Convert AMR to AU
AMR to AU Conversion Software converts AMR files
to AU quickly and easily. The converter supports common codecs for AU
file including PCM 32-bit, CCITT a-Law (8-bit), PCM 24-bit, PCM 64-bit Float, PCM 32-bit Float, ITU-T G.723 3-bit ADPCM, CCITT mu-Law (8-bit), ITU-T G.723 5-bit ADPCM, and so on.
AMR to AU Conversion Software is very easy to use
and supports batch conversion. It is full compatible with both 32-bit
and 64-bit editions Windows 10/8/7/Vista/XP/2000.
What is AMR?
Adaptive Multi-Rate (AMR) is an audio data compression scheme optimized for speech
coding. AMR was adopted as the standard speech codec by 3GPP in October 1998 and
is now widely used in GSM and UMTS. It uses link adaptation to select from one
of eight different bit rates based on link conditions. AMR is also a file format
for storing spoken audio using the AMR codec. Many modern mobile telephone handsets
will allow you to store short recordings in the AMR format. There also exists
another storage format for AMR that is suitable for applications with more advanced
demands on the storage format, like random access or synchronization with video.
This format is the 3GPP-specified 3GP container format based on ISO base media
- Sampling frequency 8 kHz/13-bit (160 samples for 20 ms frames), filtered to
- The AMR codec uses eight source codecs with bit-rates of 12.2, 10.2, 7.95,
7.40, 6.70, 5.90, 5.15 and 4.75 kbit/s.
- Generates frame length of 95, 103, 118, 134, 148, 159, 204, or 244 bits for
bit rates 4.75, 5.15, 5.90, 6.70, 7.40, 7.95, 10.2, or 12.2 kbit/s, respectively
- AMR utilizes Discontinuous Transmission (DTX), with Voice Activity Detection
(VAD) and Comfort Noise Generation (CNG) to reduce bandwidth usage during silence
- Algorithmic delay is 20 ms per frame. For bit-rates of 12.2, there is no 'algorithm'
look-ahead delay. For other rates, look-ahead delay is 5 ms. Note that there is
5 ms 'dummy' look-ahead delay, to allow seamless frame-wise mode switching with
the rest of rates.
- AMR is a hybrid speech coder which uses Algebraic Code Excited Linear Prediction
- The complexity of the algorithm is rated at 5, using a relative scale where
G.711 is 1 and G.729a is 15.
- PSQM testing under ideal conditions yields Mean Opinion Scores of 4.14 for
AMR (12.2 kbit/s), compared to 4.45 for G.711 (u-law)
- PSQM testing under network stress yields Mean Opinion Scores of 3.79 for AMR
(12.2 kbit/s), compared to 4.13 for G.711 (u-law)
What is AU?
The Au file format is a simple audio file format introduced by Sun Microsystems.
The format was common on NeXT systems and on early web pages. Originally it was
headerless, being simply 8-bit u-law encoded data at an 8000 Hz sample rate. Hardware
from other vendors often used sample rates as high as 8192 Hz, often integer factors
of video clock signals. Newer files have a header that consists of six 32-bit
words, an optional information chunk and then the data (in big endian format).
Although the format now supports many audio encoding formats, it remains associated
with the u-law logarithmic encoding. This encoding was native to the SPARCstation
1 hardware, where SunOS exposed the encoding to apps through the /dev/audio interface.
This encoding and interface became a de facto standard for Unix sound.
- Free Download
AMR to AU Conversion Software
- Install the software by instructions
- Launch AMR to AU Conversion Software
- Choose AMR Files
Click "Add Files" to choose AMR files and then add them
to conversion list.
Choose one or more AMR files you want to convert and then click Open.
- Choose "to AU"
- Convert AMR to AU
Click on "Convert" to convert AMR files to AU format; alternatively,
click on "Convert to One" to convert all files in list and
combine to a single one AU file.
The software is converting AMR files to AU format.
- Play and Browse AU File
When conversion completes, you could right-click on converted file and choose
"Play Destination" to play the AU file; or choose "Browse
Destination Folder" to open Windows Explorer to browse the outputted AU
AMR to AU Conversion Software is 100% clean and safe to install.
It's certified by major download sites.
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