[FFmpeg-user] Question about handling / unwanted changes of SAR in ffmpeg

[Reino Wijnsma]

On 25-12-2018 20:54, Uwe Freese <uwe.freese at gmx.de> wrote:
>     Stream #0:0: Video: h264 (High), yuv420p(progressive), 688x560 [SAR 64:45 DAR 2752:1575], SAR 172:121 DAR 7396:4235, 50 fps, 50 tbr, 1k tbn, 100 tbc (default)
>
> What does SAR (and DAR) mean in the brackets compared to the second SAR 172:121, which is slightly different?
As far as I know:

688    x 64/45     = 978,49w
978,49 x 1575/2752 = 560h     --> 978x560 @ bitstream level
688    x 172/121 =   977,98w
977,98 x 4235/7396 = 560h     --> 977x560 @ container level

-- Reino