VideoHelp Forum




+ Reply to Thread
Results 1 to 3 of 3
  1. I re-encode my FullHD/4K (no lower resolution !) smartphone videos with Avidemux in order to save space . I succeeded by now to reduce the video size 2-3 times using the following parameters :

    - CRF quality : 23
    - motion est. method : UMH
    - subpixel refinement: 5
    - max. motion vector search range : 32
    - max. ref. frames 6
    - max. consecutive B-frames : 16
    - no DCT decimation
    - no strong intra smoothing

    Details are important to me, their loss is visible when zooming parts of the image in the video. I'm aware that every re-encode contributes to quality loss, but I want to keep it as low as possible while reducing the bitrate without noticeing it.

    Does setting the "subpixel refinement" to 7 really sharpen the image (as in image/video filters) or is it just a claim of some which don't see a real benefit (marginal detail preservation over the drastically increased encoding time) ?

    All videos from my phone camera are H.265 recordings (20 Mbps FullHD, 50 Mbps 4K).

    It might sound silly, but what is better : conversion to H.265 or "back" to H.264 ?

    Some say x264 is better in preserving details, but what would be the bitrate reduction benefit in my case ? Would 4K bitrate have "realistic values" at all ?


    Thanks.
    Quote Quote  
  2. Does setting the "subpixel refinement" to 7 really sharpen the image (as in image/video filters) or is it just a claim of some which don't see a real benefit (marginal detail preservation over the drastically increased encoding time) ?
    No. Setting subpixel refinement to 7 does not increase the sharpness, it can improve the effectiveness of the compression, which for a fixed file size could potentially improve the image quality.

    It might sound silly, but what is better : conversion to H.265 or "back" to H.264 ?
    For HD and upwards, I would recommend x265.

    Some say x264 is better in preserving details, but what would be the bitrate reduction benefit in my case ?
    I doubt it.
    users currently on my ignore list: deadrats, Stears555
    Quote Quote  
  3. Member
    Join Date
    Aug 2018
    Location
    Wrocław
    Search PM
    Code:
    @echo off
    setlocal ENABLEDELAYEDEXPANSION
    chcp 1250 >NUL
    
    dir /b *.mp4 | findstr /v /i "edited)" >list.txt
    
    for /F "delims=;" %%F in (list.txt) do (
    	echo ---------------------------------------------------------------------------------------------------
    	echo File: "%%~dF%%~pF%%F"
    	echo ---------------------------------------------------------------------------------------------------
    	echo.
    	(
    		echo name1="%%F"
    		echo ffms2^(name1, atrack=-1^)
    
    		echo ApplyGradationCurves^(lumaPoints="16,16,255,235"^)
    		echo TemporalDegrain2^(postFFT=3^)
    		echo lsfplus^(preset="slow", strength=25^)
    			REM echo Histogram
    		echo Prefetch
    	) >%%F.avs
    	ffmpeg.exe -hide_banner -avisynth_flags +all -i "%%F.avs" -c:v libsvtav1 -preset 4 -crf 27 -c:a aac -b:a 192k "%%~nF (AV1+edited).mp4"
    	del "%%F.avs"
    	del "%%F.index"
    )
    
    del list.txt >NUL
    pause
    Remove the line with ApplyGradationCurve if your phone records in the range 16-235. The script was created with Google Pixel in mind, so there may be problems if yours is recording in VFR.
    You can also use -c:a copy for the audio track (untested).
    Quote Quote  



Similar Threads

Visit our sponsor! Try DVDFab and backup Blu-rays!