1 /********************************************************************
3 * THIS FILE IS PART OF THE Ogg Vorbis SOFTWARE CODEC SOURCE CODE. *
4 * USE, DISTRIBUTION AND REPRODUCTION OF THIS SOURCE IS GOVERNED BY *
5 * THE GNU PUBLIC LICENSE 2, WHICH IS INCLUDED WITH THIS SOURCE. *
6 * PLEASE READ THESE TERMS DISTRIBUTING. *
8 * THE OggSQUISH SOURCE CODE IS (C) COPYRIGHT 1994-2000 *
9 * by Monty <monty@xiph.org> and The XIPHOPHORUS Company *
10 * http://www.xiph.org/ *
12 ********************************************************************
14 function: simple example decoder
15 last mod: $Id: decoder_example.c,v 1.7 2000/05/12 08:38:20 msmith Exp $
17 ********************************************************************/
19 /* Takes a vorbis bitstream from stdin and writes raw stereo PCM to
20 stdout. Decodes simple and chained OggVorbis files from beginning
21 to end. Vorbisfile.a is somewhat more complex than the code below. */
23 /* Note that this is POSIX, not ANSI code */
28 #include "vorbis/codec.h"
30 #ifdef _WIN32 /* We need the following two to set stdin/stdout to binary */
35 int16_t convbuffer[4096]; /* take 8k out of the data segment, not the stack */
38 int main(int argc, char **argv){
39 ogg_sync_state oy; /* sync and verify incoming physical bitstream */
40 ogg_stream_state os; /* take physical pages, weld into a logical
42 ogg_page og; /* one Ogg bitstream page. Vorbis packets are inside */
43 ogg_packet op; /* one raw packet of data for decode */
45 vorbis_info vi; /* struct that stores all the static vorbis bitstream
47 vorbis_comment vc; /* struct that stores all the bitstream user comments */
48 vorbis_dsp_state vd; /* central working state for the packet->PCM decoder */
49 vorbis_block vb; /* local working space for packet->PCM decode */
54 #ifdef _WIN32 /* We need to set stdin/stdout to binary mode. Damn windows. */
55 /* Beware the evil ifdef. We avoid these where we can, but this one we
56 cannot. Don't add any more, you'll probably go to hell if you do. */
57 _setmode( _fileno( stdin ), _O_BINARY );
58 _setmode( _fileno( stdout ), _O_BINARY );
62 /********** Decode setup ************/
64 ogg_sync_init(&oy); /* Now we can read pages */
66 while(1){ /* we repeat if the bitstream is chained */
70 /* grab some data at the head of the stream. We want the first page
71 (which is guaranteed to be small and only contain the Vorbis
72 stream initial header) We need the first page to get the stream
75 /* submit a 4k block to libvorbis' Ogg layer */
76 buffer=ogg_sync_buffer(&oy,4096);
77 bytes=fread(buffer,1,4096,stdin);
78 ogg_sync_wrote(&oy,bytes);
80 /* Get the first page. */
81 if(ogg_sync_pageout(&oy,&og)!=1){
82 /* have we simply run out of data? If so, we're done. */
85 /* error case. Must not be Vorbis data */
86 fprintf(stderr,"Input does not appear to be an Ogg bitstream.\n");
90 /* Get the serial number and set up the rest of decode. */
91 /* serialno first; use it to set up a logical stream */
92 ogg_stream_init(&os,ogg_page_serialno(&og));
94 /* extract the initial header from the first page and verify that the
95 Ogg bitstream is in fact Vorbis data */
97 /* I handle the initial header first instead of just having the code
98 read all three Vorbis headers at once because reading the initial
99 header is an easy way to identify a Vorbis bitstream and it's
100 useful to see that functionality seperated out. */
102 vorbis_info_init(&vi);
103 vorbis_comment_init(&vc);
104 if(ogg_stream_pagein(&os,&og)<0){
105 /* error; stream version mismatch perhaps */
106 fprintf(stderr,"Error reading first page of Ogg bitstream data.\n");
110 if(ogg_stream_packetout(&os,&op)!=1){
111 /* no page? must not be vorbis */
112 fprintf(stderr,"Error reading initial header packet.\n");
116 if(vorbis_synthesis_headerin(&vi,&vc,&op)<0){
117 /* error case; not a vorbis header */
118 fprintf(stderr,"This Ogg bitstream does not contain Vorbis "
123 /* At this point, we're sure we're Vorbis. We've set up the logical
124 (Ogg) bitstream decoder. Get the comment and codebook headers and
125 set up the Vorbis decoder */
127 /* The next two packets in order are the comment and codebook headers.
128 They're likely large and may span multiple pages. Thus we reead
129 and submit data until we get our two pacakets, watching that no
130 pages are missing. If a page is missing, error out; losing a
131 header page is the only place where missing data is fatal. */
136 int result=ogg_sync_pageout(&oy,&og);
137 if(result==0)break; /* Need more data */
138 /* Don't complain about missing or corrupt data yet. We'll
139 catch it at the packet output phase */
141 ogg_stream_pagein(&os,&og); /* we can ignore any errors here
142 as they'll also become apparent
145 result=ogg_stream_packetout(&os,&op);
148 /* Uh oh; data at some point was corrupted or missing!
149 We can't tolerate that in a header. Die. */
150 fprintf(stderr,"Corrupt secondary header. Exiting.\n");
153 vorbis_synthesis_headerin(&vi,&vc,&op);
158 /* no harm in not checking before adding more */
159 buffer=ogg_sync_buffer(&oy,4096);
160 bytes=fread(buffer,1,4096,stdin);
162 fprintf(stderr,"End of file before finding all Vorbis headers!\n");
165 ogg_sync_wrote(&oy,bytes);
168 /* Throw the comments plus a few lines about the bitstream we're
171 char **ptr=vc.user_comments;
173 fprintf(stderr,"%s\n",*ptr);
176 fprintf(stderr,"\nBitstream is %d channel, %ldHz\n",vi.channels,vi.rate);
177 fprintf(stderr,"Encoded by: %s\n\n",vc.vendor);
180 convsize=4096/vi.channels;
182 /* OK, got and parsed all three headers. Initialize the Vorbis
183 packet->PCM decoder. */
184 vorbis_synthesis_init(&vd,&vi); /* central decode state */
185 vorbis_block_init(&vd,&vb); /* local state for most of the decode
186 so multiple block decodes can
187 proceed in parallel. We could init
188 multiple vorbis_block structures
191 /* The rest is just a straight decode loop until end of stream */
194 int result=ogg_sync_pageout(&oy,&og);
195 if(result==0)break; /* need more data */
196 if(result==-1){ /* missing or corrupt data at this page position */
197 fprintf(stderr,"Corrupt or missing data in bitstream; "
200 ogg_stream_pagein(&os,&og); /* can safely ignore errors at
203 result=ogg_stream_packetout(&os,&op);
204 if(result==0)break; /* need more data */
205 if(result==-1){ /* missing or corrupt data at this page position */
206 /* no reason to complain; already complained above */
208 /* we have a packet. Decode it */
212 vorbis_synthesis(&vb,&op);
213 vorbis_synthesis_blockin(&vd,&vb);
216 **pcm is a multichannel double vector. In stereo, for
217 example, pcm[0] is left, and pcm[1] is right. samples is
218 the size of each channel. Convert the float values
219 (-1.<=range<=1.) to whatever PCM format and write it out */
221 while((samples=vorbis_synthesis_pcmout(&vd,&pcm))>0){
224 int bout=(samples<convsize?samples:convsize);
226 /* convert doubles to 16 bit signed ints (host order) and
228 for(i=0;i<vi.channels;i++){
229 int16_t *ptr=convbuffer+i;
232 int val=mono[j]*32767.;
233 /* might as well guard against clipping */
248 fprintf(stderr,"Clipping in frame %ld\n",vd.sequence);
251 fwrite(convbuffer,2*vi.channels,bout,stdout);
253 vorbis_synthesis_read(&vd,bout); /* tell libvorbis how
259 if(ogg_page_eos(&og))eos=1;
263 buffer=ogg_sync_buffer(&oy,4096);
264 bytes=fread(buffer,1,4096,stdin);
265 ogg_sync_wrote(&oy,bytes);
270 /* clean up this logical bitstream; before exit we see if we're
271 followed by another [chained] */
273 ogg_stream_clear(&os);
275 /* ogg_page and ogg_packet structs always point to storage in
276 libvorbis. They're never freed or manipulated directly */
278 vorbis_block_clear(&vb);
279 vorbis_dsp_clear(&vd);
280 vorbis_info_clear(&vi); /* must be called last */
283 /* OK, clean up the framer */
286 fprintf(stderr,"Done.\n");