By adjusting the so-called quantizer for each frame, it gets the bitrate it needs to keep the requested quality level. This provides maximum compression efficiency with a single pass. This method allows the encoder to attempt to achieve a certain output quality for the whole file when output file size is of less importance. This is the recommended rate control mode for most uses. Use this rate control mode if you want to keep the best quality and care less about the file size. To know more about what the different rate control modes do see this post. This will determine the file size and also how quality is distributed. Rate control decides how many bits will be used for each frame. There are two rate control modes that are usually suggested for general use: Constant Rate Factor (CRF) or Two-Pass ABR. See HWAccelIntro for information on supported hardware H.264 encoders. If you need help compiling and installing see one of our compiling guides.

It assumes you have ffmpeg compiled with -enable-libx264.

Ffplay h264