Daniel Low
Forum Replies Created
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[Christopher Campbell] “is it possible that the files which we previously encoded @ 8Mpbs, were of a higher quality and that is why they encoded at the requested bitrate of 8Mbps?”
No, lower quality content will actually require a higher bit rate.
Lower ‘complexity’ or simple footage is what will require less data.
Simple is stuff like a talking head shot, no camera movement.
Complex is fast moving action with explosions etc or similar__________________________________________________________________
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[Brian Alexander] “I wouldn’t deinterlace the footage for a couple of reasons: “
Good luck getting 1080i content to look good in a 480i program without deinterlacing!
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It’s illegal to distribute the Prores encoder. The decoder if freely available from Apple. Do you make a habit of pirating software?
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[Christopher Campbell] “Width: 720
Height: 486
Pixel aspect ratio: NTSC CCIR 601/DV
Crop: None
Padding: None
Frame rate: 29.97
Frame Controls: Off
Codec Type: H.264
Multi-pass: On, frame reorder: Off
Pixel depth: 24
Spatial quality: 75
Min. Spatial quality: 50
Temporal quality: 50
Min. temporal quality: 50
Average data rate: 8.192 (Mbps) “None of this adds up.
At standard def you don’t need anything like 8Mb/s to achieve a visually lossless picture with H.264.
If you set spatial and temporal quality to be 75/50 (which means nothing really, but in real terms, tells the codec to retain the visual quality of the source, but decide the datarate itself) it will use whatever it requires, nothing more.
In these circumstances, you can’t force a codec to use more data per second than it needs.
Despite what you have experienced with previous encodes, the only way to force a codec to use a certain amount of data per frame or per second, is to use an I-frame only format. and these are generally in the 15, 30 or 50Mb/s arenas.
I regularly encode HD content at 4Mb/s or less and it looks great with H.264.
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[Matt Jones] “The fly in the ointment is a 720×540 square pixel frame containing downscaled interlaced video AND vector based text generated by AE.
“What is it with you and interlace?
As soon as you downscale 1080i it’s deinterlaced, your problem is that you currently are not controlling how it’s being deinterlaced.
[Matt Jones] “Here’s what I did: I output a 720×540 interlaced quicktime using the Animation codec. I opened the file in Episode, selected a template, changed the size and checked that it was deinterlacing it properly. “
Why are you outputting interlaced?.
Simply deinterlace the 1080i and work progressive from there on.
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There you go, I was going to say that Craig is your man for all things Episode related.
Craig: I assume the cheque is in the post? 😉
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[Matt Jones] “So how does that correspond to “basic” and “improved”? “
This is Quicktime specific. Always choose improved.
[Matt Jones] ” It uses the same Flip4Mac 2-pass wmv encoder that any of my other Quicktime-based application would use”
If you used a dedicated application like Episode, from Telestream (the same people who make Flip4Mac) you’d get MUCH better results and also be able to make the MPEG-1 along with every other format you’re likely to come across.
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[Matt Jones] “It looks OK, but I wanted to keep the bitrate and framerate as low as possible in case I ran into some slow Windows95 machines out there”
A locked down Win95 PC would not be able to play WMV without an update but would be able to play MPEG-1. Anyhow
[Matt Jones] “Is MPEG-4 SP also known as “improved? In my export dialog from AE I have “basic” and “Improved” Also, If I choose “ISMA”, I can’t change the frame size to custom.”
MPEG-4 SP = Simple Profile or rather MPEG-4 Part 2. (MPEG-4 Part 10 is H.264)
ISMA = Internet Streaming Media Alliance. Don’t choose it. It’s designed for streaming over IP networks
Do not use AE to transcode your videos, it’s a compositing and special effects application with some powerful video processing tools, it’s not a transcoder. Get a dedicated piece of software to do it.
[Matt Jones] “Of course mpeg-1 is the most widely accepted. If I use mpeg-1, what would you suggest as the top bitrate for playback from CD? How do you think MPEG-1 compares to WMV9 at equal bitrates? “
MPEG-1 was designed for CD playback and was released in 1992. You could happily use a video datarate of 1.5Mb/s and be safe in the knowledge that it would play on pretty well every computer out there with a CD-ROM drive.
How does it compare to WMV9? I’ll let you guess!
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Seriously guys, Google is your best friend here, there’s such a huge about of great stuff to be found on Google, I’m really rather surprised the question has been asked here!
Anyhow, this is a great site that explains deinterlacing (and therefore interlace) simply.
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Tom, meet Wikipedia:
https://en.wikipedia.org/wiki/Interlace
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