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joebloggs
On our wavelength
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Message 1 of 12
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MPEG2 > MPEG4 picture downgrade

Hi there!

Since the switch from MPEG2 to MPEG4 on alot of channels I have noticed a very sharp decrease in picture quality, is Virgin Media using a MPEG4 bitrate thats TOO low? some channels look god damn awful which didn't before?

 

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jamesofmerton
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Message 2 of 12
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Re: MPEG2 > MPEG4 picture downgrade

seem ok to me. although ideal world is particularly poor. it looks like a stream of a 1981 vhs recording.

wait for the technical guys on here to come along to see what they say.
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japitts
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Message 3 of 12
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Re: MPEG2 > MPEG4 picture downgrade

I appreciate you say this is happening on lots of channels, but do you have any specific examples?

Such detail is always beneficial to VM in fault checking and maybe other forum members in comparing with their service.

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joebloggs
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Message 4 of 12
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Re: MPEG2 > MPEG4 picture downgrade

Well today Magic TV and the other box music channels changed to MPEG4, and I have a recording of Magic TV from Christmas and there is a definite quality drop, lots more squares around text!

The sound is fine though, but definetly more blocky from heavy compression.

 

Can't get these photos to work but will leave them here incase they start working again

FullSizeRender.jpgVery blocky!FullSizeRender-1.jpg

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japitts
Super solver
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Message 5 of 12
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Re: MPEG2 > MPEG4 picture downgrade

At a guess, the bitrate could well have been reduced - Magic is one of those channels that people generally wouldn't complain about such things (not that I'm justfiying it or saying it's acceptable)

I can't fathom out how to check such things on DigitalBitRate at the moment, not sure whether you can or not.

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joebloggs
On our wavelength
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Message 6 of 12
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Re: MPEG2 > MPEG4 picture downgrade

Was watching Food Network today and my god any slight movement and it turns into this....1DA16BF9-63E6-44B9-9F58-D85AAB516714.jpeg

And to think Food Network is replacing Good Food HD

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cje85
Problem sorter
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Message 7 of 12
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Re: MPEG2 > MPEG4 picture downgrade

MPEG4 has the potential to be better than MPEG2 but the bitrates VM are using are far too low and it's no wonder there are so many complaints about pixelation on this forum.

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Roger_Gooner
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Message 8 of 12
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Re: MPEG2 > MPEG4 picture downgrade

I have a V6 and I don't have any problems. I suspect that pixelation is caused by poor signal strength.

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Hub 3.0, TP-Link Archer C8, TP-Link TL-SG1008D 8-port gigabit switch, V6
My Broadband Ping - Roger's VM Broadband Connection
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joebloggs
On our wavelength
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Message 9 of 12
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Re: MPEG2 > MPEG4 picture downgrade

Have you tried these channels on a screen at least 55"? They are terrible, only watchable if things are still but as soon as there is any movement it's like Lego Vision, HD channels look great, but SD channels since the change from MPEG2 to MPEG4 is awful, I don't receive any pixelation and my broadband is running at full speed, my house is newly wired and had numerous engineers say my signal is fine.

Also my best friend also has the same issue on her TV as we were talking about how bad it is these days.

 

P.S. The signal strength in the Diagnostics screen shows the signal strength to be between 99% and 100%

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Roger_Gooner
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Message 10 of 12
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Re: MPEG2 > MPEG4 picture downgrade

There is an issue in that whilst MPEG-2 works well in compressing 720x576, it isn't quite the same with MPEG-4. In fact, my suspicion is that the number of horizontal lines is reduced so that we've got something like 704x576 which leads to bigger images which are cropped, leading to a reduction of about 2.2%. The only things I can suggest are disabling screen overscan (which you should do anyway but is often enabled by default) and watching the HD channels if simulcast with SD.

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Hub 3.0, TP-Link Archer C8, TP-Link TL-SG1008D 8-port gigabit switch, V6
My Broadband Ping - Roger's VM Broadband Connection
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