M4A to AMR - Convert audio online
|#||Output File||Source File||Action|
1. Click "Choose Files" button to select multiple files on your computer. You can also click the dropdown button to choose online file from URL, Google Drive or Dropbox. The source file can also be video format. Video and audio file size can be up to 200M.
3. Click "Convert Now!" button to start batch conversion. It will automatically retry another server if one failed, please be patient while converting. The output files will be listed in the "Conversion Results" section. Click icon to show file QR code or save file to online storage services such as Google Drive or Dropbox.
M4A vs AMR:
|Full name||Audio-only MPEG-4||Adaptive Multi-Rate|
|File extension||.m4a||.amr, .3ga|
|Developed by||International Organization for Standardization||3GPP|
|Type of format||Media container||Audio compression format|
|Introduction||MPEG-4 Part 14 or MP4 is a digital multimedia container format most commonly used to store video and audio, but can also be used to store other data such as subtitles and still images. M4A stands for MPEG 4 Audio and is a filename extension used to represent audio files.||The Adaptive Multi-Rate (AMR or AMR-NB or GSM-AMR) audio codec is an audio compression format optimized for speech coding. AMR was adopted as the standard speech codec by 3GPP in October 1999 and is now widely used in GSM and UMTS.|
|Technical details||Audio-only MPEG-4 files generally have a .m4a extension. This is especially true of non-protected content. M4A is often compressed using AAC encoding (lossy), but can also be in Apple Lossless format.||AMR speech codec consists of a multi-rate narrowband speech codec that encodes narrowband (200-3400 Hz) signals at variable bit rates ranging from 4.75 to 12.2 kbit/s with toll quality speech starting at 7.4 kbit/s. Sampling frequency 8 kHz/13-bit (160 samples for 20 ms frames), filtered to 200-3400 Hz.|
|Associated programs||Windows Media Player, RealPlayer, MPlayer, Media Player Classic, VLC Media Player, K-Multimedia Player||Audacity, FFmpeg, MPlayer, QuickTime, VLC media player|
|Wikipedia||M4A on Wikipedia||AMR on Wikipedia|