libavcodec/shorten.c - nest-android-app/ffmpeg - Git at Google

 /*
  * 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
  *
  */

 #include <limits.h>
 #include "avcodec.h"
 #include "bytestream.h"
 #include "get_bits.h"
 #include "golomb.h"
 #include "internal.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_S8    1
 #define TYPE_U8    2
 #define TYPE_S16HL 3
 #define TYPE_U16HL 4
 #define TYPE_S16LH 5
 #define TYPE_U16LH 6

 #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

 /** indicates if the FN_* command is audio or non-audio */
 static const uint8_t is_audio_command[10] = { 1, 1, 1, 1, 0, 0, 0, 1, 1, 0 };

 #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;
     unsigned channels;

     int32_t *decoded[MAX_CHANNELS];
     int32_t *decoded_base[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;
     int got_header;
     int got_quit_command;
 } ShortenContext;

 static av_cold int shorten_decode_init(AVCodecContext *avctx)
 {
     ShortenContext *s = avctx->priv_data;
     s->avctx          = avctx;

     return 0;
 }

 static int allocate_buffers(ShortenContext *s)
 {
     int i, chan, err;

     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 AVERROR_INVALIDDATA;
         }
         if (s->blocksize + (uint64_t)s->nwrap >= UINT_MAX / sizeof(int32_t)) {
             av_log(s->avctx, AV_LOG_ERROR,
                    "s->blocksize + s->nwrap too large\n");
             return AVERROR_INVALIDDATA;
         }

         if ((err = av_reallocp_array(&s->offset[chan],
                                sizeof(int32_t),
                                FFMAX(1, s->nmean))) < 0)
             return err;

         if ((err = av_reallocp_array(&s->decoded_base[chan], (s->blocksize + s->nwrap),
                                sizeof(s->decoded_base[0][0]))) < 0)
             return err;
         for (i = 0; i < s->nwrap; i++)
             s->decoded_base[chan][i] = 0;
         s->decoded[chan] = s->decoded_base[chan] + s->nwrap;
     }

     if ((err = av_reallocp_array(&s->coeffs, s->nwrap, sizeof(*s->coeffs))) < 0)
         return err;

     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[i] <<= s->bitshift;
 }

 static int 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_U8:
         s->avctx->sample_fmt = AV_SAMPLE_FMT_U8P;
         mean = 0x80;
         break;
     case TYPE_S16HL:
     case TYPE_S16LH:
         s->avctx->sample_fmt = AV_SAMPLE_FMT_S16P;
         break;
     default:
         av_log(s->avctx, AV_LOG_ERROR, "unknown audio type\n");
         return AVERROR_PATCHWELCOME;
     }

     for (chan = 0; chan < s->channels; chan++)
         for (i = 0; i < nblock; i++)
             s->offset[chan][i] = mean;
     return 0;
 }

 static int decode_wave_header(AVCodecContext *avctx, const uint8_t *header,
                               int header_size)
 {
     int len, bps;
     short wave_format;
     GetByteContext gb;

     bytestream2_init(&gb, header, header_size);

     if (bytestream2_get_le32(&gb) != MKTAG('R', 'I', 'F', 'F')) {
         av_log(avctx, AV_LOG_ERROR, "missing RIFF tag\n");
         return AVERROR_INVALIDDATA;
     }

     bytestream2_skip(&gb, 4); /* chunk size */

     if (bytestream2_get_le32(&gb) != MKTAG('W', 'A', 'V', 'E')) {
         av_log(avctx, AV_LOG_ERROR, "missing WAVE tag\n");
         return AVERROR_INVALIDDATA;
     }

     while (bytestream2_get_le32(&gb) != MKTAG('f', 'm', 't', ' ')) {
         len = bytestream2_get_le32(&gb);
         bytestream2_skip(&gb, len);
         if (len < 0 || bytestream2_get_bytes_left(&gb) < 16) {
             av_log(avctx, AV_LOG_ERROR, "no fmt chunk found\n");
             return AVERROR_INVALIDDATA;
         }
     }
     len = bytestream2_get_le32(&gb);

     if (len < 16) {
         av_log(avctx, AV_LOG_ERROR, "fmt chunk was too short\n");
         return AVERROR_INVALIDDATA;
     }

     wave_format = bytestream2_get_le16(&gb);

     switch (wave_format) {
     case WAVE_FORMAT_PCM:
         break;
     default:
         av_log(avctx, AV_LOG_ERROR, "unsupported wave format\n");
         return AVERROR(ENOSYS);
     }

     bytestream2_skip(&gb, 2); // skip channels    (already got from shorten header)
     avctx->sample_rate = bytestream2_get_le32(&gb);
     bytestream2_skip(&gb, 4); // skip bit rate    (represents original uncompressed bit rate)
     bytestream2_skip(&gb, 2); // skip block align (not needed)
     bps = bytestream2_get_le16(&gb);
     avctx->bits_per_coded_sample = bps;

     if (bps != 16 && bps != 8) {
         av_log(avctx, AV_LOG_ERROR, "unsupported number of bits per sample: %d\n", bps);
         return AVERROR(ENOSYS);
     }

     len -= 16;
     if (len > 0)
         av_log(avctx, AV_LOG_INFO, "%d header bytes unparsed\n", len);

     return 0;
 }

 static const int fixed_coeffs[][3] = {
     { 0,  0,  0 },
     { 1,  0,  0 },
     { 2, -1,  0 },
     { 3, -3,  1 }
 };

 static int decode_subframe_lpc(ShortenContext *s, int command, int channel,
                                int residual_size, int32_t coffset)
 {
     int pred_order, sum, qshift, init_sum, i, j;
     const int *coeffs;

     if (command == FN_QLPC) {
         /* read/validate prediction order */
         pred_order = get_ur_golomb_shorten(&s->gb, LPCQSIZE);
         if ((unsigned)pred_order > s->nwrap) {
             av_log(s->avctx, AV_LOG_ERROR, "invalid pred_order %d\n",
                    pred_order);
             return AVERROR(EINVAL);
         }
         /* read LPC coefficients */
         for (i = 0; i < pred_order; i++)
             s->coeffs[i] = get_sr_golomb_shorten(&s->gb, LPCQUANT);
         coeffs = s->coeffs;

         qshift = LPCQUANT;
     } else {
         /* fixed LPC coeffs */
         pred_order = command;
         if (pred_order >= FF_ARRAY_ELEMS(fixed_coeffs)) {
             av_log(s->avctx, AV_LOG_ERROR, "invalid pred_order %d\n",
                    pred_order);
             return AVERROR_INVALIDDATA;
         }
         coeffs     = fixed_coeffs[pred_order];
         qshift     = 0;
     }

     /* subtract offset from previous samples to use in prediction */
     if (command == FN_QLPC && coffset)
         for (i = -pred_order; i < 0; i++)
             s->decoded[channel][i] -= coffset;

     /* decode residual and do LPC prediction */
     init_sum = pred_order ? (command == FN_QLPC ? s->lpcqoffset : 0) : coffset;
     for (i = 0; i < s->blocksize; i++) {
         sum = init_sum;
         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 >> qshift);
     }

     /* add offset to current samples */
     if (command == FN_QLPC && coffset)
         for (i = 0; i < s->blocksize; i++)
             s->decoded[channel][i] += coffset;

     return 0;
 }

 static int read_header(ShortenContext *s)
 {
     int i, ret;
     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 AVERROR_INVALIDDATA;
     }

     s->lpcqoffset     = 0;
     s->blocksize      = DEFAULT_BLOCK_SIZE;
     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) {
         av_log(s->avctx, AV_LOG_ERROR, "No channels reported\n");
         return AVERROR_INVALIDDATA;
     }
     if (s->channels > MAX_CHANNELS) {
         av_log(s->avctx, AV_LOG_ERROR, "too many channels: %d\n", s->channels);
         s->channels = 0;
         return AVERROR_INVALIDDATA;
     }
     s->avctx->channels = s->channels;

     /* get blocksize if version > 0 */
     if (s->version > 0) {
         int skip_bytes;
         unsigned blocksize;

         blocksize = get_uint(s, av_log2(DEFAULT_BLOCK_SIZE));
         if (!blocksize || blocksize > MAX_BLOCKSIZE) {
             av_log(s->avctx, AV_LOG_ERROR,
                    "invalid or unsupported block size: %d\n",
                    blocksize);
             return AVERROR(EINVAL);
         }
         s->blocksize = blocksize;

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

         skip_bytes = get_uint(s, NSKIPSIZE);
         if ((unsigned)skip_bytes > get_bits_left(&s->gb)/8) {
             av_log(s->avctx, AV_LOG_ERROR, "invalid skip_bytes: %d\n", skip_bytes);
             return AVERROR_INVALIDDATA;
         }

         for (i = 0; i < skip_bytes; i++)
             skip_bits(&s->gb, 8);
     }
     s->nwrap = FFMAX(NWRAP, maxnlpc);

     if ((ret = allocate_buffers(s)) < 0)
         return ret;

     if ((ret = init_offset(s)) < 0)
         return ret;

     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 AVERROR_INVALIDDATA;
     }

     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 AVERROR_INVALIDDATA;
     }

     for (i = 0; i < s->header_size; i++)
         s->header[i] = (char)get_ur_golomb_shorten(&s->gb, VERBATIM_BYTE_SIZE);

     if ((ret = decode_wave_header(s->avctx, s->header, s->header_size)) < 0)
         return ret;

     s->cur_chan = 0;
     s->bitshift = 0;

     s->got_header = 1;

     return 0;
 }

 static int shorten_decode_frame(AVCodecContext *avctx, void *data,
                                 int *got_frame_ptr, AVPacket *avpkt)
 {
     AVFrame *frame     = data;
     const uint8_t *buf = avpkt->data;
     int buf_size       = avpkt->size;
     ShortenContext *s  = avctx->priv_data;
     int i, input_buf_size = 0;
     int ret;

     /* allocate internal bitstream buffer */
     if (s->max_framesize == 0) {
         void *tmp_ptr;
         s->max_framesize = 8192; // should hopefully be enough for the first header
         tmp_ptr = av_fast_realloc(s->bitstream, &s->allocated_bitstream_size,
                                   s->max_framesize + AV_INPUT_BUFFER_PADDING_SIZE);
         if (!tmp_ptr) {
             av_log(avctx, AV_LOG_ERROR, "error allocating bitstream buffer\n");
             return AVERROR(ENOMEM);
         }
         memset(tmp_ptr, 0, s->allocated_bitstream_size);
         s->bitstream = tmp_ptr;
     }

     /* append current packet data to bitstream buffer */
     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 + AV_INPUT_BUFFER_PADDING_SIZE >
             s->allocated_bitstream_size) {
             memmove(s->bitstream, &s->bitstream[s->bitstream_index],
                     s->bitstream_size);
             s->bitstream_index = 0;
         }
         if (buf)
             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;

         /* do not decode until buffer has at least max_framesize bytes or
          * the end of the file has been reached */
         if (buf_size < s->max_framesize && avpkt->data) {
             *got_frame_ptr = 0;
             return input_buf_size;
         }
     }
     /* init and position bitstream reader */
     if ((ret = init_get_bits8(&s->gb, buf, buf_size)) < 0)
         return ret;
     skip_bits(&s->gb, s->bitindex);

     /* process header or next subblock */
     if (!s->got_header) {
         if ((ret = read_header(s)) < 0)
             return ret;
         *got_frame_ptr = 0;
         goto finish_frame;
     }

     /* if quit command was read previously, don't decode anything */
     if (s->got_quit_command) {
         *got_frame_ptr = 0;
         return avpkt->size;
     }

     s->cur_chan = 0;
     while (s->cur_chan < s->channels) {
         unsigned cmd;
         int len;

         if (get_bits_left(&s->gb) < 3 + FNSIZE) {
             *got_frame_ptr = 0;
             break;
         }

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

         if (cmd > FN_VERBATIM) {
             av_log(avctx, AV_LOG_ERROR, "unknown shorten function %d\n", cmd);
             *got_frame_ptr = 0;
             break;
         }

         if (!is_audio_command[cmd]) {
             /* process non-audio command */
             switch (cmd) {
             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: {
                 unsigned bitshift = get_ur_golomb_shorten(&s->gb, BITSHIFTSIZE);
                 if (bitshift > 31) {
                     av_log(avctx, AV_LOG_ERROR, "bitshift %d is invalid\n",
                            bitshift);
                     return AVERROR_INVALIDDATA;
                 }
                 s->bitshift = bitshift;
                 break;
             }
             case FN_BLOCKSIZE: {
                 unsigned blocksize = get_uint(s, av_log2(s->blocksize));
                 if (blocksize > s->blocksize) {
                     av_log(avctx, AV_LOG_ERROR,
                            "Increasing block size is not supported\n");
                     return AVERROR_PATCHWELCOME;
                 }
                 if (!blocksize || blocksize > MAX_BLOCKSIZE) {
                     av_log(avctx, AV_LOG_ERROR, "invalid or unsupported "
                                                 "block size: %d\n", blocksize);
                     return AVERROR(EINVAL);
                 }
                 s->blocksize = blocksize;
                 break;
             }
             case FN_QUIT:
                 s->got_quit_command = 1;
                 break;
             }
             if (cmd == FN_BLOCKSIZE || cmd == FN_QUIT) {
                 *got_frame_ptr = 0;
                 break;
             }
         } else {
             /* process audio command */
             int residual_size = 0;
             int channel = s->cur_chan;
             int32_t coffset;

             /* get Rice code for residual decoding */
             if (cmd != FN_ZERO) {
                 residual_size = get_ur_golomb_shorten(&s->gb, ENERGYSIZE);
                 /* This is a hack as version 0 differed in the definition
                  * of get_sr_golomb_shorten(). */
                 if (s->version == 0)
                     residual_size--;
             }

             /* calculate sample offset using means from previous blocks */
             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 = s->bitshift == 0 ? coffset : coffset >> s->bitshift - 1 >> 1;
             }

             /* decode samples for this channel */
             if (cmd == FN_ZERO) {
                 for (i = 0; i < s->blocksize; i++)
                     s->decoded[channel][i] = 0;
             } else {
                 if ((ret = decode_subframe_lpc(s, cmd, channel,
                                                residual_size, coffset)) < 0)
                     return ret;
             }

             /* update means with info from the current block */
             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;
             }

             /* copy wrap samples for use with next block */
             for (i = -s->nwrap; i < 0; i++)
                 s->decoded[channel][i] = s->decoded[channel][i + s->blocksize];

             /* shift samples to add in unused zero bits which were removed
              * during encoding */
             fix_bitshift(s, s->decoded[channel]);

             /* if this is the last channel in the block, output the samples */
             s->cur_chan++;
             if (s->cur_chan == s->channels) {
                 uint8_t *samples_u8;
                 int16_t *samples_s16;
                 int chan;

                 /* get output buffer */
                 frame->nb_samples = s->blocksize;
                 if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
                     return ret;

                 for (chan = 0; chan < s->channels; chan++) {
                     samples_u8  = ((uint8_t **)frame->extended_data)[chan];
                     samples_s16 = ((int16_t **)frame->extended_data)[chan];
                     for (i = 0; i < s->blocksize; i++) {
                         switch (s->internal_ftype) {
                         case TYPE_U8:
                             *samples_u8++ = av_clip_uint8(s->decoded[chan][i]);
                             break;
                         case TYPE_S16HL:
                         case TYPE_S16LH:
                             *samples_s16++ = av_clip_int16(s->decoded[chan][i]);
                             break;
                         }
                     }
                 }

                 *got_frame_ptr = 1;
             }
         }
     }
     if (s->cur_chan < s->channels)
         *got_frame_ptr = 0;

 finish_frame:
     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 AVERROR_INVALIDDATA;
     }
     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] = NULL;
         av_freep(&s->decoded_base[i]);
         av_freep(&s->offset[i]);
     }
     av_freep(&s->bitstream);
     av_freep(&s->coeffs);

     return 0;
 }

 AVCodec ff_shorten_decoder = {
     .name           = "shorten",
     .long_name      = NULL_IF_CONFIG_SMALL("Shorten"),
     .type           = AVMEDIA_TYPE_AUDIO,
     .id             = AV_CODEC_ID_SHORTEN,
     .priv_data_size = sizeof(ShortenContext),
     .init           = shorten_decode_init,
     .close          = shorten_decode_close,
     .decode         = shorten_decode_frame,
     .capabilities   = AV_CODEC_CAP_DELAY | AV_CODEC_CAP_DR1,
     .sample_fmts    = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_S16P,
                                                       AV_SAMPLE_FMT_U8P,
                                                       AV_SAMPLE_FMT_NONE },
 };
	/*
	* 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
	*
	*/

	#include <limits.h>
	#include "avcodec.h"
	#include "bytestream.h"
	#include "get_bits.h"
	#include "golomb.h"
	#include "internal.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_S8 1
	#define TYPE_U8 2
	#define TYPE_S16HL 3
	#define TYPE_U16HL 4
	#define TYPE_S16LH 5
	#define TYPE_U16LH 6

	#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

	/** indicates if the FN_* command is audio or non-audio */
	static const uint8_t is_audio_command[10] = { 1, 1, 1, 1, 0, 0, 0, 1, 1, 0 };

	#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;
	unsigned channels;

	int32_t *decoded[MAX_CHANNELS];
	int32_t *decoded_base[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;
	int got_header;
	int got_quit_command;
	} ShortenContext;

	static av_cold int shorten_decode_init(AVCodecContext *avctx)
	{
	ShortenContext *s = avctx->priv_data;
	s->avctx = avctx;

	return 0;
	}

	static int allocate_buffers(ShortenContext *s)
	{
	int i, chan, err;

	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 AVERROR_INVALIDDATA;
	}
	if (s->blocksize + (uint64_t)s->nwrap >= UINT_MAX / sizeof(int32_t)) {
	av_log(s->avctx, AV_LOG_ERROR,
	"s->blocksize + s->nwrap too large\n");
	return AVERROR_INVALIDDATA;
	}

	if ((err = av_reallocp_array(&s->offset[chan],
	sizeof(int32_t),
	FFMAX(1, s->nmean))) < 0)
	return err;

	if ((err = av_reallocp_array(&s->decoded_base[chan], (s->blocksize + s->nwrap),
	sizeof(s->decoded_base[0][0]))) < 0)
	return err;
	for (i = 0; i < s->nwrap; i++)
	s->decoded_base[chan][i] = 0;
	s->decoded[chan] = s->decoded_base[chan] + s->nwrap;
	}

	if ((err = av_reallocp_array(&s->coeffs, s->nwrap, sizeof(*s->coeffs))) < 0)
	return err;

	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[i] <<= s->bitshift;
	}

	static int 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_U8:
	s->avctx->sample_fmt = AV_SAMPLE_FMT_U8P;
	mean = 0x80;
	break;
	case TYPE_S16HL:
	case TYPE_S16LH:
	s->avctx->sample_fmt = AV_SAMPLE_FMT_S16P;
	break;
	default:
	av_log(s->avctx, AV_LOG_ERROR, "unknown audio type\n");
	return AVERROR_PATCHWELCOME;
	}

	for (chan = 0; chan < s->channels; chan++)
	for (i = 0; i < nblock; i++)
	s->offset[chan][i] = mean;
	return 0;
	}

	static int decode_wave_header(AVCodecContext avctx, const uint8_t header,
	int header_size)
	{
	int len, bps;
	short wave_format;
	GetByteContext gb;

	bytestream2_init(&gb, header, header_size);

	if (bytestream2_get_le32(&gb) != MKTAG('R', 'I', 'F', 'F')) {
	av_log(avctx, AV_LOG_ERROR, "missing RIFF tag\n");
	return AVERROR_INVALIDDATA;
	}

	bytestream2_skip(&gb, 4); /* chunk size */

	if (bytestream2_get_le32(&gb) != MKTAG('W', 'A', 'V', 'E')) {
	av_log(avctx, AV_LOG_ERROR, "missing WAVE tag\n");
	return AVERROR_INVALIDDATA;
	}

	while (bytestream2_get_le32(&gb) != MKTAG('f', 'm', 't', ' ')) {
	len = bytestream2_get_le32(&gb);
	bytestream2_skip(&gb, len);
	if (len < 0 \|\| bytestream2_get_bytes_left(&gb) < 16) {
	av_log(avctx, AV_LOG_ERROR, "no fmt chunk found\n");
	return AVERROR_INVALIDDATA;
	}
	}
	len = bytestream2_get_le32(&gb);

	if (len < 16) {
	av_log(avctx, AV_LOG_ERROR, "fmt chunk was too short\n");
	return AVERROR_INVALIDDATA;
	}

	wave_format = bytestream2_get_le16(&gb);

	switch (wave_format) {
	case WAVE_FORMAT_PCM:
	break;
	default:
	av_log(avctx, AV_LOG_ERROR, "unsupported wave format\n");
	return AVERROR(ENOSYS);
	}

	bytestream2_skip(&gb, 2); // skip channels (already got from shorten header)
	avctx->sample_rate = bytestream2_get_le32(&gb);
	bytestream2_skip(&gb, 4); // skip bit rate (represents original uncompressed bit rate)
	bytestream2_skip(&gb, 2); // skip block align (not needed)
	bps = bytestream2_get_le16(&gb);
	avctx->bits_per_coded_sample = bps;

	if (bps != 16 && bps != 8) {
	av_log(avctx, AV_LOG_ERROR, "unsupported number of bits per sample: %d\n", bps);
	return AVERROR(ENOSYS);
	}

	len -= 16;
	if (len > 0)
	av_log(avctx, AV_LOG_INFO, "%d header bytes unparsed\n", len);

	return 0;
	}

	static const int fixed_coeffs[][3] = {
	{ 0, 0, 0 },
	{ 1, 0, 0 },
	{ 2, -1, 0 },
	{ 3, -3, 1 }
	};

	static int decode_subframe_lpc(ShortenContext *s, int command, int channel,
	int residual_size, int32_t coffset)
	{
	int pred_order, sum, qshift, init_sum, i, j;
	const int *coeffs;

	if (command == FN_QLPC) {
	/* read/validate prediction order */
	pred_order = get_ur_golomb_shorten(&s->gb, LPCQSIZE);
	if ((unsigned)pred_order > s->nwrap) {
	av_log(s->avctx, AV_LOG_ERROR, "invalid pred_order %d\n",
	pred_order);
	return AVERROR(EINVAL);
	}
	/* read LPC coefficients */
	for (i = 0; i < pred_order; i++)
	s->coeffs[i] = get_sr_golomb_shorten(&s->gb, LPCQUANT);
	coeffs = s->coeffs;

	qshift = LPCQUANT;
	} else {
	/* fixed LPC coeffs */
	pred_order = command;
	if (pred_order >= FF_ARRAY_ELEMS(fixed_coeffs)) {
	av_log(s->avctx, AV_LOG_ERROR, "invalid pred_order %d\n",
	pred_order);
	return AVERROR_INVALIDDATA;
	}
	coeffs = fixed_coeffs[pred_order];
	qshift = 0;
	}

	/* subtract offset from previous samples to use in prediction */
	if (command == FN_QLPC && coffset)
	for (i = -pred_order; i < 0; i++)
	s->decoded[channel][i] -= coffset;

	/* decode residual and do LPC prediction */
	init_sum = pred_order ? (command == FN_QLPC ? s->lpcqoffset : 0) : coffset;
	for (i = 0; i < s->blocksize; i++) {
	sum = init_sum;
	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 >> qshift);
	}

	/* add offset to current samples */
	if (command == FN_QLPC && coffset)
	for (i = 0; i < s->blocksize; i++)
	s->decoded[channel][i] += coffset;

	return 0;
	}

	static int read_header(ShortenContext *s)
	{
	int i, ret;
	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 AVERROR_INVALIDDATA;
	}

	s->lpcqoffset = 0;
	s->blocksize = DEFAULT_BLOCK_SIZE;
	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) {
	av_log(s->avctx, AV_LOG_ERROR, "No channels reported\n");
	return AVERROR_INVALIDDATA;
	}
	if (s->channels > MAX_CHANNELS) {
	av_log(s->avctx, AV_LOG_ERROR, "too many channels: %d\n", s->channels);
	s->channels = 0;
	return AVERROR_INVALIDDATA;
	}
	s->avctx->channels = s->channels;

	/* get blocksize if version > 0 */
	if (s->version > 0) {
	int skip_bytes;
	unsigned blocksize;

	blocksize = get_uint(s, av_log2(DEFAULT_BLOCK_SIZE));
	if (!blocksize \|\| blocksize > MAX_BLOCKSIZE) {
	av_log(s->avctx, AV_LOG_ERROR,
	"invalid or unsupported block size: %d\n",
	blocksize);
	return AVERROR(EINVAL);
	}
	s->blocksize = blocksize;

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

	skip_bytes = get_uint(s, NSKIPSIZE);
	if ((unsigned)skip_bytes > get_bits_left(&s->gb)/8) {
	av_log(s->avctx, AV_LOG_ERROR, "invalid skip_bytes: %d\n", skip_bytes);
	return AVERROR_INVALIDDATA;
	}

	for (i = 0; i < skip_bytes; i++)
	skip_bits(&s->gb, 8);
	}
	s->nwrap = FFMAX(NWRAP, maxnlpc);

	if ((ret = allocate_buffers(s)) < 0)
	return ret;

	if ((ret = init_offset(s)) < 0)
	return ret;

	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 AVERROR_INVALIDDATA;
	}

	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 AVERROR_INVALIDDATA;
	}

	for (i = 0; i < s->header_size; i++)
	s->header[i] = (char)get_ur_golomb_shorten(&s->gb, VERBATIM_BYTE_SIZE);

	if ((ret = decode_wave_header(s->avctx, s->header, s->header_size)) < 0)
	return ret;

	s->cur_chan = 0;
	s->bitshift = 0;

	s->got_header = 1;

	return 0;
	}

	static int shorten_decode_frame(AVCodecContext avctx, void data,
	int got_frame_ptr, AVPacket avpkt)
	{
	AVFrame *frame = data;
	const uint8_t *buf = avpkt->data;
	int buf_size = avpkt->size;
	ShortenContext *s = avctx->priv_data;
	int i, input_buf_size = 0;
	int ret;

	/* allocate internal bitstream buffer */
	if (s->max_framesize == 0) {
	void *tmp_ptr;
	s->max_framesize = 8192; // should hopefully be enough for the first header
	tmp_ptr = av_fast_realloc(s->bitstream, &s->allocated_bitstream_size,
	s->max_framesize + AV_INPUT_BUFFER_PADDING_SIZE);
	if (!tmp_ptr) {
	av_log(avctx, AV_LOG_ERROR, "error allocating bitstream buffer\n");
	return AVERROR(ENOMEM);
	}
	memset(tmp_ptr, 0, s->allocated_bitstream_size);
	s->bitstream = tmp_ptr;
	}

	/* append current packet data to bitstream buffer */
	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 + AV_INPUT_BUFFER_PADDING_SIZE >
	s->allocated_bitstream_size) {
	memmove(s->bitstream, &s->bitstream[s->bitstream_index],
	s->bitstream_size);
	s->bitstream_index = 0;
	}
	if (buf)
	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;

	/* do not decode until buffer has at least max_framesize bytes or
	* the end of the file has been reached */
	if (buf_size < s->max_framesize && avpkt->data) {
	*got_frame_ptr = 0;
	return input_buf_size;
	}
	}
	/* init and position bitstream reader */
	if ((ret = init_get_bits8(&s->gb, buf, buf_size)) < 0)
	return ret;
	skip_bits(&s->gb, s->bitindex);

	/* process header or next subblock */
	if (!s->got_header) {
	if ((ret = read_header(s)) < 0)
	return ret;
	*got_frame_ptr = 0;
	goto finish_frame;
	}

	/* if quit command was read previously, don't decode anything */
	if (s->got_quit_command) {
	*got_frame_ptr = 0;
	return avpkt->size;
	}

	s->cur_chan = 0;
	while (s->cur_chan < s->channels) {
	unsigned cmd;
	int len;

	if (get_bits_left(&s->gb) < 3 + FNSIZE) {
	*got_frame_ptr = 0;
	break;
	}

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

	if (cmd > FN_VERBATIM) {
	av_log(avctx, AV_LOG_ERROR, "unknown shorten function %d\n", cmd);
	*got_frame_ptr = 0;
	break;
	}

	if (!is_audio_command[cmd]) {
	/* process non-audio command */
	switch (cmd) {
	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: {
	unsigned bitshift = get_ur_golomb_shorten(&s->gb, BITSHIFTSIZE);
	if (bitshift > 31) {
	av_log(avctx, AV_LOG_ERROR, "bitshift %d is invalid\n",
	bitshift);
	return AVERROR_INVALIDDATA;
	}
	s->bitshift = bitshift;
	break;
	}
	case FN_BLOCKSIZE: {
	unsigned blocksize = get_uint(s, av_log2(s->blocksize));
	if (blocksize > s->blocksize) {
	av_log(avctx, AV_LOG_ERROR,
	"Increasing block size is not supported\n");
	return AVERROR_PATCHWELCOME;
	}
	if (!blocksize \|\| blocksize > MAX_BLOCKSIZE) {
	av_log(avctx, AV_LOG_ERROR, "invalid or unsupported "
	"block size: %d\n", blocksize);
	return AVERROR(EINVAL);
	}
	s->blocksize = blocksize;
	break;
	}
	case FN_QUIT:
	s->got_quit_command = 1;
	break;
	}
	if (cmd == FN_BLOCKSIZE \|\| cmd == FN_QUIT) {
	*got_frame_ptr = 0;
	break;
	}
	} else {
	/* process audio command */
	int residual_size = 0;
	int channel = s->cur_chan;
	int32_t coffset;

	/* get Rice code for residual decoding */
	if (cmd != FN_ZERO) {
	residual_size = get_ur_golomb_shorten(&s->gb, ENERGYSIZE);
	/* This is a hack as version 0 differed in the definition
	* of get_sr_golomb_shorten(). */
	if (s->version == 0)
	residual_size--;
	}

	/* calculate sample offset using means from previous blocks */
	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 = s->bitshift == 0 ? coffset : coffset >> s->bitshift - 1 >> 1;
	}

	/* decode samples for this channel */
	if (cmd == FN_ZERO) {
	for (i = 0; i < s->blocksize; i++)
	s->decoded[channel][i] = 0;
	} else {
	if ((ret = decode_subframe_lpc(s, cmd, channel,
	residual_size, coffset)) < 0)
	return ret;
	}

	/* update means with info from the current block */
	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;
	}

	/* copy wrap samples for use with next block */
	for (i = -s->nwrap; i < 0; i++)
	s->decoded[channel][i] = s->decoded[channel][i + s->blocksize];

	/* shift samples to add in unused zero bits which were removed
	* during encoding */
	fix_bitshift(s, s->decoded[channel]);

	/* if this is the last channel in the block, output the samples */
	s->cur_chan++;
	if (s->cur_chan == s->channels) {
	uint8_t *samples_u8;
	int16_t *samples_s16;
	int chan;

	/* get output buffer */
	frame->nb_samples = s->blocksize;
	if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
	return ret;

	for (chan = 0; chan < s->channels; chan++) {
	samples_u8 = ((uint8_t **)frame->extended_data)[chan];
	samples_s16 = ((int16_t **)frame->extended_data)[chan];
	for (i = 0; i < s->blocksize; i++) {
	switch (s->internal_ftype) {
	case TYPE_U8:
	*samples_u8++ = av_clip_uint8(s->decoded[chan][i]);
	break;
	case TYPE_S16HL:
	case TYPE_S16LH:
	*samples_s16++ = av_clip_int16(s->decoded[chan][i]);
	break;
	}
	}
	}

	*got_frame_ptr = 1;
	}
	}
	}
	if (s->cur_chan < s->channels)
	*got_frame_ptr = 0;

	finish_frame:
	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 AVERROR_INVALIDDATA;
	}
	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] = NULL;
	av_freep(&s->decoded_base[i]);
	av_freep(&s->offset[i]);
	}
	av_freep(&s->bitstream);
	av_freep(&s->coeffs);

	return 0;
	}

	AVCodec ff_shorten_decoder = {
	.name = "shorten",
	.long_name = NULL_IF_CONFIG_SMALL("Shorten"),
	.type = AVMEDIA_TYPE_AUDIO,
	.id = AV_CODEC_ID_SHORTEN,
	.priv_data_size = sizeof(ShortenContext),
	.init = shorten_decode_init,
	.close = shorten_decode_close,
	.decode = shorten_decode_frame,
	.capabilities = AV_CODEC_CAP_DELAY \| AV_CODEC_CAP_DR1,
	.sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_S16P,
	AV_SAMPLE_FMT_U8P,
	AV_SAMPLE_FMT_NONE },
	};