Problem 2: cutting media file without re-encoding It’s very strange how that if I don’t give it the ending “k” but do give it a higher value than 64, it always bumps up the bitrate to 128kbits/s, from the default of 64k (but not to the number I actually wanted). Video:0kB audio:782kB global headers:0kB muxing overhead 0.003996% Turns out, as the ffmpeg man page hints but does not specify clearly, a “k” is required to label the units of the new bitrate. Video:0kB audio:393kB global headers:0kB muxing overhead 0.007950% Reading the man page, -b is for video bitrate, and -ab is for audio bitrate.

The original was in 256kbits/s, and I decided to use the same bitrate for the output, just for kicks. In my case, I only wanted a 30-second piece of the original file, converted to MP3. So a simple task is to transcode an audio file of some arbitrary format to MP3. Problem 1: transcoding to mp3 insists on using 64kbits/s or 128kbits/s bitrate Turns out there are some weird gotchas when using some versions of ffmpeg (in my case, SVN-r10571) on the commandline.

So here I was, trying to complete some ordinary transcoding / media file cutting tasks with ffmpeg.

Ffmpeg cut video same quality