[ale] Video codec question

Jim Popovitch jimpop at gmail.com
Mon Oct 12 23:13:16 EDT 2009


On Mon, Oct 12, 2009 at 23:03, aaron <aaron at pd.org> wrote:
> A little hard to say from seeing a single still, but it looks to
> me like previous frames or parts of frames are being retained and
> mixed with subsequent frames, which actually makes sense when you
> understand the mechanics of I/P/B frames in the mpeg compression
> schemes.
>
> You might describe it as frame retention or image lag, especially
> if the ghosts are hanging around from earlier in the stream because
> they don't know their dead.
>
> "I see dumb formats...  all the time."
>
> According to Wikipedia, m4v indicates files using an addendum spec
> (part 14) under the MPEG4 wrapper and codec "standards" umbrella.
> M4V files can include a Destructive Restriction Mechanism that is
> marketed under a ludicrously Orwellian name that rhymes with the
> more truthfully descriptive ID of ScarePlay. So you might be seeing
> artifacts from DRM, or from other Meta Data defined information
> that is possible under this wrapper but that Miro doesn't know how
> to translate.

Thanks Aaron.  The video (CommandN.tv) plays just fine under vlc, but
in miro it plays with the colors not well aligned.  That pic was just
intended to show the mis-alignment of the RGB.  I did initially
suspect DRM (not to be confused with Xorg's Display Resolution
Manager) but ruled that out when vlc worked.

-Jim P.



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