Recompressing a MPEG2 file

[HDBroadcast]

Hello,

I have an MPEG2 HD file already compressed. I want to try and keep the quality pretty much the same when I re-encode. When I bring that file clip into Adobe Premier Pro (1080 sequence), edit extra, the final out put from Adobe Media Encoder looks a-little softer with more noise (I render in MPEG2 again, hoping to match the original clip). What settings in Adobe Media Encoder can I use to keep video output looking the same without a drop in quality? Time and file size is not an issue for me, quality is.

Final output will be via HDMI to HDTV display.

(22min clips HD)

Thanks!

[DB83]

Mpeg2 is a lossy format so any re-encode of that will lose quality. The most you can expect is to retain the bitrate of the original clip.

BTW what do you mean by 'more noise'. Even a straight re-encode would not create noise. Maybe you really mean pixilation (visible squares) which is a result of too low a bit rate.

[smrpix]

Premiere Pro can smart render a number of file types including some types of mpeg2. This means under certain circumstances you need suffer no quality loss at all. You haven't provided enough information about your actual files for anyone here to say if you are in that category.

In all cases, matching the dimensions, framerate and field-ordering of your source, and using a higher bitrate will minimize loss.

[HDBroadcast]

Thank you both for the reply.

I need to re-encode this video.
Have a look at the video settings of the clip:



When I use AME (second image), these are my bit-rate settings and still getting some quality loss.

[KarMa]

Having a target bitrate of 55Mbps is a lot even for 1080i, you could get away with the same bitrate as your source if doing a 2 Pass.

[HDBroadcast]

I thought so, but if the bitrate is high = high quality why am I still getting some loss of quality?

[KarMa]

I thought so, but if the bitrate is high = high quality why am I still getting some loss of quality?

If you are encoding with 55Mbit, and getting noticeable quality loss then something is wrong. That should be nearly lossless. Either the codec is crap, or there's some prefilter messing with the video before it gets to the codec.

[poisondeathray]

You might have used the mismatched wrong sequence settings, or export settings . As mentioned earlier - make sure everything is matched in terms of field order, dimensions

You can also try bumping up the minimum bitrate

Premiere cannot smart render generic MPEG2 without 3rd party plugins , only some forms of XDCAM (specific variant of MPEG2)

[smrpix]

If you're interpolating 1440 to 1920, be sure you have the Use Maximum Render Quality option ticked.

[Detmek]

Why first picture shows 5.562Kbs as bitrate and 8.200Kbs as maximum bitrate for 1440x1080 resolution? That bitrate can be used for SD resolution (720x480, 720x576), not for HD.

If you intend to play via HDMI you can use H.264 format. It is more efficient than old MPEG2.

[newpball]

Yes, reencode to H.264 instead of old MPEG-2 and use a much higher bitrate than 5.6/8.2Mbs as that is too low for your resolution.

[theewizard]

why do you need to re-encode ?
if its not about Bitrate for streaming
or resizing to STD dvd
just use a smart render editor, to cut or do what ever it is you need
a smart render editor will only encode those frames that needed to be interpolated and leave everything else alone
assuring that quality is not changed

[HDBroadcast]

Thank you all for the reply! Gladly appreciated

Here is the video example. The original is on the left and mine is on the right (re-encoded file). Pay attention to the ten logo quality the most. See any difference?

Bitrate= 55
Target = 55
Minimum Bitrate = 10
Maximum checked.

The only difference I have changed with the footage is make is 1920 by 1080 and interpret the file as square pixels in After Effects. I might be a-little picky on this one, but I can see a slight loss in sharpness, can you see it?

[poisondeathray]

I don't see your videos, just a confusing screenshot . Are we supposed to be comparing the two "ten" logos ?

If you truly don't care about filesize, you can use a lossless codec e.g. lagarith, ut video codec, magic yuv etc... or even uncompressed video. There will be zero quality loss from export compression

But if you incurred loss from one of the other reasons (wrong or mismatched settings, deinterlacing etc.. or colorspace conversions) , then you might still see some problems, just not the additional ones from lossy compression

[HDBroadcast]

Sorry, I meant a screen shot comparing the quality. I mentioned before to look at the two ten logos to see if you see a drop in quality from the two (Left is original and right is re-encoded).

The only thing I have changed with the original footage is interpret it as "square pixels 1.00" other then that, I haven't messed with anything.

[poisondeathray]

yes there is difference - but it's not even the same logo from the same scene (the fake reflection is even at a different angle), but a static logo is probably not where you should be looking . Look and compare scenes with high motion if you're interested in looking for mpeg2 compression artifacts. Even at high bitrates you will see fine macroblocking . So if you still wanted it "perfect", and don't care about filesize - just use uncompressed or a lossless codec

If you crop it down so they are framed the same way (since you didn't upload 2 screenshots) and compare them in different tabs you will see what I mean

[HDBroadcast]

They actually were two screen shots, one video over the other to compare and I screened it into one. (Its the same scene/video)

I'm actually more interested in the quality of the logo over anything else and keeping the logo as original when it comes down to quality which has been difficult.

[poisondeathray]

Even if they were 2 overlaid and x-offset screenshots, there is a problem with the angle of the specular reflection - can't you see that ?

Your problem is solved if it was only compression problems - use a lossless codec . Not difficult at all

[HDBroadcast]

I'm confused as to what you mean by "problem with the angle of the specular reflection". That's how the video is, if that's what you mean?

[poisondeathray]

I'm confused as to what you mean by "problem with the angle of the specular reflection". That's how the video is, if that's what you mean?

Those "white" spots on the logo are what graphic design artists put on to make the logo appear "3D" ish. They are called "specular reflections"



You're said you're concerned about the logo

You compared them with a screenshot. You mentioned the same scene, but presumably they are from the same frame (that's how you're supposed to compare things)

Here is an animated gif illustrating what I mean. It's the left and right logo in your screenshot, just cropped so they are aligned and alternating back and forth. (don't pay attention to the quality, since it's a gif. Pay attention to the movement of the reflection - notice how it shifts, but the letters don't shift)

To me that indicates other problems. It's not just a quality difference from compression . Either with your process, method of comparing, maybe you messed up the screenshot - something. Something else is wrong.

What about the other parts of the video? What other things are going on? What other problems are there? There is bound to be other issues

It's easier for most people to compare things with layers. You mentioned after effects. Just put 2 versions on 2 different layers, align them and solo one of them at a time. That way you flip back & forth between them