On Tue, 2012-07-10 at 17:44 +0200, Luca Barbato wrote: > On 07/10/2012 04:19 PM, Tomas Härdin wrote: > > The backward parsing is due to PartitionPack not having any offset to > > the *next* partition - only the previous one (PreviousPartition). Since > > we don't want to parse the essence and in general can't skip over it (if > > it's frame wrapped, like OP1a), then we need to skip to FooterPartition, > > parse it and its metadata, then seek to its PreviousPartition, parse it > > etc. until we end up where we were when we stopped parsing forward. > > Brr.... > > > There's *supposed* to be a Random Index Pack at the very end of the > > file, but not all files have it. All files I've seen set > > PreviousPartition and FooterPartition correctly though. Hence this > > solution. > > > > A hypothetical file could have a RIP and no FooterPartition values set > > (like if muxed to a pipe), in which case you could fill in the > > PreviousPartition values from the RIP and use the current parsing code > > as-is. However, IIRC FooterPartition *must* be set so this point may be > > moot. > > > > Feel free to read SMPTE 377m if you're curious about the format, and the > > two dozen or so related specifications (S377m is very vague about how > > things like essence are *actually* written). > > Feels like rtp made even more hellish. > > If next morning I wake up early again I might give a stab at the encoder > side as well.
I'll just note that I don't know that much about mxfenc. While you're at it you might want to cherry-pick the DNxHD and DV patches from FFmpeg (there's a couple in the works, so I'd wait a day or two). > Thanks for the help =) This way the reasoning behind the demuxer's logic is also archived somewhere for posterity :) /Tomas _______________________________________________ libav-devel mailing list libav-devel@libav.org https://lists.libav.org/mailman/listinfo/libav-devel
