Linux Convert YouTube Flash Video (FLV) to MP3
Ever wanted to download music videos from YouTube, then extract the music component from the video and convert to MP3? Well here's how to do it!
Firstly, to download the videos from YouTube, you will need to install the Flashgot extension into your Firefox web browser. This will add a small icon at the bottom right of the browser, and when it detects video (such as when you go to YouTube), you will be able to click on the icon and the video is grabbed and (in my instance) saved to the /tmp directory.
To extract and convert to MP3 we need to use the Linux command line ffmpeg utility.
The example below shows that I have moved the target file to a directory for that artiste; in this instance it is the rather shouty Charice. Maybe I should have chosen a more uber trendy yet obscure band so I come over as hip and cool 
Quick Copy/Paste Solution for the Impatient
ffmpeg -i infile -acodec libmp3lame -ac 2 -ab 256k -vn -y outfile
Detailed Solution for the Relaxed
Ok - to run the ffmpeg utility, issue the following:
badzilla@laptop4:~/Music/Charice> ffmpeg -i Charice_* -acodec libmp3lame -ac 2 -ab 256k -vn -y "Charice - Pyramid.mp3"
FFmpeg version SVN-r25320, Copyright (c) 2000-2010 the FFmpeg developers
built on Oct 14 2010 17:24:48 with gcc 4.5.0 20100604 [gcc-4_5-branch revision 160292]
configuration: --shlibdir=/usr/lib --prefix=/usr --mandir=/usr/share/man --libdir=/usr/lib --enable-shared --enable-libmp3lame --enable-libvorbis --enable-libtheora --enable-libspeex --enable-libxvid --enable-postproc --enable-gpl --enable-x11grab --extra-cflags='-fomit-frame-pointer -fmessage-length=0 -O2 -Wall -D_FORTIFY_SOURCE=2 -fstack-protector -funwind-tables -fasynchronous-unwind-tables -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -I/usr/include/gsm' --enable-libschroedinger --enable-libdirac --enable-libgsm --enable-avfilter --enable-libvpx --enable-version3 --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libx264 --enable-libdc1394 --enable-pthreads
libavutil 50.32. 0 / 50.32. 0
libavcore 0. 9. 0 / 0. 9. 0
libavcodec 52.92. 0 / 52.92. 0
libavformat 52.79. 0 / 52.79. 0
libavdevice 52. 2. 2 / 52. 2. 2
libavfilter 1.48. 0 / 1.48. 0
libswscale 0.12. 0 / 0.12. 0
libpostproc 51. 2. 0 / 51. 2. 0
[flv @ 0x807dc30] Estimating duration from bitrate, this may be inaccurate
Seems stream 0 codec frame rate differs from container frame rate: 47.95 (5994/125) -> 24.00 (24/1)
Input #0, flv, from 'Charice___Pyramid__featuring_Iyaz___Video.flv':
Metadata:
duration : 247
starttime : 0
totalduration : 247
width : 640
height : 360
videodatarate : 788
audiodatarate : 65
totaldatarate : 857
framerate : 24
bytelength : 26474918
canseekontime : true
sourcedata : B4A7D6941HH1287223136868392
purl :
pmsg :
Duration: 00:04:06.66, start: 0.000000, bitrate: 873 kb/s
Stream #0.0: Video: h264, yuv420p, 640x360 [PAR 1:1 DAR 16:9], 806 kb/s, 24 tbr, 1k tbn, 47.95 tbc
Stream #0.1: Audio: aac, 22050 Hz, stereo, s16, 66 kb/s
Output #0, mp3, to 'Charice - Pyramid.mp3':
Metadata:
TSSE : Lavf52.79.0
Stream #0.0: Audio: libmp3lame, 22050 Hz, stereo, s16, 256 kb/s
Stream mapping:
Stream #0.1 -> #0.0
Press [q] to stop encoding
size= 4830kB time=247.30 bitrate= 160.0kbits/s
video:0kB audio:4830kB global headers:0kB muxing overhead 0.000667%
badzilla@laptop4:~/Music/Charice> ls -lash
total 31M
4.0K drwxr-xr-x 2 badzilla users 4.0K 2010-10-16 12:01 .
4.0K drwxr-xr-x 55 badzilla users 4.0K 2010-10-16 11:23 ..
26M -rw-r--r-- 1 badzilla users 26M 2010-04-14 22:05 Charice___Pyramid__featuring_Iyaz___Video.flv
4.8M -rw-r--r-- 1 badzilla users 4.8M 2010-10-16 12:01 Charice - Pyramid.mp3
badzilla@laptop4:~/Music/Charice> The original command may be lost in that little lot, so here we have it:
ffmpeg -i Charice_* -acodec libmp3lame -ac 2 -ab 256k -vn -y "Charice - Pyramid.mp3"
Or, more appropriately:
ffmpeg -i infile -acodec libmp3lame -ac 2 -ab 256k -vn -y outfile
Here we can see the MP3 file has been created and weighs in at 4.8MB. To check out everything is ok, use the mediainfo utility
badzilla@laptop4:~/Music/Charice> mediainfo "Charice - Pyramid.mp3"
General
Complete name : Charice - Pyramid.mp3
Format : MPEG Audio
File size : 4.72 MiB
Duration : 4mn 7s
Overall bit rate : 160 Kbps
Writing library : LAME3.98.4
Encoding settings : Lavf52.79.0
Audio
Format : MPEG Audio
Format version : Version 2
Format profile : Layer 3
Format_Settings_Mode : Joint stereo
Format_Settings_ModeExtension : MS Stereo
Duration : 4mn 7s
Bit rate mode : Constant
Bit rate : 160 Kbps
Channel(s) : 2 channels
Sampling rate : 22.05 KHz
Stream size : 4.72 MiB (100%)
Writing library : LAME3.98.4
badzilla@laptop4:~/Music/Charice> To finish off the job you may wish to use EasyTag to set the MP3 tags so your MP3 player can file the track correctly.
Had Problems?
Well, I certainly did. It is important that you ensure all the relevant libraries are on exactly the same version. If your attempt to convert coughs, have a look for:
WARNING: library configuration mismatchand
ffmpeg: relocation error: ffmpeg: symbol av_strerror, version LIBAVUTIL_50 not defined in file libavutil.so.50 with link time referenceand
ffmpeg: relocation error: ffmpeg: symbol avcodec_get_context_defaults3, version LIBAVCODEC_52 not defined in file libavcodec.so.52 with link time referenceAll these diagnostics mean you have libraries out of whack somewhere. Look at your installed libraries with respect to ffmpeg. On my system you will see everything matches ok.
