[Cin] Set stream sample aspect ratio in ffmpeg.C

[Terje J. Hanssen]

Den 06.01.2024 20:42, skrev Phyllis Smith:
> Applied the 3 patches and still a problem playing DVD on LG device 
> which previously worked.  Not to be difficult, but if we break 
> DVD/Bluray disc creation, it will probably never work again and I use 
> it frequently.
>
> CinGG is never going to be perfect but it has been working this way 
> for a long time and it has been usable, even if the DAR is not always 
> right.  There must be another way to reset that if needed.  But I will 
> keep testing.
>
>     I think right now we have issues with ffmpeg internals
>     (libavformat) not quite happy with stream (container) level SAR
>     being set ... it breaks our custom dvd/bluray encoding, as
>     discovered by Phyllis.
>
>     I am looking into this and audio bug but so far no solution for
>     either,sorry.
>
>
>

Yes, even that DVD and Blu-ray video discs are lesser usual than 
previously, I agree we have to keep this features working in CinGG.
I guess it is the autoplay function that may not work, and that a wrong 
aspect ratio video disc format possibly can be seen as data discs(?)

Phyllis, have  you tried if possibly VLC's Media> Open Disc can playback 
the DVD or BD video format?

As I said, also at the icon level in Gnome File manager, it it possible 
to see that the CinGG rendered webm files are visually squeezed 
horizontally, compared with the correct format muxed with FFmpeg 6.0:
easy to see the difference between 4:3 sqeezed webm vs 16:9 wide from 
(HDV) wide format.

In VLC these files are loaded squeezed as default, but it can be easily 
corrected with VLC's Videol > Aspect Ratio and select 4:3 for webm from 
SD DV sources and 16:9 for webm from HDV 1080i files.


Not to repeat myself, but below is a condensed output from how Mediainfo 
and FFprobe detect the aspect ratios of my tested SD and HDV sources and 
webm files:

Source SD DV:
-------------
mediainfo dv01_07.dv | grep Display
     Display aspect ratio                     : 4:3
ffprobe -hide_banner dv01_07.dv
       Stream #0:0: Video: dvvideo, yuv420p, 720x576 [SAR 16:15 DAR 
4:3], 25000 kb/s, 25 fps, 25 tbr, 25 tbn, 25 tbc

FFmpeg 6.0 webm:
mediainfo dv01_07_svt-av1_pr10.webm | grep Display
     Display aspect ratio                     : 4:3
ffprobe -hide_banner dv01_07_svt-av1_pr10.webm
   Stream #0:0: Video: av1 (Main), yuv420p(tv), 720x576 [SAR 1:1 DAR 
5:4], SAR 16:15 DAR 4:3, 25 fps, 25 tbr, 1k tbn, 1k tbc

Cin-aom-38_svt webm:
mediainfo dv01_07_av1_cingg.webm | grep Display
     Display aspect ratio                     : 5:4
ffprobe -hide_banner dv01_07_av1_cingg.webm
   Stream #0:0: Video: av1 (Main), yuv420p(tv, bt470bg/unknown/unknown), 
720x576 [SAR 1:1 DAR 5:4], 25 fps, 25 tbr, 1k tbn, 1k tbc


Source HDV:
-----------
mediainfo hdv07_05.m2t | grep Display
     Display aspect ratio                     : 16:9
ffprobe -hide_banner hdv07_05.m2t
   Stream #0:0[0x810]: Video: mpeg2video (Main) ([2][0][0][0] / 0x0002), 
yuv420p(tv, bt709, top first), 1440x1080 [SAR 4:3 DAR 16:9], 25000 kb/s, 
25 fps, 25 tbr, 90k tbn, 50 tbc

FFmpeg webm:
mediainfo hdv07_05_m2t_svt-av1+opus.webm | grep Display
     Display aspect ratio                     : 16:9
ffprobe -hide_banner hdv07_05_m2t_svt-av1+opus.webm
   Stream #0:0: Video: av1 (Main), yuv420p(tv, bt709), 1440x1080 [SAR 
1:1 DAR 4:3], SAR 4:3 DAR 16:9, 25 fps, 25 tbr, 1k tbn, 1k tbc

Cin-aom-38_svt webm:
mediainfo hdv07_05_m2t_cingg_svt-av1+opus.webm | grep Display
Display aspect ratio                     : 4:3
ffprobe -hide_banner hdv07_05_m2t_cingg_svt-av1+opus.webm
   Stream #0:0: Video: av1 (Main), yuv420p(pc, bt709/unknown/unknown), 
1440x1080 [SAR 1:1 DAR 4:3], 25 fps, 25 tbr, 1k tbn, 1k tbc










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