Author Topic: Problems cutting AVCHD  (Read 11519 times)

Heldenkaiser

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Re: Problems cutting AVCHD
« Reply #15 on: April 12, 2014, 01:18:34 PM »
Another Update: I installed VLC player and can now open the "copy - copy - MKV Muxer" file. It still has the wrong aspect ratio and I can't see how to fix that.

At present the best I can do is "copy - AAC - MP4 Muxer".

Jan Gruuthuse

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Re: Problems cutting AVCHD
« Reply #16 on: April 12, 2014, 06:24:32 PM »
16:9 video (1440 x 1080) when copy (video) Output Format: Mkv Muxer change this setting:
Quote
[Configure]
- [v] Force display width
- Display width: 1920
Your video should now play back in 16:9 format and also show up in mediainfo as 1440*1080 (16:9)
1440*1080 is either 4:3 or 16:9
Above setting let computer program now video is Anamorphic, has something to do with:
- Display Aspect Ratio (DAR)
- Storage Aspect Ratio (SAR)
- square/none square pixels
...
« Last Edit: April 12, 2014, 06:35:24 PM by Jan Gruuthuse »

Heldenkaiser

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Re: Problems cutting AVCHD
« Reply #17 on: April 13, 2014, 06:06:56 AM »
Thank you! This works, but the quality suffers. I see many horizontal lines in the video now.

Heldenkaiser

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Re: Problems cutting AVCHD
« Reply #18 on: April 13, 2014, 06:25:06 AM »
Here is another problem that I hadn't noticed so far. Always the last five seconds of any original video are not playing properly in Avidemux. The audio is there, but the picture hangs. What might cause this?

mean

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Re: Problems cutting AVCHD
« Reply #19 on: April 13, 2014, 06:38:08 AM »
Cutting on non-intra can cause this

Jan Gruuthuse

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Re: Problems cutting AVCHD
« Reply #20 on: April 13, 2014, 07:36:07 AM »
This works, but the quality suffers. I see many horizontal lines in the video now.
Nothing is changed to quality of video. You just using copy, nothing is changed to stream. Is this on the computer only showing these horizontal lines, or on standalone player like flatscreen, blu-ray/ dvd player to? These have dedicated hardware/ codec to play video.
My guess video was made on digital photo camera: these are compressing a lot on the stream. Causing plenty of work to show the video back.


AQUAR

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Re: Problems cutting AVCHD
« Reply #21 on: April 13, 2014, 08:10:48 AM »
Video is interlaced and anamorphic, so horizontal lines might be due to not deinterlacing on playback.

@ Heldenkaiser

Aspect ratios are a pain but I'll try a little bit to clarify (or confuse even more).
They are used throughout the media processing chain to produce pictures that keep the correct look regardless of the screen type.
For different screen types, the dots that make up the picture have different shapes.
In the digital monitor world the dots have a square geometry.
Your video is anamorphic - meaning intended for screens with elongated pixels (analog TV's!)
Scaling has to be done by the media player for screens with pixels of a different geometry (see later).

This equation is usefull:  Display aspect = Stored Aspect X Pixel Aspect
Display aspect: the video aspect as you see it on a screen.
Stored aspect: horizontal data parcels for the pixels : vertical data parcels for the pixels,   
Pixel aspect ratio: Shape of the screen pixel.

You always have the stored aspect ratio and need either Pixel aspect ratio or Display aspect ratio to completely describe how the video is to be presented.
And you also need to tell your media player what type of screen it is connected to, so it can scale as appropriate.

Pixel aspect ratio is stored in the media container (by flags -meta data), and I believe it can also be added to the .h264 video stream.
This is the fun part with pixel aspect ratios that leads to seemingly inconsistent display aspects:
Different values in the possible stored locations, media player preferences and incorrect display type settings, are responsible.
You just need to know how to fiddle them to get what you want.

Mediainfo shows aspects as derived from the container level.
But when you mux into the MP4 container, the media player is scaling based on data in the video stream (hence you get a 16:9 picture).
Note: Can use the MP42 container to get away from AAC audio.
When you mux into the MKV container the media player probably looks at data in the container and scales to that.
If you don't configure the pixel aspect in the MKV container its 1:1 (hence you get a 4:3 picture).

With MKV you can set the display aspect (in the configuration dialog) yourself and all is good (as per Jan's advice).

Best solution of all use the resample filter to redefine the video for screens with square pixels.

Finally: don't forget to use some deinterlacing strategy on playback, else you get combing.


 
« Last Edit: April 13, 2014, 11:55:15 AM by AQUAR »

Jan Gruuthuse

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Re: Problems cutting AVCHD
« Reply #22 on: April 13, 2014, 12:57:23 PM »
Another reason for horizontal lines appearing (on computer screen/monitor) is when viewing the clip with vlc and probably others to. Is when the player is not in full screen view. This is when you still see borders around the clip playing. The horizontal lines from clip do not match up with these on the monitor. Use the Toggle Fullscreen button to switch between these modes.