I am trying to shrink the size of some rather large video files while retaining a video quality of no more than roughly 2000 bitrate at the most. I set the video quality of the profile to a constant quality of 23. The video file has a bitrate of 5000 or so and after I processed it the file jumps to a bitrate of over 7000. I can drop the quality but then if I run another file with a lower bitrate against it, the quality will get quite a bit worse. If I set an average bitrate for the conversion of 2000 then files with a lower quality will get bigger. I'm not even sure why Handbrake is increasing the bitrate since I doubt it's increasing the quality.
Is there a way to set a max bitrate on a conversion without dropping or raising the bitrate on files with a lower bitrate?
Handbrake upsizing video bitrate
Re: Handbrake upsizing video bitrate
You can abuse vbv to do this.
Bitrate isn't quality across different videos.
Bitrate isn't quality across different videos.
- JohnAStebbins
- HandBrake Team
- Posts: 5726
- Joined: Sat Feb 09, 2008 7:21 pm
Re: Handbrake upsizing video bitrate
You assume correctly that HandBrake can't increase the quality. When a video is recompressed to a "higher quality" than the original, all you are doing is faithfully preserving all the compression artefacts that were in the original video.I'm not even sure why Handbrake is increasing the bitrate since I doubt it's increasing the quality
When re-encoding video, the original video is decompressed frame-by-frame and then recompressed. The encoder doesn't know anything about the original bitrate or quality of the video. It only sees raw uncompressed frames.
If you have videos of varying low-ish quality and you don't want the transcode to have a higher bitrate than the original, all you can do is tweak the quality for each transcode get the bitrate you want. A good rule of thumb is that a 6 point change in RF will roughly halve/double bitrate and filesize.
Also, as mduell points out, if you are attempting to transcode to a lower bitrate than the original and you have a specific max bitrate you would like to enforce, VBV settings are the way to go. http://www.chaneru.com/Roku/HLS/X264_Se ... bv-maxrate
With VBV and quality based encoding (RF values), the enocder will use lower bitrates where it can (in less complex scenes), but where higher bitrates are needed it will cap bitrate at the VBV settings specified.
-
- Veteran User
- Posts: 4856
- Joined: Wed May 04, 2011 11:06 pm
Re: Handbrake upsizing video bitrate
Could you please post your HB logs, instructions can be found here:
https://handbrake.fr/docs/en/latest/hel ... y-log.html
https://handbrake.fr/docs/en/latest/hel ... y-log.html