Quicksync Playback Issues

[Clark 0]

Hi everyone.

 

I'm having playback issues with a Roku TV and Emby server (I'm on the latest version). It works fine in software mode, however when using h264_qsv, when the file finishes streaming, it goes back to the middle of the file and continues playing from there, until it reaches the end again and then it goes back to the middle of the portion that was just played and repeats. Also, if I use quick replay (which rewinds about 10 seconds), the seek time on the television shows it goes backwards, however the stream picks up from about 20 seconds forward. I have tried editing transcoding settings, but quickly realized this does absolutely nothing when quicksync is enabled. Tried multiple builds of ffmpeg, and also tried a variety of formats to determine if it is a decoder issue, it happens with all formats being transcoded, as long as quicksync is enabled.  Log files are attached for a short 2:31 minute file. I did not use the quick rewind here, just let it play. I stopped it after it began the fourth playback. Full system log for the entire playback period, and the first transcode log. (They are all the same, just shorter times as requested in the system log).

 

System Log.txt

Transcode Log for 1st transcode.txt

 

I'd like to help figure out what is going on, so please let me know if you need anything else and how I can work towards testing a possible fix. Thanks.

[Luke 42085]

It sounds to me like the quick sync encoder is not writing the proper timestamps and that is what is causing the seeking problem.

[Clark 0]

It sounds to me like the quick sync encoder is not writing the proper timestamps and that is what is causing the seeking problem.

If so, is there a way I can work around this? The server was built with quicksync in mind as it isn't powerful enough to transcode properly without it.

[Luke 42085]

What about other kinds of input files, something other than hevc. Like h264 for example. How are those going? Thanks.

[Clark 0]

What about other kinds of input files, something other than hevc. Like h264 for example. How are those going? Thanks.

Well the Roku plays h264 natively, so there is no transcoding happening when an mkv is played with h264. Emby actually transcodes to h264 to play to the roku (hence the h264_qsv) I have tried input files in avi, wmv, vp8, vp9, and theora, and they all do the same thing. It is definitely something on the output side of things. I would try different quicksync configurations, but emby doesnt allow you to change any transcoding settings from the dashboard for quicksync.Thanks for helping with this.

[aptalca 71]

Well the Roku plays h264 natively, so there is no transcoding happening when an mkv is played with h264. Emby actually transcodes to h264 to play to the roku (hence the h264_qsv) I have tried input files in avi, wmv, vp8, vp9, and theora, and they all do the same thing. It is definitely something on the output side of things. I would try different quicksync configurations, but emby doesnt allow you to change any transcoding settings from the dashboard for quicksync.Thanks for helping with this.

You can lower the quality in the roku app to force it to transcode h264 for testing

[Clark 0]

You can lower the quality in the roku app to force it to transcode h264 for testing

Oh good point. I just tried that and it does transcode the h264 now. Unfortunately, the results are the same. The server log shows requests to ffmpeg from exactly 00:45,1:18,1:42,1:57,2:09,2:18,2:24,2:27,2:30. And this is all within one playback, I stopped playback after it started the repeat from the 45 second portion. Tried it with quicksync off and it works perfectly. I attached the server log for the playback with qsv.

System Log for playback.txt

[Clark 0]

Any update on this Luke?

[Luke 42085]

@@Clark, Quick Sync is something we consider an experimental feature. At this point we will not yet have the answer for every possible issue. We are all working together to improve it as much as we can. Thanks !

[Clark 0]

I know, I'd like to help. Also I'm not so sure as yet if the problem stems from the server or the client, I've only had success managing to transcode from the TV, any other device I tried to play on seems to play most of the formats natively or throws errors for the ones it can't play. Is there any way to force a transcode for any format using a client through windows? I've tried just using a browser but it direct plays through there as well

[Luke 42085]

I think it's just that the quicksync encoders and decoders still have trouble with certain media and we need to figure out exactly what those are.

[Clark 0]

I've been using the hardware encoder on this machine to do HEVC and 264 encodes with a few different encoding programs that use the hardware encoder (for speedy encodes) and the encodes come out fine. I'm inclined to believe that the way the hardware encoder writes the file in pieces for streaming is different from how it is done in software (or at least that's how the server might be seeing it) and that in turn causes unexpected behaviour. Do note that full pretranscodes using hardware work perfectly from what I've tested so far.