High Quality Mpeg problem
by Peter Knijn
on
Apr 29, 2008 at 8:51:23 am
I have this problem with mpeg encoding.
My problems in my resutls are:
- The image shows a little bit fuzzy compared to my timeline (95-%99%)
- Especially in graphic files I've used (dpt, jpg, tga, etc) the mpegs shows more square corners in curves, but this also applies to regural video (90% quality)
firstly my specs:
I use VelocityQ with v9.1.63 installed.
to be specific:
Quattrus Hardware Manager Version: 1.1.8 (Build 141)
-- Quattrus File System --
DPSVTFS.sys: 1.6.2 (Build 141)
-- Sync Support --
DpsSync.dll: 1.2.2.18
RDR4SYNC.SYS: 1.5.0.18
Dual Standard NTSC/PAL
Video Standard: PAL
Digital IO Board: Present
DVE Capable
Analog Video Outputs: 2
Video Streams: 4
Live Video Streams: 1
Graphics Framestores: 8
DVE Channels: 4
Mix Layers: 6
Audio Tracks: 8
-- I/O options --
Video: Composite, S-Video, Component, SDI
Audio: Balanced, Line, Aux In, AES, S/PDIF, SDI
Timecode: LTC, VITC, Visual TC Out
This is my problem
our company has been using the following prodecure for years when it comes to burning a productiion to DVD.
1. I output an mpeg2 directly from the timeline. using 9000kb
2. I import the mpeg in Adobe Encore 1.5 (for 2.0 won't work with the Velocity sounds card.
After burning the DVD and comparing the quality to the timeline in Quattrus, the quality is 95%-99% of the quality in Quattrus.
We always accepted this decrease, but with the ever increasing demand of our customers and ourselves we just don't accept this anymore.
WE WANT 100% QUALITY ON OUR DVD'S
I've put some examples here (for as long as it takes)
Well now for the specs in the encoding settings.
The link above has the settings to be downloaded, as well as screenshots of my settings, but I will tell it here:
Output:
Mpeg2 PAL 720x576 (with or without audio)
Hardware accelerate on
Format type: DVD PAL Mpeg2
Lower field First DV - Deinterlacing enabled
videobitrate 9000
video encoder quality 50
aspect ratio 4:3
Variable bitrate (tried constant too, the same result)
max 9627
avg:9000
min:8000
Rate control mode 1
I frames: 12
Auto GOP: None
P frames: 3
Profile ID: Main Profile
Audio settings no problems
Multiplexing type: DVD
Timestamps: I frames
After I've outputted the mpeg, I can see the decrease in quality allready, even before importing it into Adobe Encore
When I'm reading the manual of Adobe Encore, it tells me I can not use a bitrate higher than 9000kb
But when I import an mpeg in Adobe Encore, it HAS TO transcode it, and I can only choose a max of PAL DVD High Quality 7mb VBR 2 pass
I hope someone can tell me:
- how I can improve quality during mpeg output in VelocityQ
- If Adobe Encore limits my quality
- If so, what program is THE progam to use for DVD building.
Re: High Quality Mpeg problem by Chris Blair on May 13, 2008 at 4:38:20 am
An MPEG2 encoded video is compressed so you're never going to get a 100% equal copy to your original production. Every MPEG2 codec for DVD output does 2 things. First, it throws out about half your color data, reducing it to 4:2:0 YUV color space (your original is 4:2:2). Second, it compresses the video, which means it throws out some of the original data.
So even at the highest data rates, an MPEG2 video will be slightly less sharp, slightly less crisp than your original. There's no way around this fact...even using high-end hardware encoders.
Next problem...I believe the DVD spec limits the total video/audio data rate to something like 9800kb/sec. So you're exceeding the spec. Encore is telling you that, then re-encoding your video and audio to meet the spec. So you're basically compressing it twice. Once in Velocity making the MPEG2 file, and again in Encore. This seriously reduces the overall quality.
In your settings, you show that you have deinterlacing to "on." I believe it should be "off." Even if you shoot with a 30P or 24P, your video ends up being interlaced. It's way too complicated to go into in this thread...but I believe you're adding unnecessary processing and artifacts by deinterlacing your video on MPEG2 output.
You have video encoder quality at 50. I believe this should be set at the highest level available. If 50 is it, then you're ok...otherwise...take it up as high as it will go.
So, turn off de-interlace, increase your video encoder quality, and reduce your data rate in Velocity's output to an average no higher than about 7000- 7500 for the video portion. Sounds counterinutitive, but this should eliminate the re-encoding that's being done in Encore.
Also make sure you're outputting audio in a format that Encore expects. I believe it will take separate PCM .wav or MPEG layer 2 audio. If the audio isn't correct, I believe Encore will recompress the entire thing to meet that spec as well. I don't think you want to output a multiplexed MPEG2 file from Velocity (video/audio together in one file). Encore would probably de-multiplex it, possibly recompress, then multiplex upon creating your authored files. All unneeded steps in your process.
If that doesn't seriously improve quality, the only other solution is to output your Velocity timeline via hardware through SDI or component output to a dedicated hardware MPEG2 encoder.
Digital Rapids makes some very nice real-time encoding boards, but you're going to pay anywhere from $600 to $2000 for them. For my money, the quality increase is slight and only worth the cost if you're outputting a LOT of video to DVD's.
Hope that helps.
Chris Blair
Magnetic Image, Inc.
Evansville, IN.
www.videomi.com
Chris Blair
Magnetic Image, Inc.
Evansville, IN
www.videomi.com
Chris Blair
Magnetic Image, Inc.
401 E. Indiana
Evansville, IN 47711
www.videomi.com
Re: High Quality Mpeg problem by Peter Knijn on May 14, 2008 at 8:52:09 am
Thanks Chris
We are not thinking of an hardware encoder right now.
I'm trying the 7000kb option you gave me right now.
I have one problem, and that is the deinterlacing thing.
When I switch to OFF, any photos I've used in the timeline, do not show any artifacts anymore so thats great! But all my video motion is starting to strobe.
When I switch to ON, any photos I've used show artifact, BUT my video looks great without strobing motion.
Re: High Quality Mpeg problem by Chris Blair on May 15, 2008 at 1:36:23 am
There's got to be some other setting incorrect. There's no reason one should look good and the other shouldn't. Typically strobing or stuff that looks like the samples you uploaded is due to field/frame or field dominance issues.
On the Mpegsettings_image0006.jpg image you uploaded, I think the field handling should be set to interlaced, not frame, (if that's an option in that drop down box).
What I think is happening is you're selecting progressive frame output there, then in the Main Concept settings, you're switching it to interlaced. This will give you the strobing issue you're seeing. In your settings on your first post, you were selecting progressive or frame handling in Velocity, then deinterlacing that in Main Concept settings, which would also likely give you some odd artifcating.
This happens because you have Velocity doing unnecessary processing by outputting progressive, and Main Concept then deinterlacing that. If PAL is like NTSC (which I think it is when it comes to fields/frame issues), you want to output interlaced from Velocity and leave it interlaced in Main Concept. There are almost no software deinterlace filters or algorithyms that are worth a crap. They all add artifacts and potentially present field dominance issues, which is what I think you're experiencing.
Just to review a few things.
What is the origin of your still photos? A potential problem is that they're not sized correctly. For instance, if you bring in a photo and let Velocity resize it, there are a bunch of options on what it does, such as resize to fit, center, stretch etc. This can potentially cause problems since Velocity sucks at resizing still images. Then if you put that into your DVE, which is subpixel sampling it, you could experience more strobing issues.
Your photos should be sized in Photoshop (or another photo editing program) for your editing system's format (720x486 with .9 aspect ratio for NTSC, 720x576 for PAL with square pixels I think).
Another thing we do with still images is soften them some before saving for Velocity. We use a .2 gaussian blur in Photoshop, but any photo editing app can do it. Also make sure you reduce chroma levels to PAL levels...usually reducing chroma by about 20% does the trick on photos.
Yet another thing to try is to use the bandwidth limiter (if it's still in version 9 of VelocityQ) in the DVE to soften the DVE moves some.
Hope that helps.
Chris Blair
Magnetic Image, Inc.
Evansville, IN
www.videomi.com
Chris Blair
Magnetic Image, Inc.
401 E. Indiana
Evansville, IN 47711
www.videomi.com
Re: High Quality Mpeg problem by Peter Knijn on May 28, 2008 at 11:50:13 am
I've finally managed toget a result I'm happy with. Clear images, no artifacts in the images and smooth motion. all at a constant bitrate of 9000kb, so high enough to accept.
This means deinterlacing off and using the upper field.
Re: High Quality Mpeg problem by Chris Blair on May 30, 2008 at 1:54:24 am
Good to hear. MPEG2 is a great codec, but it throws out a ton of information, so the quality level it's able to achieve is amazing considering the reduction in file size.
Chris Blair
Magnetic Image, Inc.
Evansville, IN
www.videomi.com
