Also, the "proc" recording method has an interesting pipeline, involving an ephemeral metadata file and a memory sink exposed through /proc, and a userspace daemon picking up the data and writing it to disk (if this doesn't happen, audio frames going into the sink are discarded).
This pipeline leads to two or three philosophical questions: 1. Is the purpose of this design to allow for writing audio frames in a scatter-gather fashion, so that audio is written serially to storage? Conventional recording solutions suffer from the problem that under high volume, a large number of file handles are written in parallel. This thrashes the disk. In the days of mechanical disks, this would lead to frequent disk burn-out. In the SSD era the situation is slightly improved, but is still very taxing on the SSD, as I understand it, in terms of write wear/write levelling. This usually leads to a solution like writing recordings to a tmpfs area and then serially copying them out of there, one at a time. Would I be correct to assume that this pipeline is designed to address this same problem, but in a different and novel manner? 2. Is the other purpose of a RTP sink to allow the possibility of real-time call intercept and diversion to live playback? If so, are there any plans for the recording daemon to expose an RTSP interface or similar to make this easier? 3. What happens if, under high load and I/O wait conditions, the userspace recording daemon cannot read frames from the sink fast enough, or the CPU encoding workload (-> WAV/MP3) is too high? According to the documentation, the depth of the sink is only 10 frames: Packet data is held in kernel memory until retrieved by the userspace component, but only a limited number of packets (default 10) per media stream. If packets are not retrieved in time, they will be simply discarded. This makes it possible to flag all calls to be recorded and then leave it to the userspace component to decided whether to use the packet data for any purpose or not. Is it possible to increase that depth? Or is this not a concern because the userspace component is implemented in an asynchronous/threaded manner, so frames are retrieved quickly for processing and then enqueued into a local blocking queue? -- Alex -- Alex Balashov | Principal | Evariste Systems LLC Tel: +1-706-510-6800 / +1-800-250-5920 (toll-free) Web: http://www.evaristesys.com/, http://www.csrpswitch.com/ _______________________________________________ Kamailio (SER) - Users Mailing List firstname.lastname@example.org https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users