utils.c

        if (ofmt->query_codec)
            return ofmt->query_codec(codec_id, std_compliance);
        else if (ofmt->codec_tag)
            return !!av_codec_get_tag(ofmt->codec_tag, codec_id);
        else if (codec_id == ofmt->video_codec || codec_id == ofmt->audio_codec ||
                 codec_id == ofmt->subtitle_codec)
            return 1;
    }
    return AVERROR_PATCHWELCOME;
}

int avformat_network_init(void)
{
#if CONFIG_NETWORK
    int ret;
    ff_network_inited_globally = 1;
    if ((ret = ff_network_init()) < 0)
        return ret;
    ff_tls_init();
#endif
    return 0;
}

int avformat_network_deinit(void)
{
#if CONFIG_NETWORK
    ff_network_close();
    ff_tls_deinit();
#endif
    return 0;
}

int ff_add_param_change(AVPacket *pkt, int32_t channels,
                        uint64_t channel_layout, int32_t sample_rate,
                        int32_t width, int32_t height)
{
    uint32_t flags = 0;
    int size = 4;
    uint8_t *data;
    if (!pkt)
        return AVERROR(EINVAL);
    if (channels) {
        size += 4;
        flags |= AV_SIDE_DATA_PARAM_CHANGE_CHANNEL_COUNT;
    }
    if (channel_layout) {
        size += 8;
        flags |= AV_SIDE_DATA_PARAM_CHANGE_CHANNEL_LAYOUT;
    }
    if (sample_rate) {
        size += 4;
        flags |= AV_SIDE_DATA_PARAM_CHANGE_SAMPLE_RATE;
    }
    if (width || height) {
        size += 8;
        flags |= AV_SIDE_DATA_PARAM_CHANGE_DIMENSIONS;
    }
    data = av_packet_new_side_data(pkt, AV_PKT_DATA_PARAM_CHANGE, size);
    if (!data)
        return AVERROR(ENOMEM);
    bytestream_put_le32(&data, flags);
    if (channels)
        bytestream_put_le32(&data, channels);
    if (channel_layout)
        bytestream_put_le64(&data, channel_layout);
    if (sample_rate)
        bytestream_put_le32(&data, sample_rate);
    if (width || height) {
        bytestream_put_le32(&data, width);
        bytestream_put_le32(&data, height);
    }
    return 0;
}