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rafael August
compressor quality not good enough
on Aug 26, 2008 at 11:42:23 pm

I scanned the forms and wasn't able to find the answer to my question. I am trying to compress dvc pro hd video. I am unable to get a file size under 2 megs for a clip that's around 30 seconds. The video is for a commercial production website so high quality with a fast playback is a must.

Is compressor 3.03 capable of doing the job or do I need a better program like Episode? Can anyone help? Any suggestions would be greatly appreciated.

Thank you,

Rafael


I am using the following settings in compressor:

Name: 650x366HiDef_MP_Page
Description: H.264 for high-bandwidth connections
File Extension: mov
Estimated file size: 219.73 MB/hour of source
Audio Encoder
AAC, Stereo (L R), 48.000 kHz
Video Encoder
Format: QT
Width: 650
Height: 365
Pixel aspect ratio: 0.75
Crop: None
Padding: None
Frame rate: 23.976
Frame Controls: Off
Codec Type: H.264
Multi-pass: On, frame reorder: On
Pixel depth: 24
Spatial quality: 75
Min. Spatial quality: 50
Key frame interval: 150
Temporal quality: 50
Min. temporal quality: 50
Average data rate: 0.512 (Mbps)
Fast Start: on



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Daniel Low
Re: compressor quality not good enough
on Aug 27, 2008 at 7:32:13 am

This has been covered a lot in this forum, you need to search for Frame Controls. Ultimately you need frame controls on.

Your frame size is very odd and you need to set an explicit data rate - not sure what 0.512Mb/s is - maybe you mean 512Mb/s

Where did you get these settings from?

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rafael August
Re: compressor quality not good enough
on Aug 27, 2008 at 5:00:18 pm

Hi Daniel,

The settings are copied straight from the compressor settings that I set. The frame size is odd. It is a size that will fit into a player on a webpage that will keep the true aspect ratio of a hi def clip. I will try turning on frame controls. Thanks.

Rafael




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Daniel Low
Re: compressor quality not good enough
on Aug 27, 2008 at 5:10:46 pm

I actually meant how did you come up with those settings?

You shouldn't ever dictate the frame size of a video purely based on how it fits into a web page. It's best to go for a size that is correct for the video that will fit within the the space you have.

These are examples of 'correct' 16:9 frame sizes:
640 x 360
512 x 288 - this is 'probably' ideal for you.
448 x 252
384 x 216

If you don't choose a correct frames size, the quality of the video will suffer.



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rafael August
Re: compressor quality not good enough
on Aug 27, 2008 at 5:15:49 pm

I came up with the frame size in apples .mac frame constraint settings while trying to figure out a unique size that would keep the true aspect ratio. I guess it was a mistake. It's uncharted territorially for me. I'll try your frame sizes.

Thank you.

Rafael



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Daniel Low
Re: compressor quality not good enough
on Aug 27, 2008 at 9:35:51 am

Sorry, I shouldn't answer these things in a hurry when I've just woken up!

For a 30 second clip you need to average about 540k/bits per second (not taking any audio into account).

At that sort of data rate you'll probably need to reduce your frame size to get anything like a decent picture. What sort of content is it that you are working with?

It's not compressor that's the problem here, it's that you are asking rather a lot. Any application would struggle.

Anyhow, using Frame Controls will help you somewhat.

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rafael August
Re: compressor quality not good enough
on Aug 27, 2008 at 5:10:50 pm

Hi Daniel,

The content that I'm working with ranges from Grand Prix and Drag Racing to animated sequences, commercial content 30 seconds-one minute in length. There is a action movie trailer also and a couple infomercials with cars in motion.

It sounds like I'm asking too much with the frame size that I have. I will run some tests with frame controls on and then try reducing the frame size. Thank you for your help.

Rafael




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rafael August
Re: compressor quality not good enough
on Aug 27, 2008 at 6:26:37 pm

Hi Daniel,

I tried reducing the frame size to 320/240 for a standard def file that I have and turning the frame controls on. I restricted the video to 500kbs/sec with the encoder set to hi. My results are files still in the 1mb range. I would like to get down to the 50kb range. I have friends who are directing spots for well known commercial companies and they have these beautifully compressed clips with a frame size of 480x360 and a file size of 25-50 kbs. Below is the setting summary from compressor.

Is there anything else I could try.

Thanks for your help.

Rafael

File Extension: mov
Estimated file size: 393.73 KB
Audio Encoder
AAC, Stereo (L R), 48.000 kHz
Video Encoder
Format: QT
Width: 320
Height: 240
Pixel aspect ratio: NTSC CCIR 601/DV
Crop: None
Padding: None
Frame rate: 29.97
Frame Controls On:
Retiming: (Fast) Nearest Frame
Resize Filter: Linear Filter
Deinterlace Filter: Fast (Line Averaging)
Adaptive Details: On
Antialias: 0
Detail Level: 0
Field Output: Same as Source
Codec Type: H.264
Multi-pass: On, frame reorder: On
Pixel depth: 24
Spatial quality: 75
Min. Spatial quality: 50
Key frame interval: 150
Temporal quality: 50
Min. temporal quality: 50
Average data rate: 500 (Kbps)
Fast Start: on



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Daniel Low
Re: compressor quality not good enough
on Aug 27, 2008 at 6:52:27 pm

There seems to be some confusion about datarates and file sizes.

It is impossible to encode a video to 50 Kilobits per second unless you are prepared to drop the frame size to something like 160x120 or smaller.

Is it that you are getting Kilobits and KiloBytes mixed up?

50 KiloBytes = 400 Kilobits

So, are we talking file size or data rate? KiloBytes or Kilobits?

With video you generally refer to the datarate not the file size because:
filesize = the_datarate x the_duration_of_the_clip

So a 1 minute clip with a constant datarate of 500Kbit/s per second would be roughly 3750 KBytes or 3.75 MegaBytes in file size.

500 x 60 seconds/8






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rafael August
Re: compressor quality not good enough
on Aug 27, 2008 at 7:49:13 pm

Hi Daniel

I guess we are talking about file size and data rate.

Your equation makes perfect sense to me but I still feel mixed up on a lot of levels right now. I'm looking at a quicktime movie that is 30 seconds in length, has a frame size of 480x360 which is taking up 25 kb of memory on my hard disc( I'm assuming this is KiloBytes). It was compressed with the h264 and AAC codecs. The video looks great. I would like to get my files to look as good and have a file size that is similar.

It seems impossible right now unless I somehow download the compression expert setting into my brain.

Rounded out my question is, what is their data rate setting that gets such great results, has such reasonable frame sizes, that yields crisp video and a small file sizes?

Thank you for your time,

Rafael




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Daniel Low
Re: compressor quality not good enough
on Aug 27, 2008 at 9:05:01 pm

Ok, that clip sounds like it's a Reference Movie, rather than a self-contained movie

Where did you get it from / how did you get it?

If you open it in Quicktime player and get info on it (Hold down the Apple Key and press i), please give me all the details that are listed:

Source:
Format:
FPS:
Data size:
Data Rate:
Duration:

Now choose 'Save As' from the Quicktime file menu. Choose 'Save as Self-contained Movie' and put 'SC' towards the end of the file name, then save it to the same directory as the other one.

Now go and look at the file size of that newly saved file.

I think you'll see a much larger file.

__________________________________________________________________
Please post back saying what solved your problem. It could help others, and saying 'thanks' is free!


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rafael August
Re: compressor quality not good enough
on Aug 27, 2008 at 9:37:07 pm

That's exactly what it is. It's a qt reference movie. It doesn't give all the info you asked for when I get info on the file. Only duration which is 44 seconds and size which is 36 KB (33,035 bytes). I guess I was in the ballpark after all I just didn't know it was a qt reference movie. When I converted it into a self-contained it was 3.1 MB.

Thank you so much for clearing all this up.

Rafael






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