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Diffstat (limited to 'examples/decoder_example.c')
| -rw-r--r-- | examples/decoder_example.c | 313 |
1 files changed, 313 insertions, 0 deletions
diff --git a/examples/decoder_example.c b/examples/decoder_example.c new file mode 100644 index 0000000..e264e40 --- /dev/null +++ b/examples/decoder_example.c @@ -0,0 +1,313 @@ +/******************************************************************** + * * + * THIS FILE IS PART OF THE OggVorbis SOFTWARE CODEC SOURCE CODE. * + * USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS * + * GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE * + * IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING. * + * * + * THE OggVorbis SOURCE CODE IS (C) COPYRIGHT 1994-2009 * + * by the Xiph.Org Foundation http://www.xiph.org/ * + * * + ******************************************************************** + + function: simple example decoder + + ********************************************************************/ + +/* Takes a vorbis bitstream from stdin and writes raw stereo PCM to + stdout. Decodes simple and chained OggVorbis files from beginning + to end. Vorbisfile.a is somewhat more complex than the code below. */ + +/* Note that this is POSIX, not ANSI code */ + +#include <stdio.h> +#include <stdlib.h> +#include <math.h> +#include <vorbis/codec.h> + +#ifdef _WIN32 /* We need the following two to set stdin/stdout to binary */ +#include <io.h> +#include <fcntl.h> +#endif + +#if defined(__MACOS__) && defined(__MWERKS__) +#include <console.h> /* CodeWarrior's Mac "command-line" support */ +#endif + +ogg_int16_t convbuffer[4096]; /* take 8k out of the data segment, not the stack */ +int convsize=4096; + +extern void _VDBG_dump(void); + +int main(){ + ogg_sync_state oy; /* sync and verify incoming physical bitstream */ + ogg_stream_state os; /* take physical pages, weld into a logical + stream of packets */ + ogg_page og; /* one Ogg bitstream page. Vorbis packets are inside */ + ogg_packet op; /* one raw packet of data for decode */ + + vorbis_info vi; /* struct that stores all the static vorbis bitstream + settings */ + vorbis_comment vc; /* struct that stores all the bitstream user comments */ + vorbis_dsp_state vd; /* central working state for the packet->PCM decoder */ + vorbis_block vb; /* local working space for packet->PCM decode */ + + char *buffer; + int bytes; + +#ifdef _WIN32 /* We need to set stdin/stdout to binary mode. Damn windows. */ + /* Beware the evil ifdef. We avoid these where we can, but this one we + cannot. Don't add any more, you'll probably go to hell if you do. */ + _setmode( _fileno( stdin ), _O_BINARY ); + _setmode( _fileno( stdout ), _O_BINARY ); +#endif + +#if defined(macintosh) && defined(__MWERKS__) + { + int argc; + char **argv; + argc=ccommand(&argv); /* get a "command line" from the Mac user */ + /* this also lets the user set stdin and stdout */ + } +#endif + + /********** Decode setup ************/ + + ogg_sync_init(&oy); /* Now we can read pages */ + + while(1){ /* we repeat if the bitstream is chained */ + int eos=0; + int i; + + /* grab some data at the head of the stream. We want the first page + (which is guaranteed to be small and only contain the Vorbis + stream initial header) We need the first page to get the stream + serialno. */ + + /* submit a 4k block to libvorbis' Ogg layer */ + buffer=ogg_sync_buffer(&oy,4096); + bytes=fread(buffer,1,4096,stdin); + ogg_sync_wrote(&oy,bytes); + + /* Get the first page. */ + if(ogg_sync_pageout(&oy,&og)!=1){ + /* have we simply run out of data? If so, we're done. */ + if(bytes<4096)break; + + /* error case. Must not be Vorbis data */ + fprintf(stderr,"Input does not appear to be an Ogg bitstream.\n"); + exit(1); + } + + /* Get the serial number and set up the rest of decode. */ + /* serialno first; use it to set up a logical stream */ + ogg_stream_init(&os,ogg_page_serialno(&og)); + + /* extract the initial header from the first page and verify that the + Ogg bitstream is in fact Vorbis data */ + + /* I handle the initial header first instead of just having the code + read all three Vorbis headers at once because reading the initial + header is an easy way to identify a Vorbis bitstream and it's + useful to see that functionality seperated out. */ + + vorbis_info_init(&vi); + vorbis_comment_init(&vc); + if(ogg_stream_pagein(&os,&og)<0){ + /* error; stream version mismatch perhaps */ + fprintf(stderr,"Error reading first page of Ogg bitstream data.\n"); + exit(1); + } + + if(ogg_stream_packetout(&os,&op)!=1){ + /* no page? must not be vorbis */ + fprintf(stderr,"Error reading initial header packet.\n"); + exit(1); + } + + if(vorbis_synthesis_headerin(&vi,&vc,&op)<0){ + /* error case; not a vorbis header */ + fprintf(stderr,"This Ogg bitstream does not contain Vorbis " + "audio data.\n"); + exit(1); + } + + /* At this point, we're sure we're Vorbis. We've set up the logical + (Ogg) bitstream decoder. Get the comment and codebook headers and + set up the Vorbis decoder */ + + /* The next two packets in order are the comment and codebook headers. + They're likely large and may span multiple pages. Thus we read + and submit data until we get our two packets, watching that no + pages are missing. If a page is missing, error out; losing a + header page is the only place where missing data is fatal. */ + + i=0; + while(i<2){ + while(i<2){ + int result=ogg_sync_pageout(&oy,&og); + if(result==0)break; /* Need more data */ + /* Don't complain about missing or corrupt data yet. We'll + catch it at the packet output phase */ + if(result==1){ + ogg_stream_pagein(&os,&og); /* we can ignore any errors here + as they'll also become apparent + at packetout */ + while(i<2){ + result=ogg_stream_packetout(&os,&op); + if(result==0)break; + if(result<0){ + /* Uh oh; data at some point was corrupted or missing! + We can't tolerate that in a header. Die. */ + fprintf(stderr,"Corrupt secondary header. Exiting.\n"); + exit(1); + } + result=vorbis_synthesis_headerin(&vi,&vc,&op); + if(result<0){ + fprintf(stderr,"Corrupt secondary header. Exiting.\n"); + exit(1); + } + i++; + } + } + } + /* no harm in not checking before adding more */ + buffer=ogg_sync_buffer(&oy,4096); + bytes=fread(buffer,1,4096,stdin); + if(bytes==0 && i<2){ + fprintf(stderr,"End of file before finding all Vorbis headers!\n"); + exit(1); + } + ogg_sync_wrote(&oy,bytes); + } + + /* Throw the comments plus a few lines about the bitstream we're + decoding */ + { + char **ptr=vc.user_comments; + while(*ptr){ + fprintf(stderr,"%s\n",*ptr); + ++ptr; + } + fprintf(stderr,"\nBitstream is %d channel, %ldHz\n",vi.channels,vi.rate); + fprintf(stderr,"Encoded by: %s\n\n",vc.vendor); + } + + convsize=4096/vi.channels; + + /* OK, got and parsed all three headers. Initialize the Vorbis + packet->PCM decoder. */ + if(vorbis_synthesis_init(&vd,&vi)==0){ /* central decode state */ + vorbis_block_init(&vd,&vb); /* local state for most of the decode + so multiple block decodes can + proceed in parallel. We could init + multiple vorbis_block structures + for vd here */ + + /* The rest is just a straight decode loop until end of stream */ + while(!eos){ + while(!eos){ + int result=ogg_sync_pageout(&oy,&og); + if(result==0)break; /* need more data */ + if(result<0){ /* missing or corrupt data at this page position */ + fprintf(stderr,"Corrupt or missing data in bitstream; " + "continuing...\n"); + }else{ + ogg_stream_pagein(&os,&og); /* can safely ignore errors at + this point */ + while(1){ + result=ogg_stream_packetout(&os,&op); + + if(result==0)break; /* need more data */ + if(result<0){ /* missing or corrupt data at this page position */ + /* no reason to complain; already complained above */ + }else{ + /* we have a packet. Decode it */ + float **pcm; + int samples; + + if(vorbis_synthesis(&vb,&op)==0) /* test for success! */ + vorbis_synthesis_blockin(&vd,&vb); + /* + + **pcm is a multichannel float vector. In stereo, for + example, pcm[0] is left, and pcm[1] is right. samples is + the size of each channel. Convert the float values + (-1.<=range<=1.) to whatever PCM format and write it out */ + + while((samples=vorbis_synthesis_pcmout(&vd,&pcm))>0){ + int j; + int clipflag=0; + int bout=(samples<convsize?samples:convsize); + + /* convert floats to 16 bit signed ints (host order) and + interleave */ + for(i=0;i<vi.channels;i++){ + ogg_int16_t *ptr=convbuffer+i; + float *mono=pcm[i]; + for(j=0;j<bout;j++){ +#if 1 + int val=floor(mono[j]*32767.f+.5f); +#else /* optional dither */ + int val=mono[j]*32767.f+drand48()-0.5f; +#endif + /* might as well guard against clipping */ + if(val>32767){ + val=32767; + clipflag=1; + } + if(val<-32768){ + val=-32768; + clipflag=1; + } + *ptr=val; + ptr+=vi.channels; + } + } + + if(clipflag) + fprintf(stderr,"Clipping in frame %ld\n",(long)(vd.sequence)); + + + fwrite(convbuffer,2*vi.channels,bout,stdout); + + vorbis_synthesis_read(&vd,bout); /* tell libvorbis how + many samples we + actually consumed */ + } + } + } + if(ogg_page_eos(&og))eos=1; + } + } + if(!eos){ + buffer=ogg_sync_buffer(&oy,4096); + bytes=fread(buffer,1,4096,stdin); + ogg_sync_wrote(&oy,bytes); + if(bytes==0)eos=1; + } + } + + /* ogg_page and ogg_packet structs always point to storage in + libvorbis. They're never freed or manipulated directly */ + + vorbis_block_clear(&vb); + vorbis_dsp_clear(&vd); + }else{ + fprintf(stderr,"Error: Corrupt header during playback initialization.\n"); + } + + /* clean up this logical bitstream; before exit we see if we're + followed by another [chained] */ + + ogg_stream_clear(&os); + vorbis_comment_clear(&vc); + vorbis_info_clear(&vi); /* must be called last */ + } + + /* OK, clean up the framer */ + ogg_sync_clear(&oy); + + fprintf(stderr,"Done.\n"); + return(0); +} |