For example, the below query will copy the audio ( -c:a copy) from input.mp4 and convert the video to a VP9 codec ( -c:v vp9) with a bit rate of 1M/s ( -b:v), all bundled up in a Matroska container ( output.mp4).įfmpeg -i input.mp4 -c:a copy -c:v vp9 -b:v 1M output.mp4Īnother technique to improve video quality is to use the -r option to change the frame rate. It’s sometimes difficult to predict what will happen without putting something to the test. In other situations, it may only affect the file size. Changing bitrates can sometimes make a significant impact on subjective quality. The ability of humans to see and hear isn’t as simple and straightforward as we’d like to believe. The most straightforward technique is to alter the bitrate, with -b flag, which may or may not result in a difference in quality. There are a few techniques that influence the quality of a video when it is compressed to a lower size.

Timestamp 00:00:00.8995909|00:00:00.0319152Įxception thrown: '' in Īn exception of type '' occurred in we dive into the tutorial steps, let's understand how FFmpeg works in general. You can see that the difference between each write is right around 30ms, but there is one that's a little less and then it crashes, but the crash is a number of frames later: I've got a frame rate of 30 and see logs like the one below. | are you saying that one must not write a video frame unless one frame rate interval has passed since the previous frame? I having been battling this issue for a few days and I'm still blowing up almost immediately if I specify a timestamp, but it works fine if I don't. I defined FPS = 30 and worked until time 652.96 but when i tried save frame on 685,48, i have error 'Error while writing video frame'.Įrror | 1:40:30 p.

Ffmpeg library video frame rate