ffmpeg: How to convert FLV to M4A, M4B without losing quality (demux/extract AAC)

How to extract AAC autio tracks from FLV or MP4 video files with freeware command-line ffmpeg (Windows, Linux, Mac OS X)

First of all find out what type of audio is used in the video file:

ffmpeg -i inputfile.flv

You will get something like

Stream #0.1: Audio: AAC, 44100 Hz, stereo, s16, 128 kb/s

Now you know that AAC audio is used (or MP3, or Speex, or Wav,...), so use the following command:

ffmpeg -i input.flv -vn -acodec copy output.m4a

or

ffmpeg -i input.flv -vn -acodec copy output.m4b

Replay Media Catcher 4 uses ffmpeg for extracting AAC audio tracks from FLV files to M4A and M4B. If you don't like command line tools, you can use RMC 4 instead:



How to convert FLV to M4A without losing quality with Replay Media Catcher (RMC) 4 after downloading FLV / MP4 file automatically:

• Open Replay Media Catcher.
• Start Recording
• Select the "Audio Extraction (Extract AAC to M4A)" conversion preset
• Navigate to a web-site you want to record FLV stream from
• HTTP and RTMP .FLV streams will be downloaded/captured automatically. Then AAC audio tracks will be extracted to M4A files automatically.

How to convert FLV to M4B without losing quality with Replay Media Catcher (RMC) 4 after downloading FLV / MP4 file automatically:

• Open Replay Media Catcher.
• Start Recording
• Select the "Audio Extraction (Extract AAC to M4B)" conversion preset
• Navigate to a web-site you want to record FLV stream from
• HTTP and RTMP .FLV streams will be downloaded/captured automatically. Then AAC audio tracks will be extracted to M4B files automatically.

How to convert any FLV or MP4 file (with AAC audio track) to M4A with Replay Media Catcher 4:

• Open Replay Media Catcher.
• Select the "Audio Extraction (Extract AAC to M4A)" conversion preset
• Go to "Tools" -> "Convert ..."
• Select FLV files from which you want to extract AAC audio tracks
  (CTRL key can help to select multiple files) and hit the "Open" button.
• AAC tracks from the selected FLV file(s) will be extracted into M4A file(s)

How to convert any FLV or MP4 file (with AAC audio track) to M4B with Replay Media Catcher 4:

• Open Replay Media Catcher.
• Select the "Audio Extraction (Extract AAC to M4B)" conversion preset
• Go to "Tools" -> "Convert ..."
• Select FLV files from which you want to extract AAC audio tracks
  (CTRL key can help to select multiple files) and hit the "Open" button.
• AAC tracks from the selected FLV file(s) will be extracted into M4B file(s)