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libopusenc.c (23252B)


      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 {
     95    uint8_t *p   = avctx->extradata;
     96    int channels = avctx->ch_layout.nb_channels;
     97 
     98    bytestream_put_buffer(&p, "OpusHead", 8);
     99    bytestream_put_byte(&p, 1); /* Version */
    100    bytestream_put_byte(&p, channels);
    101    bytestream_put_le16(&p, avctx->initial_padding * 48000 / avctx->sample_rate); /* Lookahead samples at 48kHz */
    102    bytestream_put_le32(&p, avctx->sample_rate); /* Original sample rate */
    103    bytestream_put_le16(&p, 0); /* Gain of 0dB is recommended. */
    104 
    105    /* Channel mapping */
    106    bytestream_put_byte(&p, mapping_family);
    107    if (mapping_family != 0) {
    108        bytestream_put_byte(&p, stream_count);
    109        bytestream_put_byte(&p, coupled_stream_count);
    110        bytestream_put_buffer(&p, channel_mapping, channels);
    111    }
    112 }
    113 
    114 static int libopus_configure_encoder(AVCodecContext *avctx, OpusMSEncoder *enc,
    115                                     LibopusEncOpts *opts)
    116 {
    117    int ret;
    118 
    119    if (avctx->global_quality) {
    120        av_log(avctx, AV_LOG_ERROR,
    121               "Quality-based encoding not supported, "
    122               "please specify a bitrate and VBR setting.\n");
    123        return AVERROR(EINVAL);
    124    }
    125 
    126    ret = opus_multistream_encoder_ctl(enc, OPUS_SET_BITRATE(avctx->bit_rate));
    127    if (ret != OPUS_OK) {
    128        av_log(avctx, AV_LOG_ERROR,
    129               "Failed to set bitrate: %s\n", opus_strerror(ret));
    130        return ret;
    131    }
    132 
    133    ret = opus_multistream_encoder_ctl(enc,
    134                                       OPUS_SET_COMPLEXITY(opts->complexity));
    135    if (ret != OPUS_OK)
    136        av_log(avctx, AV_LOG_WARNING,
    137               "Unable to set complexity: %s\n", opus_strerror(ret));
    138 
    139    ret = opus_multistream_encoder_ctl(enc, OPUS_SET_VBR(!!opts->vbr));
    140    if (ret != OPUS_OK)
    141        av_log(avctx, AV_LOG_WARNING,
    142               "Unable to set VBR: %s\n", opus_strerror(ret));
    143 
    144    ret = opus_multistream_encoder_ctl(enc,
    145                                       OPUS_SET_VBR_CONSTRAINT(opts->vbr == 2));
    146    if (ret != OPUS_OK)
    147        av_log(avctx, AV_LOG_WARNING,
    148               "Unable to set constrained VBR: %s\n", opus_strerror(ret));
    149 
    150    ret = opus_multistream_encoder_ctl(enc,
    151                                       OPUS_SET_PACKET_LOSS_PERC(opts->packet_loss));
    152    if (ret != OPUS_OK)
    153        av_log(avctx, AV_LOG_WARNING,
    154               "Unable to set expected packet loss percentage: %s\n",
    155               opus_strerror(ret));
    156 
    157    ret = opus_multistream_encoder_ctl(enc,
    158                                       OPUS_SET_INBAND_FEC(opts->fec));
    159    if (ret != OPUS_OK)
    160        av_log(avctx, AV_LOG_WARNING,
    161               "Unable to set inband FEC: %s\n",
    162               opus_strerror(ret));
    163 
    164    ret = opus_multistream_encoder_ctl(enc,
    165                                       OPUS_SET_DTX(opts->dtx));
    166    if (ret != OPUS_OK)
    167        av_log(avctx, AV_LOG_WARNING,
    168               "Unable to set DTX: %s\n",
    169               opus_strerror(ret));
    170 
    171    if (avctx->cutoff) {
    172        ret = opus_multistream_encoder_ctl(enc,
    173                                           OPUS_SET_MAX_BANDWIDTH(opts->max_bandwidth));
    174        if (ret != OPUS_OK)
    175            av_log(avctx, AV_LOG_WARNING,
    176                   "Unable to set maximum bandwidth: %s\n", opus_strerror(ret));
    177    }
    178 
    179 #ifdef OPUS_SET_PHASE_INVERSION_DISABLED_REQUEST
    180    ret = opus_multistream_encoder_ctl(enc,
    181                                       OPUS_SET_PHASE_INVERSION_DISABLED(!opts->apply_phase_inv));
    182    if (ret != OPUS_OK)
    183        av_log(avctx, AV_LOG_WARNING,
    184               "Unable to set phase inversion: %s\n",
    185               opus_strerror(ret));
    186 #endif
    187    return OPUS_OK;
    188 }
    189 
    190 static int libopus_check_max_channels(AVCodecContext *avctx,
    191                                      int max_channels) {
    192    if (avctx->ch_layout.nb_channels > max_channels) {
    193        av_log(avctx, AV_LOG_ERROR, "Opus mapping family undefined for %d channels.\n",
    194               avctx->ch_layout.nb_channels);
    195        return AVERROR(EINVAL);
    196    }
    197 
    198    return 0;
    199 }
    200 
    201 static int libopus_check_vorbis_layout(AVCodecContext *avctx, int mapping_family) {
    202    av_assert2(avctx->ch_layout.nb_channels < FF_ARRAY_ELEMS(ff_vorbis_ch_layouts));
    203 
    204    if (avctx->ch_layout.order == AV_CHANNEL_ORDER_UNSPEC) {
    205        av_log(avctx, AV_LOG_WARNING,
    206               "No channel layout specified. Opus encoder will use Vorbis "
    207               "channel layout for %d channels.\n", avctx->ch_layout.nb_channels);
    208    } else if (av_channel_layout_compare(&avctx->ch_layout, &ff_vorbis_ch_layouts[avctx->ch_layout.nb_channels - 1])) {
    209        char name[32];
    210 
    211        av_channel_layout_describe(&avctx->ch_layout, name, sizeof(name));
    212        av_log(avctx, AV_LOG_ERROR,
    213               "Invalid channel layout %s for specified mapping family %d.\n",
    214               name, mapping_family);
    215 
    216        return AVERROR(EINVAL);
    217    }
    218 
    219    return 0;
    220 }
    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 {
    227    const uint8_t * channel_map = NULL;
    228    int ret;
    229 
    230    switch (mapping_family) {
    231    case -1:
    232        ret = libopus_check_max_channels(avctx, 8);
    233        if (ret == 0) {
    234            ret = libopus_check_vorbis_layout(avctx, mapping_family);
    235            /* Channels do not need to be reordered. */
    236        }
    237 
    238        break;
    239    case 0:
    240        ret = libopus_check_max_channels(avctx, 2);
    241        if (ret == 0) {
    242            ret = libopus_check_vorbis_layout(avctx, mapping_family);
    243        }
    244        break;
    245    case 1:
    246        /* Opus expects channels to be in Vorbis order. */
    247        ret = libopus_check_max_channels(avctx, 8);
    248        if (ret == 0) {
    249            ret = libopus_check_vorbis_layout(avctx, mapping_family);
    250            channel_map = ff_vorbis_channel_layout_offsets[avctx->ch_layout.nb_channels - 1];
    251        }
    252        break;
    253    case 255:
    254        ret = libopus_check_max_channels(avctx, 254);
    255        break;
    256    default:
    257        av_log(avctx, AV_LOG_WARNING,
    258               "Unknown channel mapping family %d. Output channel layout may be invalid.\n",
    259               mapping_family);
    260        ret = 0;
    261    }
    262 
    263    *channel_map_result = channel_map;
    264    return ret;
    265 }
    266 
    267 static av_cold int libopus_encode_init(AVCodecContext *avctx)
    268 {
    269    LibopusEncContext *opus = avctx->priv_data;
    270    OpusMSEncoder *enc;
    271    uint8_t libopus_channel_mapping[255];
    272    int ret = OPUS_OK;
    273    int channels = avctx->ch_layout.nb_channels;
    274    int av_ret;
    275    int coupled_stream_count, header_size, frame_size;
    276    int mapping_family;
    277 
    278    frame_size = opus->opts.frame_duration * 48000 / 1000;
    279    switch (frame_size) {
    280    case 120:
    281    case 240:
    282        if (opus->opts.application != OPUS_APPLICATION_RESTRICTED_LOWDELAY)
    283            av_log(avctx, AV_LOG_WARNING,
    284                   "LPC mode cannot be used with a frame duration of less "
    285                   "than 10ms. Enabling restricted low-delay mode.\n"
    286                   "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        opus->opts.application = OPUS_APPLICATION_RESTRICTED_LOWDELAY;
    290    case 480:
    291    case 960:
    292    case 1920:
    293    case 2880:
    294 #ifdef OPUS_FRAMESIZE_120_MS
    295    case 3840:
    296    case 4800:
    297    case 5760:
    298 #endif
    299        opus->opts.packet_size =
    300        avctx->frame_size      = frame_size * avctx->sample_rate / 48000;
    301        break;
    302    default:
    303        av_log(avctx, AV_LOG_ERROR, "Invalid frame duration: %g.\n"
    304               "Frame duration must be exactly one of: 2.5, 5, 10, 20, 40"
    305 #ifdef OPUS_FRAMESIZE_120_MS
    306               ", 60, 80, 100 or 120.\n",
    307 #else
    308               " or 60.\n",
    309 #endif
    310               opus->opts.frame_duration);
    311        return AVERROR(EINVAL);
    312    }
    313 
    314    if (avctx->compression_level < 0 || avctx->compression_level > 10) {
    315        av_log(avctx, AV_LOG_WARNING,
    316               "Compression level must be in the range 0 to 10. "
    317               "Defaulting to 10.\n");
    318        opus->opts.complexity = 10;
    319    } else {
    320        opus->opts.complexity = avctx->compression_level;
    321    }
    322 
    323    if (avctx->cutoff) {
    324        switch (avctx->cutoff) {
    325        case  4000:
    326            opus->opts.max_bandwidth = OPUS_BANDWIDTH_NARROWBAND;
    327            break;
    328        case  6000:
    329            opus->opts.max_bandwidth = OPUS_BANDWIDTH_MEDIUMBAND;
    330            break;
    331        case  8000:
    332            opus->opts.max_bandwidth = OPUS_BANDWIDTH_WIDEBAND;
    333            break;
    334        case 12000:
    335            opus->opts.max_bandwidth = OPUS_BANDWIDTH_SUPERWIDEBAND;
    336            break;
    337        case 20000:
    338            opus->opts.max_bandwidth = OPUS_BANDWIDTH_FULLBAND;
    339            break;
    340        default:
    341            av_log(avctx, AV_LOG_WARNING,
    342                   "Invalid frequency cutoff: %d. Using default maximum bandwidth.\n"
    343                   "Cutoff frequency must be exactly one of: 4000, 6000, 8000, 12000 or 20000.\n",
    344                   avctx->cutoff);
    345            avctx->cutoff = 0;
    346        }
    347    }
    348 
    349    /* Channels may need to be reordered to match opus mapping. */
    350    av_ret = libopus_validate_layout_and_get_channel_map(avctx, opus->opts.mapping_family,
    351                                                         &opus->encoder_channel_map);
    352    if (av_ret) {
    353        return av_ret;
    354    }
    355 
    356    if (opus->opts.mapping_family == -1) {
    357        /* By default, use mapping family 1 for the header but use the older
    358         * libopus multistream API to avoid surround masking. */
    359 
    360        /* Set the mapping family so that the value is correct in the header */
    361        mapping_family = channels > 2 ? 1 : 0;
    362        coupled_stream_count = opus_coupled_streams[channels - 1];
    363        opus->stream_count   = channels - coupled_stream_count;
    364        memcpy(libopus_channel_mapping,
    365               opus_vorbis_channel_map[channels - 1],
    366               channels * sizeof(*libopus_channel_mapping));
    367 
    368        enc = opus_multistream_encoder_create(
    369            avctx->sample_rate, channels, opus->stream_count,
    370            coupled_stream_count,
    371            libavcodec_libopus_channel_map[channels - 1],
    372            opus->opts.application, &ret);
    373    } else {
    374        /* Use the newer multistream API. The encoder will set the channel
    375         * mapping and coupled stream counts to its internal defaults and will
    376         * use surround masking analysis to save bits. */
    377        mapping_family = opus->opts.mapping_family;
    378        enc = opus_multistream_surround_encoder_create(
    379            avctx->sample_rate, channels, mapping_family,
    380            &opus->stream_count, &coupled_stream_count, libopus_channel_mapping,
    381            opus->opts.application, &ret);
    382    }
    383 
    384    if (ret != OPUS_OK) {
    385        av_log(avctx, AV_LOG_ERROR,
    386               "Failed to create encoder: %s\n", opus_strerror(ret));
    387        return ff_opus_error_to_averror(ret);
    388    }
    389 
    390    if (!avctx->bit_rate) {
    391        /* Sane default copied from opusenc */
    392        avctx->bit_rate = 64000 * opus->stream_count +
    393                          32000 * coupled_stream_count;
    394        av_log(avctx, AV_LOG_WARNING,
    395               "No bit rate set. Defaulting to %"PRId64" bps.\n", avctx->bit_rate);
    396    }
    397 
    398    if (avctx->bit_rate < 500 || avctx->bit_rate > 256000 * channels) {
    399        av_log(avctx, AV_LOG_ERROR, "The bit rate %"PRId64" bps is unsupported. "
    400               "Please choose a value between 500 and %d.\n", avctx->bit_rate,
    401               256000 * channels);
    402        ret = AVERROR(EINVAL);
    403        goto fail;
    404    }
    405 
    406    ret = libopus_configure_encoder(avctx, enc, &opus->opts);
    407    if (ret != OPUS_OK) {
    408        ret = ff_opus_error_to_averror(ret);
    409        goto fail;
    410    }
    411 
    412    /* Header includes channel mapping table if and only if mapping family is NOT 0 */
    413    header_size = 19 + (mapping_family == 0 ? 0 : 2 + channels);
    414    avctx->extradata = av_malloc(header_size + AV_INPUT_BUFFER_PADDING_SIZE);
    415    if (!avctx->extradata) {
    416        av_log(avctx, AV_LOG_ERROR, "Failed to allocate extradata.\n");
    417        ret = AVERROR(ENOMEM);
    418        goto fail;
    419    }
    420    avctx->extradata_size = header_size;
    421 
    422    opus->samples = av_calloc(frame_size, channels *
    423                               av_get_bytes_per_sample(avctx->sample_fmt));
    424    if (!opus->samples) {
    425        av_log(avctx, AV_LOG_ERROR, "Failed to allocate samples buffer.\n");
    426        ret = AVERROR(ENOMEM);
    427        goto fail;
    428    }
    429 
    430    ret = opus_multistream_encoder_ctl(enc, OPUS_GET_LOOKAHEAD(&avctx->initial_padding));
    431    if (ret != OPUS_OK)
    432        av_log(avctx, AV_LOG_WARNING,
    433               "Unable to get number of lookahead samples: %s\n",
    434               opus_strerror(ret));
    435 
    436    libopus_write_header(avctx, opus->stream_count, coupled_stream_count,
    437                         mapping_family, libopus_channel_mapping);
    438 
    439    ff_af_queue_init(avctx, &opus->afq);
    440 
    441    opus->enc = enc;
    442 
    443    return 0;
    444 
    445 fail:
    446    opus_multistream_encoder_destroy(enc);
    447    return ret;
    448 }
    449 
    450 static void libopus_copy_samples_with_channel_map(
    451    uint8_t *dst, const uint8_t *src, const uint8_t *channel_map,
    452    int nb_channels, int nb_samples, int bytes_per_sample) {
    453    int sample, channel;
    454    for (sample = 0; sample < nb_samples; ++sample) {
    455        for (channel = 0; channel < nb_channels; ++channel) {
    456            const size_t src_pos = bytes_per_sample * (nb_channels * sample + channel);
    457            const size_t dst_pos = bytes_per_sample * (nb_channels * sample + channel_map[channel]);
    458 
    459            memcpy(&dst[dst_pos], &src[src_pos], bytes_per_sample);
    460        }
    461    }
    462 }
    463 
    464 static int libopus_encode(AVCodecContext *avctx, AVPacket *avpkt,
    465                          const AVFrame *frame, int *got_packet_ptr)
    466 {
    467    LibopusEncContext *opus = avctx->priv_data;
    468    const int bytes_per_sample = av_get_bytes_per_sample(avctx->sample_fmt);
    469    const int channels         = avctx->ch_layout.nb_channels;
    470    const int sample_size      = channels * bytes_per_sample;
    471    const uint8_t *audio;
    472    int ret;
    473    int discard_padding;
    474 
    475    if (frame) {
    476        ret = ff_af_queue_add(&opus->afq, frame);
    477        if (ret < 0)
    478            return ret;
    479        if (opus->encoder_channel_map != NULL) {
    480            audio = opus->samples;
    481            libopus_copy_samples_with_channel_map(
    482                opus->samples, frame->data[0], opus->encoder_channel_map,
    483                channels, frame->nb_samples, bytes_per_sample);
    484        } else if (frame->nb_samples < opus->opts.packet_size) {
    485            audio = opus->samples;
    486            memcpy(opus->samples, frame->data[0], frame->nb_samples * sample_size);
    487        } else
    488            audio = frame->data[0];
    489    } else {
    490        if (!opus->afq.remaining_samples || (!opus->afq.frame_alloc && !opus->afq.frame_count))
    491            return 0;
    492        audio = opus->samples;
    493        memset(opus->samples, 0, opus->opts.packet_size * sample_size);
    494    }
    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    if ((ret = ff_alloc_packet(avctx, avpkt, (1275 * 6 + 7) * opus->stream_count)) < 0)
    500        return ret;
    501 
    502    if (avctx->sample_fmt == AV_SAMPLE_FMT_FLT)
    503        ret = opus_multistream_encode_float(opus->enc, (const float *)audio,
    504                                            opus->opts.packet_size,
    505                                            avpkt->data, avpkt->size);
    506    else
    507        ret = opus_multistream_encode(opus->enc, (const opus_int16 *)audio,
    508                                      opus->opts.packet_size,
    509                                      avpkt->data, avpkt->size);
    510 
    511    if (ret < 0) {
    512        av_log(avctx, AV_LOG_ERROR,
    513               "Error encoding frame: %s\n", opus_strerror(ret));
    514        return ff_opus_error_to_averror(ret);
    515    }
    516 
    517    av_shrink_packet(avpkt, ret);
    518 
    519    ff_af_queue_remove(&opus->afq, opus->opts.packet_size,
    520                       &avpkt->pts, &avpkt->duration);
    521 
    522    discard_padding = opus->opts.packet_size - avpkt->duration;
    523    // Check if subtraction resulted in an overflow
    524    if ((discard_padding < opus->opts.packet_size) != (avpkt->duration > 0))
    525        return AVERROR(EINVAL);
    526    if (discard_padding > 0) {
    527        uint8_t* side_data = av_packet_new_side_data(avpkt,
    528                                                     AV_PKT_DATA_SKIP_SAMPLES,
    529                                                     10);
    530        if (!side_data)
    531            return AVERROR(ENOMEM);
    532        AV_WL32(side_data + 4, discard_padding);
    533    }
    534 
    535    *got_packet_ptr = 1;
    536 
    537    return 0;
    538 }
    539 
    540 static av_cold int libopus_encode_close(AVCodecContext *avctx)
    541 {
    542    LibopusEncContext *opus = avctx->priv_data;
    543 
    544    opus_multistream_encoder_destroy(opus->enc);
    545 
    546    ff_af_queue_close(&opus->afq);
    547 
    548    av_freep(&opus->samples);
    549 
    550    return 0;
    551 }
    552 
    553 #define OFFSET(x) offsetof(LibopusEncContext, opts.x)
    554 #define FLAGS AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_ENCODING_PARAM
    555 static const AVOption libopus_options[] = {
    556    { "application",    "Intended application type",           OFFSET(application),    AV_OPT_TYPE_INT,   { .i64 = OPUS_APPLICATION_AUDIO }, OPUS_APPLICATION_VOIP, OPUS_APPLICATION_RESTRICTED_LOWDELAY, FLAGS, .unit = "application" },
    557        { "voip",           "Favor improved speech intelligibility",   0, AV_OPT_TYPE_CONST, { .i64 = OPUS_APPLICATION_VOIP },                0, 0, FLAGS, .unit = "application" },
    558        { "audio",          "Favor faithfulness to the input",         0, AV_OPT_TYPE_CONST, { .i64 = OPUS_APPLICATION_AUDIO },               0, 0, FLAGS, .unit = "application" },
    559        { "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" },
    560    { "frame_duration", "Duration of a frame in milliseconds", OFFSET(frame_duration), AV_OPT_TYPE_FLOAT, { .dbl = 20.0 }, 2.5, 120.0, FLAGS },
    561    { "packet_loss",    "Expected packet loss percentage",     OFFSET(packet_loss),    AV_OPT_TYPE_INT,   { .i64 = 0 },    0,   100,  FLAGS },
    562    { "fec",             "Enable inband FEC. Expected packet loss must be non-zero",     OFFSET(fec),    AV_OPT_TYPE_BOOL,   { .i64 = 0 }, 0, 1, FLAGS },
    563    { "vbr",            "Variable bit rate mode",              OFFSET(vbr),            AV_OPT_TYPE_INT,   { .i64 = 1 },    0,   2,    FLAGS, .unit = "vbr" },
    564        { "off",            "Use constant bit rate", 0, AV_OPT_TYPE_CONST, { .i64 = 0 }, 0, 0, FLAGS, .unit = "vbr" },
    565        { "on",             "Use variable bit rate", 0, AV_OPT_TYPE_CONST, { .i64 = 1 }, 0, 0, FLAGS, .unit = "vbr" },
    566        { "constrained",    "Use constrained VBR",   0, AV_OPT_TYPE_CONST, { .i64 = 2 }, 0, 0, FLAGS, .unit = "vbr" },
    567    { "mapping_family", "Channel Mapping Family",              OFFSET(mapping_family), AV_OPT_TYPE_INT,   { .i64 = -1 },   -1,  255,  FLAGS, .unit = "mapping_family" },
    568    { "dtx", "Enable DTX", OFFSET(dtx), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, FLAGS },
    569 #ifdef OPUS_SET_PHASE_INVERSION_DISABLED_REQUEST
    570    { "apply_phase_inv", "Apply intensity stereo phase inversion", OFFSET(apply_phase_inv), AV_OPT_TYPE_BOOL, { .i64 = 1 }, 0, 1, FLAGS },
    571 #endif
    572    { NULL },
    573 };
    574 
    575 static const AVClass libopus_class = {
    576    .class_name = "libopus",
    577    .item_name  = av_default_item_name,
    578    .option     = libopus_options,
    579    .version    = LIBAVUTIL_VERSION_INT,
    580 };
    581 
    582 static const FFCodecDefault libopus_defaults[] = {
    583    { "b",                 "0" },
    584    { "compression_level", "10" },
    585    { NULL },
    586 };
    587 
    588 static const int libopus_sample_rates[] = {
    589    48000, 24000, 16000, 12000, 8000, 0,
    590 };
    591 
    592 const FFCodec ff_libopus_encoder = {
    593    .p.name          = "libopus",
    594    CODEC_LONG_NAME("libopus Opus"),
    595    .p.type          = AVMEDIA_TYPE_AUDIO,
    596    .p.id            = AV_CODEC_ID_OPUS,
    597    .p.capabilities  = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_DELAY |
    598                       AV_CODEC_CAP_SMALL_LAST_FRAME,
    599    .caps_internal   = FF_CODEC_CAP_NOT_INIT_THREADSAFE,
    600    .priv_data_size  = sizeof(LibopusEncContext),
    601    .init            = libopus_encode_init,
    602    FF_CODEC_ENCODE_CB(libopus_encode),
    603    .close           = libopus_encode_close,
    604    .p.sample_fmts   = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16,
    605                                                      AV_SAMPLE_FMT_FLT,
    606                                                      AV_SAMPLE_FMT_NONE },
    607    .p.supported_samplerates = libopus_sample_rates,
    608    .p.priv_class    = &libopus_class,
    609    .defaults        = libopus_defaults,
    610    .p.wrapper_name  = "libopus",
    611 };