obs-studio/libobs/media-io/audio-resampler-ffmpeg.c

/******************************************************************************
    Copyright (C) 2023 by Lain Bailey <[email protected]>

    This program 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.

    This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
******************************************************************************/

#include "../util/bmem.h"
#include "audio-resampler.h"
#include "audio-io.h"
#include <libavutil/avutil.h>
#include <libavformat/avformat.h>
#include <libswresample/swresample.h>

struct audio_resampler {
	struct SwrContext *context;
	bool opened;

	uint32_t input_freq;
	enum AVSampleFormat input_format;
	uint8_t *output_buffer[MAX_AV_PLANES];
	enum AVSampleFormat output_format;
	int output_size;
	uint32_t output_ch;
	uint32_t output_freq;
	uint32_t output_planes;
#if LIBSWRESAMPLE_VERSION_INT < AV_VERSION_INT(4, 5, 100)
	uint64_t input_layout;
	uint64_t output_layout;
#else
	AVChannelLayout input_ch_layout;
	AVChannelLayout output_ch_layout;
#endif
};

static inline enum AVSampleFormat convert_audio_format(enum audio_format format)
{
	switch (format) {
	case AUDIO_FORMAT_UNKNOWN:
		return AV_SAMPLE_FMT_S16;
	case AUDIO_FORMAT_U8BIT:
		return AV_SAMPLE_FMT_U8;
	case AUDIO_FORMAT_16BIT:
		return AV_SAMPLE_FMT_S16;
	case AUDIO_FORMAT_32BIT:
		return AV_SAMPLE_FMT_S32;
	case AUDIO_FORMAT_FLOAT:
		return AV_SAMPLE_FMT_FLT;
	case AUDIO_FORMAT_U8BIT_PLANAR:
		return AV_SAMPLE_FMT_U8P;
	case AUDIO_FORMAT_16BIT_PLANAR:
		return AV_SAMPLE_FMT_S16P;
	case AUDIO_FORMAT_32BIT_PLANAR:
		return AV_SAMPLE_FMT_S32P;
	case AUDIO_FORMAT_FLOAT_PLANAR:
		return AV_SAMPLE_FMT_FLTP;
	}

	/* shouldn't get here */
	return AV_SAMPLE_FMT_S16;
}

#if LIBSWRESAMPLE_VERSION_INT < AV_VERSION_INT(4, 5, 100)
static inline uint64_t convert_speaker_layout(enum speaker_layout layout)
{
	switch (layout) {
	case SPEAKERS_UNKNOWN:
		return 0;
	case SPEAKERS_MONO:
		return AV_CH_LAYOUT_MONO;
	case SPEAKERS_STEREO:
		return AV_CH_LAYOUT_STEREO;
	case SPEAKERS_2POINT1:
		return AV_CH_LAYOUT_SURROUND;
	case SPEAKERS_4POINT0:
		return AV_CH_LAYOUT_4POINT0;
	case SPEAKERS_4POINT1:
		return AV_CH_LAYOUT_4POINT1;
	case SPEAKERS_5POINT1:
		return AV_CH_LAYOUT_5POINT1_BACK;
	case SPEAKERS_7POINT1:
		return AV_CH_LAYOUT_7POINT1;
	}

	/* shouldn't get here */
	return 0;
}
#endif

audio_resampler_t *audio_resampler_create(const struct resample_info *dst, const struct resample_info *src)
{
	struct audio_resampler *rs = bzalloc(sizeof(struct audio_resampler));
	int errcode;

	rs->opened = false;
	rs->input_freq = src->samples_per_sec;
	rs->input_format = convert_audio_format(src->format);
	rs->output_size = 0;
	rs->output_ch = get_audio_channels(dst->speakers);
	rs->output_freq = dst->samples_per_sec;
	rs->output_format = convert_audio_format(dst->format);
	rs->output_planes = is_audio_planar(dst->format) ? rs->output_ch : 1;

#if (LIBSWRESAMPLE_VERSION_INT < AV_VERSION_INT(4, 5, 100))
	rs->input_layout = convert_speaker_layout(src->speakers);
	rs->output_layout = convert_speaker_layout(dst->speakers);
	rs->context = swr_alloc_set_opts(NULL, rs->output_layout, rs->output_format, dst->samples_per_sec,
					 rs->input_layout, rs->input_format, src->samples_per_sec, 0, NULL);
#else
	int nb_ch = get_audio_channels(src->speakers);
	av_channel_layout_default(&rs->input_ch_layout, nb_ch);
	av_channel_layout_default(&rs->output_ch_layout, rs->output_ch);
	if (src->speakers == SPEAKERS_4POINT1)
		rs->input_ch_layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_4POINT1;

	if (dst->speakers == SPEAKERS_4POINT1)
		rs->output_ch_layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_4POINT1;

	swr_alloc_set_opts2(&rs->context, &rs->output_ch_layout, rs->output_format, dst->samples_per_sec,
			    &rs->input_ch_layout, rs->input_format, src->samples_per_sec, 0, NULL);
#endif

	if (!rs->context) {
		blog(LOG_ERROR, "swr_alloc_set_opts failed");
		audio_resampler_destroy(rs);
		return NULL;
	}

#if (LIBSWRESAMPLE_VERSION_INT < AV_VERSION_INT(4, 5, 100))
	if (rs->input_layout == AV_CH_LAYOUT_MONO && rs->output_ch > 1) {
#else
	AVChannelLayout test_ch = AV_CHANNEL_LAYOUT_MONO;
	if (av_channel_layout_compare(&rs->input_ch_layout, &test_ch) == 0 && rs->output_ch > 1) {
#endif
		const double matrix[MAX_AUDIO_CHANNELS][MAX_AUDIO_CHANNELS] = {
			{1},
			{1, 1},
			{1, 1, 0},
			{1, 1, 1, 1},
			{1, 1, 1, 0, 1},
			{1, 1, 1, 1, 1, 1},
			{1, 1, 1, 0, 1, 1, 1},
			{1, 1, 1, 0, 1, 1, 1, 1},
		};
		if (swr_set_matrix(rs->context, matrix[rs->output_ch - 1], 1) < 0)
			blog(LOG_DEBUG, "swr_set_matrix failed for mono upmix\n");
	}

	errcode = swr_init(rs->context);
	if (errcode != 0) {
		blog(LOG_ERROR, "avresample_open failed: error code %d", errcode);
		audio_resampler_destroy(rs);
		return NULL;
	}

	return rs;
}

void audio_resampler_destroy(audio_resampler_t *rs)
{
	if (rs) {
		if (rs->context)
			swr_free(&rs->context);
		if (rs->output_buffer[0])
			av_freep(&rs->output_buffer[0]);

		bfree(rs);
	}
}

bool audio_resampler_resample(audio_resampler_t *rs, uint8_t *output[], uint32_t *out_frames, uint64_t *ts_offset,
			      const uint8_t *const input[], uint32_t in_frames)
{
	if (!rs)
		return false;

	struct SwrContext *context = rs->context;
	int ret;

	int64_t delay = swr_get_delay(context, rs->input_freq);
	int estimated = (int)av_rescale_rnd(delay + (int64_t)in_frames, (int64_t)rs->output_freq,
					    (int64_t)rs->input_freq, AV_ROUND_UP);

	*ts_offset = (uint64_t)swr_get_delay(context, 1000000000);

	/* resize the buffer if bigger */
	if (estimated > rs->output_size) {
		if (rs->output_buffer[0])
			av_freep(&rs->output_buffer[0]);

		av_samples_alloc(rs->output_buffer, NULL, rs->output_ch, estimated, rs->output_format, 0);

		rs->output_size = estimated;
	}

	ret = swr_convert(context, rs->output_buffer, rs->output_size, (const uint8_t **)input, in_frames);

	if (ret < 0) {
		blog(LOG_ERROR, "swr_convert failed: %d", ret);
		return false;
	}

	for (uint32_t i = 0; i < rs->output_planes; i++)
		output[i] = rs->output_buffer[i];

	*out_frames = (uint32_t)ret;
	return true;
}