video-pc/AvPlayer2/video_state.cpp

// ***********************************************************/
// video_state.cpp
//
//      Copy Right @ Steven Huang. All rights reserved.
//
// A/V synchronization state. This code is referenced
// from ffplay.c in Ffmpeg library.
// ***********************************************************/
#include "video_state.h"

int infinite_buffer = -1;
int64_t start_time = AV_NOPTS_VALUE;
static enum AVPixelFormat hw_pix_fmt;

VideoStateData::VideoStateData(bool use_hardware, bool loop_play)
    : m_bUseHardware(use_hardware)
    , m_bLoopPlay(loop_play)
{}

VideoStateData::~VideoStateData()
{
    close_hardware();
    delete_video_state();
}

void VideoStateData::delete_video_state()
{
    if (m_pState) {
        stream_close(m_pState);
        m_pState = nullptr;
    }
}

VideoState* VideoStateData::get_state() const
{
    return m_pState;
}

bool VideoStateData::is_hardware_decode() const
{
    return m_bHardwareSuccess;
}

int VideoStateData::create_video_state(const char* filename)
{
    int ret = -1;
    if (!filename || !filename[0]) {
        qDebug("filename is invalid, please select a valid media file.");
        return ret;
    }

    m_pState = stream_open(filename);
    if (!m_pState) {
        qDebug("stream_open failed!");
        return ret;
    }

    return open_media(m_pState);
}

void VideoStateData::print_state() const
{
    if (const auto is = m_pState) {
        qDebug("[VideoState]PacketQueue(v:%p,a:%p,s:%p)", &is->videoq, &is->audioq, &is->subtitleq);
        qDebug("[VideoState]FrameQueue(v:%p,a:%p,s:%p)", &is->pictq, &is->sampq, &is->subpq);
        qDebug("[VideoState]Decoder(v:%p,a:%p,s:%p)", &is->viddec, &is->auddec, &is->subdec);
        qDebug("[VideoState]Clock(v:%p,a:%p,s:%p)", &is->vidclk, &is->audclk, &is->extclk);
    }
}

int VideoStateData::open_media(VideoState* is)
{
    assert(is);
    int err;
    uint i;
    int ret = -1;
    int st_index[AVMEDIA_TYPE_NB];
    AVFormatContext* ic = nullptr;
    const char* wanted_stream_spec[AVMEDIA_TYPE_NB] = {0};

    memset(st_index, -1, sizeof(st_index));

    is->eof = 0;

    ic = avformat_alloc_context();
    if (!ic) {
        av_log(nullptr, AV_LOG_FATAL, "Could not allocate context.\n");
        ret = AVERROR(ENOMEM);
        goto fail;
    }

    ic->interrupt_callback.callback = nullptr; // decode_interrupt_cb;
    ic->interrupt_callback.opaque = is;

    err = avformat_open_input(&ic, is->filename, is->iformat, nullptr);
    if (err < 0) {
        av_log(nullptr, AV_LOG_FATAL, "failed to open %s: %d", is->filename, err);
        ret = -1;
        goto fail;
    }

    is->ic = ic;

    //ic->flags |= AVFMT_FLAG_GENPTS; // gen pts

    av_format_inject_global_side_data(ic);

    //AVDictionary** opts = setup_find_stream_info_opts(ic, codec_opts);
    //int orig_nb_streams = ic->nb_streams;

    err = avformat_find_stream_info(ic, nullptr);
    if (err < 0) {
        av_log(nullptr, AV_LOG_WARNING, "%s: could not find codec parameters\n", is->filename);
        ret = -1;
        goto fail;
    }

    if (ic->pb)
        ic->pb->eof_reached = 0; // FIXME hack, ffplay maybe should not use
                                 // avio_feof() to test for the end

    // if (seek_by_bytes < 0)
    //	seek_by_bytes = (ic->iformat->flags & AVFMT_TS_DISCONT) &&
    //strcmp("ogg", ic->iformat->name);

    //is->max_frame_duration = (ic->iformat->flags & AVFMT_TS_DISCONT) ? 10.0 : 3600.0;
    is->max_frame_duration = 2.0;

    /* if seeking requested, we execute it */
    if (start_time != AV_NOPTS_VALUE) {
        int64_t timestamp;

        timestamp = start_time;
        /* add the stream start time */
        if (ic->start_time != AV_NOPTS_VALUE)
            timestamp += ic->start_time;
        ret = avformat_seek_file(ic, -1, INT64_MIN, timestamp, INT64_MAX, 0);
        if (ret < 0) {
            av_log(nullptr,
                   AV_LOG_WARNING,
                   "%s: could not seek to position %0.3f\n",
                   is->filename,
                   (double) timestamp / AV_TIME_BASE);
        }
    }

    is->realtime = is_realtime(ic);

    av_dump_format(ic, 0, is->filename, 0);

    for (i = 0; i < ic->nb_streams; i++) {
        AVStream* st = ic->streams[i];
        enum AVMediaType type = st->codecpar->codec_type;
        st->discard = AVDISCARD_ALL;
        if (type >= 0 && wanted_stream_spec[type] && st_index[type] == -1)
            if (avformat_match_stream_specifier(ic, st, wanted_stream_spec[type]) > 0)
                st_index[type] = i;
    }
    for (i = 0; i < AVMEDIA_TYPE_NB; i++) {
        if (wanted_stream_spec[i] && st_index[i] == -1) {
            av_log(nullptr,
                   AV_LOG_ERROR,
                   "Stream specifier %s does not match any %s stream\n",
                   wanted_stream_spec[i],
                   av_get_media_type_string(AVMediaType(i)));
            st_index[i] = INT_MAX;
        }
    }

    st_index[AVMEDIA_TYPE_VIDEO]
        = av_find_best_stream(ic, AVMEDIA_TYPE_VIDEO, st_index[AVMEDIA_TYPE_VIDEO], -1, nullptr, 0);
    st_index[AVMEDIA_TYPE_AUDIO] = av_find_best_stream(ic,
                                                       AVMEDIA_TYPE_AUDIO,
                                                       st_index[AVMEDIA_TYPE_AUDIO],
                                                       st_index[AVMEDIA_TYPE_VIDEO],
                                                       nullptr,
                                                       0);
    st_index[AVMEDIA_TYPE_SUBTITLE] = av_find_best_stream(ic,
                                                          AVMEDIA_TYPE_SUBTITLE,
                                                          st_index[AVMEDIA_TYPE_SUBTITLE],
                                                          (st_index[AVMEDIA_TYPE_AUDIO] >= 0
                                                               ? st_index[AVMEDIA_TYPE_AUDIO]
                                                               : st_index[AVMEDIA_TYPE_VIDEO]),
                                                          nullptr,
                                                          0);

    /* open the streams */
    if (st_index[AVMEDIA_TYPE_VIDEO] >= 0) {
        stream_component_open(is, st_index[AVMEDIA_TYPE_VIDEO]);
    }

    if (st_index[AVMEDIA_TYPE_AUDIO] >= 0) {
        stream_component_open(is, st_index[AVMEDIA_TYPE_AUDIO]);
    }

    if (st_index[AVMEDIA_TYPE_SUBTITLE] >= 0) {
        stream_component_open(is, st_index[AVMEDIA_TYPE_SUBTITLE]);
    }

    if (is->video_stream < 0 && is->audio_stream < 0) {
        av_log(nullptr,
               AV_LOG_FATAL,
               "Failed to open file '%s' or configure filtergraph\n",
               is->filename);
        ret = -1;
        goto fail;
    }

    if (infinite_buffer < 0 && is->realtime)
        infinite_buffer = 1;

    return 0;

fail:
    if (ic && !is->ic)
        avformat_close_input(&ic);
    return ret;
}

VideoState* VideoStateData::stream_open(const char* filename, const AVInputFormat* iformat)
{
    VideoState* is = nullptr;

    int startup_volume = 100;
    int av_sync_type = AV_SYNC_AUDIO_MASTER;

    is = (VideoState*) av_mallocz(sizeof(VideoState));
    if (!is)
        return nullptr;
    is->last_video_stream = is->video_stream = -1;
    is->last_audio_stream = is->audio_stream = -1;
    is->last_subtitle_stream = is->subtitle_stream = -1;
    is->filename = av_strdup(filename);
    if (!is->filename)
        goto fail;
    is->iformat = iformat;
    is->ytop = 0;
    is->xleft = 0;

    /* start video display */
    if (frame_queue_init(&is->pictq, &is->videoq, VIDEO_PICTURE_QUEUE_SIZE, 1) < 0)
        goto fail;
    if (frame_queue_init(&is->subpq, &is->subtitleq, SUBPICTURE_QUEUE_SIZE, 0) < 0)
        goto fail;
    if (frame_queue_init(&is->sampq, &is->audioq, SAMPLE_QUEUE_SIZE, 1) < 0)
        goto fail;

    if (packet_queue_init(&is->videoq) < 0 || packet_queue_init(&is->audioq) < 0
        || packet_queue_init(&is->subtitleq) < 0)
        goto fail;

    if (!(is->continue_read_thread = new QWaitCondition())) {
        av_log(nullptr, AV_LOG_FATAL, "new QWaitCondition() failed!\n");
        goto fail;
    }

    init_clock(&is->vidclk, &is->videoq.serial);
    init_clock(&is->audclk, &is->audioq.serial);
    init_clock(&is->extclk, &is->extclk.serial);
    is->audio_clock_serial = -1;
    if (startup_volume < 0)
        av_log(nullptr, AV_LOG_WARNING, "-volume=%d < 0, setting to 0\n", startup_volume);
    if (startup_volume > 100)
        av_log(nullptr, AV_LOG_WARNING, "-volume=%d > 100, setting to 100\n", startup_volume);
    startup_volume = av_clip(startup_volume, 0, 100);
    startup_volume = av_clip(SDL_MIX_MAXVOLUME * startup_volume / 100, 0, SDL_MIX_MAXVOLUME);
    is->audio_volume = startup_volume;
    is->muted = 0;
    is->av_sync_type = av_sync_type;
    // is->read_tid = m_pReadThreadId;
    is->read_thread_exit = -1;
    is->loop = int(m_bLoopPlay);

    is->threads = {nullptr};

#if USE_AVFILTER_AUDIO
    is->audio_speed = 1.0;
#endif
    return is;
fail:
    stream_close(is);
    return nullptr;
}

void VideoStateData::threads_setting(VideoState* is, const Threads& threads)
{
    if (!is)
        return;

    assert(!is->threads.read_tid);
    assert(!is->threads.video_decode_tid);
    assert(!is->threads.audio_decode_tid);
    assert(!is->threads.video_play_tid);
    assert(!is->threads.audio_play_tid);
    assert(!is->threads.subtitle_decode_tid);

    is->threads = threads;
}

void VideoStateData::read_thread_exit_wait(VideoState* is)
{
    if (!is)
        return;

    if (is->read_thread_exit != 0)
        return;

    if (is->threads.read_tid) {
        av_log(nullptr, AV_LOG_INFO, "read thread wait before!\n");
        is->threads.read_tid->wait();
        av_log(nullptr, AV_LOG_INFO, "read thread wait after!\n");
        is->threads.read_tid = nullptr;
    }
}

void VideoStateData::threads_exit_wait(VideoState* is)
{
    if (!is)
        return;

    if (is->threads.video_play_tid) {
        is->threads.video_play_tid->wait();
        is->threads.video_play_tid = nullptr;
    }

    if (is->threads.audio_play_tid) {
        is->threads.audio_play_tid->wait();
        is->threads.audio_play_tid = nullptr;
    }

    if (is->threads.video_decode_tid) {
        is->threads.video_decode_tid->wait();
        is->threads.video_decode_tid = nullptr;
    }

    if (is->threads.audio_decode_tid) {
        is->threads.audio_decode_tid->wait();
        is->threads.audio_decode_tid = nullptr;
    }

    if (is->threads.subtitle_decode_tid) {
        is->threads.subtitle_decode_tid->wait();
        is->threads.subtitle_decode_tid = nullptr;
    }
}

void VideoStateData::stream_close(VideoState* is)
{
    assert(is);

    is->abort_request = 1;

    read_thread_exit_wait(is);

    // if (is->read_thread_exit == 0)
    //{
    //	// SDL_WaitThread(is->read_tid, nullptr);
    //	//((QThread*)(is->read_tid))->wait();
    //	/*if (m_pReadThreadId)
    //		m_pReadThreadId->wait();*/
    //}

    /* close each stream */
    if (is->audio_stream >= 0)
        stream_component_close(is, is->audio_stream);
    if (is->video_stream >= 0)
        stream_component_close(is, is->video_stream);
    if (is->subtitle_stream >= 0)
        stream_component_close(is, is->subtitle_stream);

    threads_exit_wait(is); // read and decode threads exit here.

    avformat_close_input(&is->ic);

    packet_queue_destroy(&is->videoq);
    packet_queue_destroy(&is->audioq);
    packet_queue_destroy(&is->subtitleq);

    /* free all pictures */
    frame_queue_destory(&is->pictq);
    frame_queue_destory(&is->sampq);
    frame_queue_destory(&is->subpq);

    if (is->continue_read_thread) {
        delete is->continue_read_thread;
        is->continue_read_thread = nullptr;
    }

    // SDL_DestroyCond(is->continue_read_thread);
    sws_freeContext(is->img_convert_ctx);
    sws_freeContext(is->sub_convert_ctx);
    av_free(is->filename);
    /*if (is->vis_texture)
          SDL_DestroyTexture(is->vis_texture);
  if (is->vid_texture)
          SDL_DestroyTexture(is->vid_texture);
  if (is->sub_texture)
          SDL_DestroyTexture(is->sub_texture);*/

    av_free(is);
}

static enum AVPixelFormat get_hw_format(AVCodecContext* ctx, const enum AVPixelFormat* pix_fmts)
{
    for (const enum AVPixelFormat* p = pix_fmts; *p != -1; p++) {
        if (*p == hw_pix_fmt)
            return *p;
    }

    fprintf(stderr, "Failed to get HW surface format, codec_id=%d\n", (int) ctx->codec_id);
    return AV_PIX_FMT_NONE;
}

// static int hw_decoder_init(AVCodecContext* ctx, const enum AVHWDeviceType
// type)
//{
//	int err = 0;
//
//	if ((err = av_hwdevice_ctx_create(&hw_device_ctx, type, nullptr,
//nullptr, 0)) < 0) { 		fprintf(stderr, "Failed to create specified HW
//device.\n"); 		return err;
//	}
//
//	ctx->hw_device_ctx = av_buffer_ref(hw_device_ctx);
//
//	return err;
//}

int VideoStateData::hw_decoder_init(AVCodecContext* ctx, const enum AVHWDeviceType type)
{
    int err = 0;

    if ((err = av_hwdevice_ctx_create(&m_hw_device_ctx, type, nullptr, nullptr, 0)) < 0) {
        fprintf(stderr, "Failed to create specified HW device.\n");
        return err;
    }

    ctx->hw_device_ctx = av_buffer_ref(m_hw_device_ctx);

    return err;
}

bool VideoStateData::open_hardware(AVCodecContext* avctx, const AVCodec* codec, const char* device)
{
    enum AVHWDeviceType type = get_hwdevice(device);
    hw_pix_fmt = get_hwdevice_decoder(codec, type);

    avctx->get_format = get_hw_format;

    if (hw_decoder_init(avctx, type) < 0)
        return false;

    return true;
}

void VideoStateData::close_hardware()
{
    av_buffer_unref(&m_hw_device_ctx);
}

int VideoStateData::stream_component_open(VideoState* is, int stream_index)
{
    assert(is);
    AVFormatContext* ic = is->ic;
    AVCodecContext* avctx;
    const AVCodec* codec;
    AVDictionary* opts = nullptr;
    // const AVDictionaryEntry* t = nullptr;
    int sample_rate, nb_channels;
    AVChannelLayout ch_layout = {0};
    // int64_t
    int format;
    int ret = 0;
    int stream_lowres = 0;

    if (stream_index < 0 || ((unsigned int) stream_index) >= ic->nb_streams)
        return -1;

    avctx = avcodec_alloc_context3(nullptr);
    if (!avctx)
        return AVERROR(ENOMEM);

    ret = avcodec_parameters_to_context(avctx, ic->streams[stream_index]->codecpar);
    if (ret < 0)
        goto fail;
    avctx->pkt_timebase = ic->streams[stream_index]->time_base;

    codec = avcodec_find_decoder(avctx->codec_id);

    switch (avctx->codec_type) {
    case AVMEDIA_TYPE_AUDIO:
        is->last_audio_stream = stream_index;
        break;
    case AVMEDIA_TYPE_SUBTITLE:
        is->last_subtitle_stream = stream_index;
        break;
    case AVMEDIA_TYPE_VIDEO:
        is->last_video_stream = stream_index;

        if (m_bUseHardware) {
            m_bHardwareSuccess = false;
            const char* hardware_device = "dxva2"; // device = <vaapi|vdpau|dxva2|d3d11va>
            ret = open_hardware(avctx, codec, hardware_device);
            if (!ret) {
                qWarning("hardware-accelerated opened failed, device:%s", hardware_device);
                goto fail;
            }

            qInfo("hardware-accelerated opened, device:%s", hardware_device);
            m_bHardwareSuccess = true;
        }
        break;
    }

    if (!codec) {
        av_log(nullptr,
               AV_LOG_WARNING,
               "No decoder could be found for codec %s\n",
               avcodec_get_name(avctx->codec_id));
        ret = AVERROR(EINVAL);
        goto fail;
    }

    avctx->codec_id = codec->id;
    if (stream_lowres > codec->max_lowres) {
        av_log(avctx,
               AV_LOG_WARNING,
               "The maximum value for lowres supported by the decoder is %d\n",
               codec->max_lowres);
        stream_lowres = codec->max_lowres;
    }
    avctx->lowres = stream_lowres;

    // avctx->flags2 |= AV_CODEC_FLAG2_FAST;
    /*opts = filter_codec_opts(codec_opts, avctx->codec_id, ic, ic->streams[stream_index], codec);
    if (!av_dict_get(opts, "threads", NULL, 0))
        av_dict_set(&opts, "threads", "auto", 0);
    if (stream_lowres)
        av_dict_set_int(&opts, "lowres", stream_lowres, 0);*/

    if ((ret = avcodec_open2(avctx, codec, &opts)) < 0) {
        goto fail;
    }

    is->eof = 0;
    ic->streams[stream_index]->discard = AVDISCARD_DEFAULT;
    switch (avctx->codec_type) {
    case AVMEDIA_TYPE_AUDIO:
#if USE_AVFILTER_AUDIO
    {
        AVFilterContext* sink;
        // const char* afilters =
        // "aresample=8000,aformat=sample_fmts=s16:channel_layouts=mono"; //
        // "atempo=2"; const char* afilters = nullptr; const char* afilters =
        // "atempo=2.0";
        is->audio_filter_src.freq = avctx->sample_rate;
        is->audio_filter_src.ch_layout.nb_channels = avctx->ch_layout.nb_channels; // avctx->channels;
        is->audio_filter_src.ch_layout = avctx->ch_layout; //  avctx->channel_layout
        is->audio_filter_src.fmt = avctx->sample_fmt;
        if ((ret = configure_audio_filters(is, is->afilters, 0)) < 0)
            goto fail;

        sink = is->out_audio_filter;
        sample_rate = av_buffersink_get_sample_rate(sink);
        nb_channels = av_buffersink_get_channels(sink);
        // channel_layout = av_buffersink_get_channel_layout(sink);
        format = av_buffersink_get_format(sink);
        AVChannelLayout chn_layout;
        av_buffersink_get_ch_layout(sink, &chn_layout);
        qDebug("afilter sink: sample rate:%d, chn:%d, fmt:%d, chn_layout:%d",
               sample_rate,
               nb_channels,
               format,
               chn_layout.u);
    }
#else
        sample_rate = avctx->sample_rate;
        ret = av_channel_layout_copy(&ch_layout, &avctx->ch_layout);
        if (ret < 0)
            goto fail;

#endif
        /* prepare audio output */
        /*if ((ret = audio_open(is, chn_layout, nb_channels, sample_rate,
    &is->audio_tgt)) < 0) goto fail;

    is->audio_src = is->audio_tgt;*/

        is->audio_stream = stream_index;
        is->audio_st = ic->streams[stream_index];

        if ((is->ic->iformat->flags
             & (AVFMT_NOBINSEARCH | AVFMT_NOGENSEARCH | AVFMT_NO_BYTE_SEEK))) {
            is->auddec.start_pts = is->audio_st->start_time;
            is->auddec.start_pts_tb = is->audio_st->time_base;
        }

        m_bHasAudio = true;
        m_avctxAudio = avctx;
        break;

    case AVMEDIA_TYPE_VIDEO:
        is->video_stream = stream_index;
        is->video_st = ic->streams[stream_index];

        m_bHasVideo = true;
        m_avctxVideo = avctx;
        break;

    case AVMEDIA_TYPE_SUBTITLE:
        is->subtitle_stream = stream_index;
        is->subtitle_st = ic->streams[stream_index];

        m_bHasSubtitle = true;
        m_avctxSubtitle = avctx;
        break;

    default:
        break;
    }

    goto out;

fail:
    avcodec_free_context(&avctx);
out:
    av_dict_free(&opts);
    return ret;
}

void VideoStateData::stream_component_close(VideoState* is, int stream_index)
{
    assert(is);
    AVFormatContext* ic = is->ic;
    AVCodecParameters* codecpar;

    if (stream_index < 0 || ((unsigned int) stream_index) >= ic->nb_streams)
        return;

    codecpar = ic->streams[stream_index]->codecpar;

    switch (codecpar->codec_type) {
    case AVMEDIA_TYPE_AUDIO:
        decoder_abort(&is->auddec, &is->sampq);
        // SDL_CloseAudioDevice(audio_dev);
        decoder_destroy(&is->auddec);

        // swr_free(&is->swr_ctx);
        // av_freep(&is->audio_buf1);
        // is->audio_buf1_size = 0;
        // is->audio_buf = nullptr;

        /*if (is->rdft) {
            av_rdft_end(is->rdft);
            av_freep(&is->rdft_data);
            is->rdft = nullptr;
            is->rdft_bits = 0;
            }*/
        break;

    case AVMEDIA_TYPE_VIDEO:
        decoder_abort(&is->viddec, &is->pictq);
        decoder_destroy(&is->viddec);
        break;

    case AVMEDIA_TYPE_SUBTITLE:
        decoder_abort(&is->subdec, &is->subpq);
        decoder_destroy(&is->subdec);
        break;

    default:
        qDebug("Not handled yet.......code type:%d", codecpar->codec_type);
        break;
    }

    ic->streams[stream_index]->discard = AVDISCARD_ALL;
    switch (codecpar->codec_type) {
    case AVMEDIA_TYPE_AUDIO:
        is->audio_st = nullptr;
        is->audio_stream = -1;
        break;
    case AVMEDIA_TYPE_VIDEO:
        is->video_st = nullptr;
        is->video_stream = -1;
        break;
    case AVMEDIA_TYPE_SUBTITLE:
        is->subtitle_st = nullptr;
        is->subtitle_stream = -1;
        break;
    default:
        break;
    }
}

bool VideoStateData::has_video() const
{
    return m_bHasVideo;
}

bool VideoStateData::has_audio() const
{
    return m_bHasAudio;
}

bool VideoStateData::has_subtitle() const
{
    return m_bHasSubtitle;
}

AVCodecContext* VideoStateData::get_contex(AVMediaType type) const
{
    AVCodecContext* pCtx = nullptr;
    switch (type) {
    case AVMEDIA_TYPE_AUDIO:
        pCtx = m_avctxAudio;
        break;
    case AVMEDIA_TYPE_VIDEO:
        pCtx = m_avctxVideo;
        break;
    case AVMEDIA_TYPE_SUBTITLE:
        pCtx = m_avctxSubtitle;
        break;
    default:
        break;
    }
    return pCtx;
}

enum AVHWDeviceType VideoStateData::get_hwdevice(const char* device) const
{
    // device = <vaapi|vdpau|dxva2|d3d11va>
    enum AVHWDeviceType type = av_hwdevice_find_type_by_name(device);
    if (type == AV_HWDEVICE_TYPE_NONE) {
        av_log(nullptr, AV_LOG_WARNING, "Device type %s is not supported.\n", device);

        av_log(nullptr, AV_LOG_INFO, "Available device types:");
        while ((type = av_hwdevice_iterate_types(type)) != AV_HWDEVICE_TYPE_NONE)
            av_log(nullptr, AV_LOG_INFO, " %s", av_hwdevice_get_type_name(type));
        av_log(nullptr, AV_LOG_INFO, "\n");
        return AV_HWDEVICE_TYPE_NONE;
    }
    return type;
}

enum AVPixelFormat VideoStateData::get_hwdevice_decoder(const AVCodec* decoder,
                                                        enum AVHWDeviceType type) const
{
    if (!decoder || AV_HWDEVICE_TYPE_NONE == type)
        return AV_PIX_FMT_NONE;

    for (int i = 0;; i++) {
        const AVCodecHWConfig* config = avcodec_get_hw_config(decoder, i);
        if (!config) {
            av_log(nullptr,
                   AV_LOG_WARNING,
                   "Decoder %s does not support device type %s.\n",
                   decoder->name,
                   av_hwdevice_get_type_name(type));
            return AV_PIX_FMT_NONE;
        }
        if (config->methods & AV_CODEC_HW_CONFIG_METHOD_HW_DEVICE_CTX
            && config->device_type == type) {
            return config->pix_fmt;
        }
    }
    return AV_PIX_FMT_NONE;
}