24.01.2017 (Tuesday)

How to convert Flash Video files (FLV) to MP3

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Last modified: 24.08.2016


Flash Video (FLV)

FLV (Flash Video) is a multimedia container format commonly used on the Internet to deliver video content on websites. Flash Video files usually have the extension .flv or .f4v.

To properly play FLV videos in a web browser, you must install a special plug-in: Adobe Flash Player. This plugin, like FLV format was developed by Macromedia, which in 2005 was acquired by Adobe Systems.

FLV format has quickly gained a great popularity, mainly due to delivering videos in this format by Internet video sites such as YouTube, Yahoo! Video, Metacafe, Reuters and many others.

To encode video streams in FLV files are used codecs: Sorenson, VP6 and H.264. The most commonly used audio codecs are MP3 and AAC.
FLV files can be played using some software players (eg VLC, MPlayer). Unfortunately, most portable players and almost all fixed players do not support FLV format.

More information on FLV format can be found at Wikipedia.

Conversion FLV to MP3 using Free FLV to MP3 Converter

This tutorial shows step-by-step how to convert Flash Video files to MP3 format using Free FLV to MP3 Converter.

This program is completely free (for personal and commercial use) and you can download it here.

1. Starting the program and adding FLV files to the processing list

When you install and run the program, the main window will appear.

The main window of the Free FLV to MP3 Converter
The main window of the Free FLV to MP3 Converter

To convert FLV files, you must first add them to the processing list. To do this, click the Add files button and select the desired FLV files. They appear on the list. Files can also be added using drag and drop technique.

2. Conversion using profiles

The program includes a number of conversion profiles designed for the typical conversion tasks. They are available on the Profile drop-down list. To use one of profiles, simply select it on this list.

If you do not have experience in converting audio files, select the profile named Default encoder settings and click the Convert button to start the conversion.

At default settings, the application converts audio tracks from FLV files to MP3 using constant bitrate encoding (CBR), and automatically selects all the encoding parameters so as to preserve the original audio quality.
Default settings of the FLV to MP3 conversion
Default settings of the FLV to MP3 conversion

3. Conversion parameters

If you want to set manually parameters of the FLV to MP3 conversion, you can do it in the Audio section.

First, at the Output format list select MP3 - MPEG-1 Layer 3.

Then in the audio settings, select the desired bitrate, which will be used to encode the audio stream from FLV file to MP3 - this parameter determines the sound quality of the resulting MP3 file.
Bitrate is best set to a value close to the bitrate of the audio stream in the source FLV file. If you use a lower value, you should expect to lose sound quality. However, if you set the bitrate much higher than in the source file, the generated MP3 file will be very large, and the sound quality will be the same as using a lower bitrate.
If you set audio Bitrate in the Auto position, the program will automatically adjust the bitrate to a value close to the audio bitrate in the source file.

At default settings will be applied encoding at a constant bitrate (CBR). On the Bitrate mode list you can also set the variable bitrate encoding: ABR or VBR - Lame preset. You must remember that some older MP3 players support only MP3 files encoded at a constant bitrate, so if you want to use variable bitrate encoding, first check the documentation of your player.

Parameters Sampling frequency and Channels (the number of audio channels in the output file) is best left in the positions Auto, then the program automatically selects the appropriate values.

Using the Volume slider you can adjust the sound level in the resulting MP3 file. When set to 100%, the volume will not change.

4. Extracting MP3 audio tracks from FLV files

In FLV files very often audio tracks are encoded using MP3 codec. In this case, you only need to extract the original audio stream and save it to an MP3 file. When extracting audio tracks, the sound does not change - the sound in the generated MP3 file will be the same as in the source file.

To obtain information which codec was used to encode the audio in FLV file, make sure that the column Audio codec is shown - right-click the table header and in the context menu with a list of columns, select the Audio codec.

MP3 tracks in FLV files
MP3 tracks in FLV files

On the picture above you can see that the sound in the files 2, 4 and 5 has been encoded by MP3 encoder. To extract the original MP3 audio tracks from these files, on the list Output format select Try extract original audio stream.

Extracting audio tracks
Extracting audio tracks

5. Starting conversion/extraction

When you add FLV files to the file list and set all the necessary parameters, you can already start the conversion/extraction by clicking the Convert button. The Conversion window will appear, where you can track the progress of the operation.

Conversion progress
Conversion progress

With default settings, the converted files will appear in the same directory that contains the source files. You can change output folder in the Output section. Generated MP3 files will have the same name as FLV files, only the extension is changed to .mp3.