Reducing video size with same format and reducing frame size

Question

This question might be very basic  Is there a way to reduce the frame size rate of Lossy compressed  WMV  MPEG  format  to get a smaller video  of lesser size  with same format   Are there any open source or proprietary apis for this

User · Answer

ffmpeg -i  lt input mp4 gt  -b v 2048k -s 1000x600 -fs 2048k -vcodec mpeg4 -acodec copy  lt output mp4 gt     -i input file -b v videobitrate of output video in kilobytes  you have to try  -s dimensions of output video -fs FILESIZE of output video in kilobytes -vcodec videocodec  use ffmpeg -codecs to list all available codecs  -acodec audio codec for output video  only copy the audiostream  don t temper

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Instead of chosing fixed bit rates  with the H 264 codec  you can also chose a different preset as described at https   trac ffmpeg org wiki x264EncodingGuide  I also found Video encoder comparison at KeyJ s blog  archived version  an interesting read  it compares H 264 against Theora and others   Following is a comparison of various options I tried  The recorded video was originally 673M in size  taken on an iPad using RecordMyScreen  It has a duration of about 20 minutes with a resolution of 1024x768  with half of the video being blank  so I cropped it to 768x768   In order to reduce size  I lowered the resolution to 480x480  There is no audio   The results  taking the same 1024x768 as base  and applying cropping  scaling and a filter     With no special options  95M  encoding time  1m19s   With only -b 512k added  the size dropped to 77M  encoding time  1m17s   With only -preset veryslow  and no -b   it became 70M  encoding time  6m14s  With both -b 512k and -preset veryslow  the size becomes 77M  100K smaller than just -b 512k   With -preset veryslow -crf 28  I get a file of 39M which took 5m47s  with no visual quality difference to me     N 1  so take the results with a grain of salt and perform your own tests

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There is an application for both Mac  amp  Windows call Handbrake  i know this isn t command line stuff but for a quick open file - select output file format  amp  rough output size whilst keeping most of the good stuff about the video then this is good  it s a just a graphical view of ffmpeg at its best     It does support command line input for those die hard texters   https   handbrake fr downloads php

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I found myself wanting to do this too recently  so I created a tool called Shrinkwrap that uses FFmpeg to transcode videos  while preserving as much of the original metadata as possible  including file modification timestamps   You can run it as a docker container  docker run -v  path to your videos  vids bennetimo shrinkwrap   --input-extension mp4 --ffmpeg-opts crf 22 preset fast  vids  Where    path to your videos  is where the videos are that you want to convert --input-extension is the type of videos you want to process  here  mp4 --ffmpeg-opts is any arbitrary FFmpeg options you want to use to customise the transcode  Then it will recursively find all of the video files that match the extension and transcode them all into files of the same name with a -tc suffix  For more configuration options  presets for GoPro etc  see the readme  Hope this helps someone

User · Answer

ffmpeg provides this functionality   All you need to do is run someting like  ffmpeg -i  lt inputfilename gt  -s 640x480 -b 512k -vcodec mpeg1video -acodec copy  lt outputfilename gt    For newer versions of ffmpeg you need to change -b to -b v   ffmpeg -i  lt inputfilename gt  -s 640x480 -b v 512k -vcodec mpeg1video -acodec copy  lt outputfilename gt    to convert the input video file to a video with a size of 640 x 480 and a bitrate of 512 kilobits sec using the MPEG 1 video codec and just copying the original audio stream   Of course  you can plug in any values you need and play around with the size and bitrate to achieve the quality size tradeoff you are looking for   There are also a ton of other options described in the documentation  Run ffmpeg -formats or ffmpeg -codecs for a list of all of the available formats and codecs   If you don t have to target a specific codec for the final output  you can achieve better compression ratios with minimal quality loss using a state of the art codec like H 264

User · Answer

If you want to keep same screen size  you can consider using crf factor  https   trac ffmpeg org wiki Encode H 264  Here is the command which works for me   on mac you need to add -strict -2 to be able to use aac audio codec   ffmpeg -i input mp4 -c v libx264 -crf 24 -b v 1M -c a aac output mp4

[video] Reducing video size with same format and reducing frame size

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