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

                            int *got_frame_ptr, AVPacket *avpkt)

{

    const uint8_t *src = avpkt->data;

    int buf_size       = avpkt->size;

    PCMDecode *s       = avctx->priv_data;

    AVFrame *frame     = data;

    int sample_size, c, n, ret, samples_per_block;

    uint8_t *samples;

    int32_t *dst_int32_t;



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



    /* av_get_bits_per_sample returns 0 for AV_CODEC_ID_PCM_DVD */

    samples_per_block = 1;

    if (avctx->codec->id == AV_CODEC_ID_PCM_DVD) {

        if (avctx->bits_per_coded_sample != 20 &&

            avctx->bits_per_coded_sample != 24) {

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

            return AVERROR(EINVAL);

        }

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

        samples_per_block = 2;

        sample_size       = avctx->bits_per_coded_sample * 2 / 8;

    } else if (avctx->codec_id == AV_CODEC_ID_PCM_LXF) {

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

        samples_per_block = 2;

        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;

    }



    n = buf_size / sample_size;



    /* get output buffer */

    frame->nb_samples = n * samples_per_block / avctx->channels;

    if ((ret = ff_get_buffer(avctx, frame, 0)) < 0) {

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

        return ret;

    }

    samples = frame->data[0];



    switch (avctx->codec->id) {

    case AV_CODEC_ID_PCM_U32LE:

        DECODE(32, le32, src, samples, n, 0, 0x80000000)

        break;

    case AV_CODEC_ID_PCM_U32BE:

        DECODE(32, be32, src, samples, n, 0, 0x80000000)

        break;

    case AV_CODEC_ID_PCM_S24LE:

        DECODE(32, le24, src, samples, n, 8, 0)

        break;

    case AV_CODEC_ID_PCM_S24BE:

        DECODE(32, be24, src, samples, n, 8, 0)

        break;

    case AV_CODEC_ID_PCM_U24LE:

        DECODE(32, le24, src, samples, n, 8, 0x800000)

        break;

    case AV_CODEC_ID_PCM_U24BE:

        DECODE(32, be24, src, samples, n, 8, 0x800000)

        break;

    case AV_CODEC_ID_PCM_S24DAUD:

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

            uint32_t v = bytestream_get_be24(&src);

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

            AV_WN16A(samples, ff_reverse[(v >> 8) & 0xff] +

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

            samples += 2;

        }

        break;

    case AV_CODEC_ID_PCM_S16LE_PLANAR:

    {

        int av_unused n2;

        n /= avctx->channels;

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

            samples = frame->extended_data[c];

#if HAVE_BIGENDIAN

            n2 = n;

            DECODE(16, le16, src, samples, n2, 0, 0)

#else

            memcpy(samples, src, n * 2);

            src += n * 2;

#endif

        }

        break;

    }

    case AV_CODEC_ID_PCM_U16LE:

        DECODE(16, le16, src, samples, n, 0, 0x8000)

        break;

    case AV_CODEC_ID_PCM_U16BE:

        DECODE(16, be16, src, samples, n, 0, 0x8000)

        break;

    case AV_CODEC_ID_PCM_S8:

        for (; n > 0; n--)

            *samples++ = *src++ + 128;

        break;

#if HAVE_BIGENDIAN

    case AV_CODEC_ID_PCM_F64LE:

        DECODE(64, le64, src, samples, n, 0, 0)

        break;

    case AV_CODEC_ID_PCM_S32LE:

    case AV_CODEC_ID_PCM_F32LE:

        DECODE(32, le32, src, samples, n, 0, 0)

        break;

    case AV_CODEC_ID_PCM_S16LE:

        DECODE(16, le16, src, samples, n, 0, 0)

        break;

    case AV_CODEC_ID_PCM_F64BE:

    case AV_CODEC_ID_PCM_F32BE:

    case AV_CODEC_ID_PCM_S32BE:

    case AV_CODEC_ID_PCM_S16BE:

#else

    case AV_CODEC_ID_PCM_F64BE:

        DECODE(64, be64, src, samples, n, 0, 0)

        break;

    case AV_CODEC_ID_PCM_F32BE:

    case AV_CODEC_ID_PCM_S32BE:

        DECODE(32, be32, src, samples, n, 0, 0)

        break;

    case AV_CODEC_ID_PCM_S16BE:

        DECODE(16, be16, src, samples, n, 0, 0)

        break;

    case AV_CODEC_ID_PCM_F64LE:

    case AV_CODEC_ID_PCM_F32LE:

    case AV_CODEC_ID_PCM_S32LE:

    case AV_CODEC_ID_PCM_S16LE:

#endif /* HAVE_BIGENDIAN */

    case AV_CODEC_ID_PCM_U8:

        memcpy(samples, src, n * sample_size);

        break;

    case AV_CODEC_ID_PCM_ZORK:

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

            int v = *src++;

            if (v < 128)

                v = 128 - v;

            *samples++ = v;

        }

        break;

    case AV_CODEC_ID_PCM_ALAW:

    case AV_CODEC_ID_PCM_MULAW:

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

            AV_WN16A(samples, s->table[*src++]);

            samples += 2;

        }

        break;

    case AV_CODEC_ID_PCM_DVD:

    {

        const uint8_t *src8;

        dst_int32_t = (int32_t *)frame->data[0];

        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;

        }

        break;

    }

    case AV_CODEC_ID_PCM_LXF:

    {

        int i;

        n /= avctx->channels;

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

            dst_int32_t = (int32_t *)frame->extended_data[c];

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

                // extract low 20 bits and expand to 32 bits

                *dst_int32_t++ =  (src[2]         << 28) |

                                  (src[1]         << 20) |

                                  (src[0]         << 12) |

                                 ((src[2] & 0x0F) <<  8) |

                                   src[1];

                // extract high 20 bits and expand to 32 bits

                *dst_int32_t++ =  (src[4]         << 24) |

                                  (src[3]         << 16) |

                                 ((src[2] & 0xF0) <<  8) |

                                  (src[4]         <<  4) |

                                  (src[3]         >>  4);

                src += 5;

            }

        }

        break;

    }

    default:

        return -1;

    }



    *got_frame_ptr = 1;



    return buf_size;

}
