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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 "bitstream.h"
00027 #include "bytestream.h"
00028 
00034 #define BLOCKS_PER_LOOP     4608
00035 #define MAX_CHANNELS        2
00036 #define MAX_BYTESPERSAMPLE  3
00037 
00038 #define APE_FRAMECODE_MONO_SILENCE    1
00039 #define APE_FRAMECODE_STEREO_SILENCE  3
00040 #define APE_FRAMECODE_PSEUDO_STEREO   4
00041 
00042 #define HISTORY_SIZE 512
00043 #define PREDICTOR_ORDER 8
00044 
00045 #define PREDICTOR_SIZE 50
00046 
00047 #define YDELAYA (18 + PREDICTOR_ORDER*4)
00048 #define YDELAYB (18 + PREDICTOR_ORDER*3)
00049 #define XDELAYA (18 + PREDICTOR_ORDER*2)
00050 #define XDELAYB (18 + PREDICTOR_ORDER)
00051 
00052 #define YADAPTCOEFFSA 18
00053 #define XADAPTCOEFFSA 14
00054 #define YADAPTCOEFFSB 10
00055 #define XADAPTCOEFFSB 5
00056 
00061 enum APECompressionLevel {
00062     COMPRESSION_LEVEL_FAST       = 1000,
00063     COMPRESSION_LEVEL_NORMAL     = 2000,
00064     COMPRESSION_LEVEL_HIGH       = 3000,
00065     COMPRESSION_LEVEL_EXTRA_HIGH = 4000,
00066     COMPRESSION_LEVEL_INSANE     = 5000
00067 };
00070 #define APE_FILTER_LEVELS 3
00071 
00073 static const uint16_t ape_filter_orders[5][APE_FILTER_LEVELS] = {
00074     {  0,   0,    0 },
00075     { 16,   0,    0 },
00076     { 64,   0,    0 },
00077     { 32, 256,    0 },
00078     { 16, 256, 1280 }
00079 };
00080 
00082 static const uint8_t ape_filter_fracbits[5][APE_FILTER_LEVELS] = {
00083     {  0,  0,  0 },
00084     { 11,  0,  0 },
00085     { 11,  0,  0 },
00086     { 10, 13,  0 },
00087     { 11, 13, 15 }
00088 };
00089 
00090 
00092 typedef struct APEFilter {
00093     int16_t *coeffs;        
00094     int16_t *adaptcoeffs;   
00095     int16_t *historybuffer; 
00096     int16_t *delay;         
00097 
00098     int avg;
00099 } APEFilter;
00100 
00101 typedef struct APERice {
00102     uint32_t k;
00103     uint32_t ksum;
00104 } APERice;
00105 
00106 typedef struct APERangecoder {
00107     uint32_t low;           
00108     uint32_t range;         
00109     uint32_t help;          
00110     unsigned int buffer;    
00111 } APERangecoder;
00112 
00114 typedef struct APEPredictor {
00115     int32_t *buf;
00116 
00117     int32_t lastA[2];
00118 
00119     int32_t filterA[2];
00120     int32_t filterB[2];
00121 
00122     int32_t coeffsA[2][4];  
00123     int32_t coeffsB[2][5];  
00124     int32_t historybuffer[HISTORY_SIZE + PREDICTOR_SIZE];
00125 } APEPredictor;
00126 
00128 typedef struct APEContext {
00129     AVCodecContext *avctx;
00130     DSPContext dsp;
00131     int channels;
00132     int samples;                             
00133 
00134     int fileversion;                         
00135     int compression_level;                   
00136     int fset;                                
00137     int flags;                               
00138 
00139     uint32_t CRC;                            
00140     int frameflags;                          
00141     int currentframeblocks;                  
00142     int blocksdecoded;                       
00143     APEPredictor predictor;                  
00144 
00145     int32_t decoded0[BLOCKS_PER_LOOP];       
00146     int32_t decoded1[BLOCKS_PER_LOOP];       
00147 
00148     int16_t* filterbuf[APE_FILTER_LEVELS];   
00149 
00150     APERangecoder rc;                        
00151     APERice riceX;                           
00152     APERice riceY;                           
00153     APEFilter filters[APE_FILTER_LEVELS][2]; 
00154 
00155     uint8_t *data;                           
00156     uint8_t *data_end;                       
00157     const uint8_t *ptr;                      
00158     const uint8_t *last_ptr;                 
00159 
00160     int error;
00161 } APEContext;
00162 
00163 // TODO: dsputilize
00164 
00165 static av_cold int ape_decode_init(AVCodecContext * avctx)
00166 {
00167     APEContext *s = avctx->priv_data;
00168     int i;
00169 
00170     if (avctx->extradata_size != 6) {
00171         av_log(avctx, AV_LOG_ERROR, "Incorrect extradata\n");
00172         return -1;
00173     }
00174     if (avctx->bits_per_coded_sample != 16) {
00175         av_log(avctx, AV_LOG_ERROR, "Only 16-bit samples are supported\n");
00176         return -1;
00177     }
00178     if (avctx->channels > 2) {
00179         av_log(avctx, AV_LOG_ERROR, "Only mono and stereo is supported\n");
00180         return -1;
00181     }
00182     s->avctx             = avctx;
00183     s->channels          = avctx->channels;
00184     s->fileversion       = AV_RL16(avctx->extradata);
00185     s->compression_level = AV_RL16(avctx->extradata + 2);
00186     s->flags             = AV_RL16(avctx->extradata + 4);
00187 
00188     av_log(avctx, AV_LOG_DEBUG, "Compression Level: %d - Flags: %d\n", s->compression_level, s->flags);
00189     if (s->compression_level % 1000 || s->compression_level > COMPRESSION_LEVEL_INSANE) {
00190         av_log(avctx, AV_LOG_ERROR, "Incorrect compression level %d\n", s->compression_level);
00191         return -1;
00192     }
00193     s->fset = s->compression_level / 1000 - 1;
00194     for (i = 0; i < APE_FILTER_LEVELS; i++) {
00195         if (!ape_filter_orders[s->fset][i])
00196             break;
00197         s->filterbuf[i] = av_malloc((ape_filter_orders[s->fset][i] * 3 + HISTORY_SIZE) * 4);
00198     }
00199 
00200     dsputil_init(&s->dsp, avctx);
00201     avctx->sample_fmt = SAMPLE_FMT_S16;
00202     avctx->channel_layout = (avctx->channels==2) ? CH_LAYOUT_STEREO : CH_LAYOUT_MONO;
00203     return 0;
00204 }
00205 
00206 static av_cold int ape_decode_close(AVCodecContext * avctx)
00207 {
00208     APEContext *s = avctx->priv_data;
00209     int i;
00210 
00211     for (i = 0; i < APE_FILTER_LEVELS; i++)
00212         av_freep(&s->filterbuf[i]);
00213 
00214     return 0;
00215 }
00216 
00222 #define CODE_BITS    32
00223 #define TOP_VALUE    ((unsigned int)1 << (CODE_BITS-1))
00224 #define SHIFT_BITS   (CODE_BITS - 9)
00225 #define EXTRA_BITS   ((CODE_BITS-2) % 8 + 1)
00226 #define BOTTOM_VALUE (TOP_VALUE >> 8)
00227 
00229 static inline void range_start_decoding(APEContext * ctx)
00230 {
00231     ctx->rc.buffer = bytestream_get_byte(&ctx->ptr);
00232     ctx->rc.low    = ctx->rc.buffer >> (8 - EXTRA_BITS);
00233     ctx->rc.range  = (uint32_t) 1 << EXTRA_BITS;
00234 }
00235 
00237 static inline void range_dec_normalize(APEContext * ctx)
00238 {
00239     while (ctx->rc.range <= BOTTOM_VALUE) {
00240         ctx->rc.buffer <<= 8;
00241         if(ctx->ptr < ctx->data_end)
00242             ctx->rc.buffer += *ctx->ptr;
00243         ctx->ptr++;
00244         ctx->rc.low    = (ctx->rc.low << 8)    | ((ctx->rc.buffer >> 1) & 0xFF);
00245         ctx->rc.range  <<= 8;
00246     }
00247 }
00248 
00255 static inline int range_decode_culfreq(APEContext * ctx, int tot_f)
00256 {
00257     range_dec_normalize(ctx);
00258     ctx->rc.help = ctx->rc.range / tot_f;
00259     return ctx->rc.low / ctx->rc.help;
00260 }
00261 
00267 static inline int range_decode_culshift(APEContext * ctx, int shift)
00268 {
00269     range_dec_normalize(ctx);
00270     ctx->rc.help = ctx->rc.range >> shift;
00271     return ctx->rc.low / ctx->rc.help;
00272 }
00273 
00274 
00281 static inline void range_decode_update(APEContext * ctx, int sy_f, int lt_f)
00282 {
00283     ctx->rc.low  -= ctx->rc.help * lt_f;
00284     ctx->rc.range = ctx->rc.help * sy_f;
00285 }
00286 
00288 static inline int range_decode_bits(APEContext * ctx, int n)
00289 {
00290     int sym = range_decode_culshift(ctx, n);
00291     range_decode_update(ctx, 1, sym);
00292     return sym;
00293 }
00294 
00295 
00296 #define MODEL_ELEMENTS 64
00297 
00301 static const uint16_t counts_3970[22] = {
00302         0, 14824, 28224, 39348, 47855, 53994, 58171, 60926,
00303     62682, 63786, 64463, 64878, 65126, 65276, 65365, 65419,
00304     65450, 65469, 65480, 65487, 65491, 65493,
00305 };
00306 
00310 static const uint16_t counts_diff_3970[21] = {
00311     14824, 13400, 11124, 8507, 6139, 4177, 2755, 1756,
00312     1104, 677, 415, 248, 150, 89, 54, 31,
00313     19, 11, 7, 4, 2,
00314 };
00315 
00319 static const uint16_t counts_3980[22] = {
00320         0, 19578, 36160, 48417, 56323, 60899, 63265, 64435,
00321     64971, 65232, 65351, 65416, 65447, 65466, 65476, 65482,
00322     65485, 65488, 65490, 65491, 65492, 65493,
00323 };
00324 
00328 static const uint16_t counts_diff_3980[21] = {
00329     19578, 16582, 12257, 7906, 4576, 2366, 1170, 536,
00330     261, 119, 65, 31, 19, 10, 6, 3,
00331     3, 2, 1, 1, 1,
00332 };
00333 
00340 static inline int range_get_symbol(APEContext * ctx,
00341                                    const uint16_t counts[],
00342                                    const uint16_t counts_diff[])
00343 {
00344     int symbol, cf;
00345 
00346     cf = range_decode_culshift(ctx, 16);
00347 
00348     if(cf > 65492){
00349         symbol= cf - 65535 + 63;
00350         range_decode_update(ctx, 1, cf);
00351         if(cf > 65535)
00352             ctx->error=1;
00353         return symbol;
00354     }
00355     /* figure out the symbol inefficiently; a binary search would be much better */
00356     for (symbol = 0; counts[symbol + 1] <= cf; symbol++);
00357 
00358     range_decode_update(ctx, counts_diff[symbol], counts[symbol]);
00359 
00360     return symbol;
00361 } // group rangecoder
00363 
00364 static inline void update_rice(APERice *rice, int x)
00365 {
00366     int lim = rice->k ? (1 << (rice->k + 4)) : 0;
00367     rice->ksum += ((x + 1) / 2) - ((rice->ksum + 16) >> 5);
00368 
00369     if (rice->ksum < lim)
00370         rice->k--;
00371     else if (rice->ksum >= (1 << (rice->k + 5)))
00372         rice->k++;
00373 }
00374 
00375 static inline int ape_decode_value(APEContext * ctx, APERice *rice)
00376 {
00377     int x, overflow;
00378 
00379     if (ctx->fileversion < 3990) {
00380         int tmpk;
00381 
00382         overflow = range_get_symbol(ctx, counts_3970, counts_diff_3970);
00383 
00384         if (overflow == (MODEL_ELEMENTS - 1)) {
00385             tmpk = range_decode_bits(ctx, 5);
00386             overflow = 0;
00387         } else
00388             tmpk = (rice->k < 1) ? 0 : rice->k - 1;
00389 
00390         if (tmpk <= 16)
00391             x = range_decode_bits(ctx, tmpk);
00392         else {
00393             x = range_decode_bits(ctx, 16);
00394             x |= (range_decode_bits(ctx, tmpk - 16) << 16);
00395         }
00396         x += overflow << tmpk;
00397     } else {
00398         int base, pivot;
00399 
00400         pivot = rice->ksum >> 5;
00401         if (pivot == 0)
00402             pivot = 1;
00403 
00404         overflow = range_get_symbol(ctx, counts_3980, counts_diff_3980);
00405 
00406         if (overflow == (MODEL_ELEMENTS - 1)) {
00407             overflow  = range_decode_bits(ctx, 16) << 16;
00408             overflow |= range_decode_bits(ctx, 16);
00409         }
00410 
00411         base = range_decode_culfreq(ctx, pivot);
00412         range_decode_update(ctx, 1, base);
00413 
00414         x = base + overflow * pivot;
00415     }
00416 
00417     update_rice(rice, x);
00418 
00419     /* Convert to signed */
00420     if (x & 1)
00421         return (x >> 1) + 1;
00422     else
00423         return -(x >> 1);
00424 }
00425 
00426 static void entropy_decode(APEContext * ctx, int blockstodecode, int stereo)
00427 {
00428     int32_t *decoded0 = ctx->decoded0;
00429     int32_t *decoded1 = ctx->decoded1;
00430 
00431     ctx->blocksdecoded = blockstodecode;
00432 
00433     if (ctx->frameflags & APE_FRAMECODE_STEREO_SILENCE) {
00434         /* We are pure silence, just memset the output buffer. */
00435         memset(decoded0, 0, blockstodecode * sizeof(int32_t));
00436         memset(decoded1, 0, blockstodecode * sizeof(int32_t));
00437     } else {
00438         while (blockstodecode--) {
00439             *decoded0++ = ape_decode_value(ctx, &ctx->riceY);
00440             if (stereo)
00441                 *decoded1++ = ape_decode_value(ctx, &ctx->riceX);
00442         }
00443     }
00444 
00445     if (ctx->blocksdecoded == ctx->currentframeblocks)
00446         range_dec_normalize(ctx);   /* normalize to use up all bytes */
00447 }
00448 
00449 static void init_entropy_decoder(APEContext * ctx)
00450 {
00451     /* Read the CRC */
00452     ctx->CRC = bytestream_get_be32(&ctx->ptr);
00453 
00454     /* Read the frame flags if they exist */
00455     ctx->frameflags = 0;
00456     if ((ctx->fileversion > 3820) && (ctx->CRC & 0x80000000)) {
00457         ctx->CRC &= ~0x80000000;
00458 
00459         ctx->frameflags = bytestream_get_be32(&ctx->ptr);
00460     }
00461 
00462     /* Keep a count of the blocks decoded in this frame */
00463     ctx->blocksdecoded = 0;
00464 
00465     /* Initialize the rice structs */
00466     ctx->riceX.k = 10;
00467     ctx->riceX.ksum = (1 << ctx->riceX.k) * 16;
00468     ctx->riceY.k = 10;
00469     ctx->riceY.ksum = (1 << ctx->riceY.k) * 16;
00470 
00471     /* The first 8 bits of input are ignored. */
00472     ctx->ptr++;
00473 
00474     range_start_decoding(ctx);
00475 }
00476 
00477 static const int32_t initial_coeffs[4] = {
00478     360, 317, -109, 98
00479 };
00480 
00481 static void init_predictor_decoder(APEContext * ctx)
00482 {
00483     APEPredictor *p = &ctx->predictor;
00484 
00485     /* Zero the history buffers */
00486     memset(p->historybuffer, 0, PREDICTOR_SIZE * sizeof(int32_t));
00487     p->buf = p->historybuffer;
00488 
00489     /* Initialize and zero the coefficients */
00490     memcpy(p->coeffsA[0], initial_coeffs, sizeof(initial_coeffs));
00491     memcpy(p->coeffsA[1], initial_coeffs, sizeof(initial_coeffs));
00492     memset(p->coeffsB, 0, sizeof(p->coeffsB));
00493 
00494     p->filterA[0] = p->filterA[1] = 0;
00495     p->filterB[0] = p->filterB[1] = 0;
00496     p->lastA[0]   = p->lastA[1]   = 0;
00497 }
00498 
00500 static inline int APESIGN(int32_t x) {
00501     return (x < 0) - (x > 0);
00502 }
00503 
00504 static int predictor_update_filter(APEPredictor *p, const int decoded, const int filter, const int delayA, const int delayB, const int adaptA, const int adaptB)
00505 {
00506     int32_t predictionA, predictionB;
00507 
00508     p->buf[delayA]     = p->lastA[filter];
00509     p->buf[adaptA]     = APESIGN(p->buf[delayA]);
00510     p->buf[delayA - 1] = p->buf[delayA] - p->buf[delayA - 1];
00511     p->buf[adaptA - 1] = APESIGN(p->buf[delayA - 1]);
00512 
00513     predictionA = p->buf[delayA    ] * p->coeffsA[filter][0] +
00514                   p->buf[delayA - 1] * p->coeffsA[filter][1] +
00515                   p->buf[delayA - 2] * p->coeffsA[filter][2] +
00516                   p->buf[delayA - 3] * p->coeffsA[filter][3];
00517 
00518     /*  Apply a scaled first-order filter compression */
00519     p->buf[delayB]     = p->filterA[filter ^ 1] - ((p->filterB[filter] * 31) >> 5);
00520     p->buf[adaptB]     = APESIGN(p->buf[delayB]);
00521     p->buf[delayB - 1] = p->buf[delayB] - p->buf[delayB - 1];
00522     p->buf[adaptB - 1] = APESIGN(p->buf[delayB - 1]);
00523     p->filterB[filter] = p->filterA[filter ^ 1];
00524 
00525     predictionB = p->buf[delayB    ] * p->coeffsB[filter][0] +
00526                   p->buf[delayB - 1] * p->coeffsB[filter][1] +
00527                   p->buf[delayB - 2] * p->coeffsB[filter][2] +
00528                   p->buf[delayB - 3] * p->coeffsB[filter][3] +
00529                   p->buf[delayB - 4] * p->coeffsB[filter][4];
00530 
00531     p->lastA[filter] = decoded + ((predictionA + (predictionB >> 1)) >> 10);
00532     p->filterA[filter] = p->lastA[filter] + ((p->filterA[filter] * 31) >> 5);
00533 
00534     if (!decoded) // no need updating filter coefficients
00535         return p->filterA[filter];
00536 
00537     if (decoded > 0) {
00538         p->coeffsA[filter][0] -= p->buf[adaptA    ];
00539         p->coeffsA[filter][1] -= p->buf[adaptA - 1];
00540         p->coeffsA[filter][2] -= p->buf[adaptA - 2];
00541         p->coeffsA[filter][3] -= p->buf[adaptA - 3];
00542 
00543         p->coeffsB[filter][0] -= p->buf[adaptB    ];
00544         p->coeffsB[filter][1] -= p->buf[adaptB - 1];
00545         p->coeffsB[filter][2] -= p->buf[adaptB - 2];
00546         p->coeffsB[filter][3] -= p->buf[adaptB - 3];
00547         p->coeffsB[filter][4] -= p->buf[adaptB - 4];
00548     } else {
00549         p->coeffsA[filter][0] += p->buf[adaptA    ];
00550         p->coeffsA[filter][1] += p->buf[adaptA - 1];
00551         p->coeffsA[filter][2] += p->buf[adaptA - 2];
00552         p->coeffsA[filter][3] += p->buf[adaptA - 3];
00553 
00554         p->coeffsB[filter][0] += p->buf[adaptB    ];
00555         p->coeffsB[filter][1] += p->buf[adaptB - 1];
00556         p->coeffsB[filter][2] += p->buf[adaptB - 2];
00557         p->coeffsB[filter][3] += p->buf[adaptB - 3];
00558         p->coeffsB[filter][4] += p->buf[adaptB - 4];
00559     }
00560     return p->filterA[filter];
00561 }
00562 
00563 static void predictor_decode_stereo(APEContext * ctx, int count)
00564 {
00565     int32_t predictionA, predictionB;
00566     APEPredictor *p = &ctx->predictor;
00567     int32_t *decoded0 = ctx->decoded0;
00568     int32_t *decoded1 = ctx->decoded1;
00569 
00570     while (count--) {
00571         /* Predictor Y */
00572         predictionA = predictor_update_filter(p, *decoded0, 0, YDELAYA, YDELAYB, YADAPTCOEFFSA, YADAPTCOEFFSB);
00573         predictionB = predictor_update_filter(p, *decoded1, 1, XDELAYA, XDELAYB, XADAPTCOEFFSA, XADAPTCOEFFSB);
00574         *(decoded0++) = predictionA;
00575         *(decoded1++) = predictionB;
00576 
00577         /* Combined */
00578         p->buf++;
00579 
00580         /* Have we filled the history buffer? */
00581         if (p->buf == p->historybuffer + HISTORY_SIZE) {
00582             memmove(p->historybuffer, p->buf, PREDICTOR_SIZE * sizeof(int32_t));
00583             p->buf = p->historybuffer;
00584         }
00585     }
00586 }
00587 
00588 static void predictor_decode_mono(APEContext * ctx, int count)
00589 {
00590     APEPredictor *p = &ctx->predictor;
00591     int32_t *decoded0 = ctx->decoded0;
00592     int32_t predictionA, currentA, A;
00593 
00594     currentA = p->lastA[0];
00595 
00596     while (count--) {
00597         A = *decoded0;
00598 
00599         p->buf[YDELAYA] = currentA;
00600         p->buf[YDELAYA - 1] = p->buf[YDELAYA] - p->buf[YDELAYA - 1];
00601 
00602         predictionA = p->buf[YDELAYA    ] * p->coeffsA[0][0] +
00603                       p->buf[YDELAYA - 1] * p->coeffsA[0][1] +
00604                       p->buf[YDELAYA - 2] * p->coeffsA[0][2] +
00605                       p->buf[YDELAYA - 3] * p->coeffsA[0][3];
00606 
00607         currentA = A + (predictionA >> 10);
00608 
00609         p->buf[YADAPTCOEFFSA]     = APESIGN(p->buf[YDELAYA    ]);
00610         p->buf[YADAPTCOEFFSA - 1] = APESIGN(p->buf[YDELAYA - 1]);
00611 
00612         if (A > 0) {
00613             p->coeffsA[0][0] -= p->buf[YADAPTCOEFFSA    ];
00614             p->coeffsA[0][1] -= p->buf[YADAPTCOEFFSA - 1];
00615             p->coeffsA[0][2] -= p->buf[YADAPTCOEFFSA - 2];
00616             p->coeffsA[0][3] -= p->buf[YADAPTCOEFFSA - 3];
00617         } else if (A < 0) {
00618             p->coeffsA[0][0] += p->buf[YADAPTCOEFFSA    ];
00619             p->coeffsA[0][1] += p->buf[YADAPTCOEFFSA - 1];
00620             p->coeffsA[0][2] += p->buf[YADAPTCOEFFSA - 2];
00621             p->coeffsA[0][3] += p->buf[YADAPTCOEFFSA - 3];
00622         }
00623 
00624         p->buf++;
00625 
00626         /* Have we filled the history buffer? */
00627         if (p->buf == p->historybuffer + HISTORY_SIZE) {
00628             memmove(p->historybuffer, p->buf, PREDICTOR_SIZE * sizeof(int32_t));
00629             p->buf = p->historybuffer;
00630         }
00631 
00632         p->filterA[0] = currentA + ((p->filterA[0] * 31) >> 5);
00633         *(decoded0++) = p->filterA[0];
00634     }
00635 
00636     p->lastA[0] = currentA;
00637 }
00638 
00639 static void do_init_filter(APEFilter *f, int16_t * buf, int order)
00640 {
00641     f->coeffs = buf;
00642     f->historybuffer = buf + order;
00643     f->delay       = f->historybuffer + order * 2;
00644     f->adaptcoeffs = f->historybuffer + order;
00645 
00646     memset(f->historybuffer, 0, (order * 2) * sizeof(int16_t));
00647     memset(f->coeffs, 0, order * sizeof(int16_t));
00648     f->avg = 0;
00649 }
00650 
00651 static void init_filter(APEContext * ctx, APEFilter *f, int16_t * buf, int order)
00652 {
00653     do_init_filter(&f[0], buf, order);
00654     do_init_filter(&f[1], buf + order * 3 + HISTORY_SIZE, order);
00655 }
00656 
00657 static inline void do_apply_filter(APEContext * ctx, int version, APEFilter *f, int32_t *data, int count, int order, int fracbits)
00658 {
00659     int res;
00660     int absres;
00661 
00662     while (count--) {
00663         /* round fixedpoint scalar product */
00664         res = (ctx->dsp.scalarproduct_int16(f->delay - order, f->coeffs, order, 0) + (1 << (fracbits - 1))) >> fracbits;
00665 
00666         if (*data < 0)
00667             ctx->dsp.add_int16(f->coeffs, f->adaptcoeffs - order, order);
00668         else if (*data > 0)
00669             ctx->dsp.sub_int16(f->coeffs, f->adaptcoeffs - order, order);
00670 
00671         res += *data;
00672 
00673         *data++ = res;
00674 
00675         /* Update the output history */
00676         *f->delay++ = av_clip_int16(res);
00677 
00678         if (version < 3980) {
00679             /* Version ??? to < 3.98 files (untested) */
00680             f->adaptcoeffs[0]  = (res == 0) ? 0 : ((res >> 28) & 8) - 4;
00681             f->adaptcoeffs[-4] >>= 1;
00682             f->adaptcoeffs[-8] >>= 1;
00683         } else {
00684             /* Version 3.98 and later files */
00685 
00686             /* Update the adaption coefficients */
00687             absres = (res < 0 ? -res : res);
00688 
00689             if (absres > (f->avg * 3))
00690                 *f->adaptcoeffs = ((res >> 25) & 64) - 32;
00691             else if (absres > (f->avg * 4) / 3)
00692                 *f->adaptcoeffs = ((res >> 26) & 32) - 16;
00693             else if (absres > 0)
00694                 *f->adaptcoeffs = ((res >> 27) & 16) - 8;
00695             else
00696                 *f->adaptcoeffs = 0;
00697 
00698             f->avg += (absres - f->avg) / 16;
00699 
00700             f->adaptcoeffs[-1] >>= 1;
00701             f->adaptcoeffs[-2] >>= 1;
00702             f->adaptcoeffs[-8] >>= 1;
00703         }
00704 
00705         f->adaptcoeffs++;
00706 
00707         /* Have we filled the history buffer? */
00708         if (f->delay == f->historybuffer + HISTORY_SIZE + (order * 2)) {
00709             memmove(f->historybuffer, f->delay - (order * 2),
00710                     (order * 2) * sizeof(int16_t));
00711             f->delay = f->historybuffer + order * 2;
00712             f->adaptcoeffs = f->historybuffer + order;
00713         }
00714     }
00715 }
00716 
00717 static void apply_filter(APEContext * ctx, APEFilter *f,
00718                          int32_t * data0, int32_t * data1,
00719                          int count, int order, int fracbits)
00720 {
00721     do_apply_filter(ctx, ctx->fileversion, &f[0], data0, count, order, fracbits);
00722     if (data1)
00723         do_apply_filter(ctx, ctx->fileversion, &f[1], data1, count, order, fracbits);
00724 }
00725 
00726 static void ape_apply_filters(APEContext * ctx, int32_t * decoded0,
00727                               int32_t * decoded1, int count)
00728 {
00729     int i;
00730 
00731     for (i = 0; i < APE_FILTER_LEVELS; i++) {
00732         if (!ape_filter_orders[ctx->fset][i])
00733             break;
00734         apply_filter(ctx, ctx->filters[i], decoded0, decoded1, count, ape_filter_orders[ctx->fset][i], ape_filter_fracbits[ctx->fset][i]);
00735     }
00736 }
00737 
00738 static void init_frame_decoder(APEContext * ctx)
00739 {
00740     int i;
00741     init_entropy_decoder(ctx);
00742     init_predictor_decoder(ctx);
00743 
00744     for (i = 0; i < APE_FILTER_LEVELS; i++) {
00745         if (!ape_filter_orders[ctx->fset][i])
00746             break;
00747         init_filter(ctx, ctx->filters[i], ctx->filterbuf[i], ape_filter_orders[ctx->fset][i]);
00748     }
00749 }
00750 
00751 static void ape_unpack_mono(APEContext * ctx, int count)
00752 {
00753     int32_t left;
00754     int32_t *decoded0 = ctx->decoded0;
00755     int32_t *decoded1 = ctx->decoded1;
00756 
00757     if (ctx->frameflags & APE_FRAMECODE_STEREO_SILENCE) {
00758         entropy_decode(ctx, count, 0);
00759         /* We are pure silence, so we're done. */
00760         av_log(ctx->avctx, AV_LOG_DEBUG, "pure silence mono\n");
00761         return;
00762     }
00763 
00764     entropy_decode(ctx, count, 0);
00765     ape_apply_filters(ctx, decoded0, NULL, count);
00766 
00767     /* Now apply the predictor decoding */
00768     predictor_decode_mono(ctx, count);
00769 
00770     /* Pseudo-stereo - just copy left channel to right channel */
00771     if (ctx->channels == 2) {
00772         while (count--) {
00773             left = *decoded0;
00774             *(decoded1++) = *(decoded0++) = left;
00775         }
00776     }
00777 }
00778 
00779 static void ape_unpack_stereo(APEContext * ctx, int count)
00780 {
00781     int32_t left, right;
00782     int32_t *decoded0 = ctx->decoded0;
00783     int32_t *decoded1 = ctx->decoded1;
00784 
00785     if (ctx->frameflags & APE_FRAMECODE_STEREO_SILENCE) {
00786         /* We are pure silence, so we're done. */
00787         av_log(ctx->avctx, AV_LOG_DEBUG, "pure silence stereo\n");
00788         return;
00789     }
00790 
00791     entropy_decode(ctx, count, 1);
00792     ape_apply_filters(ctx, decoded0, decoded1, count);
00793 
00794     /* Now apply the predictor decoding */
00795     predictor_decode_stereo(ctx, count);
00796 
00797     /* Decorrelate and scale to output depth */
00798     while (count--) {
00799         left = *decoded1 - (*decoded0 / 2);
00800         right = left + *decoded0;
00801 
00802         *(decoded0++) = left;
00803         *(decoded1++) = right;
00804     }
00805 }
00806 
00807 static int ape_decode_frame(AVCodecContext * avctx,
00808                             void *data, int *data_size,
00809                             const uint8_t * buf, int buf_size)
00810 {
00811     APEContext *s = avctx->priv_data;
00812     int16_t *samples = data;
00813     int nblocks;
00814     int i, n;
00815     int blockstodecode;
00816     int bytes_used;
00817 
00818     if (buf_size == 0 && !s->samples) {
00819         *data_size = 0;
00820         return 0;
00821     }
00822 
00823     /* should not happen but who knows */
00824     if (BLOCKS_PER_LOOP * 2 * avctx->channels > *data_size) {
00825         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);
00826         return -1;
00827     }
00828 
00829     if(!s->samples){
00830         s->data = av_realloc(s->data, (buf_size + 3) & ~3);
00831         s->dsp.bswap_buf((uint32_t*)s->data, (const uint32_t*)buf, buf_size >> 2);
00832         s->ptr = s->last_ptr = s->data;
00833         s->data_end = s->data + buf_size;
00834 
00835         nblocks = s->samples = bytestream_get_be32(&s->ptr);
00836         n =  bytestream_get_be32(&s->ptr);
00837         if(n < 0 || n > 3){
00838             av_log(avctx, AV_LOG_ERROR, "Incorrect offset passed\n");
00839             s->data = NULL;
00840             return -1;
00841         }
00842         s->ptr += n;
00843 
00844         s->currentframeblocks = nblocks;
00845         buf += 4;
00846         if (s->samples <= 0) {
00847             *data_size = 0;
00848             return buf_size;
00849         }
00850 
00851         memset(s->decoded0,  0, sizeof(s->decoded0));
00852         memset(s->decoded1,  0, sizeof(s->decoded1));
00853 
00854         /* Initialize the frame decoder */
00855         init_frame_decoder(s);
00856     }
00857 
00858     if (!s->data) {
00859         *data_size = 0;
00860         return buf_size;
00861     }
00862 
00863     nblocks = s->samples;
00864     blockstodecode = FFMIN(BLOCKS_PER_LOOP, nblocks);
00865 
00866     s->error=0;
00867 
00868     if ((s->channels == 1) || (s->frameflags & APE_FRAMECODE_PSEUDO_STEREO))
00869         ape_unpack_mono(s, blockstodecode);
00870     else
00871         ape_unpack_stereo(s, blockstodecode);
00872 
00873     if(s->error || s->ptr > s->data_end){
00874         s->samples=0;
00875         av_log(avctx, AV_LOG_ERROR, "Error decoding frame\n");
00876         return -1;
00877     }
00878 
00879     for (i = 0; i < blockstodecode; i++) {
00880         *samples++ = s->decoded0[i];
00881         if(s->channels == 2)
00882             *samples++ = s->decoded1[i];
00883     }
00884 
00885     s->samples -= blockstodecode;
00886 
00887     *data_size = blockstodecode * 2 * s->channels;
00888     bytes_used = s->samples ? s->ptr - s->last_ptr : buf_size;
00889     s->last_ptr = s->ptr;
00890     return bytes_used;
00891 }
00892 
00893 AVCodec ape_decoder = {
00894     "ape",
00895     CODEC_TYPE_AUDIO,
00896     CODEC_ID_APE,
00897     sizeof(APEContext),
00898     ape_decode_init,
00899     NULL,
00900     ape_decode_close,
00901     ape_decode_frame,
00902     .long_name = NULL_IF_CONFIG_SMALL("Monkey's Audio"),
00903 };

Generated on Tue Nov 4 2014 12:59:21 for ffmpeg by  doxygen 1.7.1