Streaming to LG OLED CX (2020): no seeking when transcoding?

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StreamingTiger
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Streaming to LG OLED CX (2020): no seeking when transcoding?

Post by StreamingTiger » Mon Nov 30, 2020 10:08 am

Hello there!

I have a new LG OLED CX (2020 model) and tried to stream a MP4 file to it (format: MKV MPEG-4p10/AVC/h.264 with AC3/EAC3).
Without Transcoding it seems to work: file size and video duration are displayed and the seeking works.

But when I stream it with ffmpeg-transcoding (or even MEncoder), then the seeking stops to work. The TV says something like "This function/feature is currently not available".
I tried both profiles: LG-WebOS and LG-OLED (latter one after extending it to identify the CX model).

I played around a little bit with the profile and I think I narrowed it down to the option "ChunkedTransfer". It's pre-set to "true".
If I change it to "false", then the seeking seems to work *but* the video is not displayed anymore (the audio plays OK and the video stays black).

Has anyone had the same or even better: found a solution for the transcoding + seeking problem with a newer LG TV? (I would guess that the 2019 "C9" models behave the same)

StreamingTiger
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Re: Streaming to LG OLED CX (2020): no seeking when transcoding?

Post by StreamingTiger » Tue Dec 01, 2020 6:54 am

Another observation: if I enable the feature "video resuming" then already started media files do not work anymore (when streamed as-is meaning without transcoding): as soon as they are started, the loading symbol appears (which normally takes 1-2 seconds) but it does not go away. Meaning: it loads like forever. After a while the LG TV shows the error "File can not be played".
When disabling the "resume video" feature it works again.

myles
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Re: Streaming to LG OLED CX (2020): no seeking when transcoding?

Post by myles » Sat Dec 12, 2020 8:02 am

I have the same problem as OP.
In addition the is no sound when playing files with DTS audio.

StreamingTiger
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Re: Streaming to LG OLED CX (2020): no seeking when transcoding?

Post by StreamingTiger » Sat Dec 12, 2020 12:18 pm

The CX does not support DTS anymore. So you would have to activate Transcoding for DTS.
Did you try disabling "Keep DTS tracks" and disabling "Encoded audio passthrough"?

myles
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Re: Streaming to LG OLED CX (2020): no seeking when transcoding?

Post by myles » Sat Dec 12, 2020 9:16 pm

Yeah, I tried disabling Keep DTS tracks and Encoded audio passthrough for AC-3 and DTS and it still didnt work. I enabled "Show the TRANSCODE folder" and the DTS files play fine with everything besides "No transcoding". This seems like a workaround and i'd like it to work as default.
One of the other complications is that I have other devices on the same network that DO support DTS.

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mik_s
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Re: Streaming to LG OLED CX (2020): no seeking when transcoding?

Post by mik_s » Sun Dec 13, 2020 7:45 am

I think the issue with DTS is that the manufacturer has to pay a licence to support it, and since there are other codecs that do the same thing that are becoming more common that may not need a licence, they save money by dropping support for DTS in newer TVs.

If the video plays with no audio when using "No transcoding" in the transcode folder then that is the TV not supporting it. If the conf for the TV is correctly set up then UMS will detect that and transcode to a different format that can play correctly.

Seeking while transcoding can be a problem depending on the device and transcoding settings. Some devices use seek-by-byte, as the file is transcoded on the fly there is no way of knowing the size of the stream so is impossible to calculate how many bytes to move to seek, plus that data will not exist yet for FF and would have already been discarded for RWD. Usually if the device detects this it will disable the seek controls, or worse if trying to seek it ends up playing from the beginning from the file.

If the device uses seek-by-time then seeking should work, but may need a bit of experimentation to get the settings right that your TV is comfortable playing.

Also it can take a second or 2 for it to start receiving data when transcoding which may cause the "File can not be played" error. try setting TranscodeFastStart = True and see if that helps.

The best situation is to never transcode unless you really need to like when your device doesn't support DTS

IIRC video resuming works by remembering where you last watched a file, then creates a virtual file that transcodes from where you left off. Not something I use as my devices can remember themselves so don't need it, also as it is transcoded it suffers from the issues related to that. I would recommend keeping resuming disabled.

My parents got a LG TV earlier this year and I modified the LG-WebOS.conf to better support it. Can't remember the model they got and didn't focus on the transcoding settings as my laptop wasn't up to it, but might be a closer match if you want to tweak it. You might have to remove any reference to DTS in the supported section if your TV doesn't support it
Attachments
LG-WebOS-modified.conf
(3.51 KiB) Downloaded 57 times
Logs are important for us to help, Please follow This Link before asking for support. Just a forum cleaner, Will help if I can but no expert.

myles
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Re: Streaming to LG OLED CX (2020): no seeking when transcoding?

Post by myles » Sun Dec 13, 2020 11:13 pm

@mik_s
The .conf you post has helped with the forwarding issue! Thank you.
How does one go abt removing references to DTS? If the references are removed will UMS automatically know that it should transcode the audio?

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mik_s
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Re: Streaming to LG OLED CX (2020): no seeking when transcoding?

Post by mik_s » Mon Dec 14, 2020 8:15 am

Just search for dts and remove them from the supported formats section. like

Code: Select all

a:mp3|ac3|lcpm|adpcm|dts
to

Code: Select all

a:mp3|ac3|lcpm|adpcm
If UMS comes across a format not in the supported formats section of the conf it will transcode it.
Logs are important for us to help, Please follow This Link before asking for support. Just a forum cleaner, Will help if I can but no expert.

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SubJunk
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Re: Streaming to LG OLED CX (2020): no seeking when transcoding?

Post by SubJunk » Tue Dec 15, 2020 4:21 pm

If we can get TRACE logs from you after you successfully play that file @myles that will be useful, then we can see why it is working with the new config and possibly we can improve this for all LG users.

StreamingTiger
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Re: Streaming to LG OLED CX (2020): no seeking when transcoding?

Post by StreamingTiger » Wed Dec 16, 2020 5:34 am

I played around a little bit more, too: I have an MKV file with h264 and AC3 6ch and ~ 3,5 GB.

If I configure "Skip transcoding for the following extensions" with "mkv", then Seeking and AC3 sound work fine!

But when I remove this, then I have severe problems: the video starts normal but as soon as I start seeking (+/- 10-15 secs) then the sound gets choppy or the video stops totally. Seeking stops working, too.
I am using the following configuration:

Code: Select all

Supported = f:mkv             v:h264|h265|mp4|mpeg2|vp8|vp9     a:mp3|ac3|eac3|aac-lc|he-aac|adpcm|lpcm|mpa|vorbis  m:video/x-matroska

TranscodeVideo = MPEGTS-H264-AC3   # MPEGTS-H264-AAC shows the same problems
TranscodeAudio => unset/default
I was hoping that my "Supported" definition matches the file codecs and would prevent the Transcoding. But something seems to happen differently compared to the "Skip transcoding for MKV extension"!?
How/where can I see in the Logs and at which level if the Transcoding happens?

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