The M4A file format forms part of the MP4 specification, specifically the audio stream of the Mp4 format. .m4a files are essentially audio only bit streams encoded using the audio codecs from the MPEG-4 Part 14 specification. Audio encoding can be accomplished using algorithms from the lossy family or lossless family of codecs. One of the design goals of the M4A audio format was to achieve a high level compression ratio without sacrificing audio quality. In this regard, it was intended that the format would succeed the MP3 file format. Although it has done this from a technical standpoint, the MP3 format continues to be widely used.
The .amr filename extension refers to the adaptive multi-rate audio codec initially released in 1999. The format is typically used to encode speech audio and is optimized for this purpose. It can encode speech into one of two file version, either AMR-NB (narrow Band) or AMR-WB (Wide Band) which supports a broader frequency. Because of its optimization for speech audio, the format has been widely adopted as the standard speech codec for GSM and UMTS mobile phone networks by the 3rd Generation Partnership Project ' a collaborative group of organizations in the telecommunications industry.
FreeFileConvert uses tuned encoding for M4A to AMR conversions, preserving clarity while trimming file size. Finished audio streams instantly across phones, tablets, desktops, and modern browsers without extra tweaks.
Upload M4A files from desktop, tablet, or cloud storage, queue multiple jobs, and let the converter finish autonomously. Return whenever convenient to download synchronized AMR results on any device you rely on.
Process up to 5 files sized 1000 MB per batch without splitting queues manually. Mixed-format uploads convert together, producing consistent AMR audio with dependable progress tracking.
Typically an m4a audio stream is encoded using the lossy Advanced Audio Coding format or AAC compression format which has a minimal tradeoff of audio quality in favor for storage size. In situations where maximum quality is required, the Apple Lossless Audio Codec or ALAC can be used.
AMR format encodes narrow band signals between 200 and 3400 hertz at a maximum bitrate of 12.2 kilobits per second. The format employs the ACELP ' Algebraic code-excited linear prediction algorithm, a proprietary speech encoding method created by the VoiceAge Corporation.
Upload your audio file in the M4A format from your device, Dropbox, or Google Drive.
Select AMR as the output format and click Convert. Adjust optional settings if needed.
Download the converted audio file. Each file stays available for up to 5 downloads.