PeerStreamer

/*

 * Shorten decoder

 * Copyright (c) 2005 Jeff Muizelaar

 *

 * 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

 * Shorten decoder

 * @author Jeff Muizelaar

 *

 */

#define DEBUG

#include <limits.h>

#include "avcodec.h"

#include "get_bits.h"

#include "golomb.h"

#define MAX_CHANNELS 8

#define MAX_BLOCKSIZE 65535

#define OUT_BUFFER_SIZE 16384

#define ULONGSIZE 2

#define WAVE_FORMAT_PCM 0x0001

#define DEFAULT_BLOCK_SIZE 256

#define TYPESIZE 4

#define CHANSIZE 0

#define LPCQSIZE 2

#define ENERGYSIZE 3

#define BITSHIFTSIZE 2

#define TYPE_S16HL 3

#define TYPE_S16LH 5

#define NWRAP 3

#define NSKIPSIZE 1

#define LPCQUANT 5

#define V2LPCQOFFSET (1 << LPCQUANT)

#define FNSIZE 2

#define FN_DIFF0        0

#define FN_DIFF1        1

#define FN_DIFF2        2

#define FN_DIFF3        3

#define FN_QUIT         4

#define FN_BLOCKSIZE    5

#define FN_BITSHIFT     6

#define FN_QLPC         7

#define FN_ZERO         8

#define FN_VERBATIM     9

#define VERBATIM_CKSIZE_SIZE 5

#define VERBATIM_BYTE_SIZE 8

#define CANONICAL_HEADER_SIZE 44

typedef struct ShortenContext {

    AVCodecContext *avctx;

    GetBitContext gb;

    int min_framesize, max_framesize;

    int channels;

    int32_t *decoded[MAX_CHANNELS];

    int32_t *offset[MAX_CHANNELS];

    int *coeffs;

    uint8_t *bitstream;

    int bitstream_size;

    int bitstream_index;

    unsigned int allocated_bitstream_size;

    int header_size;

    uint8_t header[OUT_BUFFER_SIZE];

    int version;

    int cur_chan;

    int bitshift;

    int nmean;

    int internal_ftype;

    int nwrap;

    int blocksize;

    int bitindex;

    int32_t lpcqoffset;

} ShortenContext;

static av_cold int shorten_decode_init(AVCodecContext * avctx)

{

    ShortenContext *s = avctx->priv_data;

    s->avctx = avctx;

    avctx->sample_fmt = AV_SAMPLE_FMT_S16;

    return 0;

}

static int allocate_buffers(ShortenContext *s)

{

    int i, chan;

    int *coeffs;

    for (chan=0; chan<s->channels; chan++) {

        if(FFMAX(1, s->nmean) >= UINT_MAX/sizeof(int32_t)){

            av_log(s->avctx, AV_LOG_ERROR, "nmean too large\n");

            return -1;

        }

        if(s->blocksize + s->nwrap >= UINT_MAX/sizeof(int32_t) || s->blocksize + s->nwrap <= (unsigned)s->nwrap){

            av_log(s->avctx, AV_LOG_ERROR, "s->blocksize + s->nwrap too large\n");

            return -1;

        }

        s->offset[chan] = av_realloc(s->offset[chan], sizeof(int32_t)*FFMAX(1, s->nmean));

        s->decoded[chan] = av_realloc(s->decoded[chan], sizeof(int32_t)*(s->blocksize + s->nwrap));

        for (i=0; i<s->nwrap; i++)

            s->decoded[chan][i] = 0;

        s->decoded[chan] += s->nwrap;

    }

    coeffs = av_realloc(s->coeffs, s->nwrap * sizeof(*s->coeffs));

    if (!coeffs)

        return AVERROR(ENOMEM);

    s->coeffs = coeffs;

    return 0;

}

static inline unsigned int get_uint(ShortenContext *s, int k)

{

    if (s->version != 0)

        k = get_ur_golomb_shorten(&s->gb, ULONGSIZE);

    return get_ur_golomb_shorten(&s->gb, k);

}

static void fix_bitshift(ShortenContext *s, int32_t *buffer)

{

    int i;

    if (s->bitshift != 0)

        for (i = 0; i < s->blocksize; i++)

            buffer[s->nwrap + i] <<= s->bitshift;

}

static void init_offset(ShortenContext *s)

{

    int32_t mean = 0;

    int  chan, i;

    int nblock = FFMAX(1, s->nmean);

    /* initialise offset */

    switch (s->internal_ftype)

    {

        case TYPE_S16HL:

        case TYPE_S16LH:

            mean = 0;

            break;

        default:

            av_log(s->avctx, AV_LOG_ERROR, "unknown audio type");

            abort();

    }

    for (chan = 0; chan < s->channels; chan++)

        for (i = 0; i < nblock; i++)

            s->offset[chan][i] = mean;

}

static inline int get_le32(GetBitContext *gb)

{

    return av_bswap32(get_bits_long(gb, 32));

}

static inline short get_le16(GetBitContext *gb)

{

    return av_bswap16(get_bits_long(gb, 16));

}

static int decode_wave_header(AVCodecContext *avctx, uint8_t *header, int header_size)

{

    GetBitContext hb;

    int len;

    int chunk_size;

    short wave_format;

    init_get_bits(&hb, header, header_size*8);

    if (get_le32(&hb) != MKTAG('R','I','F','F')) {

        av_log(avctx, AV_LOG_ERROR, "missing RIFF tag\n");

        return -1;

    }

    chunk_size = get_le32(&hb);

    if (get_le32(&hb) != MKTAG('W','A','V','E')) {

        av_log(avctx, AV_LOG_ERROR, "missing WAVE tag\n");

        return -1;

    }

    while (get_le32(&hb) != MKTAG('f','m','t',' ')) {

        len = get_le32(&hb);

        skip_bits(&hb, 8*len);

    }

    len = get_le32(&hb);

    if (len < 16) {

        av_log(avctx, AV_LOG_ERROR, "fmt chunk was too short\n");

        return -1;

    }

    wave_format = get_le16(&hb);

    switch (wave_format) {

        case WAVE_FORMAT_PCM:

            break;

        default:

            av_log(avctx, AV_LOG_ERROR, "unsupported wave format\n");

            return -1;

    }

    avctx->channels = get_le16(&hb);

    avctx->sample_rate = get_le32(&hb);

    avctx->bit_rate = get_le32(&hb) * 8;

    avctx->block_align = get_le16(&hb);

    avctx->bits_per_coded_sample = get_le16(&hb);

    if (avctx->bits_per_coded_sample != 16) {

        av_log(avctx, AV_LOG_ERROR, "unsupported number of bits per sample\n");

        return -1;

    }

    len -= 16;

    if (len > 0)

        av_log(avctx, AV_LOG_INFO, "%d header bytes unparsed\n", len);

    return 0;

}

static int16_t * interleave_buffer(int16_t *samples, int nchan, int blocksize, int32_t **buffer) {

    int i, chan;

    for (i=0; i<blocksize; i++)

        for (chan=0; chan < nchan; chan++)

            *samples++ = FFMIN(buffer[chan][i], 32768);

    return samples;

}

static void decode_subframe_lpc(ShortenContext *s, int channel, int residual_size, int pred_order)

{

    int sum, i, j;

    int *coeffs = s->coeffs;

    for (i=0; i<pred_order; i++)

        coeffs[i] = get_sr_golomb_shorten(&s->gb, LPCQUANT);

    for (i=0; i < s->blocksize; i++) {

        sum = s->lpcqoffset;

        for (j=0; j<pred_order; j++)

            sum += coeffs[j] * s->decoded[channel][i-j-1];

        s->decoded[channel][i] = get_sr_golomb_shorten(&s->gb, residual_size) + (sum >> LPCQUANT);

    }

}

static int shorten_decode_frame(AVCodecContext *avctx,

        void *data, int *data_size,

        AVPacket *avpkt)

{

    const uint8_t *buf = avpkt->data;

    int buf_size = avpkt->size;

    ShortenContext *s = avctx->priv_data;

    int i, input_buf_size = 0;

    int16_t *samples = data;

    if(s->max_framesize == 0){

        s->max_framesize= 1024; // should hopefully be enough for the first header

        s->bitstream= av_fast_realloc(s->bitstream, &s->allocated_bitstream_size, s->max_framesize);

    }

    if(1 && s->max_framesize){//FIXME truncated

        buf_size= FFMIN(buf_size, s->max_framesize - s->bitstream_size);

        input_buf_size= buf_size;

        if(s->bitstream_index + s->bitstream_size + buf_size > s->allocated_bitstream_size){

            //                printf("memmove\n");

            memmove(s->bitstream, &s->bitstream[s->bitstream_index], s->bitstream_size);

            s->bitstream_index=0;

        }

        memcpy(&s->bitstream[s->bitstream_index + s->bitstream_size], buf, buf_size);

        buf= &s->bitstream[s->bitstream_index];

        buf_size += s->bitstream_size;

        s->bitstream_size= buf_size;

        if(buf_size < s->max_framesize){

            //dprintf(avctx, "wanna more data ... %d\n", buf_size);

            *data_size = 0;

            return input_buf_size;

        }

    }

    init_get_bits(&s->gb, buf, buf_size*8);

    skip_bits(&s->gb, s->bitindex);

    if (!s->blocksize)

    {

        int maxnlpc = 0;

        /* shorten signature */

        if (get_bits_long(&s->gb, 32) != AV_RB32("ajkg")) {

            av_log(s->avctx, AV_LOG_ERROR, "missing shorten magic 'ajkg'\n");

            return -1;

        }

        s->lpcqoffset = 0;

        s->blocksize = DEFAULT_BLOCK_SIZE;

        s->channels = 1;

        s->nmean = -1;

        s->version = get_bits(&s->gb, 8);

        s->internal_ftype = get_uint(s, TYPESIZE);

        s->channels = get_uint(s, CHANSIZE);

        if (s->channels > MAX_CHANNELS) {

            av_log(s->avctx, AV_LOG_ERROR, "too many channels: %d\n", s->channels);

            return -1;

        }

        /* get blocksize if version > 0 */

        if (s->version > 0) {

            int skip_bytes;

            s->blocksize = get_uint(s, av_log2(DEFAULT_BLOCK_SIZE));

            maxnlpc = get_uint(s, LPCQSIZE);

            s->nmean = get_uint(s, 0);

            skip_bytes = get_uint(s, NSKIPSIZE);

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

                skip_bits(&s->gb, 8);

            }

        }

        s->nwrap = FFMAX(NWRAP, maxnlpc);

        if (allocate_buffers(s))

            return -1;

        init_offset(s);

        if (s->version > 1)

            s->lpcqoffset = V2LPCQOFFSET;

        if (get_ur_golomb_shorten(&s->gb, FNSIZE) != FN_VERBATIM) {

            av_log(s->avctx, AV_LOG_ERROR, "missing verbatim section at beginning of stream\n");

            return -1;

        }

        s->header_size = get_ur_golomb_shorten(&s->gb, VERBATIM_CKSIZE_SIZE);

        if (s->header_size >= OUT_BUFFER_SIZE || s->header_size < CANONICAL_HEADER_SIZE) {

            av_log(s->avctx, AV_LOG_ERROR, "header is wrong size: %d\n", s->header_size);

            return -1;

        }

        for (i=0; i<s->header_size; i++)

            s->header[i] = (char)get_ur_golomb_shorten(&s->gb, VERBATIM_BYTE_SIZE);

        if (decode_wave_header(avctx, s->header, s->header_size) < 0)

            return -1;

        s->cur_chan = 0;

        s->bitshift = 0;

    }

    else

    {

        int cmd;

        int len;

        cmd = get_ur_golomb_shorten(&s->gb, FNSIZE);

        switch (cmd) {

            case FN_ZERO:

            case FN_DIFF0:

            case FN_DIFF1:

            case FN_DIFF2:

            case FN_DIFF3:

            case FN_QLPC:

                {

                    int residual_size = 0;

                    int channel = s->cur_chan;

                    int32_t coffset;

                    if (cmd != FN_ZERO) {

                        residual_size = get_ur_golomb_shorten(&s->gb, ENERGYSIZE);

                        /* this is a hack as version 0 differed in defintion of get_sr_golomb_shorten */

                        if (s->version == 0)

                            residual_size--;

                    }

                    if (s->nmean == 0)

                        coffset = s->offset[channel][0];

                    else {

                        int32_t sum = (s->version < 2) ? 0 : s->nmean / 2;

                        for (i=0; i<s->nmean; i++)

                            sum += s->offset[channel][i];

                        coffset = sum / s->nmean;

                        if (s->version >= 2)

                            coffset >>= FFMIN(1, s->bitshift);

                    }

                    switch (cmd) {

                        case FN_ZERO:

                            for (i=0; i<s->blocksize; i++)

                                s->decoded[channel][i] = 0;

                            break;

                        case FN_DIFF0:

                            for (i=0; i<s->blocksize; i++)

                                s->decoded[channel][i] = get_sr_golomb_shorten(&s->gb, residual_size) + coffset;

                            break;

                        case FN_DIFF1:

                            for (i=0; i<s->blocksize; i++)

                                s->decoded[channel][i] = get_sr_golomb_shorten(&s->gb, residual_size) + s->decoded[channel][i - 1];

                            break;

                        case FN_DIFF2:

                            for (i=0; i<s->blocksize; i++)

                                s->decoded[channel][i] = get_sr_golomb_shorten(&s->gb, residual_size) + 2*s->decoded[channel][i-1]

                                                                                                      -   s->decoded[channel][i-2];

                            break;

                        case FN_DIFF3:

                            for (i=0; i<s->blocksize; i++)

                                s->decoded[channel][i] = get_sr_golomb_shorten(&s->gb, residual_size) + 3*s->decoded[channel][i-1]

                                                                                                      - 3*s->decoded[channel][i-2]

                                                                                                      +   s->decoded[channel][i-3];

                            break;

                        case FN_QLPC:

                            {

                                int pred_order = get_ur_golomb_shorten(&s->gb, LPCQSIZE);

                                if (pred_order > s->nwrap) {

                                    av_log(avctx, AV_LOG_ERROR,

                                           "invalid pred_order %d\n",

                                           pred_order);

                                    return -1;

                                }

                                for (i=0; i<pred_order; i++)

                                    s->decoded[channel][i - pred_order] -= coffset;

                                decode_subframe_lpc(s, channel, residual_size, pred_order);

                                if (coffset != 0)

                                    for (i=0; i < s->blocksize; i++)

                                        s->decoded[channel][i] += coffset;

                            }

                    }

                    if (s->nmean > 0) {

                        int32_t sum = (s->version < 2) ? 0 : s->blocksize / 2;

                        for (i=0; i<s->blocksize; i++)

                            sum += s->decoded[channel][i];

                        for (i=1; i<s->nmean; i++)

                            s->offset[channel][i-1] = s->offset[channel][i];

                        if (s->version < 2)

                            s->offset[channel][s->nmean - 1] = sum / s->blocksize;

                        else

                            s->offset[channel][s->nmean - 1] = (sum / s->blocksize) << s->bitshift;

                    }

                    for (i=-s->nwrap; i<0; i++)

                        s->decoded[channel][i] = s->decoded[channel][i + s->blocksize];

                    fix_bitshift(s, s->decoded[channel]);

                    s->cur_chan++;

                    if (s->cur_chan == s->channels) {

                        samples = interleave_buffer(samples, s->channels, s->blocksize, s->decoded);

                        s->cur_chan = 0;

                        goto frame_done;

                    }

                    break;

                }

                break;

            case FN_VERBATIM:

                len = get_ur_golomb_shorten(&s->gb, VERBATIM_CKSIZE_SIZE);

                while (len--) {

                    get_ur_golomb_shorten(&s->gb, VERBATIM_BYTE_SIZE);

                }

                break;

            case FN_BITSHIFT:

                s->bitshift = get_ur_golomb_shorten(&s->gb, BITSHIFTSIZE);

                break;

            case FN_BLOCKSIZE:

                s->blocksize = get_uint(s, av_log2(s->blocksize));

                break;

            case FN_QUIT:

                *data_size = 0;

                return buf_size;

                break;

            default:

                av_log(avctx, AV_LOG_ERROR, "unknown shorten function %d\n", cmd);

                return -1;

                break;

        }

    }

frame_done:

    *data_size = (int8_t *)samples - (int8_t *)data;

    //    s->last_blocksize = s->blocksize;

    s->bitindex = get_bits_count(&s->gb) - 8*((get_bits_count(&s->gb))/8);

    i= (get_bits_count(&s->gb))/8;

    if (i > buf_size) {

        av_log(s->avctx, AV_LOG_ERROR, "overread: %d\n", i - buf_size);

        s->bitstream_size=0;

        s->bitstream_index=0;

        return -1;

    }

    if (s->bitstream_size) {

        s->bitstream_index += i;

        s->bitstream_size  -= i;

        return input_buf_size;

    } else

        return i;

}

static av_cold int shorten_decode_close(AVCodecContext *avctx)

{

    ShortenContext *s = avctx->priv_data;

    int i;

    for (i = 0; i < s->channels; i++) {

        s->decoded[i] -= s->nwrap;

        av_freep(&s->decoded[i]);

        av_freep(&s->offset[i]);

    }

    av_freep(&s->bitstream);

    av_freep(&s->coeffs);

    return 0;

}

static void shorten_flush(AVCodecContext *avctx){

    ShortenContext *s = avctx->priv_data;

    s->bitstream_size=

        s->bitstream_index= 0;

}

AVCodec ff_shorten_decoder = {

    "shorten",

    AVMEDIA_TYPE_AUDIO,

    CODEC_ID_SHORTEN,

    sizeof(ShortenContext),

    shorten_decode_init,

    NULL,

    shorten_decode_close,

    shorten_decode_frame,

    .flush= shorten_flush,

    .long_name= NULL_IF_CONFIG_SMALL("Shorten"),

};