Merging flv files causes a massive size increase

Question

I have 3 flv files which I wish to merge. I used the answer in this post:

which suggested this option:

mencoder -forceidx -ovc copy -oac pcm -o output.flv input1.flv input2.flv

It seems to have worked except that the merged file is 400meg in size whereas the original 3 files were about 33meg each.

Is this expected? Is there a way to join the 3 files without the massive increase in size?

I can't explain the massive increase in size. Check my answer for a solution using ffmpeg. — Patrick, Jan 18 '13 at 15:09
Hmmm, with mencoder, isn't that actually making an AVI file (but with a `.flv` suffix)? — derobert, Jan 18 '13 at 15:49

Patrick · Answer 1 · 2013-01-21T15:04:41.973

1

Create a file mylist.txt with all the files you want to have concatenated in the following form:

    # this is a comment
    file '/path/to/file1'
    file '/path/to/file2'
    file '/path/to/file3'

Then you can encode your files with:

    ffmpeg -f concat -i mylist.txt -c copy output

Edit: You may need to compile ffmpeg from source to get a recent enough version.

edited Jan 21 '13 at 15:04

answered Jan 18 '13 at 15:08

Patrick

thanks. Unfortunately I am getting: Unknown input format: 'concat' – Carl Jan 19 '13 at 22:18
okay, wait. I think I have an old ffmpeg version – Carl Jan 19 '13 at 22:22
confirmation that it works except you do need ffmpeg 1.1 which I had to install from source. Even the repository holding the latest latest for Debian only had 1.0.1 – Carl Jan 19 '13 at 23:22

1 Answers1