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Immersive Soundfield Rendition (ISR) system is an in-house low bit rate multi-channel audio codec ( 5.1-channel ). The high quality multi-channel audio compression tool is engineered with state-of-the-art patent pending algorithm namely, Multi Band Temporal Amplitude Coding (MBTAC). ISR emphasizes the accurate reproduction of multi band temporal envelope of Multichannel data. The ease of scalability of the surround image, between 2 kbit/s and 12 kbit/s, and its high quality audio with feature rich add-ons make the tool user friendly. A conventional stereo encoder can be upgraded to a multi-channel encoder with the aid of an associated low overhead ISR bitstream.
Platforms
ISR library APIs available for Windows
Decoder available for 16-bit fixed point implementation on ADSP and TI platform
For implementations on other platforms and licensing issues please contact us info@atc-labs.com
Coding Scheme
Audio Quality Spec
ISR-12
ISR-08
3.60714
MP3 Surround
3.37805
4.96428
Low Anchor
1.65476
Original
Recently conducted subjective test results are presented here. The result compares two different modes of ISR against MP3 Surround and mpeg surround. ISR uses Teslapro as its core codec. An elaborate discussion on this was presented in NY 2007 AES convention. The same is available here
Table shows the mean score of 12 expert listeners on 6 critical surround audio samples :
In the second test ISR shows significant gains in terms of quality compared to recently standardized MPEG Surround. In these tests core codec for ISR and MPEG Surround was replaced with original audio as input. The below figure shows the subjective score:
Table shows the mean score of 12 expert listeners on 6 critical surround audio samples
Mean Score
3.92857
Coding Scheme
Audio Quality Spec
ISR-08
ISR-12
4.01190
MPEG Surround
3.07143
4.95238
Low Anchor
1.60714
Original
Mean Score
3.57143
Music
ISR Coded
File Size
Download
Rock
8Kbps
12Kbps
~3.8 MB
~3.8 MB
8Kbps
12Kbps
8Kbps
12Kbps
Glock
Sax
~2.0 MB
~2.0 MB
~3.5 MB
~3.5 MB
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