Re: [DCP-o-matic] Encoding servers: error during async_read

My understanding is that the master decodes the source file and sends out frames to the slaves in raw (uncompressed) format. The bit depth and colour-subsamping (444, 422 etc) of the source material are maintained in what's sent across the network. Therefore network bandwidth depends on resolution, bit depth and colour sub-sampling of source material. I don't know if colour space conversion is performed on the slaves or the master. I've seen network speed become the limiting factor when I had 4 x 4-core iMacs on a gigabit network, encoding from ProResHQ 1920x1080 (422 colour sub-sampling). With a larger number of slaves, I've also hit a limit of the speed at which the master can decode the source file (about 60fps). Of course it'd be more efficient if the source file was streamed to slaves over the network in its native codec (compressed), but I imagine that'd be hard to implement with codecs like H264 where frames are not independent of each other (long-GOP). In your case Wolfgang, my guess is there's 2 things going on: 1. Network saturation due to 12-bit colour and no subsampling 2. Frames being corrupted/lost in transit (the async_read errors) The two issues may be related. This is all just a guess though. Maybe try reducing number of encoding threads on the slaves and see if that reduces the errors? Jim On 11/05/2018 17:21, Manuel AC via DCPomatic wrote: