Apt-X: Difference between revisions
No edit summary |
(add some information about apt-X and apt-X HD) |
||
(One intermediate revision by one other user not shown) | |||
Line 1: | Line 1: | ||
* Website: http://www.aptx.com/ | * Website: http://www.aptx.com/Technology-Portfolio.aspx | ||
* Decoder: https://github.com/FFmpeg/FFmpeg/blob/master/libavcodec/aptxdec.c | |||
apt-X is audio | apt-X is an established audio coding technology for high-performance applications in broadcast, pro audio, consumer electronics, and gaming. The technology is developed and licensed out by APTX, a privately-owned company which previously traded as Audio Processing Technology or APT. | ||
There are several variants of apt-X, each optimised for key applications in audio-over-networks (eg, AoIP, Massively Multi-player On-line Gaming) and wireless audio (for microphones, speakers, Bluetooth headphones, cordless intercoms, etc): standard apt-X, Enhanced apt-X, apt-X Live, and apt-X Lossless. | |||
For more up-to-date information, visit the apt-X entry on Wikipedia. | |||
Apt-X and apt-X HD work by splitting audio signal into four sub-bands using QMF filter and applying ADPCM on each band and packing quantised result into 16-(for apt-X) or 24-bit word (for apt-X HD). Words for different samples are interleaved. | |||
Packed word for apt-X HD (in MSB): | |||
2 bits - bits 1-2 of high band quantised sample | |||
1 bit - parity bit | |||
2 bits - band 2 quantised sample | |||
4 bits - band 1 quantised sample | |||
7 bits - low band quantised sample | |||
Packed word for apt-X HD (in MSB): | |||
4 bits - bits 1-4 of high band quantised sample | |||
1 bit - parity bit | |||
4 bits - band 2 quantised sample | |||
6 bits - band 1 quantised sample | |||
9 bits - low band quantised sample | |||
Each band has the same order-2 ADPCM applied to it. There are no differences between apt-X and apt-X HD beside the latter operating on 24-bit audio and outputting 24-bit words. | |||
[[Category:Audio Codecs]] | [[Category:Audio Codecs]] | ||
Latest revision as of 04:49, 5 January 2021
- Website: http://www.aptx.com/Technology-Portfolio.aspx
- Decoder: https://github.com/FFmpeg/FFmpeg/blob/master/libavcodec/aptxdec.c
apt-X is an established audio coding technology for high-performance applications in broadcast, pro audio, consumer electronics, and gaming. The technology is developed and licensed out by APTX, a privately-owned company which previously traded as Audio Processing Technology or APT.
There are several variants of apt-X, each optimised for key applications in audio-over-networks (eg, AoIP, Massively Multi-player On-line Gaming) and wireless audio (for microphones, speakers, Bluetooth headphones, cordless intercoms, etc): standard apt-X, Enhanced apt-X, apt-X Live, and apt-X Lossless.
For more up-to-date information, visit the apt-X entry on Wikipedia.
Apt-X and apt-X HD work by splitting audio signal into four sub-bands using QMF filter and applying ADPCM on each band and packing quantised result into 16-(for apt-X) or 24-bit word (for apt-X HD). Words for different samples are interleaved.
Packed word for apt-X HD (in MSB):
2 bits - bits 1-2 of high band quantised sample 1 bit - parity bit 2 bits - band 2 quantised sample 4 bits - band 1 quantised sample 7 bits - low band quantised sample
Packed word for apt-X HD (in MSB):
4 bits - bits 1-4 of high band quantised sample 1 bit - parity bit 4 bits - band 2 quantised sample 6 bits - band 1 quantised sample 9 bits - low band quantised sample
Each band has the same order-2 ADPCM applied to it. There are no differences between apt-X and apt-X HD beside the latter operating on 24-bit audio and outputting 24-bit words.