[FFmpeg-devel] [RFC][PATCH] Windows Television (WTV) file system handling
Tue Jan 11 03:54:03 CET 2011
On Tue, Jan 11, 2011 at 01:01:48PM +1100, Peter Ross wrote:
> On Tue, Jan 11, 2011 at 12:33:59AM +0100, Michael Niedermayer wrote:
> > On Sun, Jan 09, 2011 at 05:21:20PM +1100, Peter Ross wrote:
> > > Hi,
> > >
> > > The Windows Television (WTV) file format is a more complex beast than
> > > initially imagined.
> > >
> > > WTV is best viewed as a file system. Metadata, seek index tables, and
> > > chunked data are stored in separate files within. The fileystem uses
> > > a simple hierarchical file allocation table, with standard (4k) and big
> > > (256k) sector sizes. Standard FAT concepts apply, like fragmentation
> > > and the existence of slack space.
> > >
> > > The current WTV demuxer is not aware of the file system, and therefore
> > > only works on smalls wtv samples (<600MiB) where the files are not
> > > fragmented. Most WTV recordings are much larger. e.g. a 3hr HD recording
> > > of the tennis results in a 24GiB file and lots of fragmentation.
> > >
> > > Due to the complexity, I would really appreciate comments on the patch,
> > > especially my use of ByteIOContext.
> > Which part of the ByteIOContext use do you want comments about?
> wtvfile_read_packet(), wtvfile_seek() and wtv_open_sector() if possible.
> These functions provide a ByteIOContext instance, representing the contents
> of a file within the filesystem.
I dont think this is the most efficient way to handle it but i dont see a
problem after a quick look.
why dont you build the ByteIOContexts based on something from the underlaying
and how much seeking does this cause btw? if alot maybe the buffer sizes
could be increased
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
Breaking DRM is a little like attempting to break through a door even
though the window is wide open and the only thing in the house is a bunch
of things you dont want and which you would get tomorrow for free anyway
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