Rotate 90 clockwise:
ffmpeg -i in.mov -vf "transpose=1" out.mov
For the transpose parameter you can pass:
0 = 90CounterCLockwise and Vertical Flip (default)
1 = 90Clockwise
2 = 90CounterClockwise
3 = 90Clockwise and Vertical Flip
Use -vf "transpose=2,transpose=2" for 180 degrees.
Make sure you use a recent ffmpeg version from here (a static build will work fine).
Note that this will re-encode the audio and video parts. You can usually copy the audio without touching it, by using -c:a copy. To change the video quality, set the bitrate (for example with -b:v 1M) or have a look at the H.264 encoding guide if you want VBR options.
A solution is also to use this convenience script.
FFmpeg has three concatenation methods:
Use this method if your inputs do not have the same parameters (width, height, etc), or are not the same formats/codecs, or if you want to perform any filtering.
Note that this method performs a re-encode of all inputs. If you want to avoid the re-encode, you could re-encode just the inputs that don't match so they share the same codec and other parameters, then use the concat demuxer to avoid re-encoding everything.
ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv \
-filter_complex "[0:v] [0:a] [1:v] [1:a] [2:v] [2:a] \
concat=n=3:v=1:a=1 [v] [a]" \
-map "[v]" -map "[a]" output.mkv
Use this method when you want to avoid a re-encode and your format does not support file-level concatenation (most files used by general users do not support file-level concatenation).
$ cat mylist.txt
file '/path/to/file1'
file '/path/to/file2'
file '/path/to/file3'
$ ffmpeg -f concat -safe 0 -i mylist.txt -c copy output.mp4
For Windows:
(echo file 'first file.mp4' & echo file 'second file.mp4' )>list.txt
ffmpeg -safe 0 -f concat -i list.txt -c copy output.mp4
Use this method with formats that support file-level concatenation
(MPEG-1, MPEG-2 PS, DV). Do not use with MP4.
ffmpeg -i "concat:input1|input2" -codec copy output.mkv
This method does not work for many formats, including MP4, due to the nature of these formats and the simplistic concatenation performed by this method.
If in doubt about which method to use, try the concat demuxer.
Also see
Best Answer
FFMpeg has an option
-threads. You can define there, if it's going to beauto(default) or you can limit the number of used threads (CPU cores). Recommended that you set your number based on the amount of available threads minus 1, or 2. So if you have 8 threads, setting to-threads 6would be great. But if you have only one core and 2 gb of RAM, I'm not sure if this is the case! FFMpeg requires a lot of resources.