path: root/libavcodec/libopenh264enc.c

/*
 * OpenH264 video encoder
 * Copyright (C) 2014 Martin Storsjo
 *
 * 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 <wels/codec_api.h>
#include <wels/codec_ver.h>

#include "libavutil/attributes.h"
#include "libavutil/common.h"
#include "libavutil/opt.h"
#include "libavutil/internal.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/mathematics.h"

#include "avcodec.h"
#include "codec_internal.h"
#include "encode.h"
#include "internal.h"
#include "libopenh264.h"

#if !OPENH264_VER_AT_LEAST(1, 6)
#define SM_SIZELIMITED_SLICE SM_DYN_SLICE
#endif

#define TARGET_BITRATE_DEFAULT 2*1000*1000

typedef struct SVCContext {
    const AVClass *av_class;
    ISVCEncoder *encoder;
    int slice_mode;
    int loopfilter;
    int profile;
    int max_nal_size;
    int skip_frames;
    int skipped;
#if FF_API_OPENH264_CABAC
    int cabac;                      // deprecated
#endif
    int coder;

    // rate control mode
    int rc_mode;
} SVCContext;

#define OFFSET(x) offsetof(SVCContext, x)
#define VE AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_ENCODING_PARAM
#define DEPRECATED AV_OPT_FLAG_DEPRECATED
static const AVOption options[] = {
#if FF_API_OPENH264_SLICE_MODE
#if OPENH264_VER_AT_LEAST(1, 6)
    { "slice_mode", "set slice mode, use slices/max_nal_size", OFFSET(slice_mode), AV_OPT_TYPE_INT, { .i64 = SM_FIXEDSLCNUM_SLICE }, SM_SINGLE_SLICE, SM_RESERVED, VE|DEPRECATED, "slice_mode" },
#else
    { "slice_mode", "set slice mode, use slices/max_nal_size", OFFSET(slice_mode), AV_OPT_TYPE_INT, { .i64 = SM_AUTO_SLICE }, SM_SINGLE_SLICE, SM_RESERVED, VE|DEPRECATED, "slice_mode" },
#endif
        { "fixed", "a fixed number of slices", 0, AV_OPT_TYPE_CONST, { .i64 = SM_FIXEDSLCNUM_SLICE }, 0, 0, VE, "slice_mode" },
#if OPENH264_VER_AT_LEAST(1, 6)
        { "dyn", "Size limited (compatibility name)", 0, AV_OPT_TYPE_CONST, { .i64 = SM_SIZELIMITED_SLICE }, 0, 0, VE, "slice_mode" },
        { "sizelimited", "Size limited", 0, AV_OPT_TYPE_CONST, { .i64 = SM_SIZELIMITED_SLICE }, 0, 0, VE, "slice_mode" },
#else
        { "rowmb", "one slice per row of macroblocks", 0, AV_OPT_TYPE_CONST, { .i64 = SM_ROWMB_SLICE }, 0, 0, VE, "slice_mode" },
        { "auto", "automatic number of slices according to number of threads", 0, AV_OPT_TYPE_CONST, { .i64 = SM_AUTO_SLICE }, 0, 0, VE, "slice_mode" },
        { "dyn", "Dynamic slicing", 0, AV_OPT_TYPE_CONST, { .i64 = SM_DYN_SLICE }, 0, 0, VE, "slice_mode" },
#endif
#endif
    { "loopfilter", "enable loop filter", OFFSET(loopfilter), AV_OPT_TYPE_INT, { .i64 = 1 }, 0, 1, VE },
    { "profile", "set profile restrictions", OFFSET(profile), AV_OPT_TYPE_INT, { .i64 = FF_PROFILE_UNKNOWN }, FF_PROFILE_UNKNOWN, 0xffff, VE, "profile" },
#define PROFILE(name, value)  name, NULL, 0, AV_OPT_TYPE_CONST, { .i64 = value }, 0, 0, VE, "profile"
        { PROFILE("constrained_baseline", FF_PROFILE_H264_CONSTRAINED_BASELINE) },
        { PROFILE("main",                 FF_PROFILE_H264_MAIN) },
        { PROFILE("high",                 FF_PROFILE_H264_HIGH) },
#undef PROFILE
    { "max_nal_size", "set maximum NAL size in bytes", OFFSET(max_nal_size), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, VE },
    { "allow_skip_frames", "allow skipping frames to hit the target bitrate", OFFSET(skip_frames), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, VE },
#if FF_API_OPENH264_CABAC
    { "cabac", "Enable cabac(deprecated, use coder)", OFFSET(cabac), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, VE|DEPRECATED },
#endif
    { "coder", "Coder type",  OFFSET(coder), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, 1, VE, "coder" },
        { "default",          NULL, 0, AV_OPT_TYPE_CONST, { .i64 = -1 }, INT_MIN, INT_MAX, VE, "coder" },
        { "cavlc",            NULL, 0, AV_OPT_TYPE_CONST, { .i64 = 0 },  INT_MIN, INT_MAX, VE, "coder" },
        { "cabac",            NULL, 0, AV_OPT_TYPE_CONST, { .i64 = 1 },  INT_MIN, INT_MAX, VE, "coder" },
        { "vlc",              NULL, 0, AV_OPT_TYPE_CONST, { .i64 = 0 },  INT_MIN, INT_MAX, VE, "coder" },
        { "ac",               NULL, 0, AV_OPT_TYPE_CONST, { .i64 = 1 },  INT_MIN, INT_MAX, VE, "coder" },

    { "rc_mode", "Select rate control mode", OFFSET(rc_mode), AV_OPT_TYPE_INT, { .i64 = RC_QUALITY_MODE }, RC_OFF_MODE, RC_TIMESTAMP_MODE, VE, "rc_mode" },
        { "off",       "bit rate control off",                                                 0, AV_OPT_TYPE_CONST, { .i64 = RC_OFF_MODE },         0, 0, VE, "rc_mode" },
        { "quality",   "quality mode",                                                         0, AV_OPT_TYPE_CONST, { .i64 = RC_QUALITY_MODE },     0, 0, VE, "rc_mode" },
        { "bitrate",   "bitrate mode",                                                         0, AV_OPT_TYPE_CONST, { .i64 = RC_BITRATE_MODE },     0, 0, VE, "rc_mode" },
        { "buffer",    "using buffer status to adjust the video quality (no bitrate control)", 0, AV_OPT_TYPE_CONST, { .i64 = RC_BUFFERBASED_MODE }, 0, 0, VE, "rc_mode" },
#if OPENH264_VER_AT_LEAST(1, 4)
        { "timestamp", "bit rate control based on timestamp",                                  0, AV_OPT_TYPE_CONST, { .i64 = RC_TIMESTAMP_MODE },   0, 0, VE, "rc_mode" },
#endif

    { NULL }
};

static const AVClass class = {
    .class_name = "libopenh264enc",
    .item_name  = av_default_item_name,
    .option     = options,
    .version    = LIBAVUTIL_VERSION_INT,
};

static av_cold int svc_encode_close(AVCodecContext *avctx)
{
    SVCContext *s = avctx->priv_data;

    if (s->encoder)
        WelsDestroySVCEncoder(s->encoder);
    if (s->skipped > 0)
        av_log(avctx, AV_LOG_WARNING, "%d frames skipped\n", s->skipped);
    return 0;
}

static av_cold int svc_encode_init(AVCodecContext *avctx)
{
    SVCContext *s = avctx->priv_data;
    SEncParamExt param = { 0 };
    int err;
    int log_level;
    WelsTraceCallback callback_function;
    AVCPBProperties *props;

    if ((err = ff_libopenh264_check_version(avctx)) < 0)
        return AVERROR_ENCODER_NOT_FOUND;

    if (WelsCreateSVCEncoder(&s->encoder)) {
        av_log(avctx, AV_LOG_ERROR, "Unable to create encoder\n");
        return AVERROR_UNKNOWN;
    }

    // Pass all libopenh264 messages to our callback, to allow ourselves to filter them.
    log_level = WELS_LOG_DETAIL;
    (*s->encoder)->SetOption(s->encoder, ENCODER_OPTION_TRACE_LEVEL, &log_level);

    // Set the logging callback function to one that uses av_log() (see implementation above).
    callback_function = (WelsTraceCallback) ff_libopenh264_trace_callback;
    (*s->encoder)->SetOption(s->encoder, ENCODER_OPTION_TRACE_CALLBACK, &callback_function);

    // Set the AVCodecContext as the libopenh264 callback context so that it can be passed to av_log().
    (*s->encoder)->SetOption(s->encoder, ENCODER_OPTION_TRACE_CALLBACK_CONTEXT, &avctx);

    (*s->encoder)->GetDefaultParams(s->encoder, &param);

    if (avctx->framerate.num > 0 && avctx->framerate.den > 0) {
        param.fMaxFrameRate = av_q2d(avctx->framerate);
    } else {
        if (avctx->ticks_per_frame > INT_MAX / avctx->time_base.num) {
            av_log(avctx, AV_LOG_ERROR,
                   "Could not set framerate for libopenh264enc: integer overflow\n");
            return AVERROR(EINVAL);
        }
        param.fMaxFrameRate = 1.0 / av_q2d(avctx->time_base) / FFMAX(avctx->ticks_per_frame, 1);
    }
    param.iPicWidth                  = avctx->width;
    param.iPicHeight                 = avctx->height;
    param.iTargetBitrate             = avctx->bit_rate > 0 ? avctx->bit_rate : TARGET_BITRATE_DEFAULT;
    param.iMaxBitrate                = FFMAX(avctx->rc_max_rate, avctx->bit_rate);
    param.iRCMode                    = s->rc_mode;
    if (avctx->qmax >= 0)
        param.iMaxQp                 = av_clip(avctx->qmax, 1, 51);
    if (avctx->qmin >= 0)
        param.iMinQp                 = av_clip(avctx->qmin, 1, param.iMaxQp);
    param.iTemporalLayerNum          = 1;
    param.iSpatialLayerNum           = 1;
    param.bEnableDenoise             = 0;
    param.bEnableBackgroundDetection = 1;
    param.bEnableAdaptiveQuant       = 1;
    param.bEnableFrameSkip           = s->skip_frames;
    param.bEnableLongTermReference   = 0;
    param.iLtrMarkPeriod             = 30;
    if (avctx->gop_size >= 0)
        param.uiIntraPeriod          = avctx->gop_size;
#if OPENH264_VER_AT_LEAST(1, 4)
    param.eSpsPpsIdStrategy          = CONSTANT_ID;
#else
    param.bEnableSpsPpsIdAddition    = 0;
#endif
    param.bPrefixNalAddingCtrl       = 0;
    param.iLoopFilterDisableIdc      = !s->loopfilter;
    param.iEntropyCodingModeFlag     = s->coder >= 0 ? s->coder : 1;
    param.iMultipleThreadIdc         = avctx->thread_count;

    /* Allow specifying the libopenh264 profile through AVCodecContext. */
    if (FF_PROFILE_UNKNOWN == s->profile &&
        FF_PROFILE_UNKNOWN != avctx->profile)
        switch (avctx->profile) {
        case FF_PROFILE_H264_HIGH:
        case FF_PROFILE_H264_MAIN:
        case FF_PROFILE_H264_CONSTRAINED_BASELINE:
            s->profile = avctx->profile;
            break;
        default:
            av_log(avctx, AV_LOG_WARNING,
                   "Unsupported avctx->profile: %d.\n", avctx->profile);
            break;
        }

    if (s->profile == FF_PROFILE_UNKNOWN && s->coder >= 0)
        s->profile = s->coder == 0 ? FF_PROFILE_H264_CONSTRAINED_BASELINE :
#if OPENH264_VER_AT_LEAST(1, 8)
                                     FF_PROFILE_H264_HIGH;
#else
                                     FF_PROFILE_H264_MAIN;
#endif

    switch (s->profile) {
    case FF_PROFILE_H264_HIGH:
        av_log(avctx, AV_LOG_VERBOSE, "Using %s, "
                "select EProfileIdc PRO_HIGH in libopenh264.\n",
                param.iEntropyCodingModeFlag ? "CABAC" : "CAVLC");
        break;
    case FF_PROFILE_H264_MAIN:
        av_log(avctx, AV_LOG_VERBOSE, "Using %s, "
                "select EProfileIdc PRO_MAIN in libopenh264.\n",
                param.iEntropyCodingModeFlag ? "CABAC" : "CAVLC");
        break;
    case FF_PROFILE_H264_CONSTRAINED_BASELINE:
    case FF_PROFILE_UNKNOWN:
        s->profile = FF_PROFILE_H264_CONSTRAINED_BASELINE;
        param.iEntropyCodingModeFlag = 0;
        av_log(avctx, AV_LOG_VERBOSE, "Using CAVLC, "
               "select EProfileIdc PRO_BASELINE in libopenh264.\n");
        break;
    default:
        s->profile = FF_PROFILE_H264_CONSTRAINED_BASELINE;
        param.iEntropyCodingModeFlag = 0;
        av_log(avctx, AV_LOG_WARNING, "Unsupported profile, "
               "select EProfileIdc PRO_BASELINE in libopenh264.\n");
        break;
    }

    param.sSpatialLayers[0].iVideoWidth         = param.iPicWidth;
    param.sSpatialLayers[0].iVideoHeight        = param.iPicHeight;
    param.sSpatialLayers[0].fFrameRate          = param.fMaxFrameRate;
    param.sSpatialLayers[0].iSpatialBitrate     = param.iTargetBitrate;
    param.sSpatialLayers[0].iMaxSpatialBitrate  = param.iMaxBitrate;
    param.sSpatialLayers[0].uiProfileIdc        = s->profile;

#if OPENH264_VER_AT_LEAST(1, 7)
    if (avctx->sample_aspect_ratio.num && avctx->sample_aspect_ratio.den) {
        // Table E-1.
        static const AVRational sar_idc[] = {
            {   0,  0 }, // Unspecified (never written here).
            {   1,  1 }, {  12, 11 }, {  10, 11 }, {  16, 11 },
            {  40, 33 }, {  24, 11 }, {  20, 11 }, {  32, 11 },
            {  80, 33 }, {  18, 11 }, {  15, 11 }, {  64, 33 },
            { 160, 99 }, // Last 3 are unknown to openh264: {   4,  3 }, {   3,  2 }, {   2,  1 },
        };
        static const ESampleAspectRatio asp_idc[] = {
            ASP_UNSPECIFIED,
            ASP_1x1,      ASP_12x11,   ASP_10x11,   ASP_16x11,
            ASP_40x33,    ASP_24x11,   ASP_20x11,   ASP_32x11,
            ASP_80x33,    ASP_18x11,   ASP_15x11,   ASP_64x33,
            ASP_160x99,
        };
        int num, den, i;

        av_reduce(&num, &den, avctx->sample_aspect_ratio.num,
                  avctx->sample_aspect_ratio.den, 65535);

        for (i = 1; i < FF_ARRAY_ELEMS(sar_idc); i++) {
            if (num == sar_idc[i].num &&
                den == sar_idc[i].den)
                break;
        }
        if (i == FF_ARRAY_ELEMS(sar_idc)) {
            param.sSpatialLayers[0].eAspectRatio = ASP_EXT_SAR;
            param.sSpatialLayers[0].sAspectRatioExtWidth = num;
            param.sSpatialLayers[0].sAspectRatioExtHeight = den;
        } else {
            param.sSpatialLayers[0].eAspectRatio = asp_idc[i];
        }
        param.sSpatialLayers[0].bAspectRatioPresent = true;
    } else {
        param.sSpatialLayers[0].bAspectRatioPresent = false;
    }
#endif

    if ((avctx->slices > 1) && (s->max_nal_size)) {
        av_log(avctx, AV_LOG_ERROR,
               "Invalid combination -slices %d and -max_nal_size %d.\n",
               avctx->slices, s->max_nal_size);
        return AVERROR(EINVAL);
    }

    if (avctx->slices > 1)
        s->slice_mode = SM_FIXEDSLCNUM_SLICE;

    if (s->max_nal_size)
        s->slice_mode = SM_SIZELIMITED_SLICE;

#if OPENH264_VER_AT_LEAST(1, 6)
    param.sSpatialLayers[0].sSliceArgument.uiSliceMode = s->slice_mode;
    param.sSpatialLayers[0].sSliceArgument.uiSliceNum  = avctx->slices;
#else
    param.sSpatialLayers[0].sSliceCfg.uiSliceMode               = s->slice_mode;
    param.sSpatialLayers[0].sSliceCfg.sSliceArgument.uiSliceNum = avctx->slices;
#endif
    if (avctx->slices == 0 && s->slice_mode == SM_FIXEDSLCNUM_SLICE)
        av_log(avctx, AV_LOG_WARNING, "Slice count will be set automatically\n");

    if (s->slice_mode == SM_SIZELIMITED_SLICE) {
        if (s->max_nal_size) {
            param.uiMaxNalSize = s->max_nal_size;
#if OPENH264_VER_AT_LEAST(1, 6)
            param.sSpatialLayers[0].sSliceArgument.uiSliceSizeConstraint = s->max_nal_size;
#else
            param.sSpatialLayers[0].sSliceCfg.sSliceArgument.uiSliceSizeConstraint = s->max_nal_size;
#endif
        } else {
            av_log(avctx, AV_LOG_ERROR, "Invalid -max_nal_size, "
                   "specify a valid max_nal_size to use -slice_mode dyn\n");
            return AVERROR(EINVAL);
        }
    }

#if OPENH264_VER_AT_LEAST(1, 6)
    param.sSpatialLayers[0].uiVideoFormat = VF_UNDEF;
    if (avctx->color_range != AVCOL_RANGE_UNSPECIFIED) {
        param.sSpatialLayers[0].bVideoSignalTypePresent = true;
        param.sSpatialLayers[0].bFullRange = (avctx->color_range == AVCOL_RANGE_JPEG);
    }

    if (avctx->colorspace != AVCOL_SPC_UNSPECIFIED      ||
        avctx->color_primaries != AVCOL_PRI_UNSPECIFIED ||
        avctx->color_trc != AVCOL_TRC_UNSPECIFIED) {
        param.sSpatialLayers[0].bVideoSignalTypePresent = true;
        param.sSpatialLayers[0].bColorDescriptionPresent = true;
    }

    if (avctx->colorspace != AVCOL_SPC_UNSPECIFIED)
        param.sSpatialLayers[0].uiColorMatrix = avctx->colorspace;
    if (avctx->color_primaries != AVCOL_PRI_UNSPECIFIED)
        param.sSpatialLayers[0].uiColorPrimaries = avctx->color_primaries;
    if (avctx->color_trc != AVCOL_TRC_UNSPECIFIED)
        param.sSpatialLayers[0].uiTransferCharacteristics = avctx->color_trc;
#endif

    if ((*s->encoder)->InitializeExt(s->encoder, &param) != cmResultSuccess) {
        av_log(avctx, AV_LOG_ERROR, "Initialize failed\n");
        return AVERROR_UNKNOWN;
    }

    if (avctx->flags & AV_CODEC_FLAG_GLOBAL_HEADER) {
        SFrameBSInfo fbi = { 0 };
        int i, size = 0;
        (*s->encoder)->EncodeParameterSets(s->encoder, &fbi);
        for (i = 0; i < fbi.sLayerInfo[0].iNalCount; i++)
            size += fbi.sLayerInfo[0].pNalLengthInByte[i];
        avctx->extradata = av_mallocz(size + AV_INPUT_BUFFER_PADDING_SIZE);
        if (!avctx->extradata)
            return AVERROR(ENOMEM);
        avctx->extradata_size = size;
        memcpy(avctx->extradata, fbi.sLayerInfo[0].pBsBuf, size);
    }

    props = ff_add_cpb_side_data(avctx);
    if (!props)
        return AVERROR(ENOMEM);
    props->max_bitrate = param.iMaxBitrate;
    props->avg_bitrate = param.iTargetBitrate;

    return 0;
}

static int svc_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
                            const AVFrame *frame, int *got_packet)
{
    SVCContext *s = avctx->priv_data;
    SFrameBSInfo fbi = { 0 };
    int i, ret;
    int encoded;
    SSourcePicture sp = { 0 };
    int size = 0, layer, first_layer = 0;
    int layer_size[MAX_LAYER_NUM_OF_FRAME] = { 0 };

    sp.iColorFormat = videoFormatI420;
    for (i = 0; i < 3; i++) {
        sp.iStride[i] = frame->linesize[i];
        sp.pData[i]   = frame->data[i];
    }
    sp.iPicWidth  = avctx->width;
    sp.iPicHeight = avctx->height;

    if (frame->pict_type == AV_PICTURE_TYPE_I) {
        (*s->encoder)->ForceIntraFrame(s->encoder, true);
    }

    encoded = (*s->encoder)->EncodeFrame(s->encoder, &sp, &fbi);
    if (encoded != cmResultSuccess) {
        av_log(avctx, AV_LOG_ERROR, "EncodeFrame failed\n");
        return AVERROR_UNKNOWN;
    }
    if (fbi.eFrameType == videoFrameTypeSkip) {
        s->skipped++;
        av_log(avctx, AV_LOG_DEBUG, "frame skipped\n");
        return 0;
    }
    first_layer = 0;
    // Normal frames are returned with one single layer, while IDR
    // frames have two layers, where the first layer contains the SPS/PPS.
    // If using global headers, don't include the SPS/PPS in the returned
    // packet - thus, only return one layer.
    if (avctx->flags & AV_CODEC_FLAG_GLOBAL_HEADER)
        first_layer = fbi.iLayerNum - 1;

    for (layer = first_layer; layer < fbi.iLayerNum; layer++) {
        for (i = 0; i < fbi.sLayerInfo[layer].iNalCount; i++)
            layer_size[layer] += fbi.sLayerInfo[layer].pNalLengthInByte[i];
        size += layer_size[layer];
    }
    av_log(avctx, AV_LOG_DEBUG, "%d slices\n", fbi.sLayerInfo[fbi.iLayerNum - 1].iNalCount);

    if ((ret = ff_get_encode_buffer(avctx, avpkt, size, 0)))
        return ret;

    size = 0;
    for (layer = first_layer; layer < fbi.iLayerNum; layer++) {
        memcpy(avpkt->data + size, fbi.sLayerInfo[layer].pBsBuf, layer_size[layer]);
        size += layer_size[layer];
    }
    avpkt->pts = frame->pts;
    if (fbi.eFrameType == videoFrameTypeIDR)
        avpkt->flags |= AV_PKT_FLAG_KEY;
    *got_packet = 1;
    return 0;
}

static const FFCodecDefault svc_enc_defaults[] = {
    { "b",         "0"     },
    { "g",         "-1"    },
    { "qmin",      "-1"    },
    { "qmax",      "-1"    },
    { NULL },
};

const FFCodec ff_libopenh264_encoder = {
    .p.name         = "libopenh264",
    CODEC_LONG_NAME("OpenH264 H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10"),
    .p.type         = AVMEDIA_TYPE_VIDEO,
    .p.id           = AV_CODEC_ID_H264,
    .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_OTHER_THREADS,
    .priv_data_size = sizeof(SVCContext),
    .init           = svc_encode_init,
    FF_CODEC_ENCODE_CB(svc_encode_frame),
    .close          = svc_encode_close,
    .caps_internal  = FF_CODEC_CAP_INIT_CLEANUP |
                      FF_CODEC_CAP_AUTO_THREADS,
    .p.pix_fmts     = (const enum AVPixelFormat[]){ AV_PIX_FMT_YUV420P,
                                                    AV_PIX_FMT_NONE },
    .defaults       = svc_enc_defaults,
    .p.priv_class   = &class,
    .p.wrapper_name = "libopenh264",
};