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Old October 7th, 2012, 01:25 AM   #1
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Why is my video so pixelated and blotchy?

I'd appreciate any help to this frustrating problem.
Source is AVCHD 1920 x 1080i. Converted by NeoScene into .avi files. Imported the .avi files to Vegas Pro 8 timeline. Edited, rendered to:

Main Concept AVC .mp4
Custom frame size: 1920 x 1080
Profile: Main
Frame rate: 29.970 NTSC
Field order: Upper Field First
Pixel aspect ratio: 1
Number of reference frames: 2
Use deblocking filter: checked
Variable bit rate, maximum: 10,000,000
Average bit rate: 2,000,000
Duration of video: 15 minutes
Size of finished video in .mp4 format: 95 MB, which I just know is way too small, should be about 2 GB.

Seeing how horrible to finished video is, I re-rendered to:
Sony AVC .mp4
Entropy coding: CABAC
Note: Entropy coding option is NOT available in Main Concept template.
Bit rate: 10,000,000
Note: There are no Maximum & Average bit rates as in Main Concept.
Size of finished video in .mp4 formate: 257 MB, larger than the Main Concept render. Still too small IMO.
Quality is somewhat better, but very discernable blocking & blotchiness.

What am I doing wrong? The video on the timeline when viewed in the Preview box is of excellent quality.
Thanks for any advice!

Last edited by Norris Combs; October 7th, 2012 at 01:44 PM.
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Old October 7th, 2012, 01:43 AM   #2
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Re: Why is my video so pixelated and blotchy?

Hi Norris

I don't use Neoscene so I'm not sure what it does to the file..You are starting with a 1080 interlaced source so what is Neoscene converting it to a 1080 interlaced file or progressive???

I just put my AVCHD direct on the timeline and set project properties to suit the file and importantly set de-interlacing to BLEND and render direct to Sony AVC...even the low quality (SD template) ones look good. Can you skip the conversion process?? Even a DuoCore should handle AVCHD to render..it will be a bit jerky in playback but will still render fine

Chris
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Old October 7th, 2012, 01:22 PM   #3
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Re: Why is my video so pixelated and blotchy?

"Pixelated & blotchy" implies a bitrate problem.

10,000,000... what units? (I'm not looking at the custom settings as I write this.)

Unless the original video is noisy with visible grain due to gain, or is jerky hand-held footage, an average of 2Mbps should be in the ballpark for MP4 compression. Maybe just a little lean.

With problems like this, I find it useful to load the rendered video into MediaInfo to determine what was actually rendered.
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Old October 7th, 2012, 01:50 PM   #4
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Re: Why is my video so pixelated and blotchy?

Quote:
Originally Posted by Chris Harding View Post
Hi Norris

I don't use Neoscene so I'm not sure what it does to the file..You are starting with a 1080 interlaced source so what is Neoscene converting it to a 1080 interlaced file or progressive???

I just put my AVCHD direct on the timeline and set project properties to suit the file and importantly set de-interlacing to BLEND and render direct to Sony AVC...even the low quality (SD template) ones look good. Can you skip the conversion process?? Even a DuoCore should handle AVCHD to render..it will be a bit jerky in playback but will still render fine

Chris
Chris,
Neoscene is supposed to do this:


NeoScene - Smoother Editing for AVCHD / HDV / Canon 5DMkII/7D

Hollywood producers rely on CineForm file formats for their editing and archive workflows because CineForm offers:

the highest visual fidelity achievable
the fastest real-time editing performance
cross-platform compatibility with all major editing tools: Adobe CSx, Final Cut Studio, Avid Media Composer, and Sony Vegas
You see, camera formats are designed for recording, not editing. With Neo Scene you will convert your difficult-to-edit HDV, AVCHD, DSLR camera footage to CineForm AVI (on windows) or MOV (on mac) files and then benefit from the same theatrical quality and real-time editing performance as professionals.

Cineform

I was having intermittent problem with editing AVCHD footage on my "weak" machine, and since using Neoscene to convert the "difficult" footage to .avi files, my PC has been fine with handling it. Whether Neoscene converts my interlaced footage to interlaced or progressive or not, I don't know. I should know, but I'm not sure where to check for this. I doubt that was the case, because the timeline video (converted to .avi by Neoscene) is of excellent quality. I will try to import AVCHD directly to the timeline tonight and see if my PC can do it. As I mentioned, occasionally Vegas would just freeze when it saw AVCHD on the timeline, on my PC.
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Old October 7th, 2012, 01:55 PM   #5
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Re: Why is my video so pixelated and blotchy?

Quote:
Originally Posted by Seth Bloombaum View Post
"Pixelated & blotchy" implies a bitrate problem.

10,000,000... what units? (I'm not looking at the custom settings as I write this.)

Unless the original video is noisy with visible grain due to gain, or is jerky hand-held footage, an average of 2Mbps should be in the ballpark for MP4 compression. Maybe just a little lean.

With problems like this, I find it useful to load the rendered video into MediaInfo to determine what was actually rendered.
Seth,
The units are bps (bits per second?).
The original video is very clean, no jerky movement at all, not grainy.
What is MediaInfo, how do I load the rendered video into it?

Thanks,
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Old October 7th, 2012, 02:57 PM   #6
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Re: Why is my video so pixelated and blotchy?

File size (in bytes) is determined exclusively by bit rate. Encoding is somewhat of an art, choosing a bit rate is a balancing act between image size (in pixels), frame rate and how much detail and motion is in the video. Generally speaking, higher bit rates produce better looking video. Your original 1920x1080 AVC video was probably 21,000,000 bits per second average with a maximum of 28,000,000. Your first render at 2 Mbps was WAY too low and it's no surprise that it was a blotchy mess. Your second render at 10 Mbps was likely still too low. Is there a lot of motion in the video and is the final video intended for the web, a Blu-ray disc or viewing on a computer?
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Old October 7th, 2012, 03:00 PM   #7
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Re: Why is my video so pixelated and blotchy?

MediaInfo is an outstanding freeware app that will give you information on what codecs, bitrates, etc. are present in any video or audio clip. Find it here: MediaInfo. It's really indispensable for working with video compression.

"loading" a clip to it involves either right-clicking the clip and selecting "MediaInfo" in the context menu, or, dragging a clip onto MediaInfo.

Be sure to select one of the expanded views, like "Tree", to see all the file details.

bps would refer to bits-per-second, yes, so your bitrate of 2,000,000 bps (2Mbps) does look like it's in the ballpark for a lean encode.

Have you tried either MainConcept or Sony AVC encodes using the supplied templates? This might be a first step, simplifying and eliminating possibilities. Are your custom-encode render quality settings set to "Good" or "Best"?
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Old October 7th, 2012, 06:55 PM   #8
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Re: Why is my video so pixelated and blotchy?

Quote:
Originally Posted by John Cline View Post
File size (in bytes) is determined exclusively by bit rate. Encoding is somewhat of an art, choosing a bit rate is a balancing act between image size (in pixels), frame rate and how much detail and motion is in the video. Generally speaking, higher bit rates produce better looking video. Your original 1920x1080 AVC video was probably 21,000,000 bits per second average with a maximum of 28,000,000. Your first render at 2 Mbps was WAY too low and it's no surprise that it was a blotchy mess. Your second render at 10 Mbps was likely still too low. Is there a lot of motion in the video and is the final video intended for the web, a Blu-ray disc or viewing on a computer?
I will up the bitrate to the maximum my PC can process. The finished video is intended to be viewed on a computer, and I will also burn a copy to a BD. It's not for the web.
Thanks,
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