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Re: Stuttering on every video / Broken seeking (LG 49NANO)

Posted: Sun Oct 18, 2020 8:10 am
by Nadahar
The "seeking" information provided by LG is useless, as it's not specific. My guess is that what they call "live seek" means when playing HLS sources, which isn't relevant for UMS use.

As I've stated before, it's not enough to support seeking. I don't think I've ever come across a renderer that doesn't support byte-based seeking, but byte based seeking is only possible when playing from a file (ergo not transcoding). What's needed to be able to seek while transcoding is time-based seeking, and since LG conveniently don't mention this at all, it's likely that it's not supported.

Regarding the two devices, chances are that your TV actually contains two "renderers", some do have a second "virtual device" for things like second screen or picture in picture etc. It shouldn't make any difference if such a device is "detected" as long as UMS only interacts with the "true renderer".

When it comes to why a file is streamed or transcoded, one must study the trace log for the attempt to play that particular file. The trace log will reveal the "decisions" made and why, and it should be relatively clear from the log why a particular media file is transcoded.

Re: Stuttering on every video / Broken seeking (LG 49NANO)

Posted: Sun Oct 18, 2020 2:02 pm
by protected
It shouldn't make any difference if such a device is "detected" as long as UMS only interacts with the "true renderer".
Unfortunately that hasn't been the case. It seems to use either one randomly.

Thank you for the explanation about time-based seeking. That's a bummer but I'll see if there's anything else that can be done about that.

I've looked at trace logs and I can't figure out why it's making the decision to transcode every time. If there truly is a legitimate reason every time, then whether streaming works or not becomes largely irrelevant - since it's so rare... I'm thinking on a couple of occasions it actually tried to stream and then fell back (on mencoder?) when it failed. Some LG webpages lead me to believe things like ASS subtitles should be supported but that may not actually be the case. It would be nice if their information was more accurate.

Re: Stuttering on every video / Broken seeking (LG 49NANO)

Posted: Sun Oct 18, 2020 2:24 pm
by Nadahar
I'm not saying that UMS' decision to transcode is correct, only that you can see what leads to it in the log. Try searching for "final verdict", and then scroll back a bit and read the "decisions" leading to the "final verdict". Make sure you read the decision making for the correct file though.

I don't think it will ever try to stream and then fall-back to MEncoder. If UMS streams the file as-is, it has no more "control" over what happens - it merely sends the file to the renderer. UMS can't know if such a file actually to plays or not, only whether the renderer receives the file or not (although it's likely that if it receives it, it plays).

UMS' decision making isn't very "smart", it depends very much on the content of the renderer configuration file. So, it will pretty much make the decision the renderer configuration tells it to make. It's likely that your TV can stream quite a lot of the content, but if the renderer configuration doesn't say so, UMS will transcode it regardless. Subtitles can often cause transcoding for media that is otherwise supported, because subtitles have terrible support on many renderers. In fact, UPnP AV/DLNA doesn't officially support subtitles at all. This has led to Samsung and Panasonic making different "unofficial" ways to support subtitles, both of which UMS supports. Other manufacturers must then implement either of these unofficial standards or not support subtitles at all. I have no idea if LG usually supports one of the unofficial standards or not. The renderer configuration must also correctly reflect such support for this to work, or everything with subtitles will be transcoded. When transcoding, the subtitles are "burned in" to the video and become a part of the video, so the renderer has no idea that there are subtitles there.