[MPlayer-users] Produce 422 format pixels with mencoder for mpeg4-encoding

[James Board]

I'm recently learning that mpeg4 actually means several
different things to different people.  I reread my emails
and I can understand why I confused everyone and I'm sorry.
In this email, I'm summarizing what I learned and hoping that 
someone can tell me if anything is incorrect (so I won't make the same
mistake again).  If I listed something wrong, then please correct
me and also don't be offended.

MPEG-4 AVC in this thread refers to MPEG-4 Part 10.
    It is also commonly referred to as H.264.
    It is used in Blu-Ray discs.
    It is also widely used by streaming internet sources, such as videos from 
        Vimeo, YouTube, and the iTunes Store
    It is also widely used in various HDTV broadcasts by cable and
    satellite providers.
    It is implemented by the libx264 encoder.
    I can use this from mencoder.
    I can create video files with yuv422 format pixels.    
    libx264 is one of the best AVC encoder available.
    In terms of quality at any given bitrate, MPEG-4 AVC produces
        superior video them MPEG-4 ASP.
    Not sure how much processing power it requires to encode.  This
        would be very implementation dependent, and also configuration
        dependent.
    UNSURE: Can use this from ffmpeg?

MPEG-4 ASP: is really MPEG-4 Part 2.
    It is considered inferior to MPEG-4 AVC.
    It doesn't support YUV422 pixel formats.
    This is the standard that is implemented by libav.  For example, if
        I select codec=mpeg4 in mencoder, then MPEG-4 ASP encoding happens.
    This is the mpeg-4 encoder supported by ffmpeg.
    DivX uses this standard.
    ASP generally requires less processing power to decode.

HEVC is a successor to H.264/MPEG-4 AVC.
    The first version of the standard was published in 2013.
    UNSURE: Do any open-source codecs exist?
    UNSURE: do any Linux codecs exist?

Also
    Almost no hardware decoders support playing video that has 422 pixel format.
    Yahoo email really sucks.

Thanks for all the responses and information.