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Topic: free programme for extracting audio from .flv file without re-encoding (Read 6170 times) previous topic - next topic
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free programme for extracting audio from .flv file without re-encoding

Hello,
I'm hoping somone could please help me...
I'm looking for a free programme that will extract just the audio from a .flv file without re-encoding (I want it as lossless/close to original as possible).
Any help very much appreciated.
Thanks...

free programme for extracting audio from .flv file without re-encoding

Reply #1 –
Quote from: bomber on
I'm looking for a free programme that will extract just the audio from a .flv file without re-encoding (I want it as lossless/close to original as possible).


ffmpeg

free programme for extracting audio from .flv file without re-encoding

Reply #3 –
Quote from: bomber on
Quote from: cpchan on
Quote from: bomber on
I'm looking for a free programme that will extract just the audio from a .flv file without re-encoding (I want it as lossless/close to original as possible).


ffmpeg


Thanks, I forgot to say, will it be able to be extracted to WAVE or FLAC?


Neither. You want it to be extracted without reencoding, right?


If the audio stream is AAC, you give the command
ffmpeg -i INFILE.flv -acodec copy -vn OUTFILE.m4a

The -acodec copy says that the audio stream should be copied (rather than reencoded).  ffmpeg will understand from the .m4a extension that you want it encapsulated in an mp4 container. (The -vn says there should be no video.)

This does of course only work when the audio stream is a codec that fits the mp4 container.

free programme for extracting audio from .flv file without re-encoding

Reply #4 –
Great, I'll try it, thanks...

free programme for extracting audio from .flv file without re-encoding

Reply #5 –
Whoaw, I've downloaded it and can't see how to set it up, there's just loads and loads of files/folders, no .exe set up or anything like that!
I have no idea what to do now!

free programme for extracting audio from .flv file without re-encoding

Reply #6 –
Quote from: bomber on
Thanks, I forgot to say, will it be able to be extracted to WAVE or FLAC?


It can extract any codec that your copy of ffmpeg is compiled to support, which is extensive.

free programme for extracting audio from .flv file without re-encoding

Reply #7 –
Quote from: bomber on
Whoaw, I've downloaded it and can't see how to set it up, there's just loads and loads of files/folders, no .exe set up or anything like that!
I have no idea what to do now!


It is a comand line program. However, there is an easy GUI frontend called WinFF- give that a try. However, I personally just use the command line, so I don't know if WinFF support extraction.

free programme for extracting audio from .flv file without re-encoding

Reply #8 –
Quote from: cpchan on
Quote from: bomber on
Whoaw, I've downloaded it and can't see how to set it up, there's just loads and loads of files/folders, no .exe set up or anything like that!
I have no idea what to do now!


It is a comand line program. However, there is an easy GUI frontend called WinFF- give that a try. However, I personally just use the command line, so I don't know if WinFF support extraction.


Thanks that was really very simple with WinFF.
Open it, load the file in, choose convert to audio, and choose format eg. WAVE for CD and convert! (there doesn't seem to be any quality settings or anything I need to set before using it?).

I guess my final question is..., does anybody know of the method I just used causing any audible loss in sound quality?, in searching for a programme to extract audio from .flv's I've read quite a few of them have caused audible quality loss (which were not supposed to...), so I'd like to know if anyone is familiar enough with the process I just used/described to know whether there will be any audible quality loss? (even though there really shouldn't be).
Thanks a lot for everyone's advice...

free programme for extracting audio from .flv file without re-encoding

Reply #9 –
Quote from: bomber on
Whoaw, I've downloaded it and can't see how to set it up, there's just loads and loads of files/folders, no .exe set up or anything like that!
I have no idea what to do now!


Use command line.

Here's a tip, if you are not too familiar with it, assuming you are on a Windows box:

- Get a Windows build from http://ffmpeg.zeranoe.com/builds/ . 32- or 64-bit build depending on OS version.
- Create folder C:\Programs_portable (or whatever you choose) for applications with no installation
- ... and C:\Programs_portable\FFmpeg for this. Put everything there. There should now be an 'ffmpeg.exe' in C:\Programs_portable\FFmpeg\bin\
- Somwhere, create a folder named _to_be_converted\
- In this folder, create a new txt file with the text
Code: [Select]
for %%f in (*.flv) DO  C:\Programs_portable\FFmpeg\bin\ffmpeg.exe -i "%%f" -acodec copy -vn "%%f.m4a"
(is this right syntax, anyone? Will it escape filenames which has special characters?)
- Rename this file into '_convert_flv_to_m4a.bat'. You might have to set up Windows to show extensions -- this should no more be a .txt file!
- Drop whatever you want to convert into the folder and double-click the .bat . It will output .flv.m4a files. (Keep the '.flv' as part of the file name, then you know where you got it from.)

free programme for extracting audio from .flv file without re-encoding

Reply #10 –
Thanks for the explanation, but for now it seems to have worked extremely easy by just downloading FFMPEG, then WinFF, ready to go as soon as both have been downloaded!

free programme for extracting audio from .flv file without re-encoding

Reply #11 –
OK I have extracted the audio from the .flv file twice by using FFMPEG and WinFF.
In WinFF I just load the file, select save as audio and select WAVE for CD.
As I did this twice I compared the 2 output files in EAC "Wave Compare" and both output files have exactly the same samples..., so I know it's at least consistent!
Now I just need to know if it's caused any audible quality loss? (as I have heard other .flv audio ripping programmes have caused quality loss even though they claim not to!).
Thanks

free programme for extracting audio from .flv file without re-encoding

Reply #12 –
Quote from: bomber on
Now I just need to know if it's caused any audible quality loss? (as I have heard other .flv audio ripping programmes have caused quality loss even though they claim not to!).


There is no quality loss if you use "-acodec copy" or if you transcode to a lossless codec (eg FLAC) or a PCM stream (at the expense of file size).

free programme for extracting audio from .flv file without re-encoding

Reply #13 –
Quote from: bomber on
select WAVE for CD.


That is just space-consuming – more often than not by a factor of 10 – and if you ever want a smaller version, then you have to transcode and accept quality loss. Keep the original, then.

free programme for extracting audio from .flv file without re-encoding

Reply #14 –
Quote from: bomber on
OK I have extracted the audio from the .flv file twice by using FFMPEG and WinFF.
In WinFF I just load the file, select save as audio and select WAVE for CD.
I thought you wanted to extract the native audio? Sure, you said “without re-encoding”, which WAV technically is, but you should want to avoid decoding also. Presumably the FLV has its audio in MP3 or AAC format, so you should* extract to that. Which assumes that FFMPEG offers the ability to extract the audio stream as-is; others can confirm that in either direction or recommend other software if necessary.

Quote
As I did this twice I compared the 2 output files in EAC "Wave Compare" and both output files have exactly the same samples..., so I know it's at least consistent!
Of course, since they’re using the same program.

Quote
Now I just need to know if it's caused any audible quality loss? (as I have heard other .flv audio ripping programmes have caused quality loss even though they claim not to!).
To determine whether something is audible, you listen to it. Have you tried that?

*Should is a relative term, since I suspect you might be ripping copyrighted music from YouTube or somewhere similar, but who knows?

free programme for extracting audio from .flv file without re-encoding

Reply #15 –
Quote from: db1989 on
Presumably the FLV has its audio in MP3 or AAC format, so you should* extract to that. Which assumes that FFMPEG offers the ability to extract the audio stream as-is; others can confirm that in either direction or recommend other software if necessary.


This is exactly what "-acodec copy" does.

free programme for extracting audio from .flv file without re-encoding

Reply #16 –
Hi,

Yeah I know all the stuff about WAVE being huge, when I asked for the 'real' audio file from the .flv to be extracted I thought it was MP3 that could be kept in it's exact original form, but it's AAC, so I can't really play AAC freely on my home music players etc, and converting AAC to MP3 would be lossy, so I extracted the AAC to WAVE/PCM as that's technically going to be lossless, well at least audibly!

About my question on whether this programme is known to cause audible quality loss using this process (even though it's not supposed to as I have heard other programmes have done), I thought someone might already know the answer to this and be able to save me having to check it all out myself ;-)

Thanks for all your help!

free programme for extracting audio from .flv file without re-encoding

Reply #17 –
Quote from: bomber on
when I asked for the 'real' audio file from the .flv to be extracted I thought it was MP3 that could be kept in it's exact original form, but it's AAC, so I can't really play AAC freely on my home music players etc, and converting AAC to MP3 would be lossy, so I extracted the AAC to WAVE/PCM as that's technically going to be lossless, well at least audibly!


Is the originally audio really aac or are you confused by Porcus's example? If it is really mp3, you can extract it by using:

Code: [Select]
ffmpeg -i input.flv -acodec copy -vn output.mp3


If it is really aac and if your player supports FLAC,:

Code: [Select]
ffmpeg -i input.flv -acodec flac -vn output.flac


Quote from: bomber on
About my question on whether this programme is known to cause audible quality loss using this process (even though it's not supposed to as I have heard other programmes have done), I thought someone might already know the answer to this and be able to save me having to check it all out myself ;-)



What do you mean by "this process"? Like I said, there are 3 ways to maintain the original quality:

  • Copy the stream (-acodec copy)
  • Transcode to a lossless codec (e.g. -acodec flac)
  • Decode to PCM and put it in a wave container (e.g. -acodec pcm_s24le)




free programme for extracting audio from .flv file without re-encoding

Reply #18 –
It really is AAC.
I used the "WinFF" programme you linked me to....
All I had to do was open it, then select I wanted to extract from the .flv "audio" and I chose the format at "WAVE for CD".
As simple as that, maybe it's confusing you because you said you don't use that method...

free programme for extracting audio from .flv file without re-encoding

Reply #19 –
It is very easy to do this task using MENCODER.EXE, I posted  a detailed step-by-step procedure at another thread here
 

free programme for extracting audio from .flv file without re-encoding

Reply #20 –
Quote from: derty2 on
It is very easy to do this task using MENCODER.EXE, I posted  a detailed step-by-step procedure at another thread here


Although personally I still use mencoder for a lot of things, it is best to start migrating to ffmpeg. Mencoder have been unmaintained for a couple of years now (developmental effort for encoding is concentrated on ffmpeg)  and will disappear one of these days. Also, mencoder have problems with mp4 containers.