Sobre os arquivos GSM
Áudio GSM
Codec áudio para celulares 2G GSM (1987). Comprimido para voz em 13 kbps. Padrão telefonia móvel pré-3G. Ainda usado em VoIP legacy.
Família
Audio Files
Extensão
.gsm
Tipo MIME
audio/gsm
Pode ser usado como
COMO NASCEU O
FORMATO GSM.
GSM — Global System for Mobile communications — standardized voice over digital cellular networks in 1987 in Europe. The codec specified for GSM calls compressed 8 kHz PCM speech into 13 kbps bitstream using Regular Pulse Excitation Long-Term Prediction (RPE-LTP). That was 6 kbps less than a typical landline call and shockingly better-sounding than anyone expected for the time. Every GSM phone on Earth — the 2G networks that spread from Europe to global coverage between 1991 and 2010 — decoded this codec continuously.
Standalone .gsm files preserve recorded calls in that same 13 kbps format. A minute of voice is about 100 KB. The extension appears mostly in corporate voicemail exports, old call-center archives, and some PBX recording systems. Newer LTE and VoLTE networks use Opus or EVS, but GSM’s codec survives in billions of 2G recordings and in the lo-fi-voice aesthetic of early-2000s phone memos.
CURIOSIDADES E
FATOS INTERESSANTES.
The GSM codec compressed voice at 13 kbps — good enough for 4 billion subscribers by the time 2G peaked around 2010.
Finland's Nokia and Sweden's Ericsson built most of the first-generation GSM infrastructure — Europe's telecom standard went worldwide.
GSM audio at 8 kHz is deliberately mono and speech-only — trying to play music through GSM sounds notoriously awful.
Call-center PBXes often saved customer call recordings as .gsm for decades because the bitrate was so small.
Every iPhone can still encode audio as GSM 6.10 — a vestige of the codec's universal embedded-device presence.
VANTAGENS E
LIMITAÇÕES.
Vantagens
- Tiny bitrate (13 kbps) — hours of speech in a few MB.
- Speech-optimized — clear voice reproduction.
- Universal cellphone decoder adoption 1991-2015.
- Stable since 1987.
Limitações
- Speech-only — music sounds distorted.
- 8 kHz sampling — narrowband, muffled by modern standards.
- Legacy — LTE VoLTE moved to AMR-WB, Opus, or EVS.
- Tooling outside telecom is sparse.
Tamanhos típicos de arquivo
1 min of voice
~100 KB
1 hour voicemail archive
~6 MB
Especificações técnicas
- MIME type
- audio/gsm
- Extension
- .gsm
- Codec
- GSM 06.10 (RPE-LTP)
- Sample rate
- 8 kHz
- Bitrate
- 13 kbps
CONVERTER A PARTIR DE
GSM
Casos de uso comuns
Voice over cellular, telephony systems, low-bandwidth speech encoding
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GSM vs M4A
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Perguntas frequentes sobre GSM
Perguntas frequentes
GSM (GSM Audio) is an audio formatoo de arquivo used to store sound recordings — music, voice, podcasts, sound effects. The formato defines how the audio samples are comprimido (or stored raw), what bitrates are suportado, e how metadata como title, artist, album, e cover art is embedded. It is part of the audio arquivos family.
VLC, foobar2000, e the default media players no Windows e macOS handle GSM natively. On mobile, iOS Music e Android media apps vary in their support — popular formatoos funcionar everywhere; niche ones may need a dedicated app. If playback fails em um device, convertendo to MP3 ou AAC Geralmente solves it.
Upload the GSM to KaijuConverter e pick MP3, WAV, FLAC, AAC, OGG, ou any other target. Our FFmpeg pipeline decodes the audio e re-encodes para o target formato at sensible default bitrates (VBR ~190 kbps para music, 96 kbps para speech). Metadata e cover art travel com the audio where both formatoos support them.
GSM can be com perdas ou sem perdas depending no specific variant. com perdas variants (smaller files) discard some audio detail durante compressão in ways tuned to be inaudible; sem perdas variants preserve every sample exactly mas produce larger files. para distribution, com perdas at alta bitrate is padrão; para archival, sem perdas wins.