vorbis_analysis generates access violation - audio

Question

I'm trying to create an .ogg file, but even the example code presented generates an Access Violation when calling vorbis_analysis().
I'm using a simplified version of this encoding Example. I have tried the full example as it is, but I get the same error at the same place.
The code below is the example simplified by filling the encoding buffer with a constant instead of a wav file. The hFile is a TStreamFile instance created elsewhere.
vorbis_info vi;
vorbis_dsp_state vd;
vorbis_comment vc;
vorbis_block vb;
ogg_stream_state os;
ogg_page og;
ogg_packet op;
ogg_packet header;
ogg_packet header_comm;
ogg_packet header_code;
int res;
int len = 0;
int eos = 0;
int loop = 0;
vorbis_info_init(&vi);
res = vorbis_encode_init_vbr(&vi,2,44100,0.4f);
res = vorbis_encode_setup_init(&vi);
vorbis_comment_init(&vc);
vorbis_comment_add_tag(&vc,"TITLE","Silent noise");
res = vorbis_analysis_init(&vd,&vi);
res = vorbis_block_init(&vd,&vb);
srand(time(NULL));
res = ogg_stream_init(&os,rand());
res = vorbis_analysis_headerout(&vd,&vc,&header,&header_comm,&header_code);
res = ogg_stream_packetin(&os,&header);
res = ogg_stream_packetin(&os,&header_comm);
res = ogg_stream_packetin(&os,&header_code);
/* This ensures the actual
* audio data will start on a new page, as per spec
*/
while(ogg_stream_flush(&os,&og)) {
hFile->Write(og.header,og.header_len);
hFile->Write(og.body, og.body_len );
}
while(!eos) {
float **Buffer = vorbis_analysis_buffer(&vd,1024);
if(loop<10) {
for(int n=0; n<1024; n++) {
Buffer[0][n] = 1.0f;
Buffer[1][n] = 1.0f;
}
res = vorbis_analysis_wrote(&vd,1024);
loop++;
} else {
res = vorbis_analysis_wrote(&vd,0);
eos = true;
}
// Enough data?
while(vorbis_analysis_blockout(&vd,&vb) == 1) {
res = vorbis_analysis(&vb,&op); // <---- Access Violation
res = vorbis_bitrate_addblock(&vb);
while(vorbis_bitrate_flushpacket(&vd,&op)) {
/* weld the packet into the bitstream */
res = ogg_stream_packetin(&os,&op);
/* write out pages (if any) */
while(!eos){
if(ogg_stream_pageout(&os,&og) == 0) {
break;
}
hFile->Write(og.header,og.header_len);
hFile->Write(og.body, og.body_len );
/* this could be set above, but for illustrative purposes, I do
it here (to show that vorbis does know where the stream ends) */
if(ogg_page_eos(&og)) {
eos=1;
}
}
}
}
}
res = ogg_stream_clear(&os);
res = vorbis_block_clear(&vb);
vorbis_dsp_clear(&vd);
vorbis_comment_clear(&vc);
vorbis_info_clear(&vi);
The first part runs fine, the header is created and saved to the stream. Then I just fill the buffer with 1.0 floats for test purposes.
When there is enough data available the call to vorbis_analysis always generate Access Violation at x write of address x
The variable res always indicate success all the way down to the access violation.
I'm using static linked libogg v1.3.2 and libvorbis 1.3.5