Updated: Aug, 2016
If you need to do anything to digital video, it is well worth your while getting a copy of ffmpeg.
The project describes itself as
A complete, cross-platform solution to record, convert and stream audio and video.
I think of it as a video swiss-army knife that enables you to manipulate video, primarily in terms of converting between formats and reducing big files down.
Importantly, it is a commandline tool, so you will have to know how to launch a Terminal window.
I use brew, so installing is as simple as:
Check the ffmpeg site for alternate ways.
To convert formats, one simply has to specify the input file (with -i) and the output file. The format is determined from the file extension and ffmpeg goes about its conversion process to achieve the requested output format:
In the case of converting a mov file to a mp4, the internal audio and video streams actually do not need converting, just the container does. So you can ask ffmpeg to copy the streams while converting the container:
Sometimes you come across a lecture video and you want to extract the audio so that you or others can listen to it on a phone or in the car. ffmpeg can do that:
More Advanced Options
At the office we have need to convert our videos to a consistent output format and quality
Breaking this down:
- -c:v libx264 – use the x264 encoder, which enables certain other options below
- -preset slow – presets tell the encoder how hard to work to reduce the file size, here we’re willing to spend more time converting
- -pix_fmt yuv420p – this ensures that the video format is widely compatible
- -profile:v main – this again ensures compatibility with a variety of devices
- -movflags +faststart – this helps for files that are served via a web-browser
- -crf 26 – a quality factor between 0 (lossless) to 51 (very lossy), 26-8 is a sweet-spot between file size and quality
- -filter:v scale=-1:720 – resize any input to be 720 high and figure out the width (-1)
- -c:a libfdk_aac – use this aac encoder
- -ac 1 – go mono as we mostly have talking, not stereo music
- -ar 44100 – keep the voice quality high as that is important for listeners
- -vbr 3 – like crf, but 1 (low) to 6 (high) for audio compression
GIF file creation
If you are wanting to create a small animated gif, you can look at the instruction on this site