2pass encoding by ffmpeg at once

Question

I encode a video file by using ffmpeg like this.

$ ffmpeg -i input.avi -pass 1 -an output.mp4
$ ffmpeg -i input.avi -pass 2 -ab 128k -y output.mp4

So I typing always 2 times, is there way to encode a video by 2-pass at once?

I change a options often and of course input and output file name is different each times.

Solution

Instead of running these as 2 separate commands you can run them on one command line like so:

$ ffmpeg -i input.avi -pass 1 -an output.mp4 && \
    ffmpeg -i input.avi -pass 2 -ab 128k -y output.mp4

The difference is the && notation which will run the second command (the 2nd pass) only if the first command was successful. They're still 2 separate operations, but this will allow you to run one command line vs. the 2 you were having to do previously.

Also this will have the benefit of running the 2nd pass immediately upon completion of the 1st pass, where with your way you'd have to essentially wait for the 1st to finish before kicking off the 2nd.

Comments

[Ignacio Vazquez-Abrams]

You want to do a 2-pass encoding in one pass?

[frostschutz]

If you don't have constraints regarding file size (i.e. must fit optical media), consider using CRF instead of 2-pass.

[ironsand]

I don't know which one is better, but IMHO 2-pass encoding is better if bitrate is same. So I prefer to use 2-pass.

[JamesTheAwesomeDude]

I wonder if you could do something like ffmpeg -pass 1 -passlogfile - | ffmpeg -pass 2 -passlogfile - to encode both passes at once?

[Frank Nocke]

@JamesTheAwesomeDude Piping (|) is almost certainly wrong. Either && (only continue if no error returned) or ; (2nd command follows, no-matter-what)

[JamesTheAwesomeDude]

@FrankNocke piping would allow better parallelism in this case, if ffmpeg supports it.