Extracting audio from flv

[Mike99]

I’m trying to save the audio from an flv file and put it on a CD. I’m using Avidemux (vers 2.5.4) which someone suggested. The tutorials mention saving the audio in one of many formats including wav. Problem is that wav is not showing up for me in the Audio/video sidebar.

What steps am I missing? Is there some other format and/or settings that I can use? I personally never recorded anything using MP3, AC3, etc., so my knowledge of what can be done with these is limited.

Any suggestions would be appreciated.
Thanks in advance.

[poisondeathray]

PCM is the same as WAV

[lacywest]

Format Factory 2.6 is free ... use it to convert flv to mpg or avi ... than send it to Virtualdub [free also] ... use Virtualdub to extract the wav file ... done.

[yoda313]

Format Factory 2.6 is free ... use it to convert flv to mpg or avi ... than send it to Virtualdub [free also] ... use Virtualdub to extract the wav file ... done.

would flvextractor work for this?

Also couldn't you use the directshowsource avisynth template to open the flv directly in virtualdub without converting?

edit - I couldn't find flvextractor in the tools section. I know there is some kind of tool to strip a flv file.... don't remember the name apparently.

edit 2 - also another realtime option is to use audacity (freeware) and just record "what u hear" from your computer and save as a wav file that way. It should record exactly what is playing.

[davexnet]

I'm pretty sure AVIdemux works. Open the source file. On the left, change audio from "copy" to wav/pcm.
At the top, select audio/save.

Of course, if you want to make a real audio CD (redbook) the audio should be 44.1Khz @16 bit.
If you're just copying the files as data, it can be anything your playback device can handle.

[Mike99]

Avidemux does work quite well & is easy to use. I just don’t know all the particulars of the different formats.

I tried PCM & the “Configure” function does nothing. No menu appears. I’m presuming that’s because if anything was changed then it would not be PCM. If I save as .pcm some programs do not recognize it. Saving as .wav worked every time. Media Info shows the PCM/WAV file as 1,411.2 Kbps, 44.1 KHz, 16bits, 2 Channels, PCM (Microsoft). The original flv was 118 Kbps, 44.1 KHz, 16bits, 2 Channels, AAC (Version4) (LC).

I tried MP3 (lame) & “Configure” then gave some options, with the default Bitrate of 128. And MediaInfo does show the saved audio file as 128 Kbps, 44.1 KHz, 2 Channels, MPEG Audio (Version 1) (Layer 3).

Trying to figure out a few things I found that 1,411.2 Kbps is the Red Book audio specification. Since this will end up on a CD-R, is there an advantage of using the PCM audio which creates the 1,411.2 Kbps file to start with?

If I use MP3 is there any advantage to using anything higher than 128 Kbps since the original was 118 Kbps?

So an MP3 can be burned to a CD-R as a data file, but it appears it can also be converted to 1,411.2 Kbps when creating & burning to a CD-R. IOW it can be done either way, is that correct?

Thanks again.

[davexnet]

Yes of course it can be done either way, if you write the mp3 (or any other file, for that matter) to the disk as data,
then that's what you get. An exact representation,.bit for bit.
However, redbook audio CD is similar to wav/pcm in it's specification. I have nero 6 installed and if you open an
audio CD project and add mp3 files, it dynamically converts them to Wav before writing the disk.

If you create an audio CD from WAV files, the data is not changed . The problem with saving mp3 out of AVidemux
is you lower the sound quality a second time (the first was when the aac was originally created) But if you save it as
Wav, the sound quality is kept intact.
Hope this answers your question.

[Mike99]

davexnet,

Thanks for the answer.

Now I have a different problem with a couple other flv files. I cannot adjust the volume, it is fixed. And the audio is distorted.

MediaInfo indicates the Video Stream is AVC with the following details.

212 Kbps, 640x480 (4:3), at 30.000fps, AVC (Container profile=Unknown@3.0) (Main@L3.0) (CABAC / 3 Ref Frames)

Audio appears to be normal AAC.

The Avidemux properties appear pretty much the same as the other flv files I played with except the image is 640x480 vs. 320x240.

I tried various settings but to no avail. The only thing that I can find when searching is that AVC does not appear to be supported.

Any suggestions?

[dvstorm]

very simple....just use "total video converter"

[Ai Haibara]

edit - I couldn't find flvextractor in the tools section. I know there is some kind of tool to strip a flv file.... don't remember the name apparently.

You're probably thinking of FLV Extract. Drop the FLV on it, demux the audio stream, done.

[Mike99]

Looking into this a bit more, the videos I have problems with have a video stream similar to this.
212 Kbps, 640x480 (4:3), at 30.000fps, AVC (Container profile=Unknown@3.0) (Main@L3.0) (CABAC / 3 Ref Frames)

The ones that work OK are similar to this.
63.3 Kbps, 320x240 (4:3), at 30.000fps, AVC (Container profile=Unknown@1.3) (Main@L1.3) (CABAC / 3 Ref Frames)

What you notice immediately is the size of the image when Avidemux opens the file. And as mentioned the audio is fixed (at a low level) and is distorted on the problem ones.

AVC does work with the smaller image size videos, so I’m guessing AVC is not the issue. I’m guessing that “(Container profile=Unknown@3.0) (Main@L3.0)” is the problem. IOW the “1.3” parameter works but the “3.0” does not. I have no idea what that means.

If FLV Extract is used it appears the audio would still need to be converted to PCM/WAV. Not a problem, but it would be nice to be able to use just one program to do the job. Hopefully there is a simple solution.

[yoda313]

edit - I couldn't find flvextractor in the tools section. I know there is some kind of tool to strip a flv file.... don't remember the name apparently.

You're probably thinking of FLV Extract. Drop the FLV on it, demux the audio stream, done.

Ah thats it thanks.

@mike99 - you would have to use more than one tool if the original audio is not in audio cd format. If it is simply demuxing the audio will let you do it. But if its in a compressed form you have no choice but to convert it to audio cd format.

[poisondeathray]

you can try vdub with the flv plugin , and aac acm

if the file is normal, not corrupted, avisynth will work for practically everything with soundout() . You can use normalize() to normalize the volume

if avidemux won't let you adjust volume, if you can still save as pcm wav, then you can adjust volume in another audio program

[Mike99]

yoda313,

All 9 of the flv files I have played with have AAC audio. Avidemux did extract & save as PCM/WAV audio with 4 of the files. IOW it is capable of doing both jobs, at least some of the time. Question is why not all the time.

I did try looking at the Avidemux forum, but every subject or thread I click on gives me an error message saying I need to enable "DEBUG mode", etc. I have no idea what that has to do with looking at a forum.

[yoda313]

Question is why not all the time.

Without having the files to test personally its hard to say. Though a guess could be variable bit rate audio? I have read countless times about the problems vbr audio creates. I haven't personally dealth with it to my knowledge but that is a recurring theme here on this website regarding audio issues.

Frankly I'm not sure what the real problem is. Working with audio is usually a breeze compared to processing video. And personally I don't know why its a problem working with two or more programs. As long as you get it done that is all that matters. Streamlining is of course beneficial but if it doesn't work 100% of the time you have to bite the bullet and use more programs.

[Mike99]

yodo313,

I don’t have a problem using multiple programs if that’s what it takes. It’s just that Avidemux started out as a nice one-step program. And then davexnet mentioned saving as an mp3 first and then converting to WAV lowers the sound quality, if I understand that correctly. That makes sense because of the double conversion.

The audio formats all look the same except for size and bitrate, at least according to MediaInfo.

But the video format Container profile and Main parameters are different. That’s the only thing that I noticed. I did some searching trying to find out what those meant and came up empty handed. I'm curious so will look a bit more.

[poisondeathray]

AVC profile doesn't matter, that only affects the video. You're barking up the wrong tree

[Mike99]

Here’s MediaInfo for two videos, one plays properly in Avidemux and one does not.

This one does play properly using Avidemux.
Video
Format : AVC
Format/Info : Advanced Video Codec
Format profile : Main@L1.3
Format settings, CABAC : Yes
Format settings, ReFrames : 3 frames
Muxing mode : Container profile=Unknown@1.3
Duration : 5mn 16s
Bit rate : 63.3 Kbps
Width : 320 pixels
Height : 240 pixels
Display aspect ratio : 4:3
Frame rate mode : Constant
Frame rate : 30.000 fps
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.027
Stream size : 2.38 MiB (33%)

Audio
Format : AAC
Format/Info : Advanced Audio Codec
Format version : Version 4
Format profile : LC
Format settings, SBR : No
Duration : 5mn 16s
Bit rate : 118 Kbps
Channel(s) : 2 channels
Channel positions : Front: L R
Sampling rate : 44.1 KHz
Bit depth : 16 bits
Stream size : 4.44 MiB (62%)

This one does not play with proper audio in Avidemux. It does play properly using VLC.
Video
Format : AVC
Format/Info : Advanced Video Codec
Format profile : Main@L3.0
Format settings, CABAC : Yes
Format settings, ReFrames : 3 frames
Muxing mode : Container profile=Unknown@3.0
Duration : 2mn 45s
Bit rate : 212 Kbps
Width : 640 pixels
Height : 480 pixels
Display aspect ratio : 4:3
Frame rate mode : Constant
Frame rate : 30.000 fps
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.023
Stream size : 4.20 MiB (67%)

Audio
Format : AAC
Format/Info : Advanced Audio Codec
Format version : Version 4
Format profile : LC
Format settings, SBR : No
Duration : 2mn 45s
Bit rate : 96.5 Kbps
Channel(s) : 2 channels
Channel positions : Front: L R
Sampling rate : 44.1 KHz
Bit depth : 16 bits
Stream size : 1.91 MiB (30%)

Any thoughts why the audio is fixed & distorted?

[mikel]

https://www.videohelp.com/tools/AoA_Audio_Extractor

[poisondeathray]

you can try a different build of avidemux. Some apparently have problems with aac

if vlc plays it , you can try vlc to convert it

you can try some of the other options listed, if vlc plays it some of the should work (the avisynth one will)

[Mike99]

you can try a different build of avidemux. Some apparently have problems with aac

if vlc plays it , you can try vlc to convert it

you can try some of the other options listed, if vlc plays it some of the should work (the avisynth one will)

Interesting that you should mention this as I did try VLC a bit earlier and it did the job. Initially it did not work on 2 videos. I tried several times and it just did nothing. I got tired of using the original long filename & shortened it quite a bit and then it worked on all of them. There does not appear to be a way to edit or trim the files. But it extracts & saves to wav in one quick process.

[Mike99]

https://www.videohelp.com/tools/AoA_Audio_Extractor

I just tried AoA Audio Extractor.

I selected wav output & tried it on a couple of the problematic videos. It did extract the audio but did not create a CD compliant wav/pcm file.

Here’s what it made per MediaInfo.
Audio
ID : 0
Format : PCM
Codec ID : 1
Codec ID/Hint : Microsoft
Duration : 3mn 18s
Bit rate : 1 536 Kbps
Channel(s) : 2 channels
Sampling rate : 48.0 KHz
Bit depth : 16 bits
Stream size : 36.3 MiB (100%)

It had the typical choices of 128, 192, etc for the audio, but I did not see any settings for creating a 1,411.2 Kbps, 44.1 Khz file. It just did the 1,536 Kbps and 48.0 KHz by itself.

[bat999]

I’m trying to save the audio from an flv file and put it on a CD.
...
Any suggestions would be appreciated.

Hi
I wasn't sure what you were trying to achieve before.
If you want to use the audio from some flv files to make an Audio CD then WinFF is ideal for the job.
From here:- http://winff.org/html_new/
It's very easy to use.

It has options:-
Convert to... Audio
Device Preset... Wav for CD

This is the result:-

General
Complete name                    : filename.wav
Format                           : Wave
File size                        : 38.6 MiB
Duration                         : 3mn 49s
Overall bit rate                 : 1 411.2 Kbps

Audio
ID                               : 0
Format                           : PCM
Codec ID                         : 1
Codec ID/Hint                    : Microsoft
Duration                         : 3mn 49s
Bit rate                         : 1 411.2 Kbps
Channel(s)                       : 2 channels
Sampling rate                    : 44.1 KHz
Bit depth                        : 16 bits
Stream size                      : 38.6 MiB (100%)

[Mike99]

I tried WinFF and it works quite well. Fast & simple.

Comparing the WinFF wav files to the ones made using VLC, they are the same exact size. Are they both using the same codec? However these are just very slightly larger than the Avidemux files.

I like Avidemux because you can edit/trim the source video before extracting/converting the audio. The downside is that it did not work with half of the flv files I tried.

WinFF and VLC are pretty equivalent in ease of use & functionality.

Between these three, would one of them supposedly make a more accurate or better sounding audio file? I can’t tell the difference but maybe someone else can.

[yoda313]

@mike99 - as far as trimming all you have to do is trim after you get the wav file. Any audio editor can do that - audacity for example.

Regarding the codec - it should all be pcm wav at 16 bit 44.1 khz. If its cd audio output that you specify that is all the choice available.

[bat999]

@mike99 - as far as trimming all you have to do is trim after you get the wav file. Any audio editor can do that - audacity for example...

+1 for that method.
Create the wav files first, then edit/trim with Audacity.

[DarrellS]

You can also use Virtualdub with fcchandler's FLV plugin and AACACM. Open the file > trim if needed > Audio > Full Compression Mode > File > Save WAV.

http://fcchandler.home.comcast.net/~fcchandler/Plugins/FLV/FLV.zip
http://fcchandler.home.comcast.net/~fcchandler/AACACM/index.html

[Gavino]

+1 for that method.
Create the wav files first, then edit/trim with Audacity.

Especially if you want a very accurate cut.
A video editor can only cut (at best) to the frame, say 1/30 sec.
In an audio editor, you can zoom in and cut at the sample level, giving precision of a fraction of a millisecond.

[Mike99]

I'll give Audacity a try. I already have it but never used it.

yoda313 -
I probably did not word my question properly. Do different programs use different means to get to the same end, the wav file? There's obviously a conversion taking place & are some conversion methods or algorithms better than others?

[bat999]

Comparing the WinFF wav files to the ones made using VLC, they are the same exact size. Are they both using the same codec? However these are just very slightly larger than the Avidemux files.
...
Between these three, would one of them supposedly make a more accurate or better sounding audio file? I can’t tell the difference but maybe someone else can.

Hi
Avidemux, VLC and WinFF will probably use the same codec when converting to WAV.
It is:-
pcm_s16le PCM signed 16-bit little-endian

Avidemux is a video editing program.
It's not designed to be used as a file converter.

You can be pretty sure that the WAV files produced by VLC and WinFF are pukka.