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Crop & Resize

Started by Ruppig, December 29, 2020, 03:24:04 PM

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Ruppig

December 29, 2020, 03:24:04 PM Last Edit: December 29, 2020, 03:30:25 PM by Ruppig
Hi everyone!
I dont't get it. ;D
How can i determine the right AR (Resolution) for my TS-recordings in Avidmux after cropping.

I have a recorded interlaced PAL video with 720 x 576 resolution.
It is a movie with 72 Pixels black borders on the top and 72 Pixels black borders on the bottom.
So i use the filter to crop the borders and than i have a video with 720 X 432 resolution, but with a wrong AR.
RipBot264 does this  automatically by choosing a custom 2,40:1 AR. Handbrake does the same  automatically after cropping.
The desired resolution is 720 X 300.

How can i do this in Avimux?



eumagga0x2a

Quote from: Ruppig on December 29, 2020, 03:24:04 PMI have a recorded interlaced PAL video with 720 x 576 resolution.
It is a movie with 72 Pixels black borders on the top and 72 Pixels black borders on the bottom.

I would strongly recommend to leave it as-is and not worsen the quality – unless you want to watch it on a mobile device which doesn't support decoding of MPEG-2 in hardware. In this case you have to re-encode with a codec which the device can decode without draining the battery in matter of an hour.

If you re-encode, the first filter in the chain must be a deinterlacer*. On Windows and on macOS the choice is pretty easy – use Yadif configured to output one frame per field (effectively doubling the framerate) for smooth motion or frame for frame if a smaller filesize is important. On Linux, both VDPAU and libva deinterlacers are a very good choice too as they can also resize the picture in one go.

The default display aspect ratio for anamorphic SD video is 4:3, thus 720x576 amounts to 768x576 in square pixels. This would circumvent the problem for the cropping step entirely, device- and container-independent.

Else use the latest Avidemux nightly and force 720 as the display width in the configuration of the MP4 or MKV muxer. The necessary pixel aspect ratio will be calculated automatically. Don't do this in the encoder, few players respect the values stored in codec extradata. Don't use MPEG-TS as container.

*) Please make sure post-processing is completely disabled in Avidemux' Preferences.

Ruppig

December 31, 2020, 11:37:53 AM #2 Last Edit: December 31, 2020, 11:45:50 AM by Ruppig
Quote from: eumagga0x2a on December 29, 2020, 08:10:48 PMElse use the latest Avidemux nightly and force 720 as the display width in the configuration of the MP4 or MKV muxer. The necessary pixel aspect ratio will be calculated automatically.

Great, thank you! This was the missing point.
Somehow i have overlooked the DAR option in the muxer, which provides the calculated AR after using deinterlacing and cropping in the filter section.

Happy new year!  :D