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QTInput resizing videos 
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Joined: Thu, 2013/05/23 10:48 pm
Posts: 3
Unread post QTInput resizing videos
I have 3 videos with 3 different resolutions:
1. 872x486
2. 720x486
3. 654x486

When I use qtinput in an avisynth script without specifying anything but: QTInput("c:\mov01.mov", color=2, audio=1, info=1), I get a resolution of 720x486 on all videos. Why is it resizing the videos and as a result distorting the video? Am I missing something?


Thu, 2013/05/23 10:55 pm
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Joined: Sun, 2005/04/03 7:02 pm
Posts: 304
Location: Los Angeles, CA USA
Unread post Re: QTInput resizing videos
What methods have you used to confirm that the videos are actually encoded at those 3 resolutions? Have you checked the videos with MediaInfo? Have you opened the videos in any other program besides QuickTime player?

If you've only tried QuickTime player and if qtinput outputs a resolution of 720x486 for all three videos, they are most likely encoded to that resolution with an embedded aspect ratio which causes QuickTime player to stretch them out to their final resolutions of 872x486, 720x486 and 654x486.

And just as a side note, if the codec inside the files is h264, I recommend using ffms2 over qtinput.


Thu, 2013/05/23 11:28 pm
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Joined: Thu, 2013/05/23 10:48 pm
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Unread post Re: QTInput resizing videos
quicktime: 872x486
MediaInfo: 704*480 (16x9)

quicktime: 720x486
mediainfo: 720x486 (3:2)

quicktime: 654x486
mediainfo: 740x480 (4:3)

Below is the mediainfo on all 3 files. All 3 files have been encoded using ProRes LT.

General
Complete name : D:\____1\Alex Clare - Too Close (main) st 15 sec.mov
Format : MPEG-4
Format profile : QuickTime
Codec ID : qt
File size : 596 MiB
Duration : 3mn 43s
Overall bit rate mode : Variable
Overall bit rate : 22.4 Mbps
Encoded date : UTC 2012-11-16 03:11:54
Tagged date : UTC 2012-11-16 03:14:21
Writing library : Apple QuickTime
Media/UUID : DE179479-DD81-4550-9A12-5F13DEC82F98

Video
ID : 1
Format : ProRes
Format version : Version 0
Format profile : LT
Codec ID : apcs
Duration : 3mn 43s
Bit rate mode : Variable
Bit rate : 20.9 Mbps
Width : 704 pixels
Original width : 720 pixels
Height : 480 pixels
Original height : 486 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 29.970 fps
Standard : NTSC
Color space : YUV
Chroma subsampling : 4:2:2
Scan type : Interlaced
Scan order : Bottom Field First
Bits/(Pixel*Frame) : 2.060
Stream size : 555 MiB (93%)
Writing library : Apple
Language : English
Encoded date : UTC 2012-11-16 03:11:54
Tagged date : UTC 2012-11-16 03:14:21
Color primaries : BT.601 NTSC
Transfer characteristics : BT.709
Matrix coefficients : BT.601




General
Complete name : D:\____1\Taio Cruz - Dynamite - Main Mix - st 10 sec.mov
Format : MPEG-4
Format profile : QuickTime
Codec ID : qt
File size : 400 MiB
Duration : 3mn 23s
Overall bit rate mode : Variable
Overall bit rate : 16.4 Mbps
Encoded date : UTC 2012-09-23 02:36:54
Tagged date : UTC 2012-09-23 02:37:45
Writing library : Apple QuickTime
Media/UUID : 5D3E9E95-861D-4AA7-A1DB-A2AAAC56D23B

Video
ID : 1
Format : ProRes
Format version : Version 0
Format profile : LT
Codec ID : apcs
Duration : 3mn 23s
Bit rate mode : Variable
Bit rate : 14.9 Mbps
Width : 720 pixels
Height : 486 pixels
Display aspect ratio : 3:2
Frame rate mode : Constant
Frame rate : 23.976 fps
Standard : NTSC
Color space : YUV
Chroma subsampling : 4:2:2
Scan type : Progressive
Bits/(Pixel*Frame) : 1.775
Stream size : 362 MiB (91%)
Writing library : Apple
Language : English
Encoded date : UTC 2012-09-23 02:36:54
Tagged date : UTC 2012-09-23 02:37:45
Color primaries : BT.601 NTSC
Transfer characteristics : BT.709
Matrix coefficients : BT.601



General
Complete name : D:\____1\The Wanted - Glad You Came - Main Mix - 127 bpm - st 34 sec.mov
Format : MPEG-4
Format profile : QuickTime
Codec ID : qt
File size : 677 MiB
Duration : 3mn 18s
Overall bit rate mode : Variable
Overall bit rate : 28.7 Mbps
Encoded date : UTC 2012-12-24 16:09:56
Tagged date : UTC 2012-12-24 16:11:07
Writing library : Apple QuickTime
Media/UUID : 40DD2D53-0639-469B-A5CA-548EB6DB031E

Video
ID : 1
Format : ProRes
Format version : Version 0
Format profile : LT
Codec ID : apcs
Duration : 3mn 18s
Bit rate mode : Variable
Bit rate : 27.1 Mbps
Width : 704 pixels
Original width : 720 pixels
Height : 480 pixels
Original height : 486 pixels
Display aspect ratio : 4:3
Frame rate mode : Constant
Frame rate : 29.970 fps
Standard : NTSC
Color space : YUV
Chroma subsampling : 4:2:2
Scan type : Interlaced
Scan order : Bottom Field First
Bits/(Pixel*Frame) : 2.679
Stream size : 641 MiB (95%)
Writing library : Apple
Language : English
Encoded date : UTC 2012-12-24 16:09:56
Tagged date : UTC 2012-12-24 16:11:07
Color primaries : BT.601 NTSC
Transfer characteristics : BT.709
Matrix coefficients : BT.601


Wed, 2013/05/29 5:39 pm
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Joined: Sun, 2005/04/03 7:02 pm
Posts: 304
Location: Los Angeles, CA USA
Unread post Re: QTInput resizing videos
Well, there you have it. All of your videos are actually encoded at 720x486 (original width x original height). Quicktime player is scaling them to the output resolutions. QTInput is decoding the video exactly as it is encoded. You'll have to do the output scaling yourself in AviSynth.


Wed, 2013/05/29 6:01 pm
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Joined: Thu, 2013/05/23 10:48 pm
Posts: 3
Unread post Re: QTInput resizing videos
I appreciate your help. Just one more questions:

Where is the scaling factor? Is there a way I can get that factor in avisynth so I can apply it to the video or is it a better idea to have the video editor do the scaling before encoding in FCP?


Wed, 2013/05/29 6:19 pm
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Joined: Sun, 2005/04/03 7:02 pm
Posts: 304
Location: Los Angeles, CA USA
Unread post Re: QTInput resizing videos
I don't know how to figure out the scaling factor. It has something to do with the aspect ratio, but not exactly.

Quicktime player says 872x486 but 486 * 16 / 9 = 864
Quicktime player says 720x486 but 486 * 3 / 2 = 729
Quicktime player says 654x486 but 486 * 4 / 3 = 648

I've always just opened my files in Quicktime Player and gotten the scaled values manually from there.

You can also try mode=0. On a test file I have here, Quicktime opens the file at 864x486, qtinput mode=2 and mode=3 open the file at 720x480 and qtinput mode=0 opens it at 864x486.

Is it better to do the scaling in FCP? I don't know. If the source file (before FCP) is 872x486 and the editor/encoder scales it down to 720x486 and then Quicktime/qtinput/AviSynth scales it back up to 872x486 you will have lost some quality.


Wed, 2013/05/29 6:50 pm
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