From: Mike Brady <4265913+mikebrady@users.noreply.github.com> Date: Wed, 7 Jul 2021 09:06:01 +0000 (+0100) Subject: Update RELEASENOTES-DEVELOPMENT.md X-Git-Tag: 4.1-dev~30 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=52c24b467c80f4c37ead163a919c1d00504b4e8a;p=thirdparty%2Fshairport-sync.git Update RELEASENOTES-DEVELOPMENT.md --- diff --git a/RELEASENOTES-DEVELOPMENT.md b/RELEASENOTES-DEVELOPMENT.md index 870a2fea..5f73973d 100644 --- a/RELEASENOTES-DEVELOPMENT.md +++ b/RELEASENOTES-DEVELOPMENT.md @@ -5,16 +5,10 @@ Big Update ---- Version 4 brings limited AirPlay 2 functionality to Shairport Sync. -A major feature of Shairport Sync's AirPlay 2 support is Audio Synchronisation. This is achieved using an purpose-built passive [PTP](https://standards.ieee.org/standard/1588-2008.html) client called [`nqptp`](https://github.com/mikebrady/nqptp), which provides precise timing information that Shairport Sync uses to maintain tight synchronisation. (BTW, `nqptp` is not a "PTP slave". Instead, it passively monitors PTP traffic for timing information.) +For more information about AirPlay 2, including acknowledgements, please visit [AIRPLAY2.md]. -Acknowledgements ----- -Much of Shairport Sync's AirPlay 2 functionality is based on ideas developed at the [openairplay airplay2-receiver]( https://github.com/openairplay/airplay2-receiver) repository. - -Big thanks are due to number of individuals made direct and valuable contributions to Shairport Sync: -1. [ejurgensen](https://github.com/ejurgensen) contributed ideas and code. The `pair_ap` submodule and related code in `rtsp.c` is theirs. -2. [JD Smith](https://github.com/jdtsmith) contributed ideas, comments and suggestions along with extensive and thorough testing. -3. [Charles Omer](https://github.com/charlesomer) contributed ideas, comments, bug fixes and Docker automation (forthcoming). +#### Known Issues +- In the AirPlay 2 build, a crash can occur occasionally when the player is being selected. If you can get this to happen reliably, please let us know. Warning ---- @@ -22,53 +16,6 @@ Warning 2. There is lots we don't know about AirPlay 2. This can result in incorrect behaviour. Watch out for very high volume levels, especially if you have a powerful audio system. 3. This is a `development` branch and is probably more buggy than usual. Normal support will not be provided -- instead, we will be interested in bug reports that help improve the program. You need to be adept with Linux or FreeBSD to get involved. -AirPlay 2 Overview ----- - -#### What Works -- AirPlay 2 for iOS and Mac players. - -#### What Does Not Work -- No AirPlay 2 for Windows iTunes -- No integration with Siri or HomeKit -- No Lossless or High Definition Lossless -- No Remote Control -- No Artwork in the Metadata - -#### What Partly Works -- Incomplete functionality using AppleTV or HomePod as player. - A Shairport Sync player will work, but the selection button won't persist and the volume can't be set. - -#### Limitations -- You can only run a single instance of Shairport Sync on a device. -- The AirPlay 2 version of Shairport Sync will not run on macOS, since `nqptp` can not be installed on it. - -#### Known Issues -- A crash can occur occasionally when a Shairport Sync player is being selected for output. If you can get this to happen reliably, please let us know. - -AirPlay 2 -- What You Need ---- -AirPlay 2 support needs a more powerful CPU for decoding and synchronisation and more memory for bigger buffers and larger libraries. Raspberry Pi OS and Ubuntu 20.04 on a VM have been used extensively in development, with Alpine Linux and FreeBSD 12.2 being used to a lesser extent. - -Here are some suggestions: -* Full access, including `root` privileges, to a system at least as powerful as a Raspberry Pi 3. -* A fully up-to-date Linux. This is important, as some of the libraries must be the latest available. -* An audio output, for example an `alsa` device (or `sndio` in FreeBSD). The `stdout` and `pipe` backends continue to work as before. Other backends have not been tested. - -Guides ---- -Instructions for building Shairport Sync are different for AirPlay 2 than for AirPlay 1 -- please follow them very carefully. - -* A brief guide to building Shairport Sync for AirPlay 1 is available at [BUILDFORAP1.md](https://github.com/aillwee/shairport-sync/blob/development/BUILDFORAP1.md). -* To build Shairport Sync for AirPlay 2 on Linux, please follow the guide at [BUILDFORAP2.md](https://github.com/aillwee/shairport-sync/blob/development/BUILDFORAP2.md). -* A guide for building on FreeBSD is forthcoming. - -AirPlay 2 -- More About What Works ---- -* Two types of audio are received -- "Realtime" streams of CD quality ALAC (like AirPlay 1) and "Buffered Audio" streams of AAC stereo at 44,100 frames per second. The selection of stream type is made by the player. -* Audio is synchronised with other AirPlay 2 devices, including AirPlay 2 devices that have their own master clocks. (Note: This has not been tested with multiple nearly-identical master clock devices such as with two HomePod minis -- Shairport Sync will get confused about which is the current master.) -* Shairport Sync continues to support AirPlay 1, and offers an AirPlay 1 compatibility mode for situations where iTunes on macOS or macOS Music plays to multiple speakers and one of more of them is compatible with AirPlay 1 only. - Version 3.3.8d7 ==== **Bug Fix**