On Mon, 2019-05-06 at 21:35 +0400, Victor Gaydov wrote: > Hi, > > I'm working on Roc, a new project implementing real-time streaming over > network[1]. > > Currently it can stream PCM using RTP + FECFRAME (Reed-Solomon and > LDPC-Staircase are supported, using OpenFEC library). There are plans to > add support for more encodings (including Opus) and protocols (including > SAP/SDP). > > Among other things, we've implemented a couple of PulseAudio modules > that use Roc as a network transport. I've written an overview post > about the project and these modules[2]. > > Both Roc and PA modules are in early stage of development. PA modules > still miss some essential features, e.g. there is no latency reporting > and service discovery. > > I'd like to discuss the opportunity of submitting those modules to the > PA upstream in future. Some thoughts? > > [1] https://github.com/roc-project/roc > [2] https://gavv.github.io/articles/new-network-transport/ > > -- Victor Miscellaneous thoughts in random order: At least I'm in favor of accepting the new modules in PulseAudio, if they provide less glitches than the tunnel modules or the existing RTP modules. And I'd love to have the adaptive resampling logic maintained in an external library by someone who knows how it works (I don't understand and I don't look forward to trying to learn how the resampling code in the existing RTP modules works). I should probably mention that if you submit patches, I can't promise a timely review - there's too much work that I'm already committed to. Arun has in the past talked about some plans for reworking the RTP stuff to use GStreamer - I hope that won't be an impediment for accepting these modules. Are there any plans to support multicast? I don't know how important that is to people, it's just that I think the existing RTP modules use multicast by default (which tends to break wireless networks...) Can one receiver connect to multiple senders? If there are two client machines that want to use speakers connected to a single receiver machine, does module-roc-sink-input have to be loaded twice (and with different ports)? Any plans for dynamic latency based on stream requests? If the goal is to support low latency, it's probably desirable to have a bit larger latency for music playback, and reduce the latency on the fly when a low-latency application starts. How much of the parameters could theoretically be changed on the fly (I say theoretically, because you probably haven't implemented any such controls yet)? Imagine a GUI for configuring this system - trying different resampler profiles or latency settings on the fly could be useful. Changing the IP address or port probably doesn't need to be doable mid-stream. People have requested in the past that the tunnel sink would change the stream sample rate and format on the fly based on the application's stream, similar to how the hardware sink supports automatic sample rate switching. Would this be doable? It doesn't need to (and indeed shouldn't) be done mid-stream, but if nothing is currently using the Roc sink and a new stream appears, it would be good to configure the network stream parameters based on the application stream. The blog post has this sentence: "Roc performs the clock rate adjustment on the receiver, while PulseAudio does it on the sender" - that's not true. Doing the adjustment on the sender would require some kind of feedback system from the receiver to the sender, and that doesn't exist. PulseAudio does the adjustment on the receiver. What happens if the connection dies temporarily (receiver reboots or crashes, or there's a network outage)? Can the system automatically recover when the receiver comes back online? Can the system deal with the hardware sink changing on the fly? There will be a discontinuity in the reported latency. Similarly, can the system deal with the user changing the latency offset of a port? That too will cause a strange jump in latency reports. Can the system deal with the hardware sink suspending? The Roc sink input will be connected to the hardware sink, but the sink won't be asking for more data until the sink resumes. Based on the great documentation, Roc looks like a quality product! -- Tanu https://www.patreon.com/tanuk https://liberapay.com/tanuk _______________________________________________ pulseaudio-discuss mailing list pulseaudio-discuss@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/pulseaudio-discuss
