Video conversion in Linux

My Nikon COOLPIX P300 camera generates h264, 1920x1080 videos in a .mov container. So a 17 second video is over 40 Megabytes. I decided to convert this to a different format, with the aim of reducing the file size.

A quick search led me to ffmpeg. Running that dispalyed a message to use avconv instead.

So on to avconv.

To do a basic conversion, the command is:

avconv -i in_movie.mov out_movie.avi

This however failed with:

[ac3 @ 0x875efa0] invalid bit rate

Turns out, the default bitrate used by avconv is not supported by the default audio codec ( ac3 ) it selected. Sigh.

Solution,  modify the command to use 192k audio bitrate which it support.

avconv -i in_movie.mov -b:a 192k out_movie.avi

This worked. It generated a 3 Megabyte file, which seemed impressive, but the quality sucked since it reduced the video bit rate dramatically.

I decided to move the video bit rate closer to the original video. So the command with video bitrate set to 19000 kbps is

avconv -i in_movie.mov -b 19000k -b:a 192k -out_movie.avi

This got me good video quality but it only reduced the file size by a few Megabytes.

I decided the best reduce the resolution by 1/2 to get a lower file size with good quality video.  That command is

avconv -i in_movie.mov -b 19000k -b:a 192k -s 960x540 out_movie.avi

This reduced the 40+ Megabyte file to a 12 Megabyte file.  Success.