So it is important to decide the value based on the user requirements. With low CRF value, the bitrate and hence, the file size of the video will increase. 51 is the poorest quality with lowest file size.0 is lossless (best) with highest file size.On the other hand, the previous method will keep the same bitrate which will result in different output qualities for different inputs. This method is better if we want to have the same output quality for different kinds of input videos as FFmpeg would automatically adjust the bitrates based on the input video properties. It enables us to specify a target value that maps to a specific quality by adjusting the bitrates automatically based on the input video. The Constant Rate Factor or CRF is an option available in the libx264 encoder to set our desired output quality. Related: What is FFmpeg? Usage, Benefits, and Installation Simplified Using the CRF option to set desired quality Ideally in CBR mode, the bitrate should be perfectly constant during the entire video but that is the ideal case and is not possible to achieve with software encoders. If we try to analyze the bitrate of the output file, we would see that the difference between the highs and the lows of the bitrates in the file is very less. The FFmpeg command for the CBR conversion will be as follows : ffmpeg -i crowdrun.mp4 -b:v 2200k -maxrate 2200k -minrate 2200k -bufsize 2200k -c:v libx264 output.mp4įollowing are the screenshots of the above command: Let’s say, we need to have a CBR of 2200 kbps for our sample video. As mentioned earlier, we are going to use the libx264 encoder in all the three cases. -bufsize – Specifies the rate control buffer size that helps to maintain the bitrate according to the values of b:v, maxrate and minrateĪfter this, we also need to specify the video encoder using the -c:voption.-minrate – Specifies the minimum bitrate tolerance.-maxrate – Specifies the maximum bitrate tolerance.-b:v – Specifies the average target output bitrate of the video.In order to output a constant bitrate video, we would be using the following FFmpeg output options : Hence, if the bitrate is constant over a pre-determined time-period, the video is called a CBR-encoded video. If the bitrate is “constant” throughout a video, it is termed as a CBR video. However, it is not possible to have constant bitrate for all the frames because of the different frame types and encoding priorities. For example, 2200 kbps as a bitrate means that 2200 kilobits of data is stored per second. For a deeper discussion on bitrate, don’t miss this article on “bitrate vs. In technical terms, it is the rate of the data output of an encoder. Bitrate is the amount of information or data stored per second in any media file such as audio or video. To understand CBR, we need to understand what is bitrate. Change the resolution of the video to 1280×720. Using the CRF option to set desired quality.Creating a Constant BitRate (CBR) Video.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |