Hi all,
The AAF plugin RFC series v2 has been around on alsa-devel ML for more than two
weeks so I'm moving forward and sending it as PATCH series now.
The first 5 patches from this series are pretty much the same from the previous
version. The news are the top 2 patches which add more functionality to the
plugin. Patch 6/7 implements the dump() callback which has been useful for
debugging purposes and Patch 7/7 adds support for direct read/write transfers.
For general context information about the AAF plugin, I'm quoting below the
cover letter from the RFC series v1:
"This patchset introduces the AAF plugin to the alsa-plugins project
which enables TSN audio applications on Linux.
For those not familiarized with TSN, it stands for Time-Sensitive
Networking, and it's a set of IEEE technologies (enhancements to IEEE
802.1Q and Ethernet protocols) that provide precise time
synchronization, bounded latency and application interoperability to
bridged networks. Those technologies enable time-sensitive applications
such as audio, video and control loops to run on top of bridged
networks, co-existing with regular applications. TSN technologies are a
super set of Audio Video Bridging (AVB) technologies also developed by
IEEE. AVTP is the protocol defined to transport data in a TSN system,
and AAF is one of the formats defined by AVTP to encapsulate audio
data. AAF is specified in Chapter 7 from the AVTP spec [1].
This work is part of the effort to enable TSN technologies on upstream
Linux ecosystem. All building-blocks required to enable TSN audio
applications have been already developed and pushed to upstream
projects. Time synchronization features are provided by linuxptp
project [2], bounded latency features are provided by Linux Traffic
Control subsystem since kernel version 4.15 [3], and AVTP packetization
is provided by libavtp [4]. What is currently missing in the ecosystem
to enable TSN audio applications is a piece of software that plumbs it
all together and interfaces with Linux Audio system properly. That's
the point of the AAF plugin introduced here.
The AAF plugin is a PCM plugin that uses AVTP protocol to transmit /
receive audio data through a TSN capable network. When operating in
playback mode, the plugin reads PCM samples from the audio buffer,
encapsulates into AVTP packets and transmits to the network, mimicking
a typical AVTP Talker. When operating in capture mode, the plugin
receives AVTP packets from the network, retrieves the PCM samples, and
present them to alsa-lib layer at the presentation time, mimicking a
typical AVTP Listener."
For further information about what has been previously discussed, please refer
to RFC series v1 and v2 archives in [5] and [6]. Finally, all versions of this
series can be also found in my alsa-plugins tree in github [7].
Best regards,
Andre
[1] 1722-2016 - IEEE Standard for a Transport Protocol for Time-Sensitive
Applications in Bridged Local Area Networks
[2] http://linuxptp.sourceforge.net
[3] https://patchwork.ozlabs.org/cover/826678/
[4] https://github.com/AVnu/libavtp
[5] http://mailman.alsa-project.org/pipermail/alsa-devel/2018-August/139494.html
[6] http://mailman.alsa-project.org/pipermail/alsa-devel/2018-September/140290.html
[7] https://github.com/aguedes/alsa-plugins
Andre Guedes (7):
aaf: Introduce plugin skeleton
aaf: Load configuration parameters
aaf: Implement Playback mode support
aaf: Prepare for Capture mode support
aaf: Implement Capture mode support
aaf: Implement dump() ioplug callback
aaf: Add support for direct read/write transfers
Makefile.am | 3 +
aaf/Makefile.am | 9 +
aaf/pcm_aaf.c | 1197 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
configure.ac | 9 +
doc/aaf.txt | 142 +++++++
5 files changed, 1360 insertions(+)
create mode 100644 aaf/Makefile.am
create mode 100644 aaf/pcm_aaf.c
create mode 100644 doc/aaf.txt
--
2.14.4
_______________________________________________
Alsa-devel mailing list
Alsa-devel@xxxxxxxxxxxxxxxx
http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
