Encoding SW / Writing application

[android]

I have some videos, I was checking their properties/info

Mostly videos properties/ info has,encoding sw Lavfxx.xx.xxx this line

What is the purpose of this line??
Mostly videos have this line and some videos don't have this line

If video can work fine without that line then why

[Selur]

What is the purpose of this line

It's there to record which libav version that was used to encode the video.

If video can work fine without that line then why

if a problem occurs with the encoding, it's easier to track down which library was changed,...
(there are tons of metadata/flags on videos which are not really necessary)

[ProWo]

Lavf = Libavformat, part of the ffmpeg framework.
More info here: https://ffmpeg.org/libavformat.html

[android]

It's confusing, I want an example to understand properly

If there's a x264 codec binary and aac library then they will just encode video in .h264 track0 and .aac track1 right??

Then lavf will needed to join both tracks in to single mp4 mov etc??

Does lavf contains all formats like mp4 mov etc??

[android]

(there are tons of metadata/flags on videos which are not really necessary)

Then it will take more space compared to those videos which don't have this data,

if a problem occurs with the encoding, it's easier to track down which library was changed,...

Compressors should have options to include this type of data before encoding or not to keep, because I think this type of data is for advanced users which is not usefull for normal users ,if any problems occurs in encoding then user will try again

[Selur]

Then it will take more space compared to those videos which don't have this data,

correct, but the space needed by those are neglectable

Compressors should have options to include this type of data before encoding or not to keep, because I think this type of data is for advanced users which is not usefull for normal users ,if any problems occurs in encoding then user will try again

You are in luck if you use open source compressors, you could potentially adjust the code to your whishes.
Most folks don't care about these few bytes and think that the work of those that wrote the 'compressors&co' deserves some mentioning.