[vlc-devel] MPEG-2 decode problem

Johnny Turpin jturpin at minervanetworks.com
Mon Feb 3 22:57:04 CET 2003

There is a type of MPEG-2 encoding performed I believe by GI (General
Instruments/Motorola) encoders which uses a feature that I believe is within
the MPEG-2 video spec, but which is not very common on non-broadcast
encoders. I believe it is known as "progressive I-Frame" or I have also
heard it called "split I-Frame". Regardless of what it is called, it is not
decoded by VLC.

I am not sure of all the technical details of this type of video encode, but
the basic idea is that each I-frame is not actually a complete I-Frame, but
the I-Frames are broken into 3rds or 4ths, and are filled in successively
each I-Frame. This is simply repeated for each I-Frame encoded.

So it basically takes 3-4 I-Frames before you can start the full decoding

Unfortunately, these encoders are used by most of the major TV studios here
in the states (HBO, ESPN, Showtime, etc...)

As we have I live DVB feed of MPEG-2 transport streams featuring this type
of video, I would gladly offer sample streams to anyone who is interested in
fixing the VLC decoder.

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