Author Topic: .ts dimensions in the properties are different to the ones a video plays at  (Read 79 times)

Toner

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I recorded a show on tv the other day.
Came out as a .ts file and it played in VLC with the dimensions 1024 x 576
I brought it into avidemux to put it in a different container and crop the ads and I noticed the dimensions of the video was squashed to 704 x 576 in the preview.
I thought I was doing something wrong so I checked the properties of the file itself and they were the dimensions it listed.
When I cropped the ads out and put it into a new container, the video still played in VLC at 1024 x 576.
However when I encoded it into an 264 MP4, the new file subsequently played at 704 x 576 in VLC.
I ended up using the resize filter to encode it at 1024 x 576.

Does anyone know what is happening here?

eumagga0x2a

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Standard resolution PAL video has a 720x576 or 704x576 resolution (SAR) and is displayed either at 16:15 pixel aspect ratio (PAR) or 12:11 PAR which makes 4:3 display aspect ratio (DAR). Widescreen video has the very same SAR but is displayed at 64:45 PAR or 16:11 PAR. If you had chosen MKV as container, you could use the "force display width" output configuration option (which really just calculates and sets the DAR) to specify 1024 as display width and thus 16:9 as DAR.

In the configuration of the x264 encoder plugin in Avidemux you can specify DAR, but I am not sure that it is respected by video players.

Avidemux always uses square pixels for display.

dosdan

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1024 x 576 (AR of the captured image in the sensor)   ->   704 x 576 (AR of stored digital image)   ->  1024 x 576 (AR of displayed image)

This is a "non-square" pixels situation i.e. not a 1:1 relationship between what is stored and what is displayed.  An aware device will respond to what is stored in the media container file and display it correctly i.e. stretched back out.

The PAL D1 storage frame is either 720 x 576 or 704 x 576. (There is also a half-D1 version which is 352 x 576.)   But this same frame is also used to store PAL WS (widescreen) which, if the display AR was 1.78:1 will correctly display 704 x 576 as 1024 x 576.  You can't get something for nothing: there is no extra info being encoded in the horizontal dimension, so PAL WS, when displayed, is a little softer than standard PAL.  This would not be the case if the storage frame was actually 1024 x 576.

See: https://en.wikipedia.org/wiki/Pixel_aspect_ratio

Dan.
« Last Edit: November 12, 2017, 09:01:04 PM by dosdan »

Toner

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Thanks guys, goes over my head a bit but interesting stuff.