Editing Pro Tools (section)

===Pro Tools | HDX (2011–present)===
In October 2011, Avid introduced Pro Tools 10 and a new series of DSP [[PCI Express|PCIe cards]] named HDX. Each card mounted 18 DSP processors, manufactured by Texas Instruments, allowing an increased computational precision ([[Single-precision floating-point format|32-bit]] [[Floating-point arithmetic|floating-point]] resolution for audio processing and [[Double-precision floating-point format|64-bit]] floating-point summing, versus the previous 24-bit and 48-bit [[fixed-point arithmetic|fixed-point]] resolution of the TDM engine),<ref name=":15" /> thus improving dynamic range performance. Signal processing could be run on the embedded DSP, providing additional computational power and enabling near zero-latency for DSP-reliant plug-ins. Two [[Field-programmable gate array|FPGA]] chips handled track playback, monitoring, and internal routing, providing a lower round trip latency.

A second line of PCIe cards, called HD Native, provided low latency with a single FPGA chip but did not mount DSP (audio processing relied on the host system's CPU).<ref name=":0" /> Round trip latency at 96&nbsp;kHz was 0.7 ms for HDX and 1.7 ms for HD Native (with a 64-sample buffer).<ref>{{Cite web|last=|first=|date=|title=Compare Pro Tools HDX vs Pro Tools HD Native|url=https://www.avid.com/products/pro-tools-hd-native/specifications|archive-url=|archive-date=|access-date=2021-01-31|website=www.avid.com}}</ref>

To maintain performance consistency, HDX products were specified with a fixed maximum number of voices (each voice representing a monophonic channel). Each HDX card enabled 256 simultaneous voices at 44.1/48&nbsp;kHz; voice count halved when the sample rate doubled (128 voices at 88.2/96&nbsp;kHz, 64 voices at 176.4/192&nbsp;kHz). Up to three HDX cards could be installed on a single system for a maximum of 768/384/192 total voices and for increased processing power. On Native systems, voice count was limited to 96/48/24 voices with the standard version of Pro Tools and 256/128/64 voices with Pro Tools HD software.<ref name=":15" />

With Pro Tools 10, Avid deployed a new plug-in format for both Native and HDX systems called AAX (an acronym for Avid Audio eXtension).<ref>{{Cite web|url=https://www.pro-tools-expert.com/home-page/2014/9/22/a-z-of-pro-tools-a-is-for-aax.html|title=A-Z of Pro Tools - A is for AAX|last=Hughes|first=Russ|date=2014-09-22|website=Production Expert|language=en-GB|access-date=2019-12-17}}</ref> AAX Native replaced RTAS plug-ins and AAX DSP, a specific format running on HDX systems, replaced TDM plug-ins. AAX was developed to provide the future implementation of 64-bit plug-ins, although 32-bit versions of AAX were still used in Pro Tools 10. TDM support was dropped with HDX,<ref>{{cite web|url=http://akarchive.digidesign.com/support/docs/50/DigiRack_Plug-Ins_Guide501.pdf|title=Pro Tools DigiRack Plug-Ins Guide: Version 5.0.1 for Macintosh and Windows|year=2000|publisher=Digidesign, Inc.|page=18|access-date=2013-10-23}}</ref> while Pro Tools 10 would be the final release for Pro Tools | HD Process and Accel systems.

Notable software features introduced with Pro Tools 10 were editable clip-based gain automation (Clip gain), the ability to load the session's audio data into RAM to improve transport responsiveness (Disk caching), quadrupled Automatic Delay Compensation length, audio fades processed in real-time, timeline length extended to 24 hours, support for 32-bit float audio and mixed audio formats within the session, and the addition of Avid Channel Strip plug-in (based on Euphonix System 5 console's channel strip, following Avid's acquisition of Euphonix in 2010).<ref>{{Cite web|url=https://www.soundonsound.com/reviews/avid-pro-tools-10|title=Avid Pro Tools 10|last=Wherry|first=Mark|date=March 2012|website=[[Sound on Sound]]|access-date=2019-12-18}}</ref><ref name=":29" />