The MP4 file format and the .mp4 filename extension refer to the MPEG-4 part 14 digital multimedia format developed by the Moving Picture Experts Group. It is used as a multimedia container to wrap encoded digital video and audio streams, including subtitles and still images if required. In recent decades, the format has been popularized as one of the main standards for streaming media over the internet and other computer networks and for the digital distribution of large multimedia files. MP4 supports a large number of compression audio codecs allowing files in this format to maintain a relatively small size without discounting playback quality.
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 MP4 to AMR conversions, preserving clarity while trimming file size. Finished audio streams instantly across phones, tablets, desktops, and modern browsers without extra tweaks.
Upload MP4 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.
The MPEG-4 Part 14 is standardized as part of the MPEG-4 format in ISO/IEC 14496-14:2003. It is recognized as a container format for audio and video streams and references several filename extensions of which .mp4 is one. The MPEG-4 Part 14 is in many ways identical to Apple's QuickTime format which formed the basis of MPEG-4. However, there are slight differences in compatibility with other previously standardized MPEG features and the added support for IOD or initial object descriptors which describe elementary data streams and set profile information of the resources needed for content playback.
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 video file in the MP4 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.