Anybody know what this avconv line does?

Question

avconv -y -i input.avi -b 915k -an -f mp4 -ar 44100 -f s16le -ac 2 -i /dev/zero -acodec libfaac -ab 128k -strict experimental -shortest -vcodec libx264 output.mp4 -loglevel fatal

Answer 1

First of all, this seems to be an old version of avconv, since the command line has changed since then (but not too much).

So, let's break it down:

-y

This answers 'yes' to questions like "do you want to overwrite the output file".

-i input.avi

This gives the program the file input.avi as an input

-b 915k

This asks to change the bitrate to 915 Kibibytes per second

-an

This removes all the audio from the output.

-f mp4

Sets up MP4 as the format of the output file

-ar 44100

This sets audio sampling rate of the following input file.

-f s16le

This sets the format of the audio of the following input file.

-ac 2

This sets number of channels of audio to two.

 -i /dev/zero

This adds another input file that consists entirely of zero input

 -acodec libfaac

This reencodes the audio (silence most likely) with libfaac

 -ab 128k

Setting the audio bitrate to 128 Kbps

 -strict experimental

Allows avconv to use nonstandard approaches while encoding.

-shortest

Ends encoding when the shortest of the inputs has ended. This is needed because /dev/zero will never end.

-vcodec libx264

This sets the library to do the video encoding. The codec will be (unfortunately) h264

 output.mp4

This is the name of the output file

 -loglevel fatal

Fatal messages will be written as the log, and that's it.

In the future you may find man avconv to be your friend.