Extract Audio from MP4 Video using FFMPEG - Easy

[00:00] okay so this is how to extract audio

[00:01] from a video file and save it as an mp3

[00:04] using ffmpeg so I've got these two video

[00:07] files here and let's just play waves so

[00:10] MPV waves so you can see it's got a

[00:17] single audio track on it and let's just

[00:20] confirm that with ffmpeg so ffmpeg - I

[00:25] waves and you can see that it has one

[00:29] audio stream which is this one here so

[00:34] in order to extract that and save as an

[00:36] mp3 all we need to do is type in ffmpeg

[00:39] - I the name of our video files as waves

[00:43] and then our audio codec so - see code

[00:48] on a and we're going to use lib mp3 lame

[00:51] and now we need to decide whether we

[00:54] want a constant bitrate file or a

[00:56] variable bitrate file so in this case

[00:58] I'm just going to pick variable bitrate

[01:00] so - Q :

[01:03] a and let's go somewhere in the middle

[01:05] of the road so let's pick four and now

[01:09] all we need to do is provide an output

[01:11] file name so let's call it waves - sound

[01:14] dot mp3 and hit enter and we're done so

[01:18] if we just LS you can see that we now

[01:21] have an mp3 file and let's just play it

[01:23] with MPV

[01:31] so that's the audio extracted from our

[01:34] waves video file so what if we wanted to

[01:37] extract an audio track from a video file

[01:39] that's got multiple audio tracks so I've

[01:42] got this video cars here so let's play

[01:44] it so the first track is this weird tune

[01:52] and the second track is just another

[01:55] music track so let's quit that and let's

[01:59] just look at that with ffmpeg so ffmpeg

[02:02] - I cars so you can see that we have

[02:05] these two audio streams so all we need

[02:09] to do is modify our previous command a

[02:11] tiny bit so that we can select the audio

[02:14] track that we want to encode so let's

[02:17] just use ffmpeg to do that so ffmpeg - I

[02:22] cars and then same set up our audio

[02:25] codec so - C : a and it's going to be

[02:29] live mp3 lame and this time we're going

[02:33] to go for a constant bitrate so - B : a

[02:37] and let's set it to 320 K which is the

[02:39] highest that we can set so that's 32

[02:42] kilobytes per second so now what we need

[02:44] to do is select one of our audio tracks

[02:47] so we can do that using map so if we

[02:50] type in - map and for our second audio

[02:53] track it would be zero : - now let me

[02:57] just explain map for a second so this

[03:00] first number here and by the way all of

[03:02] these numbers start from zero in their

[03:04] scale so this first number here

[03:07] indicates the first file input - ffmpeg

[03:10] which is this file here if we had have

[03:12] actually put in another file in fact we

[03:16] can actually just do that so you can see

[03:17] so if we just use another - I waves dot

[03:26] mp4 so now we've got another input file

[03:29] so if we wanted to select an audio

[03:31] stream from this input file we would

[03:34] then set that to one so let's just go to

[03:37] the end so we'd set that to one and

[03:39] there is no second audio track within

[03:42] that file so this wouldn't work

[03:44] so we'd actually have to set it to one

[03:45] but let's just change it back to two and

[03:47] this back to zero so the first number

[03:50] indicates which file so we're selecting

[03:53] cars and the second number indicates

[03:56] which stream so zero in our caused or

[03:59] mp4 file is actually the video stream

[04:02] one is our first audio track and two is

[04:05] our second audio track so we're

[04:07] selecting the second audio track so all

[04:10] we need to do now is provide an output

[04:12] file name so let's just call it cars

[04:15] - second dot mp3 and let's hit enter

[04:20] and we're done so if we just LS and

[04:23] let's play it so NPV cars

[04:26] - second you can see that it's the

[04:31] second track play so what if we wanted

[04:36] to extract both of the audio tracks from

[04:38] that file and save them into separate

[04:40] mp3 files well we could actually do that

[04:43] in just one command line so let's just

[04:45] remove that file first so RM cars

[04:48] - second so that's gone now and if we

[04:53] just modify our previous command so

[04:55] let's just make some space and get rid

[04:56] of this because we don't need that

[04:58] anyway and all we need to do is another

[05:03] map so - map and it's the first file so

[05:07] 0 : and the first audio stream which is

[05:12] one in this particular case and just

[05:17] provide an output file name so let's

[05:19] call it cars and it's actually the first

[05:21] audio track so let's just call it first

[05:23] dot mp3

[05:29] and that's it so if we just LS now we've

[05:31] got two new mp3 files and if we play

[05:34] them so let's MPV cause - first

[05:39] [Music]

[05:41] there's the first audio track and let's

[05:44] just play the second there's the second

[05:50] audio track and that's all there is to

[05:54] it so I hope you found that useful if

[05:56] you did don't forget to subscribe and

[05:58] thanks for watching goodbye

[06:10] [Music]