1 /********************************************************************
3 * THIS FILE IS PART OF THE OggVorbis SOFTWARE CODEC SOURCE CODE. *
4 * USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS *
5 * GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *
6 * IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING. *
8 * THE OggVorbis SOURCE CODE IS (C) COPYRIGHT 1994-2001 *
9 * by the XIPHOPHORUS Company http://www.xiph.org/ *
11 ********************************************************************
13 function: simple example decoder
14 last mod: $Id: decoder_example.c,v 1.20 2001/05/27 20:33:18 xiphmont Exp $
16 ********************************************************************/
18 /* Takes a vorbis bitstream from stdin and writes raw stereo PCM to
19 stdout. Decodes simple and chained OggVorbis files from beginning
20 to end. Vorbisfile.a is somewhat more complex than the code below. */
22 /* Note that this is POSIX, not ANSI code */
27 #include <vorbis/codec.h>
29 #ifdef _WIN32 /* We need the following two to set stdin/stdout to binary */
34 #if defined(macintosh) && defined(__MWERKS__)
35 #include <console.h> /* CodeWarrior's Mac "command-line" support */
38 ogg_int16_t convbuffer[4096]; /* take 8k out of the data segment, not the stack */
41 int main(int argc, char **argv){
42 ogg_sync_state oy; /* sync and verify incoming physical bitstream */
43 ogg_stream_state os; /* take physical pages, weld into a logical
45 ogg_page og; /* one Ogg bitstream page. Vorbis packets are inside */
46 ogg_packet op; /* one raw packet of data for decode */
48 vorbis_info vi; /* struct that stores all the static vorbis bitstream
50 vorbis_comment vc; /* struct that stores all the bitstream user comments */
51 vorbis_dsp_state vd; /* central working state for the packet->PCM decoder */
52 vorbis_block vb; /* local working space for packet->PCM decode */
57 #ifdef _WIN32 /* We need to set stdin/stdout to binary mode. Damn windows. */
58 /* Beware the evil ifdef. We avoid these where we can, but this one we
59 cannot. Don't add any more, you'll probably go to hell if you do. */
60 _setmode( _fileno( stdin ), _O_BINARY );
61 _setmode( _fileno( stdout ), _O_BINARY );
64 #if defined(macintosh) && defined(__MWERKS__)
66 argc = ccommand(&argv); /* get a "command line" from the Mac user */
67 /* this also lets the user set stdin and stdout */
70 /********** Decode setup ************/
72 ogg_sync_init(&oy); /* Now we can read pages */
74 while(1){ /* we repeat if the bitstream is chained */
78 /* grab some data at the head of the stream. We want the first page
79 (which is guaranteed to be small and only contain the Vorbis
80 stream initial header) We need the first page to get the stream
83 /* submit a 4k block to libvorbis' Ogg layer */
84 buffer=ogg_sync_buffer(&oy,4096);
85 bytes=fread(buffer,1,4096,stdin);
86 ogg_sync_wrote(&oy,bytes);
88 /* Get the first page. */
89 if(ogg_sync_pageout(&oy,&og)!=1){
90 /* have we simply run out of data? If so, we're done. */
93 /* error case. Must not be Vorbis data */
94 fprintf(stderr,"Input does not appear to be an Ogg bitstream.\n");
98 /* Get the serial number and set up the rest of decode. */
99 /* serialno first; use it to set up a logical stream */
100 ogg_stream_init(&os,ogg_page_serialno(&og));
102 /* extract the initial header from the first page and verify that the
103 Ogg bitstream is in fact Vorbis data */
105 /* I handle the initial header first instead of just having the code
106 read all three Vorbis headers at once because reading the initial
107 header is an easy way to identify a Vorbis bitstream and it's
108 useful to see that functionality seperated out. */
110 vorbis_info_init(&vi);
111 vorbis_comment_init(&vc);
112 if(ogg_stream_pagein(&os,&og)<0){
113 /* error; stream version mismatch perhaps */
114 fprintf(stderr,"Error reading first page of Ogg bitstream data.\n");
118 if(ogg_stream_packetout(&os,&op)!=1){
119 /* no page? must not be vorbis */
120 fprintf(stderr,"Error reading initial header packet.\n");
124 if(vorbis_synthesis_headerin(&vi,&vc,&op)<0){
125 /* error case; not a vorbis header */
126 fprintf(stderr,"This Ogg bitstream does not contain Vorbis "
131 /* At this point, we're sure we're Vorbis. We've set up the logical
132 (Ogg) bitstream decoder. Get the comment and codebook headers and
133 set up the Vorbis decoder */
135 /* The next two packets in order are the comment and codebook headers.
136 They're likely large and may span multiple pages. Thus we reead
137 and submit data until we get our two pacakets, watching that no
138 pages are missing. If a page is missing, error out; losing a
139 header page is the only place where missing data is fatal. */
144 int result=ogg_sync_pageout(&oy,&og);
145 if(result==0)break; /* Need more data */
146 /* Don't complain about missing or corrupt data yet. We'll
147 catch it at the packet output phase */
149 ogg_stream_pagein(&os,&og); /* we can ignore any errors here
150 as they'll also become apparent
153 result=ogg_stream_packetout(&os,&op);
156 /* Uh oh; data at some point was corrupted or missing!
157 We can't tolerate that in a header. Die. */
158 fprintf(stderr,"Corrupt secondary header. Exiting.\n");
161 vorbis_synthesis_headerin(&vi,&vc,&op);
166 /* no harm in not checking before adding more */
167 buffer=ogg_sync_buffer(&oy,4096);
168 bytes=fread(buffer,1,4096,stdin);
170 fprintf(stderr,"End of file before finding all Vorbis headers!\n");
173 ogg_sync_wrote(&oy,bytes);
176 /* Throw the comments plus a few lines about the bitstream we're
179 char **ptr=vc.user_comments;
181 fprintf(stderr,"%s\n",*ptr);
184 fprintf(stderr,"\nBitstream is %d channel, %ldHz\n",vi.channels,vi.rate);
185 fprintf(stderr,"Encoded by: %s\n\n",vc.vendor);
188 convsize=4096/vi.channels;
190 /* OK, got and parsed all three headers. Initialize the Vorbis
191 packet->PCM decoder. */
192 vorbis_synthesis_init(&vd,&vi); /* central decode state */
193 vorbis_block_init(&vd,&vb); /* local state for most of the decode
194 so multiple block decodes can
195 proceed in parallel. We could init
196 multiple vorbis_block structures
199 /* The rest is just a straight decode loop until end of stream */
202 int result=ogg_sync_pageout(&oy,&og);
203 if(result==0)break; /* need more data */
204 if(result<0){ /* missing or corrupt data at this page position */
205 fprintf(stderr,"Corrupt or missing data in bitstream; "
208 ogg_stream_pagein(&os,&og); /* can safely ignore errors at
211 result=ogg_stream_packetout(&os,&op);
213 if(result==0)break; /* need more data */
214 if(result<0){ /* missing or corrupt data at this page position */
215 /* no reason to complain; already complained above */
217 /* we have a packet. Decode it */
221 if(vorbis_synthesis(&vb,&op)==0) /* test for success! */
222 vorbis_synthesis_blockin(&vd,&vb);
225 **pcm is a multichannel float vector. In stereo, for
226 example, pcm[0] is left, and pcm[1] is right. samples is
227 the size of each channel. Convert the float values
228 (-1.<=range<=1.) to whatever PCM format and write it out */
230 while((samples=vorbis_synthesis_pcmout(&vd,&pcm))>0){
233 int bout=(samples<convsize?samples:convsize);
235 /* convert floats to 16 bit signed ints (host order) and
237 for(i=0;i<vi.channels;i++){
238 ogg_int16_t *ptr=convbuffer+i;
242 int val=mono[j]*32767.f;
243 #else /* optional dither */
244 int val=mono[j]*32767.f+drand48()-0.5f;
246 /* might as well guard against clipping */
261 fprintf(stderr,"Clipping in frame %ld\n",(long)(vd.sequence));
264 fwrite(convbuffer,2*vi.channels,bout,stdout);
266 vorbis_synthesis_read(&vd,bout); /* tell libvorbis how
272 if(ogg_page_eos(&og))eos=1;
276 buffer=ogg_sync_buffer(&oy,4096);
277 bytes=fread(buffer,1,4096,stdin);
278 ogg_sync_wrote(&oy,bytes);
283 /* clean up this logical bitstream; before exit we see if we're
284 followed by another [chained] */
286 ogg_stream_clear(&os);
288 /* ogg_page and ogg_packet structs always point to storage in
289 libvorbis. They're never freed or manipulated directly */
291 vorbis_block_clear(&vb);
292 vorbis_dsp_clear(&vd);
293 vorbis_comment_clear(&vc);
294 vorbis_info_clear(&vi); /* must be called last */
297 /* OK, clean up the framer */
300 fprintf(stderr,"Done.\n");