static int oma_read_header(AVFormatContext *s)

{

    int     ret, framesize, jsflag, samplerate;

    uint32_t codec_params, channel_id;

    int16_t eid;

    uint8_t buf[EA3_HEADER_SIZE];

    uint8_t *edata;

    AVStream *st;

    ID3v2ExtraMeta *extra_meta = NULL;

    OMAContext *oc = s->priv_data;



    ff_id3v2_read(s, ID3v2_EA3_MAGIC, &extra_meta, 0);

    ret = avio_read(s->pb, buf, EA3_HEADER_SIZE);

    if (ret < EA3_HEADER_SIZE)

        return -1;



    if (memcmp(buf, ((const uint8_t[]){'E', 'A', '3'}), 3) ||

        buf[4] != 0 || buf[5] != EA3_HEADER_SIZE) {

        av_log(s, AV_LOG_ERROR, "Couldn't find the EA3 header !\n");

        return AVERROR_INVALIDDATA;

    }



    oc->content_start = avio_tell(s->pb);



    /* encrypted file */

    eid = AV_RB16(&buf[6]);

    if (eid != -1 && eid != -128 && decrypt_init(s, extra_meta, buf) < 0) {

        ff_id3v2_free_extra_meta(&extra_meta);

        return -1;

    }



    ff_id3v2_free_extra_meta(&extra_meta);



    codec_params = AV_RB24(&buf[33]);



    st = avformat_new_stream(s, NULL);

    if (!st)

        return AVERROR(ENOMEM);



    st->start_time = 0;

    st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;

    st->codecpar->codec_tag  = buf[32];

    st->codecpar->codec_id   = ff_codec_get_id(ff_oma_codec_tags,

                                               st->codecpar->codec_tag);



    switch (buf[32]) {

    case OMA_CODECID_ATRAC3:

        samplerate = ff_oma_srate_tab[(codec_params >> 13) & 7] * 100;

        if (!samplerate) {

            av_log(s, AV_LOG_ERROR, "Unsupported sample rate\n");

            return AVERROR_INVALIDDATA;

        }

        if (samplerate != 44100)

            avpriv_request_sample(s, "Sample rate %d", samplerate);



        framesize = (codec_params & 0x3FF) * 8;



        /* get stereo coding mode, 1 for joint-stereo */

        jsflag = (codec_params >> 17) & 1;



        st->codecpar->channels    = 2;

        st->codecpar->channel_layout = AV_CH_LAYOUT_STEREO;

        st->codecpar->sample_rate = samplerate;

        st->codecpar->bit_rate    = st->codecpar->sample_rate * framesize * 8 / 1024;



        /* fake the ATRAC3 extradata

         * (wav format, makes stream copy to wav work) */

        if (ff_alloc_extradata(st->codecpar, 14))

            return AVERROR(ENOMEM);



        edata = st->codecpar->extradata;

        AV_WL16(&edata[0],  1);             // always 1

        AV_WL32(&edata[2],  samplerate);    // samples rate

        AV_WL16(&edata[6],  jsflag);        // coding mode

        AV_WL16(&edata[8],  jsflag);        // coding mode

        AV_WL16(&edata[10], 1);             // always 1

        // AV_WL16(&edata[12], 0);          // always 0



        avpriv_set_pts_info(st, 64, 1, st->codecpar->sample_rate);

        break;

    case OMA_CODECID_ATRAC3P:

        channel_id = (codec_params >> 10) & 7;

        if (!channel_id) {

            av_log(s, AV_LOG_ERROR,

                   "Invalid ATRAC-X channel id: %"PRIu32"\n", channel_id);

            return AVERROR_INVALIDDATA;

        }

        st->codecpar->channel_layout = ff_oma_chid_to_native_layout[channel_id - 1];

        st->codecpar->channels       = ff_oma_chid_to_num_channels[channel_id - 1];

        framesize = ((codec_params & 0x3FF) * 8) + 8;

        samplerate = ff_oma_srate_tab[(codec_params >> 13) & 7] * 100;

        if (!samplerate) {

            av_log(s, AV_LOG_ERROR, "Unsupported sample rate\n");

            return AVERROR_INVALIDDATA;

        }

        st->codecpar->sample_rate = samplerate;

        st->codecpar->bit_rate    = samplerate * framesize * 8 / 2048;

        avpriv_set_pts_info(st, 64, 1, samplerate);

        break;

    case OMA_CODECID_MP3:

        st->need_parsing = AVSTREAM_PARSE_FULL_RAW;

        framesize = 1024;

        break;

    case OMA_CODECID_LPCM:

        /* PCM 44.1 kHz 16 bit stereo big-endian */

        st->codecpar->channels = 2;

        st->codecpar->channel_layout = AV_CH_LAYOUT_STEREO;

        st->codecpar->sample_rate = 44100;

        framesize = 1024;

        /* bit rate = sample rate x PCM block align (= 4) x 8 */

        st->codecpar->bit_rate = st->codecpar->sample_rate * 32;

        st->codecpar->bits_per_coded_sample =

            av_get_bits_per_sample(st->codecpar->codec_id);

        avpriv_set_pts_info(st, 64, 1, st->codecpar->sample_rate);

        break;

    default:

        av_log(s, AV_LOG_ERROR, "Unsupported codec %d!\n", buf[32]);

        return AVERROR(ENOSYS);

    }



    st->codecpar->block_align = framesize;



    return 0;

}
