[FFmpeg-user] No pixel format specified - meaning of yuv420p?

[Andy Furniss]

Andy Furniss wrote:

> Possibly, or you didn't restrict to baseline.
>
> You really should know what format the source video is is to do
> things properly.
>
> If say it's interlaced and stored as 422 or 411 then the default
> conversion to 420 will be wrong. You would need to add interl=1 to
> the scale filter (even then it's not truly correct, but the
> difference is hard to see). If you want to keep as interlaced you
> would also need to encode as MBAFF with libx264 and be sure to check
> field dominance is correctly flagged in stream and container.
>
> Of course if the source is interlaced and you just want something
> "disposable" for the web rather than an archive, you could just
> de-interlace it. Choices still involved = framerate/fieldrate, but
> may (depending on source format) be able to avoid source chroma
> format issues.

Do you really need baseline - it's less efficient that other profiles,
also it won't do MBAFF.