Hi,

I have some footage which is 1.1Gb in size which is way to large. So I am hoping I can convert it to lower quality for a smaller file size. Its an mp4 file and the video is 1080p but 720p would be more than adequate. So, is it possible to convert the file in kdenlive to give me a smaller file with 720p resolution. I have tried going File -> 'Transcode clips' and then choosing a Profile which is 720p and low frame rate rather than 1080p but as the job progresses the output file is almost as large as the original even before it is 10% complete!
So clearly I am doing something wrong. Can anybody explain how to get a smaller file or suggest some other software to do this if kdenlive can't do this.

For reference the original footage properties are:
container: Quicktime
Dimensions: 1920*1080
Codec: H.264
Framerate: 25 Fps
Bitrate: 3998 kbps
Audio: MPEG-4 AAC

Thanks,

Mike.

- Put your footage onto the timeline. Make sure your project settings reflect your footage (Project -> Project settings).
- Click render (CTRL + ENTER).
- In tab “Render Project” click on “more options” (bottom left).
- On the new opened “window” click on “rescale”, click on the right end of the line on the icon “preserve aspect ratio"
- and put in your desired resolution in the right field (i.e. 720).
- click on the icon “Render to file” (on the left side)

Now you get the smaller video as defined in rescale.

Kdenlive is an editor, not really efficient for simple transcoding.
FFmpeg is the best tool for that, yet the command-line interface may not be your friend.
There are graphical interfaces around, but I haven't used them for long. Maybe WinFF would be helpful.
Handbrake is also a good tool.

Kendlive also has a "transcode" option in the project clip right-click menu, that may offer you some choices you would like to try.

Well, I have understood that you want to decrease file size. What you have to do is to lower the total bitrate (audio bitrate + video bitrate). All in all the filesize does not depend on the screen size, but of course you will get better picture quality with lower bitrates on a smaller picture.

If you simply want to transcode (1080p -> 720p) you can use ffmpeg (this command line will leave your audio untouched).
ffmpeg -i INPUTFILENAME -c:v libx264 -r 25 -preset slow -crf 24 -c:a copy -vf scale=1280:720 OUTPUTFILENAME

Replace INPUTFILENAME with the correct filenames on your system and give an OUTPUTFILENAME with the same extension as the INPUTFILENAME.

You can vary the video quality by changing the -crf parameter. Higher values will give smaller files in lower quality. The -crf value should be between 18 and 31.

Maybe you want to check the crf value with a smaller part on your video. You can check the bitrate of the transcoded clip using ffprobe INPUTFILENAME. In the video details the bitrate must be lower than 3998 kbps, otherwise you will not decrease file size.