Since HandBrake has removed the option to specify target size in the GUI it has been a pain for many users to calculate the bitrate required to get the same size. However, there is still a way to calculate the bitrate to get approximately the same sized output without any other software.
With the target size option in HandBrake GUI removed, how can you calculate the approx. bitrate for a target size?
My custom setting for audio is Encoder: MP3 lame, Bitrate: 128 and I don’t change it most of the time. When compressing a video I use 5 MB per minute which seems to be of good quality to me.
Let’s try the calculation now. For raw video stream:
video size in kilobits = length in seconds * video bitrate in kilobits => video bitrate in kilobits = video size in kilobits / length in seconds [PS: it is kilobits]
Here’s an example:
I am having a movie file of 422.3 MB (which is irrelevant right now and for good because nautilus file size calculation in simply wrong nowadays) and on length 37.36 minutes (the part after decimal is just seconds). So i want a target output of approx. 38 minutes * 5 MB = 190 MB = 190 * 1024 * 8 kbits = 1556480 kbits. 37.36 minutes = 2256 seconds. So the approximate bitrate I will use will be = 1556480 / 2256 = 690 kbps.
To compensate for audio stream size, use a bitrate around 20 kbps less then that calculated.
In my observation, 600 to 620 kbps for video and 64 kbps for audio give outputs pretty close to 5 MB per minute.