/src/ffmpeg/libavcodec/libopusenc.c

Source
/*
 * Opus encoder using libopus
 * Copyright (c) 2012 Nathan Caldwell
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg 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.
 *
 * FFmpeg 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 FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <opus.h>
#include <opus_multistream.h>

#include "libavutil/channel_layout.h"
#include "libavutil/mem.h"
#include "libavutil/opt.h"
#include "avcodec.h"
#include "bytestream.h"
#include "codec_internal.h"
#include "encode.h"
#include "libopus.h"
#include "audio_frame_queue.h"
#include "vorbis_data.h"

typedef struct LibopusEncOpts {
    int vbr;
    int application;
    int packet_loss;
    int fec;
    int complexity;
    float frame_duration;
    int packet_size;
    int max_bandwidth;
    int mapping_family;
    int dtx;
#ifdef OPUS_SET_PHASE_INVERSION_DISABLED_REQUEST
    int apply_phase_inv;
#endif
} LibopusEncOpts;

typedef struct LibopusEncContext {
    AVClass *class;
    OpusMSEncoder *enc;
    int stream_count;
    uint8_t *samples;
    LibopusEncOpts opts;
    AudioFrameQueue afq;
    const uint8_t *encoder_channel_map;
} LibopusEncContext;

static const uint8_t opus_coupled_streams[8] = {
    0, 1, 1, 2, 2, 2, 2, 3
};

/* Opus internal to Vorbis channel order mapping written in the header */
static const uint8_t opus_vorbis_channel_map[8][8] = {
    { 0 },
    { 0, 1 },
    { 0, 2, 1 },
    { 0, 1, 2, 3 },
    { 0, 4, 1, 2, 3 },
    { 0, 4, 1, 2, 3, 5 },
    { 0, 4, 1, 2, 3, 5, 6 },
    { 0, 6, 1, 2, 3, 4, 5, 7 },
};

/* libavcodec to libopus channel order mapping, passed to libopus */
static const uint8_t libavcodec_libopus_channel_map[8][8] = {
    { 0 },
    { 0, 1 },
    { 0, 1, 2 },
    { 0, 1, 2, 3 },
    { 0, 1, 3, 4, 2 },
    { 0, 1, 4, 5, 2, 3 },
    { 0, 1, 5, 6, 2, 4, 3 },
    { 0, 1, 6, 7, 4, 5, 2, 3 },
};

static void libopus_write_header(AVCodecContext *avctx, int stream_count,
                                 int coupled_stream_count,
                                 int mapping_family,
                                 const uint8_t *channel_mapping)
{
    uint8_t *p   = avctx->extradata;
    int channels = avctx->ch_layout.nb_channels;

    bytestream_put_buffer(&p, "OpusHead", 8);
    bytestream_put_byte(&p, 1); /* Version */
    bytestream_put_byte(&p, channels);
    bytestream_put_le16(&p, avctx->initial_padding * 48000 / avctx->sample_rate); /* Lookahead samples at 48kHz */
    bytestream_put_le32(&p, avctx->sample_rate); /* Original sample rate */
    bytestream_put_le16(&p, 0); /* Gain of 0dB is recommended. */

    /* Channel mapping */
    bytestream_put_byte(&p, mapping_family);
    if (mapping_family != 0) {
        bytestream_put_byte(&p, stream_count);
        bytestream_put_byte(&p, coupled_stream_count);
        bytestream_put_buffer(&p, channel_mapping, channels);
    }
}

static int libopus_configure_encoder(AVCodecContext *avctx, OpusMSEncoder *enc,
                                     LibopusEncOpts *opts)
{
    int ret;

    if (avctx->global_quality) {
        av_log(avctx, AV_LOG_ERROR,
               "Quality-based encoding not supported, "
               "please specify a bitrate and VBR setting.\n");
        return AVERROR(EINVAL);
    }

    ret = opus_multistream_encoder_ctl(enc, OPUS_SET_BITRATE(avctx->bit_rate));
    if (ret != OPUS_OK) {
        av_log(avctx, AV_LOG_ERROR,
               "Failed to set bitrate: %s\n", opus_strerror(ret));
        return ret;
    }

    ret = opus_multistream_encoder_ctl(enc,
                                       OPUS_SET_COMPLEXITY(opts->complexity));
    if (ret != OPUS_OK)
        av_log(avctx, AV_LOG_WARNING,
               "Unable to set complexity: %s\n", opus_strerror(ret));

    ret = opus_multistream_encoder_ctl(enc, OPUS_SET_VBR(!!opts->vbr));
    if (ret != OPUS_OK)
        av_log(avctx, AV_LOG_WARNING,
               "Unable to set VBR: %s\n", opus_strerror(ret));

    ret = opus_multistream_encoder_ctl(enc,
                                       OPUS_SET_VBR_CONSTRAINT(opts->vbr == 2));
    if (ret != OPUS_OK)
        av_log(avctx, AV_LOG_WARNING,
               "Unable to set constrained VBR: %s\n", opus_strerror(ret));

    ret = opus_multistream_encoder_ctl(enc,
                                       OPUS_SET_PACKET_LOSS_PERC(opts->packet_loss));
    if (ret != OPUS_OK)
        av_log(avctx, AV_LOG_WARNING,
               "Unable to set expected packet loss percentage: %s\n",
               opus_strerror(ret));

    ret = opus_multistream_encoder_ctl(enc,
                                       OPUS_SET_INBAND_FEC(opts->fec));
    if (ret != OPUS_OK)
        av_log(avctx, AV_LOG_WARNING,
               "Unable to set inband FEC: %s\n",
               opus_strerror(ret));

    ret = opus_multistream_encoder_ctl(enc,
                                       OPUS_SET_DTX(opts->dtx));
    if (ret != OPUS_OK)
        av_log(avctx, AV_LOG_WARNING,
               "Unable to set DTX: %s\n",
               opus_strerror(ret));

    if (avctx->cutoff) {
        ret = opus_multistream_encoder_ctl(enc,
                                           OPUS_SET_MAX_BANDWIDTH(opts->max_bandwidth));
        if (ret != OPUS_OK)
            av_log(avctx, AV_LOG_WARNING,
                   "Unable to set maximum bandwidth: %s\n", opus_strerror(ret));
    }

#ifdef OPUS_SET_PHASE_INVERSION_DISABLED_REQUEST
    ret = opus_multistream_encoder_ctl(enc,
                                       OPUS_SET_PHASE_INVERSION_DISABLED(!opts->apply_phase_inv));
    if (ret != OPUS_OK)
        av_log(avctx, AV_LOG_WARNING,
               "Unable to set phase inversion: %s\n",
               opus_strerror(ret));
#endif
    return OPUS_OK;
}

static int libopus_check_max_channels(AVCodecContext *avctx,
                                      int max_channels) {
    if (avctx->ch_layout.nb_channels > max_channels) {
        av_log(avctx, AV_LOG_ERROR, "Opus mapping family undefined for %d channels.\n",
               avctx->ch_layout.nb_channels);
        return AVERROR(EINVAL);
    }

    return 0;
}

static int libopus_check_vorbis_layout(AVCodecContext *avctx, int mapping_family) {
    av_assert2(avctx->ch_layout.nb_channels < FF_ARRAY_ELEMS(ff_vorbis_ch_layouts));

    if (avctx->ch_layout.order == AV_CHANNEL_ORDER_UNSPEC) {
        av_log(avctx, AV_LOG_WARNING,
               "No channel layout specified. Opus encoder will use Vorbis "
               "channel layout for %d channels.\n", avctx->ch_layout.nb_channels);
    } else if (av_channel_layout_compare(&avctx->ch_layout, &ff_vorbis_ch_layouts[avctx->ch_layout.nb_channels - 1])) {
        char name[32];

        av_channel_layout_describe(&avctx->ch_layout, name, sizeof(name));
        av_log(avctx, AV_LOG_ERROR,
               "Invalid channel layout %s for specified mapping family %d.\n",
               name, mapping_family);

        return AVERROR(EINVAL);
    }

    return 0;
}

static int libopus_validate_layout_and_get_channel_map(
        AVCodecContext *avctx,
        int mapping_family,
        const uint8_t ** channel_map_result)
{
    const uint8_t * channel_map = NULL;
    int ret;

    switch (mapping_family) {
    case -1:
        ret = libopus_check_max_channels(avctx, 8);
        if (ret == 0) {
            ret = libopus_check_vorbis_layout(avctx, mapping_family);
            /* Channels do not need to be reordered. */
        }

        break;
    case 0:
        ret = libopus_check_max_channels(avctx, 2);
        if (ret == 0) {
            ret = libopus_check_vorbis_layout(avctx, mapping_family);
        }
        break;
    case 1:
        /* Opus expects channels to be in Vorbis order. */
        ret = libopus_check_max_channels(avctx, 8);
        if (ret == 0) {
            ret = libopus_check_vorbis_layout(avctx, mapping_family);
            channel_map = ff_vorbis_channel_layout_offsets[avctx->ch_layout.nb_channels - 1];
        }
        break;
    case 255:
        ret = libopus_check_max_channels(avctx, 254);
        break;
    default:
        av_log(avctx, AV_LOG_WARNING,
               "Unknown channel mapping family %d. Output channel layout may be invalid.\n",
               mapping_family);
        ret = 0;
    }

    *channel_map_result = channel_map;
    return ret;
}

static av_cold int libopus_encode_init(AVCodecContext *avctx)
{
    LibopusEncContext *opus = avctx->priv_data;
    OpusMSEncoder *enc;
    uint8_t libopus_channel_mapping[255];
    int ret = OPUS_OK;
    int channels = avctx->ch_layout.nb_channels;
    int av_ret;
    int coupled_stream_count, header_size, frame_size;
    int mapping_family;

    frame_size = opus->opts.frame_duration * 48000 / 1000;
    switch (frame_size) {
    case 120:
    case 240:
        if (opus->opts.application != OPUS_APPLICATION_RESTRICTED_LOWDELAY)
            av_log(avctx, AV_LOG_WARNING,
                   "LPC mode cannot be used with a frame duration of less "
                   "than 10ms. Enabling restricted low-delay mode.\n"
                   "Use a longer frame duration if this is not what you want.\n");
        /* Frame sizes less than 10 ms can only use MDCT mode, so switching to
         * RESTRICTED_LOWDELAY avoids an unnecessary extra 2.5ms lookahead. */
        opus->opts.application = OPUS_APPLICATION_RESTRICTED_LOWDELAY;
        av_fallthrough;
    case 480:
    case 960:
    case 1920:
    case 2880:
#ifdef OPUS_FRAMESIZE_120_MS
    case 3840:
    case 4800:
    case 5760:
#endif
        opus->opts.packet_size =
        avctx->frame_size      = frame_size * avctx->sample_rate / 48000;
        break;
    default:
        av_log(avctx, AV_LOG_ERROR, "Invalid frame duration: %g.\n"
               "Frame duration must be exactly one of: 2.5, 5, 10, 20, 40"
#ifdef OPUS_FRAMESIZE_120_MS
               ", 60, 80, 100 or 120.\n",
#else
               " or 60.\n",
#endif
               opus->opts.frame_duration);
        return AVERROR(EINVAL);
    }

    if (avctx->compression_level < 0 || avctx->compression_level > 10) {
        av_log(avctx, AV_LOG_WARNING,
               "Compression level must be in the range 0 to 10. "
               "Defaulting to 10.\n");
        opus->opts.complexity = 10;
    } else {
        opus->opts.complexity = avctx->compression_level;
    }

    if (avctx->cutoff) {
        switch (avctx->cutoff) {
        case  4000:
            opus->opts.max_bandwidth = OPUS_BANDWIDTH_NARROWBAND;
            break;
        case  6000:
            opus->opts.max_bandwidth = OPUS_BANDWIDTH_MEDIUMBAND;
            break;
        case  8000:
            opus->opts.max_bandwidth = OPUS_BANDWIDTH_WIDEBAND;
            break;
        case 12000:
            opus->opts.max_bandwidth = OPUS_BANDWIDTH_SUPERWIDEBAND;
            break;
        case 20000:
            opus->opts.max_bandwidth = OPUS_BANDWIDTH_FULLBAND;
            break;
        default:
            av_log(avctx, AV_LOG_WARNING,
                   "Invalid frequency cutoff: %d. Using default maximum bandwidth.\n"
                   "Cutoff frequency must be exactly one of: 4000, 6000, 8000, 12000 or 20000.\n",
                   avctx->cutoff);
            avctx->cutoff = 0;
        }
    }

    /* Channels may need to be reordered to match opus mapping. */
    av_ret = libopus_validate_layout_and_get_channel_map(avctx, opus->opts.mapping_family,
                                                         &opus->encoder_channel_map);
    if (av_ret) {
        return av_ret;
    }

    if (opus->opts.mapping_family == -1) {
        /* By default, use mapping family 1 for the header but use the older
         * libopus multistream API to avoid surround masking. */

        /* Set the mapping family so that the value is correct in the header */
        mapping_family = channels > 2 ? 1 : 0;
        coupled_stream_count = opus_coupled_streams[channels - 1];
        opus->stream_count   = channels - coupled_stream_count;
        memcpy(libopus_channel_mapping,
               opus_vorbis_channel_map[channels - 1],
               channels * sizeof(*libopus_channel_mapping));

        enc = opus_multistream_encoder_create(
            avctx->sample_rate, channels, opus->stream_count,
            coupled_stream_count,
            libavcodec_libopus_channel_map[channels - 1],
            opus->opts.application, &ret);
    } else {
        /* Use the newer multistream API. The encoder will set the channel
         * mapping and coupled stream counts to its internal defaults and will
         * use surround masking analysis to save bits. */
        mapping_family = opus->opts.mapping_family;
        enc = opus_multistream_surround_encoder_create(
            avctx->sample_rate, channels, mapping_family,
            &opus->stream_count, &coupled_stream_count, libopus_channel_mapping,
            opus->opts.application, &ret);
    }

    if (ret != OPUS_OK) {
        av_log(avctx, AV_LOG_ERROR,
               "Failed to create encoder: %s\n", opus_strerror(ret));
        return ff_opus_error_to_averror(ret);
    }

    if (!avctx->bit_rate) {
        /* Sane default copied from opusenc */
        avctx->bit_rate = 64000 * opus->stream_count +
                          32000 * coupled_stream_count;
        av_log(avctx, AV_LOG_WARNING,
               "No bit rate set. Defaulting to %"PRId64" bps.\n", avctx->bit_rate);
    }

    if (avctx->bit_rate < 500 || avctx->bit_rate > 256000 * channels) {
        av_log(avctx, AV_LOG_ERROR, "The bit rate %"PRId64" bps is unsupported. "
               "Please choose a value between 500 and %d.\n", avctx->bit_rate,
               256000 * channels);
        ret = AVERROR(EINVAL);
        goto fail;
    }

    ret = libopus_configure_encoder(avctx, enc, &opus->opts);
    if (ret != OPUS_OK) {
        ret = ff_opus_error_to_averror(ret);
        goto fail;
    }

    /* Header includes channel mapping table if and only if mapping family is NOT 0 */
    header_size = 19 + (mapping_family == 0 ? 0 : 2 + channels);
    avctx->extradata = av_malloc(header_size + AV_INPUT_BUFFER_PADDING_SIZE);
    if (!avctx->extradata) {
        av_log(avctx, AV_LOG_ERROR, "Failed to allocate extradata.\n");
        ret = AVERROR(ENOMEM);
        goto fail;
    }
    avctx->extradata_size = header_size;

    opus->samples = av_calloc(frame_size, channels *
                               av_get_bytes_per_sample(avctx->sample_fmt));
    if (!opus->samples) {
        av_log(avctx, AV_LOG_ERROR, "Failed to allocate samples buffer.\n");
        ret = AVERROR(ENOMEM);
        goto fail;
    }

    ret = opus_multistream_encoder_ctl(enc, OPUS_GET_LOOKAHEAD(&avctx->initial_padding));
    if (ret != OPUS_OK)
        av_log(avctx, AV_LOG_WARNING,
               "Unable to get number of lookahead samples: %s\n",
               opus_strerror(ret));

    libopus_write_header(avctx, opus->stream_count, coupled_stream_count,
                         mapping_family, libopus_channel_mapping);

    ff_af_queue_init(avctx, &opus->afq);

    opus->enc = enc;

    return 0;

fail:
    opus_multistream_encoder_destroy(enc);
    return ret;
}

static void libopus_copy_samples_with_channel_map(
    uint8_t *dst, const uint8_t *src, const uint8_t *channel_map,
    int nb_channels, int nb_samples, int bytes_per_sample) {
    int sample, channel;
    for (sample = 0; sample < nb_samples; ++sample) {
        for (channel = 0; channel < nb_channels; ++channel) {
            const size_t src_pos = bytes_per_sample * (nb_channels * sample + channel);
            const size_t dst_pos = bytes_per_sample * (nb_channels * sample + channel_map[channel]);

            memcpy(&dst[dst_pos], &src[src_pos], bytes_per_sample);
        }
    }
}

static int libopus_encode(AVCodecContext *avctx, AVPacket *avpkt,
                          const AVFrame *frame, int *got_packet_ptr)
{
    LibopusEncContext *opus = avctx->priv_data;
    const int bytes_per_sample = av_get_bytes_per_sample(avctx->sample_fmt);
    const int channels         = avctx->ch_layout.nb_channels;
    const int sample_size      = channels * bytes_per_sample;
    const uint8_t *audio;
    int ret;

    if (frame) {
        ret = ff_af_queue_add(&opus->afq, frame);
        if (ret < 0)
            return ret;
        if (opus->encoder_channel_map != NULL) {
            audio = opus->samples;
            libopus_copy_samples_with_channel_map(
                opus->samples, frame->data[0], opus->encoder_channel_map,
                channels, frame->nb_samples, bytes_per_sample);
        } else if (frame->nb_samples < opus->opts.packet_size) {
            audio = opus->samples;
            memcpy(opus->samples, frame->data[0], frame->nb_samples * sample_size);
        } else
            audio = frame->data[0];
    } else {
        if (!opus->afq.remaining_samples || (!opus->afq.frame_alloc && !opus->afq.frame_count))
            return 0;
        audio = opus->samples;
        memset(opus->samples, 0, opus->opts.packet_size * sample_size);
    }

    /* Maximum packet size taken from opusenc in opus-tools. 120ms packets
     * consist of 6 frames in one packet. The maximum frame size is 1275
     * bytes along with the largest possible packet header of 7 bytes. */
    if ((ret = ff_alloc_packet(avctx, avpkt, (1275 * 6 + 7) * opus->stream_count)) < 0)
        return ret;

    if (avctx->sample_fmt == AV_SAMPLE_FMT_FLT)
        ret = opus_multistream_encode_float(opus->enc, (const float *)audio,
                                            opus->opts.packet_size,
                                            avpkt->data, avpkt->size);
    else
        ret = opus_multistream_encode(opus->enc, (const opus_int16 *)audio,
                                      opus->opts.packet_size,
                                      avpkt->data, avpkt->size);

    if (ret < 0) {
        av_log(avctx, AV_LOG_ERROR,
               "Error encoding frame: %s\n", opus_strerror(ret));
        return ff_opus_error_to_averror(ret);
    }

    av_shrink_packet(avpkt, ret);

    ret = ff_af_queue_remove(&opus->afq, opus->opts.packet_size, avpkt);
    if (ret < 0)
        return ret;

    *got_packet_ptr = 1;

    return 0;
}

static av_cold int libopus_encode_close(AVCodecContext *avctx)
{
    LibopusEncContext *opus = avctx->priv_data;

    opus_multistream_encoder_destroy(opus->enc);

    ff_af_queue_close(&opus->afq);

    av_freep(&opus->samples);

    return 0;
}

#define OFFSET(x) offsetof(LibopusEncContext, opts.x)
#define FLAGS AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_ENCODING_PARAM
static const AVOption libopus_options[] = {
    { "application",    "Intended application type",           OFFSET(application),    AV_OPT_TYPE_INT,   { .i64 = OPUS_APPLICATION_AUDIO }, OPUS_APPLICATION_VOIP, OPUS_APPLICATION_RESTRICTED_LOWDELAY, FLAGS, .unit = "application" },
        { "voip",           "Favor improved speech intelligibility",   0, AV_OPT_TYPE_CONST, { .i64 = OPUS_APPLICATION_VOIP },                0, 0, FLAGS, .unit = "application" },
        { "audio",          "Favor faithfulness to the input",         0, AV_OPT_TYPE_CONST, { .i64 = OPUS_APPLICATION_AUDIO },               0, 0, FLAGS, .unit = "application" },
        { "lowdelay",       "Restrict to only the lowest delay modes, disable voice-optimized modes", 0, AV_OPT_TYPE_CONST, { .i64 = OPUS_APPLICATION_RESTRICTED_LOWDELAY }, 0, 0, FLAGS, .unit = "application" },
    { "frame_duration", "Duration of a frame in milliseconds", OFFSET(frame_duration), AV_OPT_TYPE_FLOAT, { .dbl = 20.0 }, 2.5, 120.0, FLAGS },
    { "packet_loss",    "Expected packet loss percentage",     OFFSET(packet_loss),    AV_OPT_TYPE_INT,   { .i64 = 0 },    0,   100,  FLAGS },
    { "fec",             "Enable inband FEC. Expected packet loss must be non-zero",     OFFSET(fec),    AV_OPT_TYPE_BOOL,   { .i64 = 0 }, 0, 1, FLAGS },
    { "vbr",            "Variable bit rate mode",              OFFSET(vbr),            AV_OPT_TYPE_INT,   { .i64 = 1 },    0,   2,    FLAGS, .unit = "vbr" },
        { "off",            "Use constant bit rate", 0, AV_OPT_TYPE_CONST, { .i64 = 0 }, 0, 0, FLAGS, .unit = "vbr" },
        { "on",             "Use variable bit rate", 0, AV_OPT_TYPE_CONST, { .i64 = 1 }, 0, 0, FLAGS, .unit = "vbr" },
        { "constrained",    "Use constrained VBR",   0, AV_OPT_TYPE_CONST, { .i64 = 2 }, 0, 0, FLAGS, .unit = "vbr" },
    { "mapping_family", "Channel Mapping Family",              OFFSET(mapping_family), AV_OPT_TYPE_INT,   { .i64 = -1 },   -1,  255,  FLAGS, .unit = "mapping_family" },
    { "dtx", "Enable DTX (Discontinuous transmission)", OFFSET(dtx), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, FLAGS },
#ifdef OPUS_SET_PHASE_INVERSION_DISABLED_REQUEST
    { "apply_phase_inv", "Apply intensity stereo phase inversion", OFFSET(apply_phase_inv), AV_OPT_TYPE_BOOL, { .i64 = 1 }, 0, 1, FLAGS },
#endif
    { NULL },
};

static const AVClass libopus_class = {
    .class_name = "libopus",
    .item_name  = av_default_item_name,
    .option     = libopus_options,
    .version    = LIBAVUTIL_VERSION_INT,
};

static const FFCodecDefault libopus_defaults[] = {
    { "b",                 "0" },
    { "compression_level", "10" },
    { NULL },
};

static const int libopus_sample_rates[] = {
    48000, 24000, 16000, 12000, 8000, 0,
};

const FFCodec ff_libopus_encoder = {
    .p.name          = "libopus",
    CODEC_LONG_NAME("libopus Opus"),
    .p.type          = AVMEDIA_TYPE_AUDIO,
    .p.id            = AV_CODEC_ID_OPUS,
    .p.capabilities  = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_DELAY |
                       AV_CODEC_CAP_SMALL_LAST_FRAME,
    .caps_internal   = FF_CODEC_CAP_NOT_INIT_THREADSAFE,
    .priv_data_size  = sizeof(LibopusEncContext),
    .init            = libopus_encode_init,
    FF_CODEC_ENCODE_CB(libopus_encode),
    .close           = libopus_encode_close,
    CODEC_SAMPLEFMTS(AV_SAMPLE_FMT_S16, AV_SAMPLE_FMT_FLT),
    CODEC_SAMPLERATES_ARRAY(libopus_sample_rates),
    .p.priv_class    = &libopus_class,
    .defaults        = libopus_defaults,
    .p.wrapper_name  = "libopus",
};

Coverage Report

Created: 2026-10-28 08:13

Line	Count	Source
1		/*
2		* Opus encoder using libopus
3		* Copyright (c) 2012 Nathan Caldwell
4		*
5		* This file is part of FFmpeg.
6		*
7		* FFmpeg is free software; you can redistribute it and/or
8		* modify it under the terms of the GNU Lesser General Public
9		* License as published by the Free Software Foundation; either
10		* version 2.1 of the License, or (at your option) any later version.
11		*
12		* FFmpeg is distributed in the hope that it will be useful,
13		* but WITHOUT ANY WARRANTY; without even the implied warranty of
14		* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15		* Lesser General Public License for more details.
16		*
17		* You should have received a copy of the GNU Lesser General Public
18		* License along with FFmpeg; if not, write to the Free Software
19		* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20		*/
21
22		#include <opus.h>
23		#include <opus_multistream.h>
24
25		#include "libavutil/channel_layout.h"
26		#include "libavutil/mem.h"
27		#include "libavutil/opt.h"
28		#include "avcodec.h"
29		#include "bytestream.h"
30		#include "codec_internal.h"
31		#include "encode.h"
32		#include "libopus.h"
33		#include "audio_frame_queue.h"
34		#include "vorbis_data.h"
35
36		typedef struct LibopusEncOpts {
37		int vbr;
38		int application;
39		int packet_loss;
40		int fec;
41		int complexity;
42		float frame_duration;
43		int packet_size;
44		int max_bandwidth;
45		int mapping_family;
46		int dtx;
47		#ifdef OPUS_SET_PHASE_INVERSION_DISABLED_REQUEST
48		int apply_phase_inv;
49		#endif
50		} LibopusEncOpts;
51
52		typedef struct LibopusEncContext {
53		AVClass *class;
54		OpusMSEncoder *enc;
55		int stream_count;
56		uint8_t *samples;
57		LibopusEncOpts opts;
58		AudioFrameQueue afq;
59		const uint8_t *encoder_channel_map;
60		} LibopusEncContext;
61
62		static const uint8_t opus_coupled_streams[8] = {
63		0, 1, 1, 2, 2, 2, 2, 3
64		};
65
66		/* Opus internal to Vorbis channel order mapping written in the header */
67		static const uint8_t opus_vorbis_channel_map[8][8] = {
68		{ 0 },
69		{ 0, 1 },
70		{ 0, 2, 1 },
71		{ 0, 1, 2, 3 },
72		{ 0, 4, 1, 2, 3 },
73		{ 0, 4, 1, 2, 3, 5 },
74		{ 0, 4, 1, 2, 3, 5, 6 },
75		{ 0, 6, 1, 2, 3, 4, 5, 7 },
76		};
77
78		/* libavcodec to libopus channel order mapping, passed to libopus */
79		static const uint8_t libavcodec_libopus_channel_map[8][8] = {
80		{ 0 },
81		{ 0, 1 },
82		{ 0, 1, 2 },
83		{ 0, 1, 2, 3 },
84		{ 0, 1, 3, 4, 2 },
85		{ 0, 1, 4, 5, 2, 3 },
86		{ 0, 1, 5, 6, 2, 4, 3 },
87		{ 0, 1, 6, 7, 4, 5, 2, 3 },
88		};
89
90		static void libopus_write_header(AVCodecContext *avctx, int stream_count,
91		int coupled_stream_count,
92		int mapping_family,
93		const uint8_t *channel_mapping)
94	0	{
95	0	uint8_t *p = avctx->extradata;
96	0	int channels = avctx->ch_layout.nb_channels;
97
98	0	bytestream_put_buffer(&p, "OpusHead", 8);
99	0	bytestream_put_byte(&p, 1); /* Version */
100	0	bytestream_put_byte(&p, channels);
101	0	bytestream_put_le16(&p, avctx->initial_padding * 48000 / avctx->sample_rate); /* Lookahead samples at 48kHz */
102	0	bytestream_put_le32(&p, avctx->sample_rate); /* Original sample rate */
103	0	bytestream_put_le16(&p, 0); /* Gain of 0dB is recommended. */
104
105		/* Channel mapping */
106	0	bytestream_put_byte(&p, mapping_family);
107	0	if (mapping_family != 0) {
108	0	bytestream_put_byte(&p, stream_count);
109	0	bytestream_put_byte(&p, coupled_stream_count);
110	0	bytestream_put_buffer(&p, channel_mapping, channels);
111	0	}
112	0	}
113
114		static int libopus_configure_encoder(AVCodecContext avctx, OpusMSEncoder enc,
115		LibopusEncOpts *opts)
116	0	{
117	0	int ret;
118
119	0	if (avctx->global_quality) {
120	0	av_log(avctx, AV_LOG_ERROR,
121	0	"Quality-based encoding not supported, "
122	0	"please specify a bitrate and VBR setting.\n");
123	0	return AVERROR(EINVAL);
124	0	}
125
126	0	ret = opus_multistream_encoder_ctl(enc, OPUS_SET_BITRATE(avctx->bit_rate));
127	0	if (ret != OPUS_OK) {
128	0	av_log(avctx, AV_LOG_ERROR,
129	0	"Failed to set bitrate: %s\n", opus_strerror(ret));
130	0	return ret;
131	0	}
132
133	0	ret = opus_multistream_encoder_ctl(enc,
134	0	OPUS_SET_COMPLEXITY(opts->complexity));
135	0	if (ret != OPUS_OK)
136	0	av_log(avctx, AV_LOG_WARNING,
137	0	"Unable to set complexity: %s\n", opus_strerror(ret));
138
139	0	ret = opus_multistream_encoder_ctl(enc, OPUS_SET_VBR(!!opts->vbr));
140	0	if (ret != OPUS_OK)
141	0	av_log(avctx, AV_LOG_WARNING,
142	0	"Unable to set VBR: %s\n", opus_strerror(ret));
143
144	0	ret = opus_multistream_encoder_ctl(enc,
145	0	OPUS_SET_VBR_CONSTRAINT(opts->vbr == 2));
146	0	if (ret != OPUS_OK)
147	0	av_log(avctx, AV_LOG_WARNING,
148	0	"Unable to set constrained VBR: %s\n", opus_strerror(ret));
149
150	0	ret = opus_multistream_encoder_ctl(enc,
151	0	OPUS_SET_PACKET_LOSS_PERC(opts->packet_loss));
152	0	if (ret != OPUS_OK)
153	0	av_log(avctx, AV_LOG_WARNING,
154	0	"Unable to set expected packet loss percentage: %s\n",
155	0	opus_strerror(ret));
156
157	0	ret = opus_multistream_encoder_ctl(enc,
158	0	OPUS_SET_INBAND_FEC(opts->fec));
159	0	if (ret != OPUS_OK)
160	0	av_log(avctx, AV_LOG_WARNING,
161	0	"Unable to set inband FEC: %s\n",
162	0	opus_strerror(ret));
163
164	0	ret = opus_multistream_encoder_ctl(enc,
165	0	OPUS_SET_DTX(opts->dtx));
166	0	if (ret != OPUS_OK)
167	0	av_log(avctx, AV_LOG_WARNING,
168	0	"Unable to set DTX: %s\n",
169	0	opus_strerror(ret));
170
171	0	if (avctx->cutoff) {
172	0	ret = opus_multistream_encoder_ctl(enc,
173	0	OPUS_SET_MAX_BANDWIDTH(opts->max_bandwidth));
174	0	if (ret != OPUS_OK)
175	0	av_log(avctx, AV_LOG_WARNING,
176	0	"Unable to set maximum bandwidth: %s\n", opus_strerror(ret));
177	0	}
178
179	0	#ifdef OPUS_SET_PHASE_INVERSION_DISABLED_REQUEST
180	0	ret = opus_multistream_encoder_ctl(enc,
181	0	OPUS_SET_PHASE_INVERSION_DISABLED(!opts->apply_phase_inv));
182	0	if (ret != OPUS_OK)
183	0	av_log(avctx, AV_LOG_WARNING,
184	0	"Unable to set phase inversion: %s\n",
185	0	opus_strerror(ret));
186	0	#endif
187	0	return OPUS_OK;
188	0	}
189
190		static int libopus_check_max_channels(AVCodecContext *avctx,
191	0	int max_channels) {
192	0	if (avctx->ch_layout.nb_channels > max_channels) {
193	0	av_log(avctx, AV_LOG_ERROR, "Opus mapping family undefined for %d channels.\n",
194	0	avctx->ch_layout.nb_channels);
195	0	return AVERROR(EINVAL);
196	0	}
197
198	0	return 0;
199	0	}
200
201	0	static int libopus_check_vorbis_layout(AVCodecContext *avctx, int mapping_family) {
202	0	av_assert2(avctx->ch_layout.nb_channels < FF_ARRAY_ELEMS(ff_vorbis_ch_layouts));
203
204	0	if (avctx->ch_layout.order == AV_CHANNEL_ORDER_UNSPEC) {
205	0	av_log(avctx, AV_LOG_WARNING,
206	0	"No channel layout specified. Opus encoder will use Vorbis "
207	0	"channel layout for %d channels.\n", avctx->ch_layout.nb_channels);
208	0	} else if (av_channel_layout_compare(&avctx->ch_layout, &ff_vorbis_ch_layouts[avctx->ch_layout.nb_channels - 1])) {
209	0	char name[32];
210
211	0	av_channel_layout_describe(&avctx->ch_layout, name, sizeof(name));
212	0	av_log(avctx, AV_LOG_ERROR,
213	0	"Invalid channel layout %s for specified mapping family %d.\n",
214	0	name, mapping_family);
215
216	0	return AVERROR(EINVAL);
217	0	}
218
219	0	return 0;
220	0	}
221
222		static int libopus_validate_layout_and_get_channel_map(
223		AVCodecContext *avctx,
224		int mapping_family,
225		const uint8_t ** channel_map_result)
226	0	{
227	0	const uint8_t * channel_map = NULL;
228	0	int ret;
229
230	0	switch (mapping_family) {
231	0	case -1:
232	0	ret = libopus_check_max_channels(avctx, 8);
233	0	if (ret == 0) {
234	0	ret = libopus_check_vorbis_layout(avctx, mapping_family);
235		/* Channels do not need to be reordered. */
236	0	}
237
238	0	break;
239	0	case 0:
240	0	ret = libopus_check_max_channels(avctx, 2);
241	0	if (ret == 0) {
242	0	ret = libopus_check_vorbis_layout(avctx, mapping_family);
243	0	}
244	0	break;
245	0	case 1:
246		/* Opus expects channels to be in Vorbis order. */
247	0	ret = libopus_check_max_channels(avctx, 8);
248	0	if (ret == 0) {
249	0	ret = libopus_check_vorbis_layout(avctx, mapping_family);
250	0	channel_map = ff_vorbis_channel_layout_offsets[avctx->ch_layout.nb_channels - 1];
251	0	}
252	0	break;
253	0	case 255:
254	0	ret = libopus_check_max_channels(avctx, 254);
255	0	break;
256	0	default:
257	0	av_log(avctx, AV_LOG_WARNING,
258	0	"Unknown channel mapping family %d. Output channel layout may be invalid.\n",
259	0	mapping_family);
260	0	ret = 0;
261	0	}
262
263	0	*channel_map_result = channel_map;
264	0	return ret;
265	0	}
266
267		static av_cold int libopus_encode_init(AVCodecContext *avctx)
268	0	{
269	0	LibopusEncContext *opus = avctx->priv_data;
270	0	OpusMSEncoder *enc;
271	0	uint8_t libopus_channel_mapping[255];
272	0	int ret = OPUS_OK;
273	0	int channels = avctx->ch_layout.nb_channels;
274	0	int av_ret;
275	0	int coupled_stream_count, header_size, frame_size;
276	0	int mapping_family;
277
278	0	frame_size = opus->opts.frame_duration * 48000 / 1000;
279	0	switch (frame_size) {
280	0	case 120:
281	0	case 240:
282	0	if (opus->opts.application != OPUS_APPLICATION_RESTRICTED_LOWDELAY)
283	0	av_log(avctx, AV_LOG_WARNING,
284	0	"LPC mode cannot be used with a frame duration of less "
285	0	"than 10ms. Enabling restricted low-delay mode.\n"
286	0	"Use a longer frame duration if this is not what you want.\n");
287		/* Frame sizes less than 10 ms can only use MDCT mode, so switching to
288		* RESTRICTED_LOWDELAY avoids an unnecessary extra 2.5ms lookahead. */
289	0	opus->opts.application = OPUS_APPLICATION_RESTRICTED_LOWDELAY;
290	0	av_fallthrough;
291	0	case 480:
292	0	case 960:
293	0	case 1920:
294	0	case 2880:
295	0	#ifdef OPUS_FRAMESIZE_120_MS
296	0	case 3840:
297	0	case 4800:
298	0	case 5760:
299	0	#endif
300	0	opus->opts.packet_size =
301	0	avctx->frame_size = frame_size * avctx->sample_rate / 48000;
302	0	break;
303	0	default:
304	0	av_log(avctx, AV_LOG_ERROR, "Invalid frame duration: %g.\n"
305	0	"Frame duration must be exactly one of: 2.5, 5, 10, 20, 40"
306	0	#ifdef OPUS_FRAMESIZE_120_MS
307	0	", 60, 80, 100 or 120.\n",
308		#else
309		" or 60.\n",
310		#endif
311	0	opus->opts.frame_duration);
312	0	return AVERROR(EINVAL);
313	0	}
314
315	0	if (avctx->compression_level < 0 \|\| avctx->compression_level > 10) {
316	0	av_log(avctx, AV_LOG_WARNING,
317	0	"Compression level must be in the range 0 to 10. "
318	0	"Defaulting to 10.\n");
319	0	opus->opts.complexity = 10;
320	0	} else {
321	0	opus->opts.complexity = avctx->compression_level;
322	0	}
323
324	0	if (avctx->cutoff) {
325	0	switch (avctx->cutoff) {
326	0	case 4000:
327	0	opus->opts.max_bandwidth = OPUS_BANDWIDTH_NARROWBAND;
328	0	break;
329	0	case 6000:
330	0	opus->opts.max_bandwidth = OPUS_BANDWIDTH_MEDIUMBAND;
331	0	break;
332	0	case 8000:
333	0	opus->opts.max_bandwidth = OPUS_BANDWIDTH_WIDEBAND;
334	0	break;
335	0	case 12000:
336	0	opus->opts.max_bandwidth = OPUS_BANDWIDTH_SUPERWIDEBAND;
337	0	break;
338	0	case 20000:
339	0	opus->opts.max_bandwidth = OPUS_BANDWIDTH_FULLBAND;
340	0	break;
341	0	default:
342	0	av_log(avctx, AV_LOG_WARNING,
343	0	"Invalid frequency cutoff: %d. Using default maximum bandwidth.\n"
344	0	"Cutoff frequency must be exactly one of: 4000, 6000, 8000, 12000 or 20000.\n",
345	0	avctx->cutoff);
346	0	avctx->cutoff = 0;
347	0	}
348	0	}
349
350		/* Channels may need to be reordered to match opus mapping. */
351	0	av_ret = libopus_validate_layout_and_get_channel_map(avctx, opus->opts.mapping_family,
352	0	&opus->encoder_channel_map);
353	0	if (av_ret) {
354	0	return av_ret;
355	0	}
356
357	0	if (opus->opts.mapping_family == -1) {
358		/* By default, use mapping family 1 for the header but use the older
359		* libopus multistream API to avoid surround masking. */
360
361		/* Set the mapping family so that the value is correct in the header */
362	0	mapping_family = channels > 2 ? 1 : 0;
363	0	coupled_stream_count = opus_coupled_streams[channels - 1];
364	0	opus->stream_count = channels - coupled_stream_count;
365	0	memcpy(libopus_channel_mapping,
366	0	opus_vorbis_channel_map[channels - 1],
367	0	channels * sizeof(*libopus_channel_mapping));
368
369	0	enc = opus_multistream_encoder_create(
370	0	avctx->sample_rate, channels, opus->stream_count,
371	0	coupled_stream_count,
372	0	libavcodec_libopus_channel_map[channels - 1],
373	0	opus->opts.application, &ret);
374	0	} else {
375		/* Use the newer multistream API. The encoder will set the channel
376		* mapping and coupled stream counts to its internal defaults and will
377		* use surround masking analysis to save bits. */
378	0	mapping_family = opus->opts.mapping_family;
379	0	enc = opus_multistream_surround_encoder_create(
380	0	avctx->sample_rate, channels, mapping_family,
381	0	&opus->stream_count, &coupled_stream_count, libopus_channel_mapping,
382	0	opus->opts.application, &ret);
383	0	}
384
385	0	if (ret != OPUS_OK) {
386	0	av_log(avctx, AV_LOG_ERROR,
387	0	"Failed to create encoder: %s\n", opus_strerror(ret));
388	0	return ff_opus_error_to_averror(ret);
389	0	}
390
391	0	if (!avctx->bit_rate) {
392		/* Sane default copied from opusenc */
393	0	avctx->bit_rate = 64000 * opus->stream_count +
394	0	32000 * coupled_stream_count;
395	0	av_log(avctx, AV_LOG_WARNING,
396	0	"No bit rate set. Defaulting to %"PRId64" bps.\n", avctx->bit_rate);
397	0	}
398
399	0	if (avctx->bit_rate < 500 \|\| avctx->bit_rate > 256000 * channels) {
400	0	av_log(avctx, AV_LOG_ERROR, "The bit rate %"PRId64" bps is unsupported. "
401	0	"Please choose a value between 500 and %d.\n", avctx->bit_rate,
402	0	256000 * channels);
403	0	ret = AVERROR(EINVAL);
404	0	goto fail;
405	0	}
406
407	0	ret = libopus_configure_encoder(avctx, enc, &opus->opts);
408	0	if (ret != OPUS_OK) {
409	0	ret = ff_opus_error_to_averror(ret);
410	0	goto fail;
411	0	}
412
413		/* Header includes channel mapping table if and only if mapping family is NOT 0 */
414	0	header_size = 19 + (mapping_family == 0 ? 0 : 2 + channels);
415	0	avctx->extradata = av_malloc(header_size + AV_INPUT_BUFFER_PADDING_SIZE);
416	0	if (!avctx->extradata) {
417	0	av_log(avctx, AV_LOG_ERROR, "Failed to allocate extradata.\n");
418	0	ret = AVERROR(ENOMEM);
419	0	goto fail;
420	0	}
421	0	avctx->extradata_size = header_size;
422
423	0	opus->samples = av_calloc(frame_size, channels *
424	0	av_get_bytes_per_sample(avctx->sample_fmt));
425	0	if (!opus->samples) {
426	0	av_log(avctx, AV_LOG_ERROR, "Failed to allocate samples buffer.\n");
427	0	ret = AVERROR(ENOMEM);
428	0	goto fail;
429	0	}
430
431	0	ret = opus_multistream_encoder_ctl(enc, OPUS_GET_LOOKAHEAD(&avctx->initial_padding));
432	0	if (ret != OPUS_OK)
433	0	av_log(avctx, AV_LOG_WARNING,
434	0	"Unable to get number of lookahead samples: %s\n",
435	0	opus_strerror(ret));
436
437	0	libopus_write_header(avctx, opus->stream_count, coupled_stream_count,
438	0	mapping_family, libopus_channel_mapping);
439
440	0	ff_af_queue_init(avctx, &opus->afq);
441
442	0	opus->enc = enc;
443
444	0	return 0;
445
446	0	fail:
447	0	opus_multistream_encoder_destroy(enc);
448	0	return ret;
449	0	}
450
451		static void libopus_copy_samples_with_channel_map(
452		uint8_t dst, const uint8_t src, const uint8_t *channel_map,
453	0	int nb_channels, int nb_samples, int bytes_per_sample) {
454	0	int sample, channel;
455	0	for (sample = 0; sample < nb_samples; ++sample) {
456	0	for (channel = 0; channel < nb_channels; ++channel) {
457	0	const size_t src_pos = bytes_per_sample * (nb_channels * sample + channel);
458	0	const size_t dst_pos = bytes_per_sample * (nb_channels * sample + channel_map[channel]);
459
460	0	memcpy(&dst[dst_pos], &src[src_pos], bytes_per_sample);
461	0	}
462	0	}
463	0	}
464
465		static int libopus_encode(AVCodecContext avctx, AVPacket avpkt,
466		const AVFrame frame, int got_packet_ptr)
467	0	{
468	0	LibopusEncContext *opus = avctx->priv_data;
469	0	const int bytes_per_sample = av_get_bytes_per_sample(avctx->sample_fmt);
470	0	const int channels = avctx->ch_layout.nb_channels;
471	0	const int sample_size = channels * bytes_per_sample;
472	0	const uint8_t *audio;
473	0	int ret;
474
475	0	if (frame) {
476	0	ret = ff_af_queue_add(&opus->afq, frame);
477	0	if (ret < 0)
478	0	return ret;
479	0	if (opus->encoder_channel_map != NULL) {
480	0	audio = opus->samples;
481	0	libopus_copy_samples_with_channel_map(
482	0	opus->samples, frame->data[0], opus->encoder_channel_map,
483	0	channels, frame->nb_samples, bytes_per_sample);
484	0	} else if (frame->nb_samples < opus->opts.packet_size) {
485	0	audio = opus->samples;
486	0	memcpy(opus->samples, frame->data[0], frame->nb_samples * sample_size);
487	0	} else
488	0	audio = frame->data[0];
489	0	} else {
490	0	if (!opus->afq.remaining_samples \|\| (!opus->afq.frame_alloc && !opus->afq.frame_count))
491	0	return 0;
492	0	audio = opus->samples;
493	0	memset(opus->samples, 0, opus->opts.packet_size * sample_size);
494	0	}
495
496		/* Maximum packet size taken from opusenc in opus-tools. 120ms packets
497		* consist of 6 frames in one packet. The maximum frame size is 1275
498		* bytes along with the largest possible packet header of 7 bytes. */
499	0	if ((ret = ff_alloc_packet(avctx, avpkt, (1275 * 6 + 7) * opus->stream_count)) < 0)
500	0	return ret;
501
502	0	if (avctx->sample_fmt == AV_SAMPLE_FMT_FLT)
503	0	ret = opus_multistream_encode_float(opus->enc, (const float *)audio,
504	0	opus->opts.packet_size,
505	0	avpkt->data, avpkt->size);
506	0	else
507	0	ret = opus_multistream_encode(opus->enc, (const opus_int16 *)audio,
508	0	opus->opts.packet_size,
509	0	avpkt->data, avpkt->size);
510
511	0	if (ret < 0) {
512	0	av_log(avctx, AV_LOG_ERROR,
513	0	"Error encoding frame: %s\n", opus_strerror(ret));
514	0	return ff_opus_error_to_averror(ret);
515	0	}
516
517	0	av_shrink_packet(avpkt, ret);
518
519	0	ret = ff_af_queue_remove(&opus->afq, opus->opts.packet_size, avpkt);
520	0	if (ret < 0)
521	0	return ret;
522
523	0	*got_packet_ptr = 1;
524
525	0	return 0;
526	0	}
527
528		static av_cold int libopus_encode_close(AVCodecContext *avctx)
529	0	{
530	0	LibopusEncContext *opus = avctx->priv_data;
531
532	0	opus_multistream_encoder_destroy(opus->enc);
533
534	0	ff_af_queue_close(&opus->afq);
535
536	0	av_freep(&opus->samples);
537
538	0	return 0;
539	0	}
540
541		#define OFFSET(x) offsetof(LibopusEncContext, opts.x)
542		#define FLAGS AV_OPT_FLAG_AUDIO_PARAM \| AV_OPT_FLAG_ENCODING_PARAM
543		static const AVOption libopus_options[] = {
544		{ "application", "Intended application type", OFFSET(application), AV_OPT_TYPE_INT, { .i64 = OPUS_APPLICATION_AUDIO }, OPUS_APPLICATION_VOIP, OPUS_APPLICATION_RESTRICTED_LOWDELAY, FLAGS, .unit = "application" },
545		{ "voip", "Favor improved speech intelligibility", 0, AV_OPT_TYPE_CONST, { .i64 = OPUS_APPLICATION_VOIP }, 0, 0, FLAGS, .unit = "application" },
546		{ "audio", "Favor faithfulness to the input", 0, AV_OPT_TYPE_CONST, { .i64 = OPUS_APPLICATION_AUDIO }, 0, 0, FLAGS, .unit = "application" },
547		{ "lowdelay", "Restrict to only the lowest delay modes, disable voice-optimized modes", 0, AV_OPT_TYPE_CONST, { .i64 = OPUS_APPLICATION_RESTRICTED_LOWDELAY }, 0, 0, FLAGS, .unit = "application" },
548		{ "frame_duration", "Duration of a frame in milliseconds", OFFSET(frame_duration), AV_OPT_TYPE_FLOAT, { .dbl = 20.0 }, 2.5, 120.0, FLAGS },
549		{ "packet_loss", "Expected packet loss percentage", OFFSET(packet_loss), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 100, FLAGS },
550		{ "fec", "Enable inband FEC. Expected packet loss must be non-zero", OFFSET(fec), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, FLAGS },
551		{ "vbr", "Variable bit rate mode", OFFSET(vbr), AV_OPT_TYPE_INT, { .i64 = 1 }, 0, 2, FLAGS, .unit = "vbr" },
552		{ "off", "Use constant bit rate", 0, AV_OPT_TYPE_CONST, { .i64 = 0 }, 0, 0, FLAGS, .unit = "vbr" },
553		{ "on", "Use variable bit rate", 0, AV_OPT_TYPE_CONST, { .i64 = 1 }, 0, 0, FLAGS, .unit = "vbr" },
554		{ "constrained", "Use constrained VBR", 0, AV_OPT_TYPE_CONST, { .i64 = 2 }, 0, 0, FLAGS, .unit = "vbr" },
555		{ "mapping_family", "Channel Mapping Family", OFFSET(mapping_family), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, 255, FLAGS, .unit = "mapping_family" },
556		{ "dtx", "Enable DTX (Discontinuous transmission)", OFFSET(dtx), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, FLAGS },
557		#ifdef OPUS_SET_PHASE_INVERSION_DISABLED_REQUEST
558		{ "apply_phase_inv", "Apply intensity stereo phase inversion", OFFSET(apply_phase_inv), AV_OPT_TYPE_BOOL, { .i64 = 1 }, 0, 1, FLAGS },
559		#endif
560		{ NULL },
561		};
562
563		static const AVClass libopus_class = {
564		.class_name = "libopus",
565		.item_name = av_default_item_name,
566		.option = libopus_options,
567		.version = LIBAVUTIL_VERSION_INT,
568		};
569
570		static const FFCodecDefault libopus_defaults[] = {
571		{ "b", "0" },
572		{ "compression_level", "10" },
573		{ NULL },
574		};
575
576		static const int libopus_sample_rates[] = {
577		48000, 24000, 16000, 12000, 8000, 0,
578		};
579
580		const FFCodec ff_libopus_encoder = {
581		.p.name = "libopus",
582		CODEC_LONG_NAME("libopus Opus"),
583		.p.type = AVMEDIA_TYPE_AUDIO,
584		.p.id = AV_CODEC_ID_OPUS,
585		.p.capabilities = AV_CODEC_CAP_DR1 \| AV_CODEC_CAP_DELAY \|
586		AV_CODEC_CAP_SMALL_LAST_FRAME,
587		.caps_internal = FF_CODEC_CAP_NOT_INIT_THREADSAFE,
588		.priv_data_size = sizeof(LibopusEncContext),
589		.init = libopus_encode_init,
590		FF_CODEC_ENCODE_CB(libopus_encode),
591		.close = libopus_encode_close,
592		CODEC_SAMPLEFMTS(AV_SAMPLE_FMT_S16, AV_SAMPLE_FMT_FLT),
593		CODEC_SAMPLERATES_ARRAY(libopus_sample_rates),
594		.p.priv_class = &libopus_class,
595		.defaults = libopus_defaults,
596		.p.wrapper_name = "libopus",
597		};