Hi Sam and fzinken and thanks for the help here. I have been confused by formats and am trying to understand AV1.
Checking the formats available on the particular video I was working on, here is an extract of the resolutions available:-
135 mp4 854x480 480p 606k , avc1.4d401e, 25fps, video only, 53.84MiB
247 webm 1280x720 720p 849k , vp9, 25fps, video only, 74.95MiB
136 mp4 1280x720 720p 851k , avc1.4d401f, 25fps, video only, 74.03MiB
398 mp4 1280x720 720p 1001k , av01.0.05M.08, 25fps, video only, 99.16MiB
18 mp4 640x360 360p 439k , avc1.42001E, 25fps, mp4a.40.2@ 96k (44100Hz), 78.60MiB (best)
I have no idea why “best” is shown for the 18 format line but believe my earlier tries must have been using 398 which is shown as av01 because of the file size I recognized when downloading. I have now run this again with 136 and it seems to be working. I say “seems” as I am not at the right machine to try it till this evening.
I wish I were wiser but many thanks for the help with identifying the problem.
Regards,
Budge