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I’ve been ripping my collection of anime dvds with MakeMKV and converting them into .mp4 files using Ffmpeg.

There are a couple things I need help with- I’ve noticed that using the command ffmpeg -i input.mkv output.mp4 works in converting the mkv into a playable mp4 file in QuickTime player but that it has a smaller file size than the original MKV file.

Does this indicate a loss in quality?

I’ve used another command Ffmpeg -i input.mkv -c copy output.mp4

to convert the MKV file into mp4 and the file is identical in size but will not play in QuickTime as the previous converted file did despite both being mp4.

Does this mean that this mp4 file is just as recognisable as an mkv file?

I then did another command which may be the best as it plays in QuickTime but it resulted in by far the largest output file size.

Ffmpeg -i input.mkv -crf 01 output.mp4

The last command I used is almost the same as previous but doesn’t play in QuickTime for unknown reasons.

Ffmpeg -i input.mkv -crf 00 output.mp4

Results in huge file size and mp4 file which won’t play in QuickTime.

Please can you shed some light on these issues and advise me on if these commands are best to use for lossless quality?

The Dvds and files are standard definition and animated in the 90s so that might be worth mentioning.

genpfault
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Liam
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1 Answers1

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the constant rate factor belongs to the h264 encoding, at 0 ffmpeg renders the video as uncompressed and it's used only for complex video editing

Following this Guide

ffmpeg -i input.mkv -c:v h264 -crf 17 -preset 'placebo' output.mp4

-crf constant rate factor the number goes from 0 to 50,the bigger the number,lower are the file size and quality,at 17 it shouldn't have any loss of video
-preset is the encoding speed
-f is the format

if that doesn't work you have to convert your files to the mov format

tony
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  • Thanks Tony for the detailed reply. I’m planning on also using these converted files for video editing in the future, music videos mainly. Would these converted files be suitable for that? I’m very new to Ffmpeg and appreciate the info! Can you give me a brief summary of what the effects of additional commands are as opposed to the basic Ffmpeg-i file.mkv file.mp4? Also what are the advantages of using -crf 17 instead of -crf 01 etc? – Liam Sep 23 '22 at 10:58
  • You should edit your question placing the tag around the code parts.Follow the guide that I posted.For the rest your question is too generic, visit https://ffmpeg.org/ffmpeg-all.html to have an idea. – tony Sep 23 '22 at 16:26