static int decode_frame_mp3on4(AVCodecContext *avctx, void *data,

                               int *got_frame_ptr, AVPacket *avpkt)

{

    const uint8_t *buf     = avpkt->data;

    int buf_size           = avpkt->size;

    MP3On4DecodeContext *s = avctx->priv_data;

    MPADecodeContext *m;

    int fsize, len = buf_size, out_size = 0;

    uint32_t header;

    OUT_INT *out_samples;

    OUT_INT *outptr, *bp;

    int fr, j, n, ch, ret;



    /* get output buffer */

    s->frame->nb_samples = MPA_FRAME_SIZE;

    if ((ret = avctx->get_buffer(avctx, s->frame)) < 0) {

        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");

        return ret;


    out_samples = (OUT_INT *)s->frame->data[0];



    // Discard too short frames

    if (buf_size < HEADER_SIZE)




    // If only one decoder interleave is not needed

    outptr = s->frames == 1 ? out_samples : s->decoded_buf;



    avctx->bit_rate = 0;



    ch = 0;

    for (fr = 0; fr < s->frames; fr++) {

        fsize = AV_RB16(buf) >> 4;

        fsize = FFMIN3(fsize, len, MPA_MAX_CODED_FRAME_SIZE);

        m     = s->mp3decctx[fr];

        assert(m != NULL);







        header = (AV_RB32(buf) & 0x000fffff) | s->syncword; // patch header



        if (ff_mpa_check_header(header) < 0) // Bad header, discard block

            break;



        avpriv_mpegaudio_decode_header((MPADecodeHeader *)m, header);



        if (ch + m->nb_channels > avctx->channels) {

            av_log(avctx, AV_LOG_ERROR, "frame channel count exceeds codec "

                                        "channel count\n");



        ch += m->nb_channels;



        out_size += mp_decode_frame(m, outptr, buf, fsize);

        buf      += fsize;

        len      -= fsize;



        if (s->frames > 1) {

            n = m->avctx->frame_size*m->nb_channels;

            /* interleave output data */

            bp = out_samples + s->coff[fr];

            if (m->nb_channels == 1) {

                for (j = 0; j < n; j++) {

                    *bp = s->decoded_buf[j];

                    bp += avctx->channels;


            } else {

                for (j = 0; j < n; j++) {

                    bp[0] = s->decoded_buf[j++];

                    bp[1] = s->decoded_buf[j];

                    bp   += avctx->channels;




        avctx->bit_rate += m->bit_rate;




    /* update codec info */

    avctx->sample_rate = s->mp3decctx[0]->sample_rate;



    s->frame->nb_samples = out_size / (avctx->channels * sizeof(OUT_INT));

    *got_frame_ptr   = 1;

    *(AVFrame *)data = *s->frame;



    return buf_size;
