What is the AL file format?
An .al file is a raw A-law audio file containing uncompressed PCM audio encoded with A-law companding as defined in the ITU-T G.711 standard. The format carries no file header - audio samples begin at byte 0, so sample rate, channel count, and recording length must be known from context.
A-law companding is a logarithmic compression scheme that maps 13-bit linear PCM samples into 8-bit values, giving telephone-quality speech a useful dynamic range at a fixed data rate of 8,000 bytes per second (8 kHz mono). This is the standard for telephony across Europe, Asia, and Africa; the North American and Japanese counterpart is µ-law, stored with the .ulaw or .ul extension.
The .al extension originated in Unix workstation audio toolchains of the 1980s and 1990s. The same A-law data was also commonly wrapped in .au (Sun Audio) containers, which add a descriptive header identifying the encoding and sample rate. The .al extension is Unix-specific and rarely encountered on Windows or macOS.
Despite its age, G.711 A-law remains the dominant codec on public switched telephone networks and in VoIP systems (RTP payload type 8). Tools such as SoX (sox) can decode .al files by specifying the encoding, sample rate, and channel count explicitly; Audacity can import them via its raw audio import function. Converted output is typically saved as .wav.
Security & safety
RISK: LOWHeaderless raw audio - no executable code possible. Cannot trigger exploits through codec parsing (no parser metadata). Very low risk.
Format details
in a nutshell- Oracle Database Autoextend/Alert Log - Oracle uses .al for alert log and archive log files - a plain-text database diagnostic file entirely unrelated to audio.
- AutoIt Compiled Script (historical) - Some older AutoIt versions used .al for compiled script files.
Programs that open AL files
Windows2 apps
VLC media player
Open-source May play raw A-law with Media → Open File; if not recognized, use FFmpeg conversion first. 
Audacity
Open-source File → Import → Raw Data → select file, set encoding to A-Law, sample rate 8000 Hz, mono, big-endian. 
macOS1 app
Linux2 apps
SoX (Sound eXchange)
Open-source sox -r 8000 -e a-law -c 1 -b 8 input.al output.wav - converts to WAV. Technical details
deep spec| Encoding | Raw 8-bit A-law companded PCM samples; no file header or container |
| Companding algorithm | A-law (ITU-T G.711): maps 13-bit linear PCM to 8-bit values using a piecewise logarithmic function; achieves ~36 dB SNR for speech |
| Data rate | 8,000 bytes/second at standard telephony rate (8 kHz mono); 1 minute of audio ≈ 480 KB |
| Standard sample rate | 8,000 Hz (G.711 narrowband telephone); 16,000 Hz for wideband (G.711.1) |
| Byte order | Big-endian (Sun/Unix convention; no header to confirm) |
| Header | None - raw samples begin at byte 0; sample rate, channel count, and length must be supplied externally |
| Channels | Mono (1 channel) standard for telephone; stereo possible but uncommon |
| Geographic standard | European, Asian, and African telephony standard; North American/Japanese equivalent is µ-law (.ul/.ulaw, RTP payload type 0) |
| MIME type | audio/x-alaw-basic; also audio/basic (shared with µ-law) |
| Primary application | PSTN telephony, VoIP (SIP/RTP G.711 A-law payload type 8), IVR systems, call recording |
| Identification limitation | No magic bytes; cannot be identified by file signature alone - format must be inferred from extension or system context |
| Related headerless format | .ul/.ulaw (µ-law G.711); .au (Sun Audio) provides the same A-law data with an added descriptive header |
| Released | 1972 (G.711 standard); .al extension common in Unix workstations ~1985-1995 |
| Latest version | G.711 (unchanged since 1988 revision) |
| Open standard | Yes · royalty-free |
| Specification | www.itu.int |
AL conversions
Community Q&A
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