-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi! I want to encode wav file into fixed window length vorbis file. I don't know if "window" is good name for that, but i mean MDCT buffer size. This buffer is passed to mdct_backward() as "in" and it's size is determined by "init->n" variable which is also passed to this function. So, when I say "window size" I mean "init->n" value. I noticed, that when decoding ogg vorbis file, window size is changing and it's values for normal quality sound are: mostly 1024, somethimes 512 and very rarely 256. I noticed also, that when decoding file resampled to 11kHz this value is always 512 (for files I tested). When I resampled to 5,5kHz there was no change in window size. I tried many combinations of oggenc options, but the lowest window size, I obtained was still 512. But I want to make file with window size = 256. Is there way to accomplish that? And now, why I need this. I'm working on ogg vorbis decoder optimised for SUN SPARC machines. SUN provides library (medialib, mlib) of multimedia functions, which are written in VIS assembly, so they are fast. I want to optimise bacward MDCT, and use medialib function for it. But here is a problem: medialib IMDCT has hard-coded buffer size = 256. It is not possible to use it for larger buffers (I think - I tried to use it twice on two halfes of 512 buffer on many ways). And the second problem is my project deadline is comming soon, so I want to make decoder that works only on files with windows size = 256 :P Thanks in advance for any help! - -- c0g@wp.pl -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.1 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQE+Hb+tPqmVt5WhbA8RAozrAKCTe0jXowIVNQX/3UoDfb3zcYQ+OwCgkbzK Sy+0jq9UP/P1pPcP9j5u0Rw=BCqB -----END PGP SIGNATURE----- --- >8 ---- List archives: http://www.xiph.org/archives/ Ogg project homepage: http://www.xiph.org/ogg/ To unsubscribe from this list, send a message to 'vorbis-dev-request@xiph.org' containing only the word 'unsubscribe' in the body. No subject is needed. Unsubscribe messages sent to the list will be ignored/filtered.
Emmett Plant
2003-Jan-09 14:15 UTC
[vorbis-dev] encoding to fixed window length vorbis file
Hey there! Comment out line 202, 205 and 206 from envelope.c, recompile and encode a 44KHz stereo file. This will harm quality, but you probably already know that. Emmett Plant CEO, Xiph.org Foundation (Oh, I am so not this cool. Thanks go to Garf for the pick-up.) On 1/9/03 1:30 PM, "c0g" <c0g@wp.pl> wrote:> -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Hi! > I want to encode wav file into fixed window length vorbis file. I don't > know if "window" is good name for that, but i mean MDCT buffer size. > This buffer is passed to mdct_backward() as "in" and it's size is > determined by "init->n" variable which is also passed to this function. > So, when I say "window size" I mean "init->n" value. > I noticed, that when decoding ogg vorbis file, window size is changing > and it's values for normal quality sound are: mostly 1024, somethimes > 512 and very rarely 256. > I noticed also, that when decoding file resampled to 11kHz this value is > always 512 (for files I tested). When I resampled to 5,5kHz there was no > change in window size. I tried many combinations of oggenc options, but > the lowest window size, I obtained was still 512. > > But I want to make file with window size = 256. > > Is there way to accomplish that? > > And now, why I need this. > I'm working on ogg vorbis decoder optimised for SUN SPARC machines. SUN > provides library (medialib, mlib) of multimedia functions, which are > written in VIS assembly, so they are fast. I want to optimise bacward > MDCT, and use medialib function for it. But here is a problem: medialib > IMDCT has hard-coded buffer size = 256. It is not possible to use it for > larger buffers (I think - I tried to use it twice on two halfes of 512 > buffer on many ways). And the second problem is my project deadline is > comming soon, so I want to make decoder that works only on files with > windows size = 256 :P > > Thanks in advance for any help! > > - -- > c0g@wp.pl > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1.2.1 (MingW32) > Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org > > iD8DBQE+Hb+tPqmVt5WhbA8RAozrAKCTe0jXowIVNQX/3UoDfb3zcYQ+OwCgkbzK > Sy+0jq9UP/P1pPcP9j5u0Rw> =BCqB > -----END PGP SIGNATURE----- > > --- >8 ---- > List archives: http://www.xiph.org/archives/ > Ogg project homepage: http://www.xiph.org/ogg/ > To unsubscribe from this list, send a message to 'vorbis-dev-request@xiph.org' > containing only the word 'unsubscribe' in the body. No subject is needed. > Unsubscribe messages sent to the list will be ignored/filtered.--- >8 ---- List archives: http://www.xiph.org/archives/ Ogg project homepage: http://www.xiph.org/ogg/ To unsubscribe from this list, send a message to 'vorbis-dev-request@xiph.org' containing only the word 'unsubscribe' in the body. No subject is needed. Unsubscribe messages sent to the list will be ignored/filtered.