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ffmpeg / libavcore / audioconvert.c @ 8b69c2f4

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/*
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 * Copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
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 *
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 * This file is part of FFmpeg.
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 *
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 * FFmpeg is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * FFmpeg is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with FFmpeg; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
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/**
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 * @file
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 * audio conversion routines
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 */
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#include "libavutil/avstring.h"
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#include "audioconvert.h"
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static const char * const channel_names[] = {
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    "FL", "FR", "FC", "LFE", "BL",  "BR",  "FLC", "FRC",
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    "BC", "SL", "SR", "TC",  "TFL", "TFC", "TFR", "TBL",
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    "TBC", "TBR",
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    [29] = "DL",
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    [30] = "DR",
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};
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static const char *get_channel_name(int channel_id)
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{
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    if (channel_id < 0 || channel_id >= FF_ARRAY_ELEMS(channel_names))
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        return NULL;
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    return channel_names[channel_id];
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}
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static const struct {
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    const char *name;
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    int         nb_channels;
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    int64_t     layout;
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} channel_layout_map[] = {
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    { "mono",        1,  AV_CH_LAYOUT_MONO },
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    { "stereo",      2,  AV_CH_LAYOUT_STEREO },
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    { "4.0",         4,  AV_CH_LAYOUT_4POINT0 },
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    { "quad",        4,  AV_CH_LAYOUT_QUAD },
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    { "5.0",         5,  AV_CH_LAYOUT_5POINT0 },
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    { "5.0",         5,  AV_CH_LAYOUT_5POINT0_BACK },
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    { "5.1",         6,  AV_CH_LAYOUT_5POINT1 },
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    { "5.1",         6,  AV_CH_LAYOUT_5POINT1_BACK },
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    { "5.1+downmix", 8,  AV_CH_LAYOUT_5POINT1|AV_CH_LAYOUT_STEREO_DOWNMIX, },
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    { "7.1",         8,  AV_CH_LAYOUT_7POINT1 },
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    { "7.1(wide)",   8,  AV_CH_LAYOUT_7POINT1_WIDE },
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    { "7.1+downmix", 10, AV_CH_LAYOUT_7POINT1|AV_CH_LAYOUT_STEREO_DOWNMIX, },
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    { 0 }
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};
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int64_t av_get_channel_layout(const char *name)
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{
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    int i = 0;
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    do {
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        if (!strcmp(channel_layout_map[i].name, name))
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            return channel_layout_map[i].layout;
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        i++;
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    } while (channel_layout_map[i].name);
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    return 0;
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}
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void av_get_channel_layout_string(char *buf, int buf_size,
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                                  int nb_channels, int64_t channel_layout)
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{
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    int i;
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    if (nb_channels <= 0)
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        nb_channels = av_get_channel_layout_nb_channels(channel_layout);
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    for (i = 0; channel_layout_map[i].name; i++)
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        if (nb_channels    == channel_layout_map[i].nb_channels &&
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            channel_layout == channel_layout_map[i].layout) {
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            av_strlcpy(buf, channel_layout_map[i].name, buf_size);
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            return;
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        }
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    snprintf(buf, buf_size, "%d channels", nb_channels);
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    if (channel_layout) {
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        int i,ch;
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        av_strlcat(buf, " (", buf_size);
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        for(i=0,ch=0; i<64; i++) {
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            if ((channel_layout & (1L<<i))) {
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                const char *name = get_channel_name(i);
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                if (name) {
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                    if (ch>0) av_strlcat(buf, "|", buf_size);
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                    av_strlcat(buf, name, buf_size);
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                }
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                ch++;
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            }
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        }
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        av_strlcat(buf, ")", buf_size);
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    }
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}
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int av_get_channel_layout_nb_channels(int64_t channel_layout)
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{
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    int count;
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    uint64_t x = channel_layout;
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    for (count = 0; x; count++)
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        x &= x-1; // unset lowest set bit
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    return count;
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}