Black Hole
May contain traces of nut
This might not be news to some, but I've been playing around with StDef BBC FOUR recordings and discovering stuff. In particular: broadcasts of old 4:3 material (Come Dancing), no doubt scraped up from some unearthed video tape.
The continuity announcements fill the 16:9 frame, then the programme material is not 4:3 but actually transmitted as 16:9 with the pillarbox bars included in the image. But, if set to "auto", the centre 4:3 stretches to fill the screen (short & fat), so there must be a flag which tells the display to over-scan.
The pixel format is 704 x 576 throughout, with a pixel aspect ratio 16:11 ( 16 x 704 : 11 x 576 = 11,264 : 6,336 = 16:9 ). When saved as a snapshot in VLC, the resulting .png ( 1:1 pixels ) is 1024 x 576 ( = 16:9 ) containing black sidebars 128 pixels wide each, so to display the video on a screen with square pixels, the 704 original pixels have to be resampled to make 1024 (or more likely 1920, with the 576 vertical pixels resampled to 1080).
Curiously, my version (5) of VideoReDo TV Suite does not interpret the aspect settings correctly and shows the 16:9 "outer frame" in a 4:3 envelope, thus displaying the original 4:3 "inner frame" as 1:1! This is what caused me considerable consternation until I could untangle where the fault is (VideoReDo!). The output of a save from VideoReDo plays correctly in VLC (and still does not display correctly when re-imported into VideoReDo).
I had intended that, for archival purposes, the video file would only contain 4:3 material – but that was when I expected the transmission was 4:3. Removing the side bars and outputting 4:3 will require re-encoding, and I presume the sidebars themselves don't contribute much to the size of the file, so they'll just have to stay.
Is it the case that all broadcasts of 4:3 material include the sidebars in an overall 16:9, and just signal the display (TV) to zoom in with a flag?
The continuity announcements fill the 16:9 frame, then the programme material is not 4:3 but actually transmitted as 16:9 with the pillarbox bars included in the image. But, if set to "auto", the centre 4:3 stretches to fill the screen (short & fat), so there must be a flag which tells the display to over-scan.
The pixel format is 704 x 576 throughout, with a pixel aspect ratio 16:11 ( 16 x 704 : 11 x 576 = 11,264 : 6,336 = 16:9 ). When saved as a snapshot in VLC, the resulting .png ( 1:1 pixels ) is 1024 x 576 ( = 16:9 ) containing black sidebars 128 pixels wide each, so to display the video on a screen with square pixels, the 704 original pixels have to be resampled to make 1024 (or more likely 1920, with the 576 vertical pixels resampled to 1080).
Curiously, my version (5) of VideoReDo TV Suite does not interpret the aspect settings correctly and shows the 16:9 "outer frame" in a 4:3 envelope, thus displaying the original 4:3 "inner frame" as 1:1! This is what caused me considerable consternation until I could untangle where the fault is (VideoReDo!). The output of a save from VideoReDo plays correctly in VLC (and still does not display correctly when re-imported into VideoReDo).
I had intended that, for archival purposes, the video file would only contain 4:3 material – but that was when I expected the transmission was 4:3. Removing the side bars and outputting 4:3 will require re-encoding, and I presume the sidebars themselves don't contribute much to the size of the file, so they'll just have to stay.
Is it the case that all broadcasts of 4:3 material include the sidebars in an overall 16:9, and just signal the display (TV) to zoom in with a flag?