hgpuke 2 Posted January 16, 2019 Share Posted January 16, 2019 Yesterday I downloaded the new version of Emby Server to my Synology DS916+. I had so much hopes for this new version, especially when it comes to transcoding performance. Here are my observations after running a small test with different transcoding options. Test movie: Jurassic World, BD-rip done by standard settings in DVDFab 11 resulting in a 1080p H264 MP4 container and Subtitles in VOBSUB format included in the MP4. 5Mb/s bitrate. SRT subtitle added by Emby. Server: Emby Server 4.0.0.2 running on Synology DS916+ using an Intel Pentium N3710 CPU with 4 cores and 8GB of RAM. Client: Emby Web client running in Microsoft Edge browser. Use case 1: No subtitles or SRT subtitle: Results: No transcoding needed (hence Direct Play). Very little CPU used (below 5%) in the NAS. Use case 2: 1080P original bitrate (no downsampling). VOBSUB subtitle. HW assisted decoding and encoding (VAAPI). Results: 15-17 fps transcoding speed. Dropped frames. Stuttering playback. 23% CPU load on the NAS. Verdict: Not usable. Use case 3: 1080P original bitrate (no downsampling). VOBSUB subtitle. SW decoding and encoding. Results: 30+ fps transcoding speed. No dropped frames. Perfect playback. 95-99% CPU load on NAS. Verdict: Usable, but only for one stream and no other activity on the NAS. Use case 4: 1080P original bitrate (no downsampling). VOBSUB subtitle. SW decoding, HW assisted encoding (VAAPI). Results: 18 fps transcoding speed. Dropped frames. Stuttering playback. 32% CPU load on the NAS. Verdict: Not usable. Use case 5: 1080P original bitrate (no downsampling). VOBSUB subtitle. HW assisted decoding (VAAPI), SW encoding. Results: 27fps transcoding speed. Few dropped frames. Good playback. 70-80% CPU load on the NAS. Verdict: Usable but only for one stream. Other activity on the NAS is possible. Use case 6: 1080P downscaling to 720P@2Mbps. No subtitle or SRT subtitle (does not matter). HW assisted decoding, SW encoding. Results: 57fps transcoding speed. No dropped frames. Good playback. 40% CPU load on the NAS. Verdict: Usable Use case 6: 1080P downscaling to 720P@4Mbps. No subtitle or SRT subtitle (does not matter). HW assisted decoding, SW encoding. Results: 57fps transcoding speed. No dropped frames. Good playback. 60-70% CPU load on the NAS. Verdict: Usable So on to my conclusions: Using embedded "picture type" subtitles like VOBSUB makes the server transcode, leading to a high workload for the NAS. Always use SRT subtitles when possible. If VOBSUB subtitles have to be used, using HW assisted decoding and SW encoding results in a usable solution for 1080P resolution films. So on to my questions: 1. Are my results in line with your expectations? 2. Could a future version of the server either a) be made to transcode quicker, or dynamically switch between HW assisted and SW transcoding depending on what framerate it is able to acheive? Thanks for a great product! Link to comment Share on other sites More sharing options...
solabc16 379 Posted January 16, 2019 Share Posted January 16, 2019 Hello @@hgpuke Thanks for the detailed feedback, that's really useful and appreciated. If you are able to run the Send Logs utility, I can analyse the data in more detail : https://github.com/MediaBrowser/Wiki/wiki/Synology-:-How-to-Send-us-Support-Logs VOBSUB is a challenge and not specific to Emby Server, we have an active discussion going on around this - so for now, all I can say is stay tuned. Best - James Link to comment Share on other sites More sharing options...
hgpuke 2 Posted January 16, 2019 Author Share Posted January 16, 2019 Hi @@solabc16! Thanks for your answer, I will try to send you the log file once I get back home today (I have no access to ssh from work due to security restrictions). I suppose you have no use of the logs that I can get from inside the server control panel? - Hans-Göran Link to comment Share on other sites More sharing options...
hgpuke 2 Posted January 16, 2019 Author Share Posted January 16, 2019 @@solabc16 Logs sent successfully: sendlogs_DS916plus_synology_braswell_916+_20190116T171716UTC.tgz -- Hans-Göran Link to comment Share on other sites More sharing options...
solabc16 379 Posted January 16, 2019 Share Posted January 16, 2019 Thanks for the logs @@hgpuke, appreciated. I'll take a look next week, once things have settled down following the release. Best - James Link to comment Share on other sites More sharing options...
Luke 37068 Posted January 16, 2019 Share Posted January 16, 2019 Use case 2: 1080P original bitrate (no downsampling). VOBSUB subtitle. HW assisted decoding and encoding (VAAPI). Results: 15-17 fps transcoding speed. Dropped frames. Stuttering playback. 23% CPU load on the NAS. Verdict: Not usable. Use case 3: 1080P original bitrate (no downsampling). VOBSUB subtitle. SW decoding and encoding. Results: 30+ fps transcoding speed. No dropped frames. Perfect playback. 95-99% CPU load on NAS. Verdict: Usable, but only for one stream and no other activity on the NAS. Use case 4: 1080P original bitrate (no downsampling). VOBSUB subtitle. SW decoding, HW assisted encoding (VAAPI). Results: 18 fps transcoding speed. Dropped frames. Stuttering playback. 32% CPU load on the NAS. Verdict: Not usable. Use case 5: 1080P original bitrate (no downsampling). VOBSUB subtitle. HW assisted decoding (VAAPI), SW encoding. Results: 27fps transcoding speed. Few dropped frames. Good playback. 70-80% CPU load on the NAS. Verdict: Usable but only for one stream. Other activity on the NAS is possible. For these examples, burning in subtitles is a very costly process, so this isn't too much of a surprise. Link to comment Share on other sites More sharing options...
hgpuke 2 Posted January 17, 2019 Author Share Posted January 17, 2019 (edited) For these examples, burning in subtitles is a very costly process, so this isn't too much of a surprise. Yes, I am aware that "burning" subtitles is a costly process. I had high hopes that the use of hardware assisted encoding and decoding would make it more feasible, however. In my case, it turns out that the CPU part of the Pentium N processor was more capable at doing this than the GPU part. This came as a surprise to me, at least. @@softworkz Having said that, I am very delighted with the hardware acceleration of "normal" transcoding, i e downsampling either resolution and/or bitrate. As an example, downsampling a movie using native 1080P resolution from 13 Mbps to 6 Mbps uses only 15% of the CPU at times when the transcoding buffer is filled, and almost nothing in between. Edited January 17, 2019 by hgpuke Link to comment Share on other sites More sharing options...
softworkz 3335 Posted January 17, 2019 Share Posted January 17, 2019 Normally this would be a surprise indeed. But there's a bit more to it: The comparison is not quite fair in many cases, because the software usually produces a video of much lower bitrate than actually requested, while most hardware encoders are closely matching those values. You may check this on your system by comparing the file sizes of the transcoded segment files (*.ts) between hardware and software transcoding. (please make sure that you don't resume but start playback from the beginning in both cases.) Link to comment Share on other sites More sharing options...
solabc16 379 Posted January 17, 2019 Share Posted January 17, 2019 (edited) Hello @@hgpuke You need to take into consideration my update to your post on this thread as well : https://emby.media/community/index.php?/topic/67225-newbie-looking-for-advice-on-how-to-avoid-transcoding-with-subs/?p=680420 In scenario #2, it's not a coincidence that the CPU is pegged at ~25%. This is a four core machine, and with respect to the above post, this is one thread on one core trying to process the VOBSUB subtitle. The h/w assisted decoding and encoding (VAAPI) is indeed doing its thing and doing it well, hence the relatively low CPU utilisation. However, as the raw horsepower of the CPU isn't sufficient to handle the part that can only be performed in software, the overall suitability for the workload is negative. Best - James Edited January 17, 2019 by solabc16 Link to comment Share on other sites More sharing options...
hgpuke 2 Posted January 17, 2019 Author Share Posted January 17, 2019 Hello @@hgpuke You need to take into consideration my update to your post on this thread as well : https://emby.media/community/index.php?/topic/67225-newbie-looking-for-advice-on-how-to-avoid-transcoding-with-subs/?p=680420 In scenario #2, it's not a coincidence that the CPU is pegged at ~25%. This is a four core machine, and with respect to the above post, this is one thread on one core trying to process the VOBSUB subtitle. The h/w assisted decoding and encoding (VAAPI) is indeed doing its thing and doing it well, hence the relatively low CPU utilisation. However, as the raw horsepower of the CPU isn't sufficient to handle the part that can only be performed in software, meaning the overall suitability for the workload is negative. Best - James Thanks for the clarification! Now I think I understand this topic well! Link to comment Share on other sites More sharing options...
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