/* * ALAC (Apple Lossless Audio Codec) decoder * Copyright (c) 2005 David Hammerton * * 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 * ALAC (Apple Lossless Audio Codec) decoder * @author 2005 David Hammerton * @see http://crazney.net/programs/itunes/alac.html * * Note: This decoder expects a 36-byte QuickTime atom to be * passed through the extradata[_size] fields. This atom is tacked onto * the end of an 'alac' stsd atom and has the following format: * * 32 bits  atom size * 32 bits  tag                  ("alac") * 32 bits  tag version          (0) * 32 bits  samples per frame    (used when not set explicitly in the frames) *  8 bits  compatible version   (0) *  8 bits  sample size *  8 bits  history mult         (40) *  8 bits  initial history      (10) *  8 bits  rice param limit     (14) *  8 bits  channels * 16 bits  maxRun               (255) * 32 bits  max coded frame size (0 means unknown) * 32 bits  average bitrate      (0 means unknown) * 32 bits  samplerate */ #include <inttypes.h> #include "libavutil/channel_layout.h"#include "libavutil/opt.h"#include "avcodec.h"#include "get_bits.h"#include "bytestream.h"#include "internal.h"#include "thread.h"#include "unary.h"#include "mathops.h"#include "alac_data.h"#include "alacdsp.h" #define ALAC_EXTRADATA_SIZE 36 typedef struct ALACContext {    AVClass *class;    AVCodecContext *avctx;    GetBitContext gb;    int channels;     int32_t *predict_error_buffer[2];    int32_t *output_samples_buffer[2];    int32_t *extra_bits_buffer[2];     uint32_t max_samples_per_frame;    uint8_t  sample_size;    uint8_t  rice_history_mult;    uint8_t  rice_initial_history;    uint8_t  rice_limit;    int      sample_rate;     int extra_bits;     /**< number of extra bits beyond 16-bit */    int nb_samples;     /**< number of samples in the current frame */     int direct_output;    int extra_bit_bug;     ALACDSPContext dsp;} ALACContext; static inline unsigned int decode_scalar(GetBitContext *gb, int k, int bps){    unsigned int x = get_unary_0_9(gb);     if (x > 8) { /* RICE THRESHOLD */        /* use alternative encoding */        x = get_bits_long(gb, bps);    } else if (k != 1) {        int extrabits = show_bits(gb, k);         /* multiply x by 2^k - 1, as part of their strange algorithm */        x = (x << k) - x;         if (extrabits > 1) {            x += extrabits - 1;            skip_bits(gb, k);        } else            skip_bits(gb, k - 1);    }    return x;} static int rice_decompress(ALACContext *alac, int32_t *output_buffer,                            int nb_samples, int bps, int rice_history_mult){    int i;    unsigned int history = alac->rice_initial_history;    int sign_modifier = 0;     for (i = 0; i < nb_samples; i++) {        int k;        unsigned int x;         if(get_bits_left(&alac->gb) <= 0)            return -1;         /* calculate rice param and decode next value */        k = av_log2((history >> 9) + 3);        k = FFMIN(k, alac->rice_limit);        x = decode_scalar(&alac->gb, k, bps);        x += sign_modifier;        sign_modifier = 0;        output_buffer[i] = (x >> 1) ^ -(x & 1);         /* update the history */        if (x > 0xffff)            history = 0xffff;        else            history +=         x * rice_history_mult -                       ((history * rice_history_mult) >> 9);         /* special case: there may be compressed blocks of 0 */        if ((history < 128) && (i + 1 < nb_samples)) {            int block_size;             /* calculate rice param and decode block size */            k = 7 - av_log2(history) + ((history + 16) >> 6);            k = FFMIN(k, alac->rice_limit);            block_size = decode_scalar(&alac->gb, k, 16);             if (block_size > 0) {                if (block_size >= nb_samples - i) {                    av_log(alac->avctx, AV_LOG_ERROR,                           "invalid zero block size of %d %d %d\n", block_size,                           nb_samples, i);                    block_size = nb_samples - i - 1;                }                memset(&output_buffer[i + 1], 0,                       block_size * sizeof(*output_buffer));                i += block_size;            }            if (block_size <= 0xffff)                sign_modifier = 1;            history = 0;        }    }    return 0;} static inline int sign_only(int v){    return v ? FFSIGN(v) : 0;} static void lpc_prediction(int32_t *error_buffer, int32_t *buffer_out,                           int nb_samples, int bps, int16_t *lpc_coefs,                           int lpc_order, int lpc_quant){    int i;    int32_t *pred = buffer_out;     /* first sample always copies */    *buffer_out = *error_buffer;     if (nb_samples <= 1)        return;     if (!lpc_order) {        memcpy(&buffer_out[1], &error_buffer[1],               (nb_samples - 1) * sizeof(*buffer_out));        return;    }     if (lpc_order == 31) {        /* simple 1st-order prediction */        for (i = 1; i < nb_samples; i++) {            buffer_out[i] = sign_extend(buffer_out[i - 1] + error_buffer[i],                                        bps);        }        return;    }     /* read warm-up samples */    for (i = 1; i <= lpc_order && i < nb_samples; i++)        buffer_out[i] = sign_extend(buffer_out[i - 1] + error_buffer[i], bps);     /* NOTE: 4 and 8 are very common cases that could be optimized. */     for (; i < nb_samples; i++) {        int j;        int val = 0;        int error_val = error_buffer[i];        int error_sign;        int d = *pred++;         /* LPC prediction */        for (j = 0; j < lpc_order; j++)            val += (pred[j] - d) * lpc_coefs[j];        val = (val + (1 << (lpc_quant - 1))) >> lpc_quant;        val += d + error_val;        buffer_out[i] = sign_extend(val, bps);         /* adapt LPC coefficients */        error_sign = sign_only(error_val);        if (error_sign) {            for (j = 0; j < lpc_order && error_val * error_sign > 0; j++) {                int sign;                val  = d - pred[j];                sign = sign_only(val) * error_sign;                lpc_coefs[j] -= sign;                val *= sign;                error_val -= (val >> lpc_quant) * (j + 1);            }        }    }} static int decode_element(AVCodecContext *avctx, AVFrame *frame, int ch_index,                          int channels){    ALACContext *alac = avctx->priv_data;    int has_size, bps, is_compressed, decorr_shift, decorr_left_weight, ret;    uint32_t output_samples;    int i, ch;     skip_bits(&alac->gb, 4);  /* element instance tag */    skip_bits(&alac->gb, 12); /* unused header bits */     /* the number of output samples is stored in the frame */    has_size = get_bits1(&alac->gb);     alac->extra_bits = get_bits(&alac->gb, 2) << 3;    bps = alac->sample_size - alac->extra_bits + channels - 1;    if (bps > 32U) {        av_log(avctx, AV_LOG_ERROR, "bps is unsupported: %d\n", bps);        return AVERROR_PATCHWELCOME;    }     /* whether the frame is compressed */    is_compressed = !get_bits1(&alac->gb);     if (has_size)        output_samples = get_bits_long(&alac->gb, 32);    else        output_samples = alac->max_samples_per_frame;    if (!output_samples || output_samples > alac->max_samples_per_frame) {        av_log(avctx, AV_LOG_ERROR, "invalid samples per frame: %"PRIu32"\n",               output_samples);        return AVERROR_INVALIDDATA;    }    if (!alac->nb_samples) {        ThreadFrame tframe = { .f = frame };        /* get output buffer */        frame->nb_samples = output_samples;        if ((ret = ff_thread_get_buffer(avctx, &tframe, 0)) < 0)            return ret;    } else if (output_samples != alac->nb_samples) {        av_log(avctx, AV_LOG_ERROR, "sample count mismatch: %"PRIu32" != %d\n",               output_samples, alac->nb_samples);        return AVERROR_INVALIDDATA;    }    alac->nb_samples = output_samples;    if (alac->direct_output) {        for (ch = 0; ch < channels; ch++)            alac->output_samples_buffer[ch] = (int32_t *)frame->extended_data[ch_index + ch];    }     if (is_compressed) {        int16_t lpc_coefs[2][32];        int lpc_order[2];        int prediction_type[2];        int lpc_quant[2];        int rice_history_mult[2];         if (!alac->rice_limit) {            avpriv_request_sample(alac->avctx,                                  "Compression with rice limit 0");            return AVERROR(ENOSYS);        }         decorr_shift       = get_bits(&alac->gb, 8);        decorr_left_weight = get_bits(&alac->gb, 8);         for (ch = 0; ch < channels; ch++) {            prediction_type[ch]   = get_bits(&alac->gb, 4);            lpc_quant[ch]         = get_bits(&alac->gb, 4);            rice_history_mult[ch] = get_bits(&alac->gb, 3);            lpc_order[ch]         = get_bits(&alac->gb, 5);             if (lpc_order[ch] >= alac->max_samples_per_frame)                return AVERROR_INVALIDDATA;             /* read the predictor table */            for (i = lpc_order[ch] - 1; i >= 0; i--)                lpc_coefs[ch][i] = get_sbits(&alac->gb, 16);        }         if (alac->extra_bits) {            for (i = 0; i < alac->nb_samples; i++) {                if(get_bits_left(&alac->gb) <= 0)                    return -1;                for (ch = 0; ch < channels; ch++)                    alac->extra_bits_buffer[ch][i] = get_bits(&alac->gb, alac->extra_bits);            }        }        for (ch = 0; ch < channels; ch++) {            int ret=rice_decompress(alac, alac->predict_error_buffer[ch],                            alac->nb_samples, bps,                            rice_history_mult[ch] * alac->rice_history_mult / 4);            if(ret<0)                return ret;             /* adaptive FIR filter */            if (prediction_type[ch] == 15) {                /* Prediction type 15 runs the adaptive FIR twice.                 * The first pass uses the special-case coef_num = 31, while                 * the second pass uses the coefs from the bitstream.                 *                 * However, this prediction type is not currently used by the                 * reference encoder.                 */                lpc_prediction(alac->predict_error_buffer[ch],                               alac->predict_error_buffer[ch],                               alac->nb_samples, bps, NULL, 31, 0);            } else if (prediction_type[ch] > 0) {                av_log(avctx, AV_LOG_WARNING, "unknown prediction type: %i\n",                       prediction_type[ch]);            }            lpc_prediction(alac->predict_error_buffer[ch],                           alac->output_samples_buffer[ch], alac->nb_samples,                           bps, lpc_coefs[ch], lpc_order[ch], lpc_quant[ch]);        }    } else {        /* not compressed, easy case */        for (i = 0; i < alac->nb_samples; i++) {            if(get_bits_left(&alac->gb) <= 0)                return -1;            for (ch = 0; ch < channels; ch++) {                alac->output_samples_buffer[ch][i] =                         get_sbits_long(&alac->gb, alac->sample_size);            }        }        alac->extra_bits   = 0;        decorr_shift       = 0;        decorr_left_weight = 0;    }     if (channels == 2) {        if (alac->extra_bits && alac->extra_bit_bug) {            alac->dsp.append_extra_bits[1](alac->output_samples_buffer, alac->extra_bits_buffer,                                           alac->extra_bits, channels, alac->nb_samples);        }         if (decorr_left_weight) {            alac->dsp.decorrelate_stereo(alac->output_samples_buffer, alac->nb_samples,                                         decorr_shift, decorr_left_weight);        }         if (alac->extra_bits && !alac->extra_bit_bug) {            alac->dsp.append_extra_bits[1](alac->output_samples_buffer, alac->extra_bits_buffer,                                           alac->extra_bits, channels, alac->nb_samples);        }    } else if (alac->extra_bits) {        alac->dsp.append_extra_bits[0](alac->output_samples_buffer, alac->extra_bits_buffer,                                       alac->extra_bits, channels, alac->nb_samples);    }     switch(alac->sample_size) {    case 16: {        for (ch = 0; ch < channels; ch++) {            int16_t *outbuffer = (int16_t *)frame->extended_data[ch_index + ch];            for (i = 0; i < alac->nb_samples; i++)                *outbuffer++ = alac->output_samples_buffer[ch][i];        }}        break;    case 20: {        for (ch = 0; ch < channels; ch++) {            for (i = 0; i < alac->nb_samples; i++)                alac->output_samples_buffer[ch][i] <<= 12;        }}        break;    case 24: {        for (ch = 0; ch < channels; ch++) {            for (i = 0; i < alac->nb_samples; i++)                alac->output_samples_buffer[ch][i] <<= 8;        }}        break;    }     return 0;} static int alac_decode_frame(AVCodecContext *avctx, void *data,                             int *got_frame_ptr, AVPacket *avpkt){    ALACContext *alac = avctx->priv_data;    AVFrame *frame    = data;    enum AlacRawDataBlockType element;    int channels;    int ch, ret, got_end;     if ((ret = init_get_bits8(&alac->gb, avpkt->data, avpkt->size)) < 0)        return ret;     got_end = 0;    alac->nb_samples = 0;    ch = 0;    while (get_bits_left(&alac->gb) >= 3) {        element = get_bits(&alac->gb, 3);        if (element == TYPE_END) {            got_end = 1;            break;        }        if (element > TYPE_CPE && element != TYPE_LFE) {            av_log(avctx, AV_LOG_ERROR, "syntax element unsupported: %d\n", element);            return AVERROR_PATCHWELCOME;        }         channels = (element == TYPE_CPE) ? 2 : 1;        if (ch + channels > alac->channels ||            ff_alac_channel_layout_offsets[alac->channels - 1][ch] + channels > alac->channels) {            av_log(avctx, AV_LOG_ERROR, "invalid element channel count\n");            return AVERROR_INVALIDDATA;        }         ret = decode_element(avctx, frame,                             ff_alac_channel_layout_offsets[alac->channels - 1][ch],                             channels);        if (ret < 0 && get_bits_left(&alac->gb))            return ret;         ch += channels;    }    if (!got_end) {        av_log(avctx, AV_LOG_ERROR, "no end tag found. incomplete packet.\n");        return AVERROR_INVALIDDATA;    }     if (avpkt->size * 8 - get_bits_count(&alac->gb) > 8) {        av_log(avctx, AV_LOG_ERROR, "Error : %d bits left\n",               avpkt->size * 8 - get_bits_count(&alac->gb));    }     if (alac->channels == ch)        *got_frame_ptr = 1;    else        av_log(avctx, AV_LOG_WARNING, "Failed to decode all channels\n");     return avpkt->size;} static av_cold int alac_decode_close(AVCodecContext *avctx){    ALACContext *alac = avctx->priv_data;     int ch;    for (ch = 0; ch < FFMIN(alac->channels, 2); ch++) {        av_freep(&alac->predict_error_buffer[ch]);        if (!alac->direct_output)            av_freep(&alac->output_samples_buffer[ch]);        av_freep(&alac->extra_bits_buffer[ch]);    }     return 0;} static int allocate_buffers(ALACContext *alac){    int ch;    int buf_size = alac->max_samples_per_frame * sizeof(int32_t);     for (ch = 0; ch < 2; ch++) {        alac->predict_error_buffer[ch]  = NULL;        alac->output_samples_buffer[ch] = NULL;        alac->extra_bits_buffer[ch]     = NULL;    }     for (ch = 0; ch < FFMIN(alac->channels, 2); ch++) {        FF_ALLOC_OR_GOTO(alac->avctx, alac->predict_error_buffer[ch],                         buf_size, buf_alloc_fail); 

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