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Video quality.

Added by Tommy - over 9 years ago

Hi,

Does tvheadend alter/transcode/scale/compress or in any other way change the video stream it receives from the transponder when working with DVB?

The video quality I get with XBMC (and VLC) isn't very good. Moving parts of the picture gets very "foggy". Is this normal? Any pointers of what the cause may be?

I've done side-by-side comparisons with the output from a dreambox tuned to the same channel and the image there is way better. :/

Thanks,


Replies (6)

RE: Video quality. - Added by Hein Rigolo over 9 years ago

Tvheadend does not change the video data it receives ... but it could be that the player does not correctly de-interlace the video stream or anything else that it does to the video.

RE: Video quality. - Added by Stephen Neal over 9 years ago

Yep - it is almost certainly your de-interlacing settings in XBMC and VLC that are the issue (and possibly your video levelspace).

SD 576i and HD 1080i broadcasts are interlaced (720p is not) and need de-interlacing to 50Hz (not 25Hz) if you want good quality motion. This is not the default in VLC (you need to set de-interlace to on and use a decent algorithm like YADIF x 2) and often not in XBMC either (and not all video cards are supported for decent de-interlacing in XBMC) If you haven't got decent de-interlacing you'll see fast motion on native interlaced content (sport, news, entertainment etc.) break up into lines, or appear more juddery.

Also - broadcast video is coded in a 16-235 levelspace - whereas some PCs run with 0-255 - and you can get into all sorts of problems between the two. (Some displays are fixed at 0-255 aka FULL, some at 16-235 aka LIMITED, some let you switch - giving you two places to get it wrong...)

And of course if you're in Europe you need to ensure you are running your PC at a 50Hz refresh rate for European TV (not 60Hz - as you'll get 10Hz judder from repeated frames otherwise)

TV Headend doesn't alter the video or audio streams for live streaming so shouldn't have any impact on picture quality.

RE: Video quality. - Added by Ulf Larsson over 9 years ago

I've experienced exactly the same as Tommy. The funny thing is that if I do a recording in TVHeadened and then play the file then the video quality is perfect, using the same PC and XBMC to play the file as the live stream.

I also tested a few other PCs as frontend with the same result.
I've used XBMC in Windows and in Linux and also Showtime (Linux of course). All with the same result.

Live HD TV looks like SD TV!

So a question to all TVHeadend users: What kind of frontend do you use in order to get a real HD quality experience.
Hardware and software please.

Ulf

RE: Video quality. - Added by Eric Valette over 9 years ago

I use XBMC locally and remotely and everything is fine of france HD channels.

RE: Video quality. - Added by Ulf Larsson over 9 years ago

What kind of PC and video card do you use?

RE: Video quality. - Added by Eric Valette over 9 years ago

Ulf Larsson wrote:

What kind of PC and video card do you use?

Half a dozen at least with either ION1, AMD fusion, non VDPAU compatible nvidia cards, Intel GM45 but with powerfull processors, ...

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