If you have ffmpeg and lame installed, you can easily convert flash video files (.flv) such as youtube videos to mpeg or mp3 files. Ok, in case you don’t know where these videos are stored. Firefox has a Cache directory. Under In Linux, you have a good chance of finding it under .mozilla/firefox/=somealphanumeric=.default/Cache This is where the Flash videos are usually stored. They won’t have the .flv ending though! To convert an flv file to mp3, use ffmpeg. I guess, you will also need lame in order to encode mp3 correctly, ffmpeg has tons of options. I used i (inputfile), ar (sample rate), ab (audio bitrate) and ac (audio channels).
Note: In more receent ffmpeg version you might need to add an extra “k” for kilobyte, e.g. “-ab 160k“
[chris@hismachine:~]$ ffmpeg -i flashvideo.flv -ar 44100 -ab 160k -ac 2 output.mp3
In order to convert an flv file to mpeg, you can use something like this.
[chris@hismachine:~]$ ffmpeg -i flashvideo.flv -s 352x288 -b 512 -ab 128 output.mpg
The options here are s (size) and b (video bitrate). Play around with ffmpeg’s options and try different bitrates etc. However, bear in mind that if the input video is bad quality then the output won’t be any better 
Tags: convert, ffmpeg, flash video, flv, lame, mp3, mpeg, mpg
April 20, 2008 at 4:39 pm
[...] taken from here [...]
June 13, 2008 at 11:35 pm
Hi,
I tried your example with an flv file but I seem to have a problem, the output file is tiny and doesn’t play.
Here’s what I entered:
ffmpeg -i Linkin-Park_Given-Up.flv -ar 44100 -ab 160 -ac 2 Linkin-Park_Given-Up.mp3
And here’s the output:
Seems stream 0 codec frame rate differs from container frame rate: 1000.00 (1000/1) -> 12.00 (12/1)
Input #0, flv, from ‘Linkin-Park_Given-Up.flv’:
Duration: 00:03:11.8, start: 0.000000, bitrate: 64 kb/s
Stream #0.0: Video: flv, yuv420p, 320×240, 12.00 fps(r)
Stream #0.1: Audio: mp3, 44100 Hz, mono, 64 kb/s
Output #0, mp2, to ‘Linkin-Park_Given-Up.mp3′:
Stream #0.0: Audio: mp2, 44100 Hz, stereo, 0 kb/s
Stream mapping:
Stream #0.1 -> #0.0
Press [q] to stop encoding
size= 79kB time=191.7 bitrate= 3.4kbits/s
video:0kB audio:79kB global headers:0kB muxing overhead 0.000000%
I don’t mean to be a pain in the ass, but I have no idea how to use ffmpeg. Any help you can provide will be appreciated.
June 14, 2008 at 1:21 pm
Hmm… it works fine for me, I used the command you quoted. Maybe try a newer ffmpeg version, that might do the trick. http://ffmpeg.mplayerhq.hu/
Let us know how it goes…
July 16, 2008 at 2:06 pm
My code:
ffmpeg -i 28593.flv -ar 4100 -ab 500 -ac 2 test.mp3
I am also tried your example but i got the following error. The converted mp3 file is very small..
FFmpeg version SVN-r12312, Copyright (c) 2000-2008 Fabrice Bellard, et al.
configuration: –enable-gpl –enable-pthreads –enable-libx264 –enable-libamr-nb –enable-libamr-wb –enable-nonfree
libavutil version: 49.6.0
libavcodec version: 51.50.1
libavformat version: 52.7.0
libavdevice version: 52.0.0
built on Mar 4 2008 21:54:37, gcc: 4.1.2 20070626 (Red Hat 4.1.2-14)
Input #0, flv, from ‘/home/dev5/public_html/flash/fortesting/QuickcamRecorder/28593.flv’:
Duration: 00:00:17.4, start: 0.000000, bitrate: N/A
Stream #0.0: Video: flv, yuv420p, 160×120 [PAR 0:1 DAR 0:1], 1000.00 tb(r)
Stream #0.1: Audio: nellymoser, 8000 Hz, mono
WARNING: The bitrate parameter is set too low. It takes bits/s as argument, not kbits/s
Output #0, mp2, to ‘/home/dev5/public_html/flash/fortesting/QuickcamRecorder/test.mp3′:
Stream #0.0: Audio: mp2, 44100 Hz, stereo, 0 kb/s
Stream mapping:
Stream #0.1 -> #0.0
Press [q] to stop encoding
size= 7kB time=17.4 bitrate= 3.4kbits/s
video:0kB audio:7kB global headers:0kB muxing overhead 0.000000%
July 16, 2008 at 2:29 pm
looks like you have a very small audio “ar”, try this one:
ffmpeg -i 28593.flv -ar 44100 -ab 160 -ac 2 test.mp3
July 19, 2008 at 8:50 am
i have also tried this one
ffmpeg -i 28593.flv -ar 44100 -ab 160 -ac 2 test.mp3
But i got the same error.. can you please help me..
September 29, 2008 at 12:05 pm
Do you have lame installed? My ffmpeg is compiled with:
–prefix=/usr –enable-shared –libdir=/usr/lib –enable-liba52 –enable-pp –enable-gpl –enable-pthreads –enable-libnut –enable-libtheora –enable-libvorbis –enable-x11grab –enable-dirac –enable-libmp3lame –enable-libfaad –enable-libfaac –enable-libx264 –enable-libxvid –enable-libamr_nb –enable-libamr_wb
(default mandriva rpm)
November 13, 2008 at 9:16 pm
I Used This Script + Modified for a .Bash
$ ffmpeg -i Input.flv OutPut.mp3
-ar and -ab is completely uneccarsary, They Are Mainly Used for Lowering Quality hence lowering the file size
Im 11 And I was Able to edit and use, I wonder what a 15 year old maybe capapble of or even a 20-year-old.
Thanks For Share.
November 19, 2008 at 9:13 am
No, they are not unnecessary! Without the options you will encode a 64kbit file with low quality. Of course, if the source .flv file already is low quality you cannot improve it but omitting the options might lower the quality. Try it with two files and listen to the difference. For example, I tried it with this one:
http://uk.youtube.com/watch?v=PU7J5MSIr6U
Without the option you will get a 1.9M file with lousy quality. Adding “-ar 44100 -ab 160″ the quality of the file is much better (size 4.7M).
December 12, 2008 at 3:26 am
I am not 11 or 15 or 20, *sigh* I am 38…er I think, I can’t remember. Somewhere between 35-38 or so. But I think I am getting the error as well.
The file is 93kb and its not working. What is odd is it starts to encode the audio, and you think “Cool, its going to work.” but then it craps out. I do get a warning before it starts to encode which might be an indicator of the problem.
“WARNING: The bitrate parameter is set too low. It takes bits/s as argument, not kbits/s”
How can you set this?
Just to be thorough here is the whole kitten kaboodle…
ffmpeg -i crap.flv -ar 44100 -ab 160 -ac 2 crappy.mp3
FFmpeg version r11872+debian_3:0.svn20080206-12ubuntu3, Copyright (c) 2000-2008 Fabrice Bellard, et al.
configuration: –enable-gpl –enable-pp –enable-swscaler –enable-x11grab –prefix=/usr –enable-libgsm –enable-libtheora –enable-libvorbis –enable-pthreads –disable-strip –enable-libfaad –enable-libfaadbin –enable-liba52 –enable-liba52bin –enable-libdc1394 –disable-armv5te –disable-armv6 –disable-altivec –disable-vis –enable-shared –disable-static
libavutil version: 49.6.0
libavcodec version: 51.50.0
libavformat version: 52.7.0
libavdevice version: 52.0.0
built on Oct 3 2008 22:40:31, gcc: 4.3.2
Seems stream 0 codec frame rate differs from container frame rate: 1000.00 (1000/1) -> 25.00 (25/1)
Input #0, flv, from ‘crap.flv’:
Duration: 00:03:45.0, start: 0.000000, bitrate: 64 kb/s
Stream #0.0: Video: flv, yuv420p, 320×240 [PAR 0:1 DAR 0:1], 25.00 tb(r)
Stream #0.1: Audio: mp3, 22050 Hz, mono, 64 kb/s
WARNING: The bitrate parameter is set too low. It takes bits/s as argument, not kbits/s
File ‘crappy.mp3′ already exists. Overwrite ? [y/N] y
Output #0, mp2, to ‘crappy.mp3′:
Stream #0.0: Audio: mp2, 44100 Hz, stereo, 0 kb/s
Stream mapping:
Stream #0.1 -> #0.0
Press [q] to stop encoding
size= 93kB time=225.0 bitrate= 3.4kbits/s
video:0kB audio:93kB global headers:0kB muxing overhead 0.000000%
December 12, 2008 at 3:35 am
hmm I think I figured it out. Try…
ffmpeg -i crap.flv -ar 44100 -ab 160000 -ac 2 crappy.mp3
I missed the hint the programmer was trying to give me…
“It takes bits/s as argument, not kbits/s”
so 160 should actually be 160000
That’s one for the old fogey and zip for the the 11 year old, right?
December 12, 2008 at 4:53 pm
that’s weird, maybe they changed it in the more recent versions, my manpage entry for ffmpeg (built Jan07) still says:
-ab bitrate
Set the audio bitrate in kbit/s (default = 64).
January 5, 2009 at 5:06 pm
You need to put the “k” at the end of 160
ffmpeg -i crap.flv -ar 44100 -ab 160k -ac 2 crappy.mp3
And also if you don put the -ac or -ab or -ar by default u will get a mono audio file with 64k quality
January 5, 2009 at 5:20 pm
Yes, that is the case for more recent versions of ffmpeg, originally you did not, I will add it to the post, thanks!
January 6, 2009 at 3:23 am
Hey chris, put it also on the command line, people usually copy from it to use it
June 11, 2009 at 6:47 am
Hey Domm,
Nice one. Spout off and then show your 11 year old ignorance. Ha,ha..
July 28, 2009 at 7:44 pm
Yes, I must agree Jamie.
When you get to the serene age of 15, Domm, you’ll learn that what ever you post on a blog’s comment section will make you look stupid, no matter what the content.
October 24, 2009 at 7:59 am
Thanks for the post! Helped a lot!