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libavcodec/apedec.c

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00001 /*
00002  * Monkey's Audio lossless audio decoder
00003  * Copyright (c) 2007 Benjamin Zores <ben@geexbox.org>
00004  *  based upon libdemac from Dave Chapman.
00005  *
00006  * This file is part of FFmpeg.
00007  *
00008  * FFmpeg is free software; you can redistribute it and/or
00009  * modify it under the terms of the GNU Lesser General Public
00010  * License as published by the Free Software Foundation; either
00011  * version 2.1 of the License, or (at your option) any later version.
00012  *
00013  * FFmpeg is distributed in the hope that it will be useful,
00014  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00015  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00016  * Lesser General Public License for more details.
00017  *
00018  * You should have received a copy of the GNU Lesser General Public
00019  * License along with FFmpeg; if not, write to the Free Software
00020  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00021  */
00022 
00023 #define ALT_BITSTREAM_READER_LE
00024 #include "avcodec.h"
00025 #include "dsputil.h"
00026 #include "get_bits.h"
00027 #include "bytestream.h"
00028 #include "libavutil/audioconvert.h"
00029 
00035 #define BLOCKS_PER_LOOP     4608
00036 #define MAX_CHANNELS        2
00037 #define MAX_BYTESPERSAMPLE  3
00038 
00039 #define APE_FRAMECODE_MONO_SILENCE    1
00040 #define APE_FRAMECODE_STEREO_SILENCE  3
00041 #define APE_FRAMECODE_PSEUDO_STEREO   4
00042 
00043 #define HISTORY_SIZE 512
00044 #define PREDICTOR_ORDER 8
00045 
00046 #define PREDICTOR_SIZE 50
00047 
00048 #define YDELAYA (18 + PREDICTOR_ORDER*4)
00049 #define YDELAYB (18 + PREDICTOR_ORDER*3)
00050 #define XDELAYA (18 + PREDICTOR_ORDER*2)
00051 #define XDELAYB (18 + PREDICTOR_ORDER)
00052 
00053 #define YADAPTCOEFFSA 18
00054 #define XADAPTCOEFFSA 14
00055 #define YADAPTCOEFFSB 10
00056 #define XADAPTCOEFFSB 5
00057 
00062 enum APECompressionLevel {
00063     COMPRESSION_LEVEL_FAST       = 1000,
00064     COMPRESSION_LEVEL_NORMAL     = 2000,
00065     COMPRESSION_LEVEL_HIGH       = 3000,
00066     COMPRESSION_LEVEL_EXTRA_HIGH = 4000,
00067     COMPRESSION_LEVEL_INSANE     = 5000
00068 };
00071 #define APE_FILTER_LEVELS 3
00072 
00074 static const uint16_t ape_filter_orders[5][APE_FILTER_LEVELS] = {
00075     {  0,   0,    0 },
00076     { 16,   0,    0 },
00077     { 64,   0,    0 },
00078     { 32, 256,    0 },
00079     { 16, 256, 1280 }
00080 };
00081 
00083 static const uint8_t ape_filter_fracbits[5][APE_FILTER_LEVELS] = {
00084     {  0,  0,  0 },
00085     { 11,  0,  0 },
00086     { 11,  0,  0 },
00087     { 10, 13,  0 },
00088     { 11, 13, 15 }
00089 };
00090 
00091 
00093 typedef struct APEFilter {
00094     int16_t *coeffs;        
00095     int16_t *adaptcoeffs;   
00096     int16_t *historybuffer; 
00097     int16_t *delay;         
00098 
00099     int avg;
00100 } APEFilter;
00101 
00102 typedef struct APERice {
00103     uint32_t k;
00104     uint32_t ksum;
00105 } APERice;
00106 
00107 typedef struct APERangecoder {
00108     uint32_t low;           
00109     uint32_t range;         
00110     uint32_t help;          
00111     unsigned int buffer;    
00112 } APERangecoder;
00113 
00115 typedef struct APEPredictor {
00116     int32_t *buf;
00117 
00118     int32_t lastA[2];
00119 
00120     int32_t filterA[2];
00121     int32_t filterB[2];
00122 
00123     int32_t coeffsA[2][4];  
00124     int32_t coeffsB[2][5];  
00125     int32_t historybuffer[HISTORY_SIZE + PREDICTOR_SIZE];
00126 } APEPredictor;
00127 
00129 typedef struct APEContext {
00130     AVCodecContext *avctx;
00131     DSPContext dsp;
00132     int channels;
00133     int samples;                             
00134 
00135     int fileversion;                         
00136     int compression_level;                   
00137     int fset;                                
00138     int flags;                               
00139 
00140     uint32_t CRC;                            
00141     int frameflags;                          
00142     int currentframeblocks;                  
00143     int blocksdecoded;                       
00144     APEPredictor predictor;                  
00145 
00146     int32_t decoded0[BLOCKS_PER_LOOP];       
00147     int32_t decoded1[BLOCKS_PER_LOOP];       
00148 
00149     int16_t* filterbuf[APE_FILTER_LEVELS];   
00150 
00151     APERangecoder rc;                        
00152     APERice riceX;                           
00153     APERice riceY;                           
00154     APEFilter filters[APE_FILTER_LEVELS][2]; 
00155 
00156     uint8_t *data;                           
00157     uint8_t *data_end;                       
00158     const uint8_t *ptr;                      
00159     const uint8_t *last_ptr;                 
00160 
00161     int error;
00162 } APEContext;
00163 
00164 // TODO: dsputilize
00165 
00166 static av_cold int ape_decode_close(AVCodecContext * avctx)
00167 {
00168     APEContext *s = avctx->priv_data;
00169     int i;
00170 
00171     for (i = 0; i < APE_FILTER_LEVELS; i++)
00172         av_freep(&s->filterbuf[i]);
00173 
00174     av_freep(&s->data);
00175     return 0;
00176 }
00177 
00178 static av_cold int ape_decode_init(AVCodecContext * avctx)
00179 {
00180     APEContext *s = avctx->priv_data;
00181     int i;
00182 
00183     if (avctx->extradata_size != 6) {
00184         av_log(avctx, AV_LOG_ERROR, "Incorrect extradata\n");
00185         return -1;
00186     }
00187     if (avctx->bits_per_coded_sample != 16) {
00188         av_log(avctx, AV_LOG_ERROR, "Only 16-bit samples are supported\n");
00189         return -1;
00190     }
00191     if (avctx->channels > 2) {
00192         av_log(avctx, AV_LOG_ERROR, "Only mono and stereo is supported\n");
00193         return -1;
00194     }
00195     s->avctx             = avctx;
00196     s->channels          = avctx->channels;
00197     s->fileversion       = AV_RL16(avctx->extradata);
00198     s->compression_level = AV_RL16(avctx->extradata + 2);
00199     s->flags             = AV_RL16(avctx->extradata + 4);
00200 
00201     av_log(avctx, AV_LOG_DEBUG, "Compression Level: %d - Flags: %d\n", s->compression_level, s->flags);
00202     if (s->compression_level % 1000 || s->compression_level > COMPRESSION_LEVEL_INSANE) {
00203         av_log(avctx, AV_LOG_ERROR, "Incorrect compression level %d\n", s->compression_level);
00204         return -1;
00205     }
00206     s->fset = s->compression_level / 1000 - 1;
00207     for (i = 0; i < APE_FILTER_LEVELS; i++) {
00208         if (!ape_filter_orders[s->fset][i])
00209             break;
00210         FF_ALLOC_OR_GOTO(avctx, s->filterbuf[i],
00211                          (ape_filter_orders[s->fset][i] * 3 + HISTORY_SIZE) * 4,
00212                          filter_alloc_fail);
00213     }
00214 
00215     dsputil_init(&s->dsp, avctx);
00216     avctx->sample_fmt = AV_SAMPLE_FMT_S16;
00217     avctx->channel_layout = (avctx->channels==2) ? AV_CH_LAYOUT_STEREO : AV_CH_LAYOUT_MONO;
00218     return 0;
00219 filter_alloc_fail:
00220     ape_decode_close(avctx);
00221     return AVERROR(ENOMEM);
00222 }
00223 
00229 #define CODE_BITS    32
00230 #define TOP_VALUE    ((unsigned int)1 << (CODE_BITS-1))
00231 #define SHIFT_BITS   (CODE_BITS - 9)
00232 #define EXTRA_BITS   ((CODE_BITS-2) % 8 + 1)
00233 #define BOTTOM_VALUE (TOP_VALUE >> 8)
00234 
00236 static inline void range_start_decoding(APEContext * ctx)
00237 {
00238     ctx->rc.buffer = bytestream_get_byte(&ctx->ptr);
00239     ctx->rc.low    = ctx->rc.buffer >> (8 - EXTRA_BITS);
00240     ctx->rc.range  = (uint32_t) 1 << EXTRA_BITS;
00241 }
00242 
00244 static inline void range_dec_normalize(APEContext * ctx)
00245 {
00246     while (ctx->rc.range <= BOTTOM_VALUE) {
00247         ctx->rc.buffer <<= 8;
00248         if(ctx->ptr < ctx->data_end)
00249             ctx->rc.buffer += *ctx->ptr;
00250         ctx->ptr++;
00251         ctx->rc.low    = (ctx->rc.low << 8)    | ((ctx->rc.buffer >> 1) & 0xFF);
00252         ctx->rc.range  <<= 8;
00253     }
00254 }
00255 
00262 static inline int range_decode_culfreq(APEContext * ctx, int tot_f)
00263 {
00264     range_dec_normalize(ctx);
00265     ctx->rc.help = ctx->rc.range / tot_f;
00266     return ctx->rc.low / ctx->rc.help;
00267 }
00268 
00274 static inline int range_decode_culshift(APEContext * ctx, int shift)
00275 {
00276     range_dec_normalize(ctx);
00277     ctx->rc.help = ctx->rc.range >> shift;
00278     return ctx->rc.low / ctx->rc.help;
00279 }
00280 
00281 
00288 static inline void range_decode_update(APEContext * ctx, int sy_f, int lt_f)
00289 {
00290     ctx->rc.low  -= ctx->rc.help * lt_f;
00291     ctx->rc.range = ctx->rc.help * sy_f;
00292 }
00293 
00295 static inline int range_decode_bits(APEContext * ctx, int n)
00296 {
00297     int sym = range_decode_culshift(ctx, n);
00298     range_decode_update(ctx, 1, sym);
00299     return sym;
00300 }
00301 
00302 
00303 #define MODEL_ELEMENTS 64
00304 
00308 static const uint16_t counts_3970[22] = {
00309         0, 14824, 28224, 39348, 47855, 53994, 58171, 60926,
00310     62682, 63786, 64463, 64878, 65126, 65276, 65365, 65419,
00311     65450, 65469, 65480, 65487, 65491, 65493,
00312 };
00313 
00317 static const uint16_t counts_diff_3970[21] = {
00318     14824, 13400, 11124, 8507, 6139, 4177, 2755, 1756,
00319     1104, 677, 415, 248, 150, 89, 54, 31,
00320     19, 11, 7, 4, 2,
00321 };
00322 
00326 static const uint16_t counts_3980[22] = {
00327         0, 19578, 36160, 48417, 56323, 60899, 63265, 64435,
00328     64971, 65232, 65351, 65416, 65447, 65466, 65476, 65482,
00329     65485, 65488, 65490, 65491, 65492, 65493,
00330 };
00331 
00335 static const uint16_t counts_diff_3980[21] = {
00336     19578, 16582, 12257, 7906, 4576, 2366, 1170, 536,
00337     261, 119, 65, 31, 19, 10, 6, 3,
00338     3, 2, 1, 1, 1,
00339 };
00340 
00347 static inline int range_get_symbol(APEContext * ctx,
00348                                    const uint16_t counts[],
00349                                    const uint16_t counts_diff[])
00350 {
00351     int symbol, cf;
00352 
00353     cf = range_decode_culshift(ctx, 16);
00354 
00355     if(cf > 65492){
00356         symbol= cf - 65535 + 63;
00357         range_decode_update(ctx, 1, cf);
00358         if(cf > 65535)
00359             ctx->error=1;
00360         return symbol;
00361     }
00362     /* figure out the symbol inefficiently; a binary search would be much better */
00363     for (symbol = 0; counts[symbol + 1] <= cf; symbol++);
00364 
00365     range_decode_update(ctx, counts_diff[symbol], counts[symbol]);
00366 
00367     return symbol;
00368 } // group rangecoder
00370 
00371 static inline void update_rice(APERice *rice, int x)
00372 {
00373     int lim = rice->k ? (1 << (rice->k + 4)) : 0;
00374     rice->ksum += ((x + 1) / 2) - ((rice->ksum + 16) >> 5);
00375 
00376     if (rice->ksum < lim)
00377         rice->k--;
00378     else if (rice->ksum >= (1 << (rice->k + 5)))
00379         rice->k++;
00380 }
00381 
00382 static inline int ape_decode_value(APEContext * ctx, APERice *rice)
00383 {
00384     int x, overflow;
00385 
00386     if (ctx->fileversion < 3990) {
00387         int tmpk;
00388 
00389         overflow = range_get_symbol(ctx, counts_3970, counts_diff_3970);
00390 
00391         if (overflow == (MODEL_ELEMENTS - 1)) {
00392             tmpk = range_decode_bits(ctx, 5);
00393             overflow = 0;
00394         } else
00395             tmpk = (rice->k < 1) ? 0 : rice->k - 1;
00396 
00397         if (tmpk <= 16)
00398             x = range_decode_bits(ctx, tmpk);
00399         else {
00400             x = range_decode_bits(ctx, 16);
00401             x |= (range_decode_bits(ctx, tmpk - 16) << 16);
00402         }
00403         x += overflow << tmpk;
00404     } else {
00405         int base, pivot;
00406 
00407         pivot = rice->ksum >> 5;
00408         if (pivot == 0)
00409             pivot = 1;
00410 
00411         overflow = range_get_symbol(ctx, counts_3980, counts_diff_3980);
00412 
00413         if (overflow == (MODEL_ELEMENTS - 1)) {
00414             overflow  = range_decode_bits(ctx, 16) << 16;
00415             overflow |= range_decode_bits(ctx, 16);
00416         }
00417 
00418         if (pivot < 0x10000) {
00419             base = range_decode_culfreq(ctx, pivot);
00420             range_decode_update(ctx, 1, base);
00421         } else {
00422             int base_hi = pivot, base_lo;
00423             int bbits = 0;
00424 
00425             while (base_hi & ~0xFFFF) {
00426                 base_hi >>= 1;
00427                 bbits++;
00428             }
00429             base_hi = range_decode_culfreq(ctx, base_hi + 1);
00430             range_decode_update(ctx, 1, base_hi);
00431             base_lo = range_decode_culfreq(ctx, 1 << bbits);
00432             range_decode_update(ctx, 1, base_lo);
00433 
00434             base = (base_hi << bbits) + base_lo;
00435         }
00436 
00437         x = base + overflow * pivot;
00438     }
00439 
00440     update_rice(rice, x);
00441 
00442     /* Convert to signed */
00443     if (x & 1)
00444         return (x >> 1) + 1;
00445     else
00446         return -(x >> 1);
00447 }
00448 
00449 static void entropy_decode(APEContext * ctx, int blockstodecode, int stereo)
00450 {
00451     int32_t *decoded0 = ctx->decoded0;
00452     int32_t *decoded1 = ctx->decoded1;
00453 
00454     ctx->blocksdecoded = blockstodecode;
00455 
00456     if (ctx->frameflags & APE_FRAMECODE_STEREO_SILENCE) {
00457         /* We are pure silence, just memset the output buffer. */
00458         memset(decoded0, 0, blockstodecode * sizeof(int32_t));
00459         memset(decoded1, 0, blockstodecode * sizeof(int32_t));
00460     } else {
00461         while (blockstodecode--) {
00462             *decoded0++ = ape_decode_value(ctx, &ctx->riceY);
00463             if (stereo)
00464                 *decoded1++ = ape_decode_value(ctx, &ctx->riceX);
00465         }
00466     }
00467 
00468     if (ctx->blocksdecoded == ctx->currentframeblocks)
00469         range_dec_normalize(ctx);   /* normalize to use up all bytes */
00470 }
00471 
00472 static void init_entropy_decoder(APEContext * ctx)
00473 {
00474     /* Read the CRC */
00475     ctx->CRC = bytestream_get_be32(&ctx->ptr);
00476 
00477     /* Read the frame flags if they exist */
00478     ctx->frameflags = 0;
00479     if ((ctx->fileversion > 3820) && (ctx->CRC & 0x80000000)) {
00480         ctx->CRC &= ~0x80000000;
00481 
00482         ctx->frameflags = bytestream_get_be32(&ctx->ptr);
00483     }
00484 
00485     /* Keep a count of the blocks decoded in this frame */
00486     ctx->blocksdecoded = 0;
00487 
00488     /* Initialize the rice structs */
00489     ctx->riceX.k = 10;
00490     ctx->riceX.ksum = (1 << ctx->riceX.k) * 16;
00491     ctx->riceY.k = 10;
00492     ctx->riceY.ksum = (1 << ctx->riceY.k) * 16;
00493 
00494     /* The first 8 bits of input are ignored. */
00495     ctx->ptr++;
00496 
00497     range_start_decoding(ctx);
00498 }
00499 
00500 static const int32_t initial_coeffs[4] = {
00501     360, 317, -109, 98
00502 };
00503 
00504 static void init_predictor_decoder(APEContext * ctx)
00505 {
00506     APEPredictor *p = &ctx->predictor;
00507 
00508     /* Zero the history buffers */
00509     memset(p->historybuffer, 0, PREDICTOR_SIZE * sizeof(int32_t));
00510     p->buf = p->historybuffer;
00511 
00512     /* Initialize and zero the coefficients */
00513     memcpy(p->coeffsA[0], initial_coeffs, sizeof(initial_coeffs));
00514     memcpy(p->coeffsA[1], initial_coeffs, sizeof(initial_coeffs));
00515     memset(p->coeffsB, 0, sizeof(p->coeffsB));
00516 
00517     p->filterA[0] = p->filterA[1] = 0;
00518     p->filterB[0] = p->filterB[1] = 0;
00519     p->lastA[0]   = p->lastA[1]   = 0;
00520 }
00521 
00523 static inline int APESIGN(int32_t x) {
00524     return (x < 0) - (x > 0);
00525 }
00526 
00527 static av_always_inline int predictor_update_filter(APEPredictor *p, const int decoded, const int filter, const int delayA, const int delayB, const int adaptA, const int adaptB)
00528 {
00529     int32_t predictionA, predictionB, sign;
00530 
00531     p->buf[delayA]     = p->lastA[filter];
00532     p->buf[adaptA]     = APESIGN(p->buf[delayA]);
00533     p->buf[delayA - 1] = p->buf[delayA] - p->buf[delayA - 1];
00534     p->buf[adaptA - 1] = APESIGN(p->buf[delayA - 1]);
00535 
00536     predictionA = p->buf[delayA    ] * p->coeffsA[filter][0] +
00537                   p->buf[delayA - 1] * p->coeffsA[filter][1] +
00538                   p->buf[delayA - 2] * p->coeffsA[filter][2] +
00539                   p->buf[delayA - 3] * p->coeffsA[filter][3];
00540 
00541     /*  Apply a scaled first-order filter compression */
00542     p->buf[delayB]     = p->filterA[filter ^ 1] - ((p->filterB[filter] * 31) >> 5);
00543     p->buf[adaptB]     = APESIGN(p->buf[delayB]);
00544     p->buf[delayB - 1] = p->buf[delayB] - p->buf[delayB - 1];
00545     p->buf[adaptB - 1] = APESIGN(p->buf[delayB - 1]);
00546     p->filterB[filter] = p->filterA[filter ^ 1];
00547 
00548     predictionB = p->buf[delayB    ] * p->coeffsB[filter][0] +
00549                   p->buf[delayB - 1] * p->coeffsB[filter][1] +
00550                   p->buf[delayB - 2] * p->coeffsB[filter][2] +
00551                   p->buf[delayB - 3] * p->coeffsB[filter][3] +
00552                   p->buf[delayB - 4] * p->coeffsB[filter][4];
00553 
00554     p->lastA[filter] = decoded + ((predictionA + (predictionB >> 1)) >> 10);
00555     p->filterA[filter] = p->lastA[filter] + ((p->filterA[filter] * 31) >> 5);
00556 
00557     sign = APESIGN(decoded);
00558     p->coeffsA[filter][0] += p->buf[adaptA    ] * sign;
00559     p->coeffsA[filter][1] += p->buf[adaptA - 1] * sign;
00560     p->coeffsA[filter][2] += p->buf[adaptA - 2] * sign;
00561     p->coeffsA[filter][3] += p->buf[adaptA - 3] * sign;
00562     p->coeffsB[filter][0] += p->buf[adaptB    ] * sign;
00563     p->coeffsB[filter][1] += p->buf[adaptB - 1] * sign;
00564     p->coeffsB[filter][2] += p->buf[adaptB - 2] * sign;
00565     p->coeffsB[filter][3] += p->buf[adaptB - 3] * sign;
00566     p->coeffsB[filter][4] += p->buf[adaptB - 4] * sign;
00567 
00568     return p->filterA[filter];
00569 }
00570 
00571 static void predictor_decode_stereo(APEContext * ctx, int count)
00572 {
00573     APEPredictor *p = &ctx->predictor;
00574     int32_t *decoded0 = ctx->decoded0;
00575     int32_t *decoded1 = ctx->decoded1;
00576 
00577     while (count--) {
00578         /* Predictor Y */
00579         *decoded0 = predictor_update_filter(p, *decoded0, 0, YDELAYA, YDELAYB, YADAPTCOEFFSA, YADAPTCOEFFSB);
00580         decoded0++;
00581         *decoded1 = predictor_update_filter(p, *decoded1, 1, XDELAYA, XDELAYB, XADAPTCOEFFSA, XADAPTCOEFFSB);
00582         decoded1++;
00583 
00584         /* Combined */
00585         p->buf++;
00586 
00587         /* Have we filled the history buffer? */
00588         if (p->buf == p->historybuffer + HISTORY_SIZE) {
00589             memmove(p->historybuffer, p->buf, PREDICTOR_SIZE * sizeof(int32_t));
00590             p->buf = p->historybuffer;
00591         }
00592     }
00593 }
00594 
00595 static void predictor_decode_mono(APEContext * ctx, int count)
00596 {
00597     APEPredictor *p = &ctx->predictor;
00598     int32_t *decoded0 = ctx->decoded0;
00599     int32_t predictionA, currentA, A, sign;
00600 
00601     currentA = p->lastA[0];
00602 
00603     while (count--) {
00604         A = *decoded0;
00605 
00606         p->buf[YDELAYA] = currentA;
00607         p->buf[YDELAYA - 1] = p->buf[YDELAYA] - p->buf[YDELAYA - 1];
00608 
00609         predictionA = p->buf[YDELAYA    ] * p->coeffsA[0][0] +
00610                       p->buf[YDELAYA - 1] * p->coeffsA[0][1] +
00611                       p->buf[YDELAYA - 2] * p->coeffsA[0][2] +
00612                       p->buf[YDELAYA - 3] * p->coeffsA[0][3];
00613 
00614         currentA = A + (predictionA >> 10);
00615 
00616         p->buf[YADAPTCOEFFSA]     = APESIGN(p->buf[YDELAYA    ]);
00617         p->buf[YADAPTCOEFFSA - 1] = APESIGN(p->buf[YDELAYA - 1]);
00618 
00619         sign = APESIGN(A);
00620         p->coeffsA[0][0] += p->buf[YADAPTCOEFFSA    ] * sign;
00621         p->coeffsA[0][1] += p->buf[YADAPTCOEFFSA - 1] * sign;
00622         p->coeffsA[0][2] += p->buf[YADAPTCOEFFSA - 2] * sign;
00623         p->coeffsA[0][3] += p->buf[YADAPTCOEFFSA - 3] * sign;
00624 
00625         p->buf++;
00626 
00627         /* Have we filled the history buffer? */
00628         if (p->buf == p->historybuffer + HISTORY_SIZE) {
00629             memmove(p->historybuffer, p->buf, PREDICTOR_SIZE * sizeof(int32_t));
00630             p->buf = p->historybuffer;
00631         }
00632 
00633         p->filterA[0] = currentA + ((p->filterA[0] * 31) >> 5);
00634         *(decoded0++) = p->filterA[0];
00635     }
00636 
00637     p->lastA[0] = currentA;
00638 }
00639 
00640 static void do_init_filter(APEFilter *f, int16_t * buf, int order)
00641 {
00642     f->coeffs = buf;
00643     f->historybuffer = buf + order;
00644     f->delay       = f->historybuffer + order * 2;
00645     f->adaptcoeffs = f->historybuffer + order;
00646 
00647     memset(f->historybuffer, 0, (order * 2) * sizeof(int16_t));
00648     memset(f->coeffs, 0, order * sizeof(int16_t));
00649     f->avg = 0;
00650 }
00651 
00652 static void init_filter(APEContext * ctx, APEFilter *f, int16_t * buf, int order)
00653 {
00654     do_init_filter(&f[0], buf, order);
00655     do_init_filter(&f[1], buf + order * 3 + HISTORY_SIZE, order);
00656 }
00657 
00658 static void do_apply_filter(APEContext * ctx, int version, APEFilter *f, int32_t *data, int count, int order, int fracbits)
00659 {
00660     int res;
00661     int absres;
00662 
00663     while (count--) {
00664         /* round fixedpoint scalar product */
00665         res = ctx->dsp.scalarproduct_and_madd_int16(f->coeffs, f->delay - order, f->adaptcoeffs - order, order, APESIGN(*data));
00666         res = (res + (1 << (fracbits - 1))) >> fracbits;
00667         res += *data;
00668         *data++ = res;
00669 
00670         /* Update the output history */
00671         *f->delay++ = av_clip_int16(res);
00672 
00673         if (version < 3980) {
00674             /* Version ??? to < 3.98 files (untested) */
00675             f->adaptcoeffs[0]  = (res == 0) ? 0 : ((res >> 28) & 8) - 4;
00676             f->adaptcoeffs[-4] >>= 1;
00677             f->adaptcoeffs[-8] >>= 1;
00678         } else {
00679             /* Version 3.98 and later files */
00680 
00681             /* Update the adaption coefficients */
00682             absres = FFABS(res);
00683             if (absres)
00684                 *f->adaptcoeffs = ((res & (1<<31)) - (1<<30)) >> (25 + (absres <= f->avg*3) + (absres <= f->avg*4/3));
00685             else
00686                 *f->adaptcoeffs = 0;
00687 
00688             f->avg += (absres - f->avg) / 16;
00689 
00690             f->adaptcoeffs[-1] >>= 1;
00691             f->adaptcoeffs[-2] >>= 1;
00692             f->adaptcoeffs[-8] >>= 1;
00693         }
00694 
00695         f->adaptcoeffs++;
00696 
00697         /* Have we filled the history buffer? */
00698         if (f->delay == f->historybuffer + HISTORY_SIZE + (order * 2)) {
00699             memmove(f->historybuffer, f->delay - (order * 2),
00700                     (order * 2) * sizeof(int16_t));
00701             f->delay = f->historybuffer + order * 2;
00702             f->adaptcoeffs = f->historybuffer + order;
00703         }
00704     }
00705 }
00706 
00707 static void apply_filter(APEContext * ctx, APEFilter *f,
00708                          int32_t * data0, int32_t * data1,
00709                          int count, int order, int fracbits)
00710 {
00711     do_apply_filter(ctx, ctx->fileversion, &f[0], data0, count, order, fracbits);
00712     if (data1)
00713         do_apply_filter(ctx, ctx->fileversion, &f[1], data1, count, order, fracbits);
00714 }
00715 
00716 static void ape_apply_filters(APEContext * ctx, int32_t * decoded0,
00717                               int32_t * decoded1, int count)
00718 {
00719     int i;
00720 
00721     for (i = 0; i < APE_FILTER_LEVELS; i++) {
00722         if (!ape_filter_orders[ctx->fset][i])
00723             break;
00724         apply_filter(ctx, ctx->filters[i], decoded0, decoded1, count, ape_filter_orders[ctx->fset][i], ape_filter_fracbits[ctx->fset][i]);
00725     }
00726 }
00727 
00728 static void init_frame_decoder(APEContext * ctx)
00729 {
00730     int i;
00731     init_entropy_decoder(ctx);
00732     init_predictor_decoder(ctx);
00733 
00734     for (i = 0; i < APE_FILTER_LEVELS; i++) {
00735         if (!ape_filter_orders[ctx->fset][i])
00736             break;
00737         init_filter(ctx, ctx->filters[i], ctx->filterbuf[i], ape_filter_orders[ctx->fset][i]);
00738     }
00739 }
00740 
00741 static void ape_unpack_mono(APEContext * ctx, int count)
00742 {
00743     int32_t left;
00744     int32_t *decoded0 = ctx->decoded0;
00745     int32_t *decoded1 = ctx->decoded1;
00746 
00747     if (ctx->frameflags & APE_FRAMECODE_STEREO_SILENCE) {
00748         entropy_decode(ctx, count, 0);
00749         /* We are pure silence, so we're done. */
00750         av_log(ctx->avctx, AV_LOG_DEBUG, "pure silence mono\n");
00751         return;
00752     }
00753 
00754     entropy_decode(ctx, count, 0);
00755     ape_apply_filters(ctx, decoded0, NULL, count);
00756 
00757     /* Now apply the predictor decoding */
00758     predictor_decode_mono(ctx, count);
00759 
00760     /* Pseudo-stereo - just copy left channel to right channel */
00761     if (ctx->channels == 2) {
00762         while (count--) {
00763             left = *decoded0;
00764             *(decoded1++) = *(decoded0++) = left;
00765         }
00766     }
00767 }
00768 
00769 static void ape_unpack_stereo(APEContext * ctx, int count)
00770 {
00771     int32_t left, right;
00772     int32_t *decoded0 = ctx->decoded0;
00773     int32_t *decoded1 = ctx->decoded1;
00774 
00775     if (ctx->frameflags & APE_FRAMECODE_STEREO_SILENCE) {
00776         /* We are pure silence, so we're done. */
00777         av_log(ctx->avctx, AV_LOG_DEBUG, "pure silence stereo\n");
00778         return;
00779     }
00780 
00781     entropy_decode(ctx, count, 1);
00782     ape_apply_filters(ctx, decoded0, decoded1, count);
00783 
00784     /* Now apply the predictor decoding */
00785     predictor_decode_stereo(ctx, count);
00786 
00787     /* Decorrelate and scale to output depth */
00788     while (count--) {
00789         left = *decoded1 - (*decoded0 / 2);
00790         right = left + *decoded0;
00791 
00792         *(decoded0++) = left;
00793         *(decoded1++) = right;
00794     }
00795 }
00796 
00797 static int ape_decode_frame(AVCodecContext * avctx,
00798                             void *data, int *data_size,
00799                             AVPacket *avpkt)
00800 {
00801     const uint8_t *buf = avpkt->data;
00802     int buf_size = avpkt->size;
00803     APEContext *s = avctx->priv_data;
00804     int16_t *samples = data;
00805     uint32_t nblocks;
00806     int i, n;
00807     int blockstodecode;
00808     int bytes_used;
00809 
00810     if (buf_size == 0 && !s->samples) {
00811         *data_size = 0;
00812         return 0;
00813     }
00814 
00815     /* should not happen but who knows */
00816     if (BLOCKS_PER_LOOP * 2 * avctx->channels > *data_size) {
00817         av_log (avctx, AV_LOG_ERROR, "Packet size is too big to be handled in lavc! (max is %d where you have %d)\n", *data_size, s->samples * 2 * avctx->channels);
00818         return -1;
00819     }
00820 
00821     if(!s->samples){
00822         void *tmp_data = av_realloc(s->data, (buf_size + 3) & ~3);
00823         if (!tmp_data)
00824             return AVERROR(ENOMEM);
00825         s->data = tmp_data;
00826         s->dsp.bswap_buf((uint32_t*)s->data, (const uint32_t*)buf, buf_size >> 2);
00827         s->ptr = s->last_ptr = s->data;
00828         s->data_end = s->data + buf_size;
00829 
00830         nblocks = bytestream_get_be32(&s->ptr);
00831         n =  bytestream_get_be32(&s->ptr);
00832         if(n < 0 || n > 3){
00833             av_log(avctx, AV_LOG_ERROR, "Incorrect offset passed\n");
00834             s->data = NULL;
00835             return -1;
00836         }
00837         s->ptr += n;
00838 
00839         buf += 4;
00840         if (!nblocks || nblocks > INT_MAX) {
00841             av_log(avctx, AV_LOG_ERROR, "Invalid sample count: %u.\n", nblocks);
00842             *data_size = 0;
00843             return AVERROR_INVALIDDATA;
00844         }
00845         s->currentframeblocks = s->samples = nblocks;
00846 
00847         memset(s->decoded0,  0, sizeof(s->decoded0));
00848         memset(s->decoded1,  0, sizeof(s->decoded1));
00849 
00850         /* Initialize the frame decoder */
00851         init_frame_decoder(s);
00852     }
00853 
00854     if (!s->data) {
00855         *data_size = 0;
00856         return buf_size;
00857     }
00858 
00859     nblocks = s->samples;
00860     blockstodecode = FFMIN(BLOCKS_PER_LOOP, nblocks);
00861 
00862     s->error=0;
00863 
00864     if ((s->channels == 1) || (s->frameflags & APE_FRAMECODE_PSEUDO_STEREO))
00865         ape_unpack_mono(s, blockstodecode);
00866     else
00867         ape_unpack_stereo(s, blockstodecode);
00868     emms_c();
00869 
00870     if(s->error || s->ptr > s->data_end){
00871         s->samples=0;
00872         av_log(avctx, AV_LOG_ERROR, "Error decoding frame\n");
00873         return -1;
00874     }
00875 
00876     for (i = 0; i < blockstodecode; i++) {
00877         *samples++ = s->decoded0[i];
00878         if(s->channels == 2)
00879             *samples++ = s->decoded1[i];
00880     }
00881 
00882     s->samples -= blockstodecode;
00883 
00884     *data_size = blockstodecode * 2 * s->channels;
00885     bytes_used = s->samples ? s->ptr - s->last_ptr : buf_size;
00886     s->last_ptr = s->ptr;
00887     return bytes_used;
00888 }
00889 
00890 static void ape_flush(AVCodecContext *avctx)
00891 {
00892     APEContext *s = avctx->priv_data;
00893     s->samples= 0;
00894 }
00895 
00896 AVCodec ff_ape_decoder = {
00897     "ape",
00898     AVMEDIA_TYPE_AUDIO,
00899     CODEC_ID_APE,
00900     sizeof(APEContext),
00901     ape_decode_init,
00902     NULL,
00903     ape_decode_close,
00904     ape_decode_frame,
00905     .capabilities = CODEC_CAP_SUBFRAMES,
00906     .flush = ape_flush,
00907     .long_name = NULL_IF_CONFIG_SMALL("Monkey's Audio"),
00908 };

Generated on Fri Feb 22 2013 07:24:25 for FFmpeg by  doxygen 1.7.1