sorry about the delay... this it the first I'm seeing the message, maybe it got stuck in moderation because of the cross posting.
--- Christian HJ Wiesner <[EMAIL PROTECTED]> wrote > I was wondering how suitable both are with respect to video editing, > especially if it comes to sample precise cutting. What is the > absolute minimal number of samples per frame in a FLAC stream ? minimum is 1 sample per frame. > Can we change the number of samples in the same track ? do you mean can the number of samples vary from frame to frame? if you are putting it in matroska and the container is managing the sample numbering and seeking, the answer is an easy "yes". if you are relying on libFLAC to tell you the sample number for a frame: due to a flaw in the native codec design, if you vary the number of samples per frame it will not always be possible for the decoder to give an accurate sample number. then seeking through libFLAC will also be a problem. the flaw is that usually the frame number is encoded in the frame header, not the sample number, so to get the sample number you have to multiply the frame number by the block size. it is possible to encode the sample number in the frame header but there is not a bit in the header that tells you which way it is encoded, you have to infer it from other data that is complicated and flawed. and libFLAC only uses fixed blocksizes and only writes frame numbers, so if you are editing such a thing in such a way that you cut the first frame, the sample number calculation will be off by the number of samples cut. from this you can see though that if you are using your container for the sample numbering and seeking, and ignoring libFLAC's sample number there will be no problem. however if the stream is exported to a native FLAC stream it will have to be reframed which unfortunately means reencoded (unless/until I get to fixing the format). I am contemplating fixing this problem in the format eventually (along with others) but older decoders will not be able to read such streams, so if I do it, it will have to be done carefully to avoid disrupting users. I would bundle it up with other format changes and compression increases. Josh __________________________________ Do you Yahoo!? Yahoo! Mail - You care about security. So do we. http://promotions.yahoo.com/new_mail _______________________________________________ Flac-dev mailing list Flac-dev@xiph.org http://lists.xiph.org/mailman/listinfo/flac-dev