Re: Question About syncing
DIANE SHAPRIEL <[email protected]>
| Newsgroups | gmane.comp.multimedia.ogg.vorbis.general |
|---|---|
| Message-ID | <[email protected]> |
<[email protected]> Re: [Vorbis] Question About syncing On Tuesday 12 May 2009 12:16:08 pm you wrote: > On Tue, May 12, 2009 at 10:02 AM, devel <[email protected]> wrote: > > What exactly does it mean when, in the decoder_example.c file, you try > > to extract the information from the comments and codebook headers and you > > loose sync? What is actually being check to determine when sync is lost?. > > I known one part of it is that there is a gaps in the stream. Is the CRC > > value the determining factor? Please detail! I read a lot of the > > documents. I still am a little fuzzy. > > "Losing sync" in the context of the vorbis code usually means > synchronization between the libogg read position and the beginning of > the next Ogg page in the stream. This is verified two ways: presence > of the 'OggS' magic sequence at the current read position, correct CRC > value for the subsequent page data. Normally, there will be a page > right where the code expects it to be. If the 'OggS' or CRC check > fail, then the file is corrupt, and it tries to find a place where > decoding can begin again by searching forward for the next 'OggS' > marking a new page and they trying the CRC from that point. When that > happens, the reader is said to have "regained sync" after "hole in > data". As I indicate in a previous post "Help with old to new sources" I am trying to upgrade and learn how the decode method is achieve. The biggest problem I am having is chaining at the moment. The code will play the first stream successfully but the second stream in the chain fails in the CodeBookAndPreMetaData function. I was encourage to write a simplified tutorial but I would like all of the code to work. I want to understand how to fix this but use it as a good problem solving exercise. attach is a file (HowToCodeOggVorbis.tar.gz). w3rn -rr ---------- Walla! Mail - Get your free unlimited mail today _______________________________________________ Vorbis mailing list [email protected] http://lists.xiph.org/mailman/listinfo/vorbis