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delta frame in uncompressed avi?

 
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compusic



Joined: 22 Sep 2006
Posts: 35

PostPosted: Fri 24 Nov 2006, 4:38    Post subject: delta frame in uncompressed avi? Reply with quote

I just use flash 8 to export uncompressed avi file(24bit color). but after import such avi files into premiere pro 2 or final cut pro 5, btw the hardwares are top ones, both systems respond very slowly, it seems the systems are not powerful enough to handle those files. on pc system, after Premiere trying to playback the file for some times, it's often said "memory is too low".

After some checking, I have found that the avi files have only one keyframe and all the others are delta frames. that's the cause!!! since I compare with other uncompressed avi files with all the frames are key frames. all-key-frames avi files have no such problem! I think the editing softwares have to calculate every frame except the first one - the key frame, and that put a very heavy load to the system, is it right?

here is the question, is avi file with delta frames really uncompressed or lossless?

And the export type setting in premiere has "microsoft avi" and "uncompressed microsoft avi", it seems in fact the later one is compressed type, since it's forced to uses 4:2:2 YUV color space. anyone can explain the two types in details please?

btw, anyone know how to let Flash 8 export all-key-frame avi? even I set all the frames to key frames in Flash 8, the file exported still has only one key frame, and all the others delta frames.

thanks in advance.
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RMN
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Joined: 04 Feb 2003
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Location: Lisboa, Portugal

PostPosted: Sat 25 Nov 2006, 4:41    Post subject: Reply with quote

If it uses delta frames, it's compressed. Probably with lossless compression, but still compressed.

I don't have Flash 8, so I really can't give you any specific advice, but using the "uncompressed" codec is usually not a very good idea. You can use HuffYUV, which is faster, creates smaller files, and is also lossless.

You can get HuffYUV and read the installation instructions here:

http://neuron2.net/www.math.berkeley.edu/benrg/huffyuv.html

RMN
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compusic



Joined: 22 Sep 2006
Posts: 35

PostPosted: Sun 26 Nov 2006, 14:59    Post subject: Reply with quote

thanks for reply.

This reminds me another thing. that's HDV Intermediate Codec.


there's no editing system can deal with native HDV native codec easily, it's usually converted to HDV Intermediate Codec, something like a uncompressed all-key-frame format. is it right?
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RMN
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Location: Lisboa, Portugal

PostPosted: Sun 26 Nov 2006, 17:03    Post subject: Reply with quote

It's not uncompressed, but I think it has no temporal compression, yes (similar to MJPEG or I-picture-only MPEG-2). It's not very hard to make an editing program work with temporal compression, but in some cases it's hard to ensure that the video plays back in real-time, especially when rendering real-time effects. Still, it would be possible using a fast system, as long as the GOPs are not huge (and in tape-based format they are usually pretty small). But it would require a lot of extra work for the programmers.

So the easy "solution" is to use these intermediate formats. The "cost" is extra drive space and some loss of quality. You can also go for truly uncompressed video (using SDI capture cards), but those create really huge files, especially if you're working in HD, and need a very fast array to sustain real-time capture and playback.

RMN
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