV clips to limited after tonemapping so FrameInfo works
    ##clip1 = core.resize.Bicubic(clip1, format=vs.YUV444P16, range=0)
    ##clip2 = core.resize.Bicubic(clip2, format=vs.YUV444P16, range=0)
    ##clip2 = core.resize.Bicubic(clip3, format=vs.YUV444P16, range=0)
    ## Fix Gamma bug (When one source is much brighter than others) [16 BIT REQUIRED]
    ##clip1 = core.std.Levels(clip1, gamma=0.88, min_in=4096, max_in=60160, min_out=4096, max_out=60160, planes=0)
    ##clip2 = core.std.Levels(clip2, gamma=0.88, min_in=4096, max_in=60160, min_out=4096, max_out=60160, planes=0)
    ##clip3 = core.std.Levels(clip3, gamma=0.88, min_in=4096, max_in=60160, min_out=4096, max_out=60160, planes=0)
    ##Fix Double range compression (When one source looks very washed out)
    ##clip1 = core.resize.Point(clip1, range_in=0, range=1, dither_type="error_diffusion")
    ##clip1 = core.std.SetFrameProp(clip1, prop="_ColorRange", intval=1)
    ## Displays the frame number, type, and group name in the top left corner
    clip1= FrameInfo(clip1, source1)
    clip2= FrameInfo(clip2, source2)
    clip3= FrameInfo(clip3, source3)
    ## Slow.pics labelling for automatic comparisons
    clip1 = clip1.std.SetFrameProp('Name', data = source1)
    clip2 = clip2.std.SetFrameProp('Name', data = source2)
    clip3 = clip3.std.SetFrameProp('Name', data = source3)
    ## Comment/Uncomment as needed depending on how many clips you're comparing
  8. That's it for the setup, now to use vspreview you just need to run this command in your terminal or paste it in a text file and save it as comp.bat:

    vspreview "C:\Path\To\comp.vpy"

    Now, when making comps you just edit comp.vpy to include the necessary file paths, comment/uncomment lines as required, edit the crop, trim, upscale, etc values when needed and then run comp.bat or run vspreview comp.vpy directly from your terminal.

# Screenshotting Automatically (Easiest)

If you don't want to take screenshots and upload them manually, then you can simply use VS-Preview's automatic comparison function.

  • Click the comp button in the bottom right of the toolbar.
  • Make sure all Picture Types are selected, or only select B if you want matching frame-types
  • Tick the public box to make the comparison available on the slow.pics homepage
  • Name the collection appropriately for Slow.pics, get the TMDB ID from https://www.themoviedb.org/ and paste it in the TMDB box, with it correctly set to Movie/TV depending on the content.
  • Under random enter a frame count amount, you should use a large amount of images to make the comparison as effective as possible, ideally at least 40 as not all frames will be useful.
  • Hit Start Upload and patiently wait while vspreview collects the frames and uploads the comparison.

# Screenshotting Manaully (Recommended)

  • Press Shift & Right Arrow keys to move forward a set amount of frames (configurable in playback section of the toolbar)
  • Number keys to switch between video sources and compare quality.
  • Press Shift & S keys to take and save screenshots.
  • Aim to screenshot a variety of scenes like light/dark, low/high motion, etc.
  • Try and match frame type when screenshotting, e.g. all sources on a B frame, single frame jump comes in handy for when they don't match (Shift + Arrow keys).
  • See QoL changes below to make this slightly easier on your fingers
    • Note: If a source file does not have B frames for you to match, you should skip matching frame type entirely for that source. This is usually true for Crunchyroll WEB-DLs, which have no B frames.

# Quality of Life Changes for Screenshotting Manually via VS-Preview

  • Use slow.pics friendly file naming, so you can drag all the images onto the site and have them automaically sorted In VSPreview on the bottom bar select Misc, set file name template to {frame}_{script_name}_({index}).

  • Jump through frames quickly In VSPreview on the bottom bar select Playback, directly right of the playback keys set the 1 value to 120.

  • Take screenshots quicker by setting the save image button to enter Open %localappdata%\Programs\Python\Python310\Lib\site-packages\vspreview\toolbars\misc and edit toolbar.py - Line 166: Replace QKeyCombination(Qt.Modifier.SHIFT, Qt.Key.Key_S).toCombined(), self.save_frame_as_button.click with (Qt.Key_Return), self.save_frame_as_button.click . - If you can't spam fast enough, in vs-preview click settings and set PNG compression to a lower level (higher value).

  • Swap binds to save your pinky finger, so you no longer have to hold shift all the time Open %localappdata%\Programs\Python\Python310\Lib\site-packages\vspreview\toolbars\playback\ and edit toolbar.py - Select lines 180-187, delete them, and paste

      self.main.add_shortcut(QKeyCombination(Qt.SHIFT, Qt.Key.Key_Left), self.seek_to_prev_button.click)
      self.main.add_shortcut(QKeyCombination(Qt.SHIFT, Qt.Key.Key_Right), self.seek_to_next_button.click)
      self.main.add_shortcut(Qt.Key.Key_Left, self.seek_n_frames_b_button.click)
      self.main.add_shortcut(Qt.Key.Key_Right, self.seek_n_frames_f_button.click)

# Automatic Comparison Scripts


  1. Install Python 3.10
  2. Install Vapoursynth
  3. Install dependencies via running the following command in your terminal:
    pip install pathlib anitopy pyperclip requests requests_toolbelt
  4. Download LSMASHSource and open it. Inside the zip, open the x64 folder, copy LSMASHSource.dll and paste it in %appdata%\VapourSynth\plugins64
  5. (Optional) Install FFmpeg and add it to PATH.


  1. Put comp.py into the same folder where the video files you want to compare are located.
  2. Rename your files to have the typical [Group] Show - EP.mkv naming, since the script will try to parse the group and show name.
  3. When there's no group, such as BDMV or WEB-DL, use the source/service as the group tag. For example:
    ├── [JPBD] Youjo Senki - 01.m2ts 
    ├── [Crunchyroll WEB-DL] Youjo Senki - 01.mkv
    ├── [Group] Youjo Senki - 01.mkv
    └── comp.py
    This will result in images named as JPBD.png, Crunchyroll WEB-DL.png, and Group.png from JPBD, Crunchyroll WEB-DL, and Group respectively.
  4. Adjust the variables in the script accordingly.
  5. Run the script via either double clicking it or by running py comp.py in your terminal.

# Manually with MPV

  • Install MPV
  • Screenshots are to be taken using MPV.
  • Slow.pics must be used for making comparisons.
  • Any other video-altering settings (different scalers, shaders, etc) are not allowed to be used.
  • Hardware decoding must be disabled.
  • Both screenshots are to be the exact same frame.
  • Both screenshots must be taken at the same resolution, take scaled screenshots if necessary.
  • Always scale to the highest resolution.
  • Subtitles are to be disabled.
  • Comparisons must be titled the name of the anime, and all encodes must be labelled accordingly.
  • You must include source in the comparison, this will usually be the BDMV/Remux when BluRay encodes are being compared or WEB-DL if WEB encodes are being compared.

MPV config must be the one as shown below: