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Regular PAL DVDs with 720x576 being transcoded as max 480p


NukeFromOrbit

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NukeFromOrbit

Hi,

I'm pretty new with Emby but I've been looking into this issue a bit now and thought it would be good to ask for some input. Maybe this is a known issue. I have been searching for previous discussions around this topic but still haven't found good reasons or workarounds. 

I've just recently moved over from Plex to Emby, and I'm happy about that and I'm a Premium subscriber to support Emby (monthly).

Anyway, I was watching Stargate SG-1 and I noticed it was really bad quality. At first I thought that I maybe have just gotten used to Bluray lately, but I had to verify with the source material and there was a significant difference. 

I rip all my DVDs directly to MKV (pass-through, no conversion) to get all audio tracks and subtitles into one file. So the quality is original DVD.

Just as an example of what I'm talking about I'm attaching two images. First one is Emby through Chrome and second is VLC directly on the MKV file.
Both images taken from SG-1 S02 E22 at around 19 seconds into the video and I've brighten them up using levels to make the details a bit easier to see.

image.png.0c93a6ea937362c41614e1dc99c97e7d.pngimage.png.ce1abdba84ac6ba7ef2651181e3cf069.png

Then I noticed that Emby shows 480p 4mbit as max. The video is 720x576.

Stream #0:0: Video: mpeg2video (Main), yuv420p(tv, top first), 720x576 [SAR 64:45 DAR 16:9], Level 8, 25 fps, 25 tbr, 1k tbn (default)

This resolution is very common for PAL DVDs 

I understand that Chrome does not support mpeg2, so the video has to be transcoded to x264. I tried to use Emby Theatre, which is great, especially for a home theatre setup or similar, but I really prefer using a browser when I'm at my computer.  This means that all my DVDs that are of this solution will be bad quality streaming through Chrome.

So the question is. Why is this happening? is it possible to fix the transcoding to not lose that much detail and resolution?

Attatching the transcode log if  it can help.

ffmpeg-transcode-0527404b-8496-4511-9f30-6cfb6ac8ce72_1.txt

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Happy2Play

But you have the same going in as you have coming out.

19:24:19.529   Stream #0:0: Video: mpeg2video (Main), yuv420p(tv, top first), 720x576 [SAR 64:45 DAR 16:9], Level 8, 25 fps, 25 tbr, 1k tbn (default)

19:24:19.561   Stream #0:0: Video: h264, yuv420p(tv, progressive), 720x576 [SAR 64:45 DAR 16:9], q=2-31, 25 fps, 90k tbn

But I guess it could something with this Interlaced media.

Not sure but adjusting these transcode setting could make a difference also.

image.png.a19cc8feb91f3bdcff60328be685ee7e.png

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NukeFromOrbit

Hm. Interesting and thank you for replying.

Then there might be two different issues. One is that web client is showing 480p 4Mbps as maximum quality, and the other is that auto detect for encoding preset/crf is maybe not working as it should? 

Why would it show 480p as quality for a 720x576 video? it doesn't really make sense to do that even with interlaced videos.
And is there something I can do to improve the auto settings? or do I just need to override the transcoding settings?  They might require different settings for different source material, right (like SD vs HD vs 4K)?

I'm just thinking that this could be a pretty common issue. If transcoding for browsers with common resolutions of original DVD video turns out this bad by default, then it might cause issues for many people. The server is very capable, so it's not that.

image.png.e14fd828dd0c86f4c698718da9aecd0b.png

 

image.png.8815553591e10270822a476ca34129e7.png

Edited by NukeFromOrbit
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NukeFromOrbit

I did try to change the CRF from 23 (default) to 18 and that did make it look better. But this settings is supposed to be different for different source material. I think 23 is ok-ish for bluray and 18 is ok-ish for DVD.  Maybe it should be possible to autodetect within a range or some fixed settings for different scenarios? 

And there is still the illusion of Emby downgrading the material to 480p since that is what is shown in the web player. Maybe that is just a plain old bug? :)

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Happy2Play

Will look for other topic but this is known as it is more about the bitrate then the resolution shown so that quality scale during playback is skewed.  There are no 576 options as it is not 480, 720, 1080, or 4K, but as the log shows resolution was maintained.  See this with items with odd resolutions also.

 

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NukeFromOrbit

Would it be worth it to suggest some changes to this in the feature request section? or maybe bug report for the 480p thing?

First would be to maybe use the actual resolution or just the actual bitrate (or both). Showing the user the wrong resolution will cause regular support cases, so it would probably be best to show the real information.

Second, the default CRF for sub HD content should be automatically set to something better than 23. This default setting is greatly impacting everyone that is trying to watch a regular DVD through Emby. That is not particularly good for the average user and should be fairly easy to improve I think.

Again, thank you very much for responding Happy2Play. Greatly appreciated :)  And btw, that hardware you have (in your tag) looks seriously awesome!

Edited by NukeFromOrbit
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Happy2Play

Here is the most recent topic on the during playback quality setting and looks like Luke has found the issue.  But at the same time this resolution media technically does not have a category per the quality list.  But it currently does not downscale your media either.

 

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NukeFromOrbit

Thank you for that link.

720x576 is a very common resolution, so it would make sense to have it shown correctly I think. At least not show 480p instead, that is bound to cause people to start asking questions (like I did). Maybe that is not currently possible, and that bitrate is all that is available to the web player?  then it would probably be best just to show the bitrate and a guessed resolution, but that is just my opinion and I completely understands that is not up to me :)

I understand that it didn't really downscale the resolution, so that is all good. But I still think that the default CRF of 23 is something that should be improved for SD content. Especially in combination with the guessed resolution using bitrate. 

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