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/*

 * LPCM codecs for PCM formats found in Video DVD streams

 * Copyright (c) 2013 Christian Schmidt

 *

 * This file is part of FFmpeg.

 *

 * FFmpeg is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * FFmpeg is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with FFmpeg; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

/**

 * @file

 * LPCM codecs for PCM formats found in Video DVD streams

 */

#include "avcodec.h"

#include "bytestream.h"

#include "internal.h"

typedef struct PCMDVDContext {

    uint32_t last_header;    // Cached header to see if parsing is needed

    int block_size;          // Size of a block of samples in bytes

    int last_block_size;     // Size of the last block of samples in bytes

    int samples_per_block;   // Number of samples per channel per block

    int groups_per_block;    // Number of 20/24bit sample groups per block

    uint8_t *extra_samples;  // Pointer to leftover samples from a frame

    int extra_sample_count;  // Number of leftover samples in the buffer

} PCMDVDContext;

static av_cold int pcm_dvd_decode_init(AVCodecContext *avctx)

{

    PCMDVDContext *s = avctx->priv_data;

    /* Invalid header to force parsing of the first header */

    s->last_header = -1;

    /* reserve space for 8 channels, 3 bytes/sample, 4 samples/block */

    if (!(s->extra_samples = av_malloc(8 * 3 * 4)))

        return AVERROR(ENOMEM);

    return 0;

}

static av_cold int pcm_dvd_decode_uninit(AVCodecContext *avctx)

{

    PCMDVDContext *s = avctx->priv_data;

    av_freep(&s->extra_samples);

    return 0;

}

static int pcm_dvd_parse_header(AVCodecContext *avctx, const uint8_t *header)

{

    /* no traces of 44100 and 32000Hz in any commercial software or player */

    static const uint32_t frequencies[4] = { 48000, 96000, 44100, 32000 };

    PCMDVDContext *s = avctx->priv_data;

    int header_int = (header[0] & 0xe0) | (header[1] << 8) | (header[2] << 16);

    /* early exit if the header didn't change apart from the frame number */

    if (s->last_header == header_int)

        return 0;

    if (avctx->debug & FF_DEBUG_PICT_INFO)

        av_dlog(avctx, "pcm_dvd_parse_header: header = %02x%02x%02x\n",

                header[0], header[1], header[2]);

    /*

     * header[0] emphasis (1), muse(1), reserved(1), frame number(5)

     * header[1] quant (2), freq(2), reserved(1), channels(3)

     * header[2] dynamic range control (0x80 = off)

     */

    /* Discard potentially existing leftover samples from old channel layout */

    s->extra_sample_count = 0;

    /* get the sample depth and derive the sample format from it */

    avctx->bits_per_coded_sample = 16 + (header[1] >> 6 & 3) * 4;

    if (avctx->bits_per_coded_sample == 28) {

        av_log(avctx, AV_LOG_ERROR,

               "PCM DVD unsupported sample depth %i\n",

               avctx->bits_per_coded_sample);

        return AVERROR_INVALIDDATA;

    }

    avctx->sample_fmt = avctx->bits_per_coded_sample == 16 ? AV_SAMPLE_FMT_S16

                                                           : AV_SAMPLE_FMT_S32;

    avctx->bits_per_raw_sample = avctx->bits_per_coded_sample;

    /* get the sample rate */

    avctx->sample_rate = frequencies[header[1] >> 4 & 3];

    /* get the number of channels */

    avctx->channels = 1 + (header[1] & 7);

    /* calculate the bitrate */

    avctx->bit_rate = avctx->channels *

                      avctx->sample_rate *

                      avctx->bits_per_coded_sample;

    /* 4 samples form a group in 20/24bit PCM on DVD Video.

     * A block is formed by the number of groups that are

     * needed to complete a set of samples for each channel. */

    if (avctx->bits_per_coded_sample == 16) {

        s->samples_per_block = 1;

        s->block_size        = avctx->channels * 2;

    } else {

        switch (avctx->channels) {

        case 1:

        case 2:

        case 4:

            /* one group has all the samples needed */

            s->block_size        = 4 * avctx->bits_per_coded_sample / 8;

            s->samples_per_block = 4 / avctx->channels;

            s->groups_per_block  = 1;

            break;

        case 8:

            /* two groups have all the samples needed */

            s->block_size        = 8 * avctx->bits_per_coded_sample / 8;

            s->samples_per_block = 1;

            s->groups_per_block  = 2;

            break;

        default:

            /* need avctx->channels groups */

            s->block_size        = 4 * avctx->channels *

                                   avctx->bits_per_coded_sample / 8;

            s->samples_per_block = 4;

            s->groups_per_block  = avctx->channels;

            break;

        }

    }

    if (avctx->debug & FF_DEBUG_PICT_INFO)

        av_dlog(avctx,

                "pcm_dvd_parse_header: %d channels, %d bits per sample, %d Hz, %d bit/s\n",

                avctx->channels, avctx->bits_per_coded_sample,

                avctx->sample_rate, avctx->bit_rate);

    s->last_header = header_int;

    return 0;

}

static void *pcm_dvd_decode_samples(AVCodecContext *avctx, const uint8_t *src,

                                    void *dst, int blocks)

{

    PCMDVDContext *s = avctx->priv_data;

    int16_t *dst16   = dst;

    int32_t *dst32   = dst;

    GetByteContext gb;

    int i;

    uint8_t t;

    int samples;

    bytestream2_init(&gb, src, blocks * s->block_size);

    switch (avctx->bits_per_coded_sample) {

    case 16:

#if HAVE_BIGENDIAN

        bytestream2_get_buffer(&gb, dst16, blocks * s->block_size);

        dst16 += blocks * s->block_size / 2;

#else

        samples = blocks * avctx->channels;

        do {

            *dst16++ = bytestream2_get_be16u(&gb);

        } while (--samples);

#endif

        return dst16;

    case 20:

        if (avctx->channels == 1) {

            do {

                for (i = 2; i; i--) {

                    dst32[0] = bytestream2_get_be16u(&gb) << 16;

                    dst32[1] = bytestream2_get_be16u(&gb) << 16;

                    t = bytestream2_get_byteu(&gb);

                    *dst32++ += (t & 0xf0) << 8;

                    *dst32++ += (t & 0x0f) << 12;

                }

            } while (--blocks);

        } else {

        do {

            for (i = s->groups_per_block; i; i--) {

                dst32[0] = bytestream2_get_be16u(&gb) << 16;

                dst32[1] = bytestream2_get_be16u(&gb) << 16;

                dst32[2] = bytestream2_get_be16u(&gb) << 16;

                dst32[3] = bytestream2_get_be16u(&gb) << 16;

                t = bytestream2_get_byteu(&gb);

                *dst32++ += (t & 0xf0) << 8;

                *dst32++ += (t & 0x0f) << 12;

                t = bytestream2_get_byteu(&gb);

                *dst32++ += (t & 0xf0) << 8;

                *dst32++ += (t & 0x0f) << 12;

            }

        } while (--blocks);

        }

        return dst32;

    case 24:

        if (avctx->channels == 1) {

            do {

                for (i = 2; i; i--) {

                    dst32[0] = bytestream2_get_be16u(&gb) << 16;

                    dst32[1] = bytestream2_get_be16u(&gb) << 16;

                    *dst32++ += bytestream2_get_byteu(&gb) << 8;

                    *dst32++ += bytestream2_get_byteu(&gb) << 8;

                }

            } while (--blocks);

        } else {

        do {

            for (i = s->groups_per_block; i; i--) {

                dst32[0] = bytestream2_get_be16u(&gb) << 16;

                dst32[1] = bytestream2_get_be16u(&gb) << 16;

                dst32[2] = bytestream2_get_be16u(&gb) << 16;

                dst32[3] = bytestream2_get_be16u(&gb) << 16;

                *dst32++ += bytestream2_get_byteu(&gb) << 8;

                *dst32++ += bytestream2_get_byteu(&gb) << 8;

                *dst32++ += bytestream2_get_byteu(&gb) << 8;

                *dst32++ += bytestream2_get_byteu(&gb) << 8;

            }

        } while (--blocks);

        }

        return dst32;

    default:

        return NULL;

    }

}

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

                                int *got_frame_ptr, AVPacket *avpkt)

{

    AVFrame *frame     = data;

    const uint8_t *src = avpkt->data;

    int buf_size       = avpkt->size;

    PCMDVDContext *s   = avctx->priv_data;

    int retval;

    int blocks;

    void *dst;

    if (buf_size < 3) {

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

        return AVERROR_INVALIDDATA;

    }

    if ((retval = pcm_dvd_parse_header(avctx, src)))

        return retval;

    if (s->last_block_size != s->block_size) {

        av_log(avctx, AV_LOG_WARNING, "block_size has changed\n");

        s->extra_sample_count = 0;

    }

    s->last_block_size = s->block_size;

    src      += 3;

    buf_size -= 3;

    blocks = (buf_size + s->extra_sample_count) / s->block_size;

    /* get output buffer */

    frame->nb_samples = blocks * s->samples_per_block;

    if ((retval = ff_get_buffer(avctx, frame, 0)) < 0)

        return retval;

    dst = frame->data[0];

    /* consume leftover samples from last packet */

    if (s->extra_sample_count) {

        int missing_samples = s->block_size - s->extra_sample_count;

        if (buf_size >= missing_samples) {

            memcpy(s->extra_samples + s->extra_sample_count, src,

                   missing_samples);

            dst = pcm_dvd_decode_samples(avctx, s->extra_samples, dst, 1);

            src += missing_samples;

            buf_size -= missing_samples;

            s->extra_sample_count = 0;

            blocks--;

        } else {

            /* new packet still doesn't have enough samples */

            memcpy(s->extra_samples + s->extra_sample_count, src, buf_size);

            s->extra_sample_count += buf_size;

            return avpkt->size;

        }

    }

    /* decode remaining complete samples */

    if (blocks) {

        pcm_dvd_decode_samples(avctx, src, dst, blocks);

        buf_size -= blocks * s->block_size;

    }

    /* store leftover samples */

    if (buf_size) {

        src += blocks * s->block_size;

        memcpy(s->extra_samples, src, buf_size);

        s->extra_sample_count = buf_size;

    }

    *got_frame_ptr = 1;

    return avpkt->size;

}

AVCodec ff_pcm_dvd_decoder = {

    .name           = "pcm_dvd",

    .long_name      = NULL_IF_CONFIG_SMALL("PCM signed 16|20|24-bit big-endian for DVD media"),

    .type           = AVMEDIA_TYPE_AUDIO,

    .id             = AV_CODEC_ID_PCM_DVD,

    .priv_data_size = sizeof(PCMDVDContext),

    .init           = pcm_dvd_decode_init,

    .decode         = pcm_dvd_decode_frame,

    .close          = pcm_dvd_decode_uninit,

    .capabilities   = CODEC_CAP_DR1,

    .sample_fmts    = (const enum AVSampleFormat[]) {

        AV_SAMPLE_FMT_S16, AV_SAMPLE_FMT_S32, AV_SAMPLE_FMT_NONE

    }

};