XmediaRecode – Variable Frame Rate Mode

[Moralez]

Is it possible to re-encode a video with XmediaRecode and get an output video with a Frame rate mode of Variable?
Variable is not listed in the drop down box for Rate control mode: in XmediaRecode. I tried 2 pass ABR and it doesn’t produce a variable frame rate mode according to MediaInfo.

I’m trying to reduce the size of some 1 GB videos and I use to thing that reducing the bit rate was all that was needed. That will reduce the size but reducing it too low will also reduce the quality. All my 1 GB videos have a bit rate of 3000 kb/s and a frame rate mode of Constant. My smaller videos (same run time) have a frame rate mode of Variable. I have one video with a bit rate of 6800 kb/s and Variable frame rate mode and it is only 300 MB. All the videos are x264.

I don’t know what the pros and cons are between Constant and Variable other than file size. I was able to reduce a 1.3GB file down to 650 MB by selecting Constant Quality with a setting of 20.0 but the Frame rate mode in still Constant.

Perhaps XmediaRecode isn’t the best application to use for what I’m trying to do.

[badyu17]

Maybe your smaller videos are wrongly flagged as variable while in reality being constant frame rate. Newer ffmpeg versions do that with mkv files.

[jagabo]

Rate Control modes and ABR have nothing to do with frame rate, they are bitrate settings. Generally, variable vs. constant frame rate has little effect on the file size. Bitrate is what effect file size. If you want a smaller file use a lower bitrate.

[aedipuss]

the only exception i know of being video comprised of a series of still pictures allowing framerate to drop to 0.

[Moralez]

If you want a smaller file use a lower bitrate.

That's what I always thought. Instead of trying to find the best (quality vs size) bit rate I think I'll use the Constant Quality setting in Xmediarecode with a setting of 20 (default). It might not work for all videos and if it doesn't then I'll try something else.

[jagabo]

Instead of trying to find the best (quality vs size) bit rate I think I'll use the Constant Quality setting in Xmediarecode with a setting of 20

I almost always use crf mode with x264 (and the slow preset). With most video at crf 18 it's hard to spot any differences between the source and new video at normal playback speed. At 12 it's hard to spot differences even looking at enlarged still frames.

[Moralez]

Instead of trying to find the best (quality vs size) bit rate I think I'll use the Constant Quality setting in Xmediarecode with a setting of 20

I almost always use crf mode with x264 (and the slow preset).

What are the advantages of using slow preset? Medium is the default.