static int pcm_decode_frame(AVCodecContext *avctx,

                            void *data, int *data_size,

                            AVPacket *avpkt)

{

    const uint8_t *buf = avpkt->data;

    int buf_size = avpkt->size;

    PCMDecode *s = avctx->priv_data;

    int sample_size, c, n, i;

    short *samples;

    const uint8_t *src, *src8, *src2[MAX_CHANNELS];

    uint8_t *dstu8;

    int16_t *dst_int16_t;

    int32_t *dst_int32_t;

    int64_t *dst_int64_t;

    uint16_t *dst_uint16_t;

    uint32_t *dst_uint32_t;



    samples = data;

    src = buf;



    if (avctx->sample_fmt!=avctx->codec->sample_fmts[0]) {

        av_log(avctx, AV_LOG_ERROR, "invalid sample_fmt\n");

        return -1;

    }



    if(avctx->channels <= 0 || avctx->channels > MAX_CHANNELS){

        av_log(avctx, AV_LOG_ERROR, "PCM channels out of bounds\n");

        return -1;

    }



    sample_size = av_get_bits_per_sample(avctx->codec_id)/8;



    /* av_get_bits_per_sample returns 0 for CODEC_ID_PCM_DVD */

    if (CODEC_ID_PCM_DVD == avctx->codec_id)

        /* 2 samples are interleaved per block in PCM_DVD */

        sample_size = avctx->bits_per_coded_sample * 2 / 8;

    else if (avctx->codec_id == CODEC_ID_PCM_LXF)

        /* we process 40-bit blocks per channel for LXF */

        sample_size = 5;



    if (sample_size == 0) {

        av_log(avctx, AV_LOG_ERROR, "Invalid sample_size\n");

        return AVERROR(EINVAL);

    }



    n = avctx->channels * sample_size;



    if(n && buf_size % n){

        if (buf_size < n) {

            av_log(avctx, AV_LOG_ERROR, "invalid PCM packet\n");

            return -1;

        }else

            buf_size -= buf_size % n;

    }



    buf_size= FFMIN(buf_size, *data_size/2);

    *data_size=0;



    n = buf_size/sample_size;



    switch(avctx->codec->id) {

    case CODEC_ID_PCM_U32LE:

        DECODE(uint32_t, le32, src, samples, n, 0, 0x80000000)

        break;

    case CODEC_ID_PCM_U32BE:

        DECODE(uint32_t, be32, src, samples, n, 0, 0x80000000)

        break;

    case CODEC_ID_PCM_S24LE:

        DECODE(int32_t, le24, src, samples, n, 8, 0)

        break;

    case CODEC_ID_PCM_S24BE:

        DECODE(int32_t, be24, src, samples, n, 8, 0)

        break;

    case CODEC_ID_PCM_U24LE:

        DECODE(uint32_t, le24, src, samples, n, 8, 0x800000)

        break;

    case CODEC_ID_PCM_U24BE:

        DECODE(uint32_t, be24, src, samples, n, 8, 0x800000)

        break;

    case CODEC_ID_PCM_S24DAUD:

        for(;n>0;n--) {

          uint32_t v = bytestream_get_be24(&src);

          v >>= 4; // sync flags are here

          *samples++ = av_reverse[(v >> 8) & 0xff] +

                       (av_reverse[v & 0xff] << 8);

        }

        break;

    case CODEC_ID_PCM_S16LE_PLANAR:

        n /= avctx->channels;

        for(c=0;c<avctx->channels;c++)

            src2[c] = &src[c*n*2];

        for(;n>0;n--)

            for(c=0;c<avctx->channels;c++)

                *samples++ = bytestream_get_le16(&src2[c]);

        src = src2[avctx->channels-1];

        break;

    case CODEC_ID_PCM_U16LE:

        DECODE(uint16_t, le16, src, samples, n, 0, 0x8000)

        break;

    case CODEC_ID_PCM_U16BE:

        DECODE(uint16_t, be16, src, samples, n, 0, 0x8000)

        break;

    case CODEC_ID_PCM_S8:

        dstu8= (uint8_t*)samples;

        for(;n>0;n--) {

            *dstu8++ = *src++ + 128;

        }

        samples= (short*)dstu8;

        break;

#if HAVE_BIGENDIAN

    case CODEC_ID_PCM_F64LE:

        DECODE(int64_t, le64, src, samples, n, 0, 0)

        break;

    case CODEC_ID_PCM_S32LE:

    case CODEC_ID_PCM_F32LE:

        DECODE(int32_t, le32, src, samples, n, 0, 0)

        break;

    case CODEC_ID_PCM_S16LE:

        DECODE(int16_t, le16, src, samples, n, 0, 0)

        break;

    case CODEC_ID_PCM_F64BE:

    case CODEC_ID_PCM_F32BE:

    case CODEC_ID_PCM_S32BE:

    case CODEC_ID_PCM_S16BE:

#else

    case CODEC_ID_PCM_F64BE:

        DECODE(int64_t, be64, src, samples, n, 0, 0)

        break;

    case CODEC_ID_PCM_F32BE:

    case CODEC_ID_PCM_S32BE:

        DECODE(int32_t, be32, src, samples, n, 0, 0)

        break;

    case CODEC_ID_PCM_S16BE:

        DECODE(int16_t, be16, src, samples, n, 0, 0)

        break;

    case CODEC_ID_PCM_F64LE:

    case CODEC_ID_PCM_F32LE:

    case CODEC_ID_PCM_S32LE:

    case CODEC_ID_PCM_S16LE:

#endif /* HAVE_BIGENDIAN */

    case CODEC_ID_PCM_U8:

        memcpy(samples, src, n*sample_size);

        src += n*sample_size;

        samples = (short*)((uint8_t*)data + n*sample_size);

        break;

    case CODEC_ID_PCM_ZORK:

        for(;n>0;n--) {

            int x= *src++;

            if(x&128) x-= 128;

            else      x = -x;

            *samples++ = x << 8;

        }

        break;

    case CODEC_ID_PCM_ALAW:

    case CODEC_ID_PCM_MULAW:

        for(;n>0;n--) {

            *samples++ = s->table[*src++];

        }

        break;

    case CODEC_ID_PCM_DVD:

        dst_int32_t = data;

        n /= avctx->channels;

        switch (avctx->bits_per_coded_sample) {

        case 20:

            while (n--) {

                c = avctx->channels;

                src8 = src + 4*c;

                while (c--) {

                    *dst_int32_t++ = (bytestream_get_be16(&src) << 16) + ((*src8   &0xf0) << 8);

                    *dst_int32_t++ = (bytestream_get_be16(&src) << 16) + ((*src8++ &0x0f) << 12);

                }

                src = src8;

            }

            break;

        case 24:

            while (n--) {

                c = avctx->channels;

                src8 = src + 4*c;

                while (c--) {

                    *dst_int32_t++ = (bytestream_get_be16(&src) << 16) + ((*src8++) << 8);

                    *dst_int32_t++ = (bytestream_get_be16(&src) << 16) + ((*src8++) << 8);

                }

                src = src8;

            }

            break;

        default:

            av_log(avctx, AV_LOG_ERROR, "PCM DVD unsupported sample depth\n");

            return -1;

        }

        samples = (short *) dst_int32_t;

        break;

    case CODEC_ID_PCM_LXF:

        dst_int32_t = data;

        n /= avctx->channels;

        //unpack and de-planerize

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

            for (c = 0, src8 = src + i*5; c < avctx->channels; c++, src8 += n*5) {

                //extract low 20 bits and expand to 32 bits

                *dst_int32_t++ = (src8[2] << 28) | (src8[1] << 20) | (src8[0] << 12) |

                                 ((src8[2] & 0xF) << 8) | src8[1];

            }



            for (c = 0, src8 = src + i*5; c < avctx->channels; c++, src8 += n*5) {

                //extract high 20 bits and expand to 32 bits

                *dst_int32_t++ = (src8[4] << 24) | (src8[3] << 16) |

                                 ((src8[2] & 0xF0) << 8) | (src8[4] << 4) | (src8[3] >> 4);

            }

        }

        src += n * avctx->channels * 5;

        samples = (short *) dst_int32_t;

        break;

    default:

        return -1;

    }

    *data_size = (uint8_t *)samples - (uint8_t *)data;

    return src - buf;

}
