SMP to AMR Converter

SMP is the native file format of SampleVision, a sample editing application developed by Turtle Beach Systems around 1990. SampleVision was among the first PC-based visual sample editors, letting musicians view waveforms on screen and perform cut, copy, paste, and loop-point editing — capabilities previously limited to expensive dedicated hardware samplers. The SMP format stores 16-bit mono PCM audio along with sampling-specific metadata: loop start and end points, sustain loops, release loops, and MIDI root note assignments. This made SMP files directly useful for creating and exchanging patches between hardware samplers via MIDI Sample Dump Standard (SDS) transfers, which SampleVision automated through its interface. A primary advantage was bridging the PC world with professional sampling hardware from Akai, E-mu, Ensoniq, and Roland — devices that had tiny screens and minimal editing tools. The format also supported common sample rates (22050, 44100 Hz) and brief text descriptions alongside audio data. Though Turtle Beach pivoted to gaming peripherals and SampleVision was discontinued, SMP files persist in vintage sample library archives and can be converted using SoX.

AMR (Adaptive Multi-Rate) is a compressed audio format optimized for speech, standardized by the European Telecommunications Standards Institute and adopted as a mandatory codec for GSM and 3G mobile networks. The codec dynamically switches between eight bit rates — from 4.75 to 12.2 kbps — depending on network conditions and background noise levels. When link quality drops, the encoder shifts to a lower rate, trading marginal clarity for transmission reliability. This adaptive mechanism is defined by the 3GPP specifications and represents one of the most widely deployed voice codecs globally, used in billions of mobile calls. The primary advantage is compression efficiency: one minute of AMR audio at 12.2 kbps occupies roughly 90 KB, practical for voice memos, voicemail, and MMS on bandwidth-constrained networks. Another benefit is built-in voice activity detection and comfort noise generation, reducing transmission during silence. While AMR is unsuitable for music due to its narrow bandwidth (300-3400 Hz), it excels at delivering intelligible speech under challenging network conditions.