| Name | AMR | MP4 |
| Full name | AMR - Adaptive Multi-Rate | MP4 - MPEG-4 Part 14 |
| File extension | .amr, .3ga | .mp4, .m4a, .m4p, .m4b, .m4r, .m4v |
| MIME type | audio/amr | video/mp4 |
| Developed by | 3GPP | International Organization for Standardization |
| Type of format | Audio compression format | Media container |
| Description | 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. | MPEG-4 Part 14 or MP4 is a digital multimedia format most commonly used to store video and audio and store other data such as subtitles and still images. Like most modern container formats, it allows streaming over the Internet. |
| Technical details | 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. | Most kinds of data can be embedded in MPEG-4 Part 14 files through private streams. A separate hint track is used to include streaming information in the file. |
| File conversion | AMR conversion | MP4 conversion |
| Associated programs | Audacity, FFmpeg, MPlayer, QuickTime, VLC media player | Windows Media Player, RealPlayer, MPlayer, Media Player Classic, VLC Media Player, K-Multimedia Player |
| Wiki | https://en.wikipedia.org/wiki/Adaptive_Multi-Rate_audio_codec | https://en.wikipedia.org/wiki/MPEG-4_Part_14 |
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Supported Audio File Formats: WAV, MP3, AC3, AAC, M4A, MPC, MPA, MP2, WMA, FLAC, SHN, APE, OGG, WV, AMR to MP3, AAC, AC3, WMA, FLAC, OGG Vorbis, OGG FLAC or WAV. Click the Free Download button below to try Pazera Free Audio Extractor at once. Top 6: Free MP3 WMA Converter. Free MP3 WMA Converter is the best tool for converting audio files. Best Ways to Convert AMR to MP3 on Mac. ALL2MP3 for Mac (Recommended) All2MP3 for Mac is the most famous media-to-MP3 converter on Mac OS, which has been used by millions of users for years. Its greatest feature is to convert almost source media files in any formats to MP3, including audio formats like AMR, WAV, WMA, AAC, M4A, M4B, OGG, FLAC, ALAC, etc. Solution 1: Free Online Tool – Apowersoft Free Online Audio Converter. This is a convenient way to convert AMR to MP3 online. It supports conversion of any audio file including AMR to MP3 or other audio formats like WAV, WMA, AAC, FLAC, OGG and RA. The basic user interface is easy for every user to understand. AMR to MP3 - Convert file now View other audio file formats Technical Details The AMR codec uses eight source codecs with bit-rates of 12.2, 10.2, 7.95, 7.40, 6.70, 5.90, 5.15 and 4.75 kbit/s and has a sampling frequency of 8kHz which is filtered to 200-3400 Hz. AMR codec files require very little space on your mobile device, but are too compressed to be read by media players on a PC or Mac. Although AMR codec files free up a lot of space on your phone compared to an MP3, AMR is exclusive to your mobile device and cannot be read by alternative media players, like iTunes or Windows Media Player.