mpv/audio/format.c

/*
 * Copyright (C) 2005 Alex Beregszaszi
 *
 * This file is part of mpv.
 *
 * mpv is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * mpv is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with mpv.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <inttypes.h>
#include <limits.h>
#include <assert.h>

#include "common/common.h"
#include "audio/filter/af.h"

int af_fmt2bps(int format)
{
    switch (format & AF_FORMAT_BITS_MASK) {
    case AF_FORMAT_8BIT:  return 1;
    case AF_FORMAT_16BIT: return 2;
    case AF_FORMAT_24BIT: return 3;
    case AF_FORMAT_32BIT: return 4;
    case AF_FORMAT_64BIT: return 8;
    }
    return 0;
}

int af_fmt2bits(int format)
{
    return af_fmt2bps(format) * 8;
}

static int bits_to_mask(int bits)
{
    switch (bits) {
    case 8:  return AF_FORMAT_8BIT;
    case 16: return AF_FORMAT_16BIT;
    case 24: return AF_FORMAT_24BIT;
    case 32: return AF_FORMAT_32BIT;
    case 64: return AF_FORMAT_64BIT;
    }
    return 0;
}

int af_fmt_change_bits(int format, int bits)
{
    if (!af_fmt_is_valid(format))
        return 0;
    int mask = bits_to_mask(bits);
    format = (format & ~AF_FORMAT_BITS_MASK) | mask;
    return af_fmt_is_valid(format) ? format : 0;
}

// All formats are considered signed, except explicitly unsigned int formats.
bool af_fmt_unsigned(int format)
{
    return format == AF_FORMAT_U8 || format == AF_FORMAT_U8P;
}

static const int planar_formats[][2] = {
    {AF_FORMAT_U8P,     AF_FORMAT_U8},
    {AF_FORMAT_S16P,    AF_FORMAT_S16},
    {AF_FORMAT_S32P,    AF_FORMAT_S32},
    {AF_FORMAT_FLOATP,  AF_FORMAT_FLOAT},
    {AF_FORMAT_DOUBLEP, AF_FORMAT_DOUBLE},
};

// Return the planar format corresponding to the given format.
// If the format is already planar, return it.
// Return 0 if there's no equivalent.
int af_fmt_to_planar(int format)
{
    for (int n = 0; n < MP_ARRAY_SIZE(planar_formats); n++) {
        if (planar_formats[n][1] == format)
            return planar_formats[n][0];
        if (planar_formats[n][0] == format)
            return format;
    }
    return 0;
}

// Return the interleaved format corresponding to the given format.
// If the format is already interleaved, return it.
// Always succeeds if format is actually planar; otherwise return 0.
int af_fmt_from_planar(int format)
{
    for (int n = 0; n < MP_ARRAY_SIZE(planar_formats); n++) {
        if (planar_formats[n][0] == format)
            return planar_formats[n][1];
    }
    return format;
}

const struct af_fmt_entry af_fmtstr_table[] = {
    {"u8",          AF_FORMAT_U8},
    {"s16",         AF_FORMAT_S16},
    {"s24",         AF_FORMAT_S24},
    {"s32",         AF_FORMAT_S32},
    {"float",       AF_FORMAT_FLOAT},
    {"double",      AF_FORMAT_DOUBLE},

    {"u8p",         AF_FORMAT_U8P},
    {"s16p",        AF_FORMAT_S16P},
    {"s32p",        AF_FORMAT_S32P},
    {"floatp",      AF_FORMAT_FLOATP},
    {"doublep",     AF_FORMAT_DOUBLEP},

    {"spdif-aac",   AF_FORMAT_S_AAC},
    {"spdif-ac3",   AF_FORMAT_S_AC3},
    {"spdif-dts",   AF_FORMAT_S_DTS},
    {"spdif-dtshd", AF_FORMAT_S_DTSHD},
    {"spdif-eac3",  AF_FORMAT_S_EAC3},
    {"spdif-mp3",   AF_FORMAT_S_MP3},
    {"spdif-truehd",AF_FORMAT_S_TRUEHD},

    {0}
};

bool af_fmt_is_valid(int format)
{
    for (int i = 0; af_fmtstr_table[i].name; i++) {
        if (af_fmtstr_table[i].format == format)
            return true;
    }
    return false;
}

const char *af_fmt_to_str(int format)
{
    for (int i = 0; af_fmtstr_table[i].name; i++) {
        if (af_fmtstr_table[i].format == format)
            return af_fmtstr_table[i].name;
    }

    return "??";
}

int af_fmt_seconds_to_bytes(int format, float seconds, int channels, int samplerate)
{
    assert(!AF_FORMAT_IS_PLANAR(format));
    int bps      = af_fmt2bps(format);
    int framelen = channels * bps;
    int bytes    = seconds  * bps * samplerate;
    if (bytes % framelen)
        bytes += framelen - (bytes % framelen);
    return bytes;
}

int af_str2fmt_short(bstr str)
{
    for (int i = 0; af_fmtstr_table[i].name; i++) {
        if (!bstrcasecmp0(str, af_fmtstr_table[i].name))
            return af_fmtstr_table[i].format;
    }
    return 0;
}

void af_fill_silence(void *dst, size_t bytes, int format)
{
    memset(dst, af_fmt_unsigned(format) ? 0x80 : 0, bytes);
}

#define FMT_DIFF(type, a, b) (((a) & type) - ((b) & type))

// Returns a "score" that serves as heuristic how lossy or hard a conversion is.
// If the formats are equal, 1024 is returned. If they are gravely incompatible
// (like s16<->ac3), INT_MIN is returned. If there is implied loss of precision
// (like s16->s8), a value <0 is returned.
int af_format_conversion_score(int dst_format, int src_format)
{
    if (dst_format == AF_FORMAT_UNKNOWN || src_format == AF_FORMAT_UNKNOWN)
        return INT_MIN;
    if (dst_format == src_format)
        return 1024;
    // Can't be normally converted
    if (AF_FORMAT_IS_SPECIAL(dst_format) || AF_FORMAT_IS_SPECIAL(src_format))
        return INT_MIN;
    int score = 1024;
    if (FMT_DIFF(AF_FORMAT_INTERLEAVING_MASK, dst_format, src_format))
        score -= 1;     // has to (de-)planarize
    if (FMT_DIFF(AF_FORMAT_TYPE_MASK, dst_format, src_format)) {
        int dst_bits = dst_format & AF_FORMAT_BITS_MASK;
        if ((dst_format & AF_FORMAT_TYPE_MASK) == AF_FORMAT_F) {
            // For int->float, always prefer 32 bit float.
            score -= dst_bits == AF_FORMAT_32BIT ? 8 : 0;
        } else {
            // For float->int, always prefer highest bit depth int
            score -= 8 * (AF_FORMAT_64BIT - dst_bits);
        }
    } else {
        int bits = FMT_DIFF(AF_FORMAT_BITS_MASK, dst_format, src_format);
        if (bits > 0) {
            score -= 8 * bits;          // has to add padding
        } else if (bits < 0) {
            score -= 1024 - 8 * bits;   // has to reduce bit depth
        }
    }
    // Consider this the worst case.
    if (FMT_DIFF(AF_FORMAT_TYPE_MASK, dst_format, src_format))
        score -= 2048;  // has to convert float<->int
    return score;
}

// Return the number of samples that make up one frame in this format.
// You get the byte size by multiplying them with sample size and channel count.
int af_format_sample_alignment(int format)
{
    switch (format) {
    case AF_FORMAT_S_AAC:       return 16384 / 4;
    case AF_FORMAT_S_AC3:       return 6144 / 4;
    case AF_FORMAT_S_DTSHD:     return 32768 / 16;
    case AF_FORMAT_S_DTS:       return 2048 / 4;
    case AF_FORMAT_S_EAC3:      return 24576 / 4;
    case AF_FORMAT_S_MP3:       return 4608 / 4;
    case AF_FORMAT_S_TRUEHD:    return 61440 / 16;
    default:                    return 1;
    }
}