[MPlayer-users] Re: Playing xcd image files

[D Richard Felker III]

On Fri, Jun 20, 2003 at 06:21:41AM -0500, Jonathan Rogers wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> Moritz Bunkus wrote:
> >Not true. Ogm does not contain error correction codes (ECC). The Ogg
> >pages do contain a checksum, but this is error detection at best, and
> >nothing more.
> 
> That's not surprising, since if it did contain ECC, it would have 
> similar overhead to CD Mode 1. As has been suggested in other fora, like 
> Doom9, video and audio can get away with error concealment, rather than 
> correction. So, the question is: What happens if MPlayer reads an OGG 
> packet with a bad bit or two? Will it be able to discard a frame or 
> sample or several frames or samples and keep going? If so, Mode 2 could 
> be very useful.

Discarding a frame is a very bad idea. libavcodec will attempt to
conceal errors in video, and of course playback will keep going unless
the data is totally trashed... The checksums in the ogg page headers
are completely useless for this though.

Rich