Replies – Forums – Daniel Low – Page 144

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Daniel Low
September 27, 2008 at 12:53 pm in reply to: Fast Start Compressed Header – Compressor

You’re getting pixel aspect ratio (PAR) and frame aspect ratios mixed up:

640×480
720×480
720×486
720×576
768×576

Are all 4:3 (1.33:1) Frame aspect ratio

All have non-square pixel aspect ratios except 640×480 and 768×576 which have square pixels.

(N.B. 720×480 & 720×576 can also be 16:9 Anamorphic)

You crop the 640×480 with the same amounts as the 720×480

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Daniel Low
September 26, 2008 at 6:33 pm in reply to: Fast Start Compressed Header – Compressor

Try these cropping values:

720×480 – l/r 36 t/b 24 –
720×486 – l/r 36 t/b 26

They are TV safe area crops for NTSC.

Page 225 of the compressor 3 user manual will guide you through setting Fast Start Compressed Header up, or page 165 for compressor 2 manual

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Daniel Low
September 26, 2008 at 6:23 pm in reply to: Flip4Mac – first few seconds, lots of artifacting

It should only need a maximum of 5mb/s and even then that’s too high for just talking heads.

What have you got for your keyframe setting?

Are you deinterlacing?

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Daniel Low
September 26, 2008 at 4:59 pm in reply to: Flip4Mac – first few seconds, lots of artifacting

Wow that’s very high. It maybe that your player can’t play this back and is artifacting. What are you viewing it in?

Is it a full HD clip 1920×1080?

Why are you using WMV?

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Daniel Low
September 26, 2008 at 4:46 pm in reply to: Flip4Mac – first few seconds, lots of artifacting

Why don’t you want to tell me the datarate?

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Daniel Low
September 26, 2008 at 4:39 pm in reply to: Flip4Mac – first few seconds, lots of artifacting

Ok, so no fade up from black?

Are there a couple of black frames at the beginning or a title or something that’s trowing it off course?

What data rate are you using?

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Daniel Low
September 26, 2008 at 4:18 pm in reply to: Flip4Mac – first few seconds, lots of artifacting

What do these first few frames consist of?

What settings are you using?

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Daniel Low
September 26, 2008 at 4:15 pm in reply to: H264 to MPEG-2 – very different transcode times

Handbrake is a very efficient transcoder, it’s actually great at producing very high quality pictures at low bit rates. It’s designed to rip a 4GB movie and fit it into 650MB without any loss in quality.

What you have found by skipping through the Handbrake clip is that there are far greater distances between H.264’s equivalent of I-frames. I-frames contain a full frame of information, all the other frames need to calculate themselves based on that I-frame.

So when compressor starts to process it, it has to look ahead at each frame and each time it lands on anything other than an i-frame it needs to calculate the result and this takes time. The greater the distance between i-frames the longer the calculation.

Look under the ‘Options explained’ (Frames) section here to see how complex this process can be
https://trac.handbrake.fr/wiki/x264Options

Combustion won’t have anything like as complex an encoder and as such it’s easier to read from.

If you converted both clips to an I-frame only format you’ll find that they both transcode at the same rate.

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Daniel Low
September 26, 2008 at 8:23 am in reply to: Fast Start Compressed Header – Compressor

Sorry, recompress, not decompress!

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Daniel Low
September 26, 2008 at 8:20 am in reply to: bit rate

The maximum total bit rate for DVD is 10.08mb/s with video at a max of 9.8mb/s.
If you’re not getting a high quality encode at around 8.5mb/s 2-pass, then either your source is crap, your settings are wrong or your encoding software is useless. Or a combination of the three.

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