FFmpeg: libavcodec/mpegaudio.c Source File

00001 /*
00002  * MPEG Audio common code
00003  * Copyright (c) 2001, 2002 Fabrice Bellard
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * FFmpeg is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with FFmpeg; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00027 #include "mpegaudio.h"
00028 
00029 
00030 /* bitrate is in kb/s */
00031 int ff_mpa_l2_select_table(int bitrate, int nb_channels, int freq, int lsf)
00032 {
00033     int ch_bitrate, table;
00034 
00035     ch_bitrate = bitrate / nb_channels;
00036     if (!lsf) {
00037         if ((freq == 48000 && ch_bitrate >= 56) ||
00038             (ch_bitrate >= 56 && ch_bitrate <= 80))
00039             table = 0;
00040         else if (freq != 48000 && ch_bitrate >= 96)
00041             table = 1;
00042         else if (freq != 32000 && ch_bitrate <= 48)
00043             table = 2;
00044         else
00045             table = 3;
00046     } else {
00047         table = 4;
00048     }
00049     return table;
00050 }