105 lines
2.8 KiB
C
105 lines
2.8 KiB
C
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/*
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extract_frams: utlize the framebyframe API and mpg123_framedata to extract the MPEG frames out of a stream (strip off anything else).
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This is example code only sensible to be considered in the public domain.
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Initially written by Thomas Orgis.
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*/
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#include <mpg123.h>
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/* unistd.h is not available under MSVC,
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io.h defines the read and write functions */
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#ifndef _MSC_VER
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#include <unistd.h>
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#else
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#include <io.h>
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#endif
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#include <stdio.h>
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#include <string.h>
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/** The actual work on the existing handle. */
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int do_work(mpg123_handle *m);
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/** The main program. */
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int main(int argc, char **argv)
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{
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int ret = 0;
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mpg123_handle *m;
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#if MPG123_API_VERSION < 46
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// Newer versions of the library don't need that anymore, but it is safe
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// to have the no-op call present for compatibility with old versions.
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mpg123_init();
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#endif
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m = mpg123_new(NULL, &ret);
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if(m == NULL)
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{
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fprintf(stderr, "Cannot create handle: %s", mpg123_plain_strerror(ret));
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}
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else
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{
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fprintf(stderr, "I'll take your dirty MPEG audio from standard input and will write the extracted pure MPEG data to standard output.\n");
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if(argc > 1 && strcmp(argv[1], "--noinfo") == 0)
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{
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fprintf(stderr, "Enabling parsing/consuming of the Info frame so that it will not appear in output.\n");
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ret = mpg123_param(m, MPG123_REMOVE_FLAGS, MPG123_IGNORE_INFOFRAME, 0.);
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}
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else
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{
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fprintf(stderr, "If you'd have given --noinfo as argument, I would omit a LAME/Xing info frame.\n");
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ret = mpg123_param(m, MPG123_ADD_FLAGS, MPG123_IGNORE_INFOFRAME, 0.);
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}
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if(ret == 0) ret = do_work(m);
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if(ret != 0) fprintf(stderr, "Some error occured: %s\n", mpg123_strerror(m));
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mpg123_delete(m); /* Closes, too. */
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}
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return ret;
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}
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int do_work(mpg123_handle *m)
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{
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int ret;
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size_t count = 0;
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ret = mpg123_open_fd(m, STDIN_FILENO);
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if(ret != MPG123_OK) return ret;
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ssize_t wret = 0;
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while( !wret && (ret = mpg123_framebyframe_next(m)) == MPG123_OK || ret == MPG123_NEW_FORMAT )
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{
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unsigned long header;
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unsigned char *bodydata;
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size_t bodybytes;
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if(mpg123_framedata(m, &header, &bodydata, &bodybytes) == MPG123_OK)
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{
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/* Need to extract the 4 header bytes from the native storage in the correct order. */
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unsigned char hbuf[4];
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int i;
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for(i=0; i<4; ++i) hbuf[i] = (unsigned char) ((header >> ((3-i)*8)) & 0xff);
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/* Now write out both header and data, fire and forget. */
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wret = write(STDOUT_FILENO, hbuf, 4);
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if(!wret)
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wret = write(STDOUT_FILENO, bodydata, bodybytes);
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fprintf(stderr, "%zu: header 0x%08lx, %zu body bytes\n", ++count, header, bodybytes);
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}
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}
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if(ret != MPG123_DONE)
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fprintf(stderr, "Some error occured (non-fatal?): %s\n", mpg123_strerror(m));
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if(wret)
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{
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fprintf(stderr, "Write error.\n");
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ret = MPG123_ERR;
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}
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fprintf(stderr, "Done with %zu MPEG frames.\n", count);
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return 0;
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}
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