Can't stereo to mono with mencoder

[kyroii]

Hi,

I have a video stereo.avi (xvid+mp3) and I want to output a new one in mono so that's what I do with mencoder:

mencoder stereo.avi -ovc copy -oac mp3lame -lameopts cbr:br=128:mode=3 -o mono.avi

that doesn't work, it still has 2 channels

I've also tried:

mencoder stereo.avi -ovc copy -oac mp3lame -lameopts cbr:br=128:mode=3 -af -pan=1:0.5:0.5 -channels 1 -o mono.avi

And doesn't work

What I'm doing wrong? Any help is appreciated.

Thank you.

[markhu]

These both worked for me just today under Ubuntu 10.04:

2007 mencoder -ovc copy -oac mp3lame -af pan=1:0.5:0.5 stereofile.MP4 -o mono-pan.mp4

2020 mencoder -ovc copy -oac mp3lame -af channels=1 stereofile.MP4 -o mono-chan.MP4

The first one produced
Stream #0.1: Audio: mp3, 48000 Hz, mono, s16, 96 kb/s

And the second produced
Stream #0.1: Audio: mp3, 48000 Hz, mono, s16, 80 kb/s

And they both sound like mono. Before, they had only one channel of stereo.

[markhu]

Also, you can boost the volume at the same time by adding the volume=24:0 to the -af audio filter args.

Concatenate filters with a comma like this:

$ mencoder -ovc copy -oac mp3lame -af channels=1,volume=30 infile.mp4 -o outfile.mp4

One problem I have not solved yet is that the resulting files are not playable by Totem, a popular Linux medi player. My current work-around is to use ffmpeg to process it. Something innocuous like this:

$ ffmpeg -b 3M -acodec aac -i infile.avi outfile.avi

BTW, the "2007" and "2010" prefixes in my previous comment are merely artifacts of my running the Linux history command and can be ignored.