Hello I'm discovering Lame. I know C++ quite well but don't know sound processing at all. This is my question :
I try to do a very simple program : open an mp3, read and copy the first 30 seconds to a new mp3 file. I'm currently in the first step : read then mp3 and write raw data. I looked at the frontend sample and tried to simplify it. The program compiles and runs with no error, but produces a zero bytes output file. I must be missing something, but I thought that default parameters would be enough to make it work... The problem is that "iread" is always zero, and I don't understand why. Here is my code (below) I'm running macosx 10.5 and latest source download of lame 398-2 (I compiled lame with no particular options , configure+make) Thanks for any help. -- Riccardo Cohen Architecte du Logiciel http://www.architectedulogiciel.fr +33 (0)6.09.83.64.49 #include <lame.h> #include <stdio.h> #include <string.h> // memset mp3data_struct mp3input_data; void WriteBytes(FILE * fp, char *p, int n) { /* No error condition checking */ while (n-- > 0) putc(*p++, fp); } int lame_decode_fromfile(FILE * fd, short pcm_l[], short pcm_r[], mp3data_struct * mp3data) { int ret = 0; size_t len = 0; unsigned char buf[1024]; /* first see if we still have data buffered in the decoder: */ ret = lame_decode1_headers(buf, len, pcm_l, pcm_r, mp3data); if (ret != 0) return ret; /* read until we get a valid output frame */ while (1) { len = fread(buf, 1, 1024, fd); if (len == 0) { /* we are done reading the file, but check for buffered data */ ret = lame_decode1_headers(buf, len, pcm_l, pcm_r, mp3data); if (ret <= 0) { lame_decode_exit(); /* release mp3decoder memory */ return -1; /* done with file */ } break; } ret = lame_decode1_headers(buf, len, pcm_l, pcm_r, mp3data); if (ret == -1) { lame_decode_exit(); /* release mp3decoder memory */ return -1; } if (ret > 0) break; } return ret; } int read_samples_mp3(lame_global_flags * const gfp, FILE * const musicin, short int mpg123pcm[2][1152]) { int out; static const char type_name[] = "MP3 file"; out = lame_decode_fromfile(musicin, mpg123pcm[0], mpg123pcm[1], &mp3input_data); /* * out < 0: error, probably EOF * out = 0: not possible with lame_decode_fromfile() ??? * out > 0: number of output samples */ if (out < 0) { memset(mpg123pcm, 0, sizeof(**mpg123pcm) * 2 * 1152); return 0; } return out; } int main(int argc, char **argv) { printf("start...\n"); short int buffer[2][1152]; lame_global_flags *gfp; gfp = lame_init(); int ret_code = lame_init_params(gfp); if (ret_code>=0) { FILE *inf=fopen("/Users/rc/zdrop/etoiles.mp3","rb"); FILE *outf=fopen("/Users/rc/zdrop/out.mp3","wb"); int skip_start = 528 + 1;/* mp3 decoder has a 528 sample delay, plus user supplied "skip" */ if (inf!=NULL) { if (outf!=NULL && inf!=NULL) { int idx,iread; do { iread=read_samples_mp3(gfp,inf,buffer); if (iread>=0) { for (idx=0;idx<iread;idx++) { printf("*"); WriteBytes(outf, (char *) &buffer[0][idx], sizeof(short)); WriteBytes(outf, (char *) &buffer[1][idx], sizeof(short)); } fflush(outf); } }while(iread > 0); fclose(outf); } else printf("cannot open outf\n"); fclose(inf); } else printf("cannot open inf\n"); } else printf("error init\n"); lame_close(gfp); printf("... end\n"); return(0); } _______________________________________________ mp3encoder mailing list mp3encoder@minnie.tuhs.org https://minnie.tuhs.org/mailman/listinfo/mp3encoder
