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mpv/audio/format.c

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/*
* 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 Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with mpv. If not, see <http://www.gnu.org/licenses/>.
*/
#include <limits.h>
#include "common/common.h"
#include "format.h"
// number of bytes per sample, 0 if invalid/unknown
int af_fmt_to_bytes(int format)
{
switch (af_fmt_from_planar(format)) {
case AF_FORMAT_U8: return 1;
case AF_FORMAT_S16: return 2;
case AF_FORMAT_S32: return 4;
case AF_FORMAT_S64: return 8;
case AF_FORMAT_FLOAT: return 4;
case AF_FORMAT_DOUBLE: return 8;
}
if (af_fmt_is_spdif(format))
return 2;
return 0;
}
// All formats are considered signed, except explicitly unsigned int formats.
bool af_fmt_is_unsigned(int format)
{
return format == AF_FORMAT_U8 || format == AF_FORMAT_U8P;
}
bool af_fmt_is_float(int format)
{
format = af_fmt_from_planar(format);
return format == AF_FORMAT_FLOAT || format == AF_FORMAT_DOUBLE;
}
// true for both unsigned and signed ints
bool af_fmt_is_int(int format)
{
return format && !af_fmt_is_spdif(format) && !af_fmt_is_float(format);
}
bool af_fmt_is_spdif(int format)
{
return af_format_sample_alignment(format) > 1;
}
bool af_fmt_is_pcm(int format)
{
return af_fmt_is_valid(format) && !af_fmt_is_spdif(format);
}
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_S64P, AF_FORMAT_S64},
{AF_FORMAT_FLOATP, AF_FORMAT_FLOAT},
{AF_FORMAT_DOUBLEP, AF_FORMAT_DOUBLE},
};
bool af_fmt_is_planar(int format)
{
for (int n = 0; n < MP_ARRAY_SIZE(planar_formats); n++) {
if (planar_formats[n][0] == format)
return true;
}
return false;
}
// Return the planar format corresponding to the given format.
// If the format is already planar or if there's no equivalent,
// return it.
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];
}
return format;
}
// Return the interleaved format corresponding to the given format.
// If the format is already interleaved or if there's no equivalent,
// return it.
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;
}
bool af_fmt_is_valid(int format)
{
return format > 0 && format < AF_FORMAT_COUNT;
}
const char *af_fmt_to_str(int format)
{
switch (format) {
case AF_FORMAT_U8: return "u8";
case AF_FORMAT_S16: return "s16";
case AF_FORMAT_S32: return "s32";
case AF_FORMAT_S64: return "s64";
case AF_FORMAT_FLOAT: return "float";
case AF_FORMAT_DOUBLE: return "double";
case AF_FORMAT_U8P: return "u8p";
case AF_FORMAT_S16P: return "s16p";
case AF_FORMAT_S32P: return "s32p";
case AF_FORMAT_S64P: return "s64p";
case AF_FORMAT_FLOATP: return "floatp";
case AF_FORMAT_DOUBLEP: return "doublep";
case AF_FORMAT_S_AAC: return "spdif-aac";
case AF_FORMAT_S_AC3: return "spdif-ac3";
case AF_FORMAT_S_DTS: return "spdif-dts";
case AF_FORMAT_S_DTSHD: return "spdif-dtshd";
case AF_FORMAT_S_EAC3: return "spdif-eac3";
case AF_FORMAT_S_MP3: return "spdif-mp3";
case AF_FORMAT_S_TRUEHD: return "spdif-truehd";
}
return "??";
}
void af_fill_silence(void *dst, size_t bytes, int format)
{
memset(dst, af_fmt_is_unsigned(format) ? 0x80 : 0, bytes);
}
// 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_fmt_is_pcm(dst_format) || !af_fmt_is_pcm(src_format))
return INT_MIN;
int score = 1024;
if (af_fmt_is_planar(dst_format) != af_fmt_is_planar(src_format))
score -= 1; // has to (de-)planarize
if (af_fmt_is_float(dst_format) != af_fmt_is_float(src_format)) {
int dst_bytes = af_fmt_to_bytes(dst_format);
if (af_fmt_is_float(dst_format)) {
// For int->float, consider a lower bound on the precision difference.
int bytes = (dst_bytes == 4 ? 3 : 6) - af_fmt_to_bytes(src_format);
if (bytes >= 0) {
score -= 8 * bytes; // excess precision
} else {
score += 1024 * (bytes - 1); // precision is lost (i.e. s32 -> float)
}
} else {
// float->int is the worst case. Penalize heavily and
// prefer highest bit depth int.
score -= 1048576 * (8 - dst_bytes);
}
score -= 512; // penalty for any float <-> int conversion
} else {
int bytes = af_fmt_to_bytes(dst_format) - af_fmt_to_bytes(src_format);
if (bytes > 0) {
score -= 8 * bytes; // has to add padding
} else if (bytes < 0) {
score += 1024 * (bytes - 1); // has to reduce bit depth
}
}
return score;
}
struct entry {
int fmt;
int score;
};
static int cmp_entry(const void *a, const void *b)
{
#define CMP_INT(a, b) (a > b ? 1 : (a < b ? -1 : 0))
return -CMP_INT(((struct entry *)a)->score, ((struct entry *)b)->score);
}
// Return a list of sample format compatible to src_format, sorted by order
// of preference. out_formats[0] will be src_format (as long as it's valid),
// and the list is terminated with 0 (AF_FORMAT_UNKNOWN).
// Keep in mind that this also returns formats with flipped interleaving
// (e.g. for s16, it returns [s16, s16p, ...]).
// out_formats must be an int[AF_FORMAT_COUNT + 1] array.
void af_get_best_sample_formats(int src_format, int *out_formats)
{
int num = 0;
struct entry e[AF_FORMAT_COUNT + 1];
for (int fmt = 1; fmt < AF_FORMAT_COUNT; fmt++) {
int score = af_format_conversion_score(fmt, src_format);
if (score > INT_MIN)
e[num++] = (struct entry){fmt, score};
}
qsort(e, num, sizeof(e[0]), cmp_entry);
for (int n = 0; n < num; n++)
out_formats[n] = e[n].fmt;
out_formats[num] = 0;
}
// Return the best match to src_samplerate from the list provided in the array
// *available, which must be terminated by 0, or itself NULL. If *available is
// empty or NULL, return a negative value. Exact match to src_samplerate is
// most preferred, followed by the lowest integer multiple, followed by the
// maximum of *available.
int af_select_best_samplerate(int src_samplerate, const int *available)
{
if (!available)
return -1;
int min_mult_rate = INT_MAX;
int max_rate = INT_MIN;
for (int i = 0; available[i]; i++) {
if (available[i] == src_samplerate)
return available[i];
if (!(available[i] % src_samplerate))
min_mult_rate = MPMIN(min_mult_rate, available[i]);
max_rate = MPMAX(max_rate, available[i]);
}
if (min_mult_rate < INT_MAX)
return min_mult_rate;
if (max_rate > INT_MIN)
return max_rate;
return -1;
}
// 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;
}
}
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