Answers.Body: <p>You can only estimate the bitrate as proportion of your crop. If you have 30,000 Kbps for 1920*1080 pixel, then for 1080*1080 pixel this would mean 16,875 Kbps. If there is more complexity inside the crop region than outside, I would even increase the target bitrate further.</p>
  
  <p>However, if your videos are not that long and not intended for streaming I wouldn't invest too much thought into saving some disk space. The video quality will degrade anyway with the encoding process and a high bitrate will help you avoiding too much loss.</p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2015-09-20T00:12:44.703Z
Answers.Text: That's what I was afraid of.  It's not easy being a pedant trying to find the absolute perfect bitrate to yield the best quality/disk space ratio.  I'll probably just use original bitrate in the new video for good measure, though using the proportional calculation would probably be just as good.
Answers.UserDisplayName: oscilatingcretin
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2015-09-19T08:11:28.747Z
Answers.LastActivityDate: 2015-09-19T08:11:28.747Z
Answers.UserDisplayName: Fred42vid
Body: <p>I have some videos I recorded with my cell phone that I want to crop using Avisynth's <code>crop()</code>.  I am using x264vfw with VirtualDub which asks for a target bitrate.  I usually just get the bitrate from the vid's properties in Windows Explorer and plug that value in for the target bitrate for the new encoded video, but, since I am cropping it, I don't want to use the full bitrate.  Ideally, I would be able to find out the bitrate of only the region I am wishing to crop.  After all, if the original video is 1920x1080 with a total bitrate of 30 mbps (30,000 kbps) and I want to crop it down to a 1080x1080 region, I don't want to use the bitrate of the full, uncropped video.</p>
  
Tags: <encoding><bitrate>
Title: Is there a way to get the bitrate of a specific region of a video?
UserDisplayName: oscilatingcretin
ThreadText: # Is there a way to get the bitrate of a specific region of a video?
  
  (Asked by: username_0 on 2015-09-19)
  
  I have some videos I recorded with my cell phone that I want to crop using Avisynth's `crop()`. I am using x264vfw with VirtualDub which asks for a target bitrate. I usually just get the bitrate from the vid's properties in Windows Explorer and plug that value in for the target bitrate for the new encoded video, but, since I am cropping it, I don't want to use the full bitrate. Ideally, I would be able to find out the bitrate of only the region I am wishing to crop. After all, if the original video is 1920x1080 with a total bitrate of 30 mbps (30,000 kbps) and I want to crop it down to a 1080x1080 region, I don't want to use the bitrate of the full, uncropped video.
  
  **Tags:** encoding, bitrate
  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_1 on 2015-09-19. Score: 3 | Accepted answer
  
  You can only estimate the bitrate as proportion of your crop. If you have 30,000 Kbps for 1920\*1080 pixel, then for 1080\*1080 pixel this would mean 16,875 Kbps. If there is more complexity inside the crop region than outside, I would even increase the target bitrate further.
  
  However, if your videos are not that long and not intended for streaming I wouldn't invest too much thought into saving some disk space. The video quality will degrade anyway with the encoding process and a high bitrate will help you avoiding too much loss.
  
  > **Comments:**
  > **username_0**: That's what I was afraid of.  It's not easy being a pedant trying to find the absolute perfect bitrate to yield the best quality/disk space ratio.  I'll probably just use original bitrate in the new video for good measure, though using the proportional calculation would probably be just as good.  
  
  ---
  
  