annotate ffmpeg/libavcodec/nellymoserdec.c @ 13:844d341cf643 tip

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/*
 * NellyMoser audio decoder
 * Copyright (c) 2007 a840bda5870ba11f19698ff6eb9581dfb0f95fa5,
 *                    539459aeb7d425140b62a3ec7dbf6dc8e408a306, and
 *                    520e17cd55896441042b14df2566a6eb610ed444
 * Copyright (c) 2007 Loic Minier <lool at dooz.org>
 *                    Benjamin Larsson
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */

/**
 * @file
 * The 3 alphanumeric copyright notices are md5summed they are from the original
 * implementors. The original code is available from http://code.google.com/p/nelly2pcm/
 */

#include "libavutil/channel_layout.h"
#include "libavutil/float_dsp.h"
#include "libavutil/lfg.h"
#include "libavutil/random_seed.h"
#include "avcodec.h"
#include "fft.h"
#include "fmtconvert.h"
#include "internal.h"
#include "nellymoser.h"
#include "sinewin.h"

#define BITSTREAM_READER_LE
#include "get_bits.h"


typedef struct NellyMoserDecodeContext {
    AVCodecContext* avctx;
    AVLFG           random_state;
    GetBitContext   gb;
    float           scale_bias;
    AVFloatDSPContext fdsp;
    FFTContext      imdct_ctx;
    DECLARE_ALIGNED(32, float, imdct_buf)[2][NELLY_BUF_LEN];
    float          *imdct_out;
    float          *imdct_prev;
} NellyMoserDecodeContext;

static void nelly_decode_block(NellyMoserDecodeContext *s,
                               const unsigned char block[NELLY_BLOCK_LEN],
                               float audio[NELLY_SAMPLES])
{
    int i,j;
    float buf[NELLY_FILL_LEN], pows[NELLY_FILL_LEN];
    float *aptr, *bptr, *pptr, val, pval;
    int bits[NELLY_BUF_LEN];
    unsigned char v;

    init_get_bits(&s->gb, block, NELLY_BLOCK_LEN * 8);

    bptr = buf;
    pptr = pows;
    val = ff_nelly_init_table[get_bits(&s->gb, 6)];
    for (i=0 ; i<NELLY_BANDS ; i++) {
        if (i > 0)
            val += ff_nelly_delta_table[get_bits(&s->gb, 5)];
        pval = -pow(2, val/2048) * s->scale_bias;
        for (j = 0; j < ff_nelly_band_sizes_table[i]; j++) {
            *bptr++ = val;
            *pptr++ = pval;
        }

    }

    ff_nelly_get_sample_bits(buf, bits);

    for (i = 0; i < 2; i++) {
        aptr = audio + i * NELLY_BUF_LEN;

        init_get_bits(&s->gb, block, NELLY_BLOCK_LEN * 8);
        skip_bits_long(&s->gb, NELLY_HEADER_BITS + i*NELLY_DETAIL_BITS);

        for (j = 0; j < NELLY_FILL_LEN; j++) {
            if (bits[j] <= 0) {
                aptr[j] = M_SQRT1_2*pows[j];
                if (av_lfg_get(&s->random_state) & 1)
                    aptr[j] *= -1.0;
            } else {
                v = get_bits(&s->gb, bits[j]);
                aptr[j] = ff_nelly_dequantization_table[(1<<bits[j])-1+v]*pows[j];
            }
        }
        memset(&aptr[NELLY_FILL_LEN], 0,
               (NELLY_BUF_LEN - NELLY_FILL_LEN) * sizeof(float));

        s->imdct_ctx.imdct_half(&s->imdct_ctx, s->imdct_out, aptr);
        s->fdsp.vector_fmul_window(aptr, s->imdct_prev + NELLY_BUF_LEN / 2,
                                   s->imdct_out, ff_sine_128,
                                   NELLY_BUF_LEN / 2);
        FFSWAP(float *, s->imdct_out, s->imdct_prev);
    }
}

static av_cold int decode_init(AVCodecContext * avctx) {
    NellyMoserDecodeContext *s = avctx->priv_data;

    s->avctx = avctx;
    s->imdct_out = s->imdct_buf[0];
    s->imdct_prev = s->imdct_buf[1];
    av_lfg_init(&s->random_state, 0);
    ff_mdct_init(&s->imdct_ctx, 8, 1, 1.0);

    avpriv_float_dsp_init(&s->fdsp, avctx->flags & CODEC_FLAG_BITEXACT);

    s->scale_bias = 1.0/(32768*8);
    avctx->sample_fmt = AV_SAMPLE_FMT_FLT;

    /* Generate overlap window */
    if (!ff_sine_128[127])
        ff_init_ff_sine_windows(7);

    avctx->channels       = 1;
    avctx->channel_layout = AV_CH_LAYOUT_MONO;

    return 0;
}

static int decode_tag(AVCodecContext *avctx, void *data,
                      int *got_frame_ptr, AVPacket *avpkt)
{
    AVFrame *frame     = data;
    const uint8_t *buf = avpkt->data;
    const uint8_t *side=av_packet_get_side_data(avpkt, 'F', NULL);
    int buf_size = avpkt->size;
    NellyMoserDecodeContext *s = avctx->priv_data;
    int blocks, i, ret;
    float   *samples_flt;

    blocks     = buf_size / NELLY_BLOCK_LEN;

    if (blocks <= 0) {
        av_log(avctx, AV_LOG_ERROR, "Packet is too small\n");
        return AVERROR_INVALIDDATA;
    }

    if (buf_size % NELLY_BLOCK_LEN) {
        av_log(avctx, AV_LOG_WARNING, "Leftover bytes: %d.\n",
               buf_size % NELLY_BLOCK_LEN);
    }
    /* Normal numbers of blocks for sample rates:
     *  8000 Hz - 1
     * 11025 Hz - 2
     * 16000 Hz - 3
     * 22050 Hz - 4
     * 44100 Hz - 8
     */
    if(side && blocks>1 && avctx->sample_rate%11025==0 && (1<<((side[0]>>2)&3)) == blocks)
        avctx->sample_rate= 11025*(blocks/2);

    /* get output buffer */
    frame->nb_samples = NELLY_SAMPLES * blocks;
    if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
        return ret;
    samples_flt = (float *)frame->data[0];

    for (i=0 ; i<blocks ; i++) {
        nelly_decode_block(s, buf, samples_flt);
        samples_flt += NELLY_SAMPLES;
        buf += NELLY_BLOCK_LEN;
    }

    *got_frame_ptr = 1;

    return buf_size;
}

static av_cold int decode_end(AVCodecContext * avctx) {
    NellyMoserDecodeContext *s = avctx->priv_data;

    ff_mdct_end(&s->imdct_ctx);

    return 0;
}

AVCodec ff_nellymoser_decoder = {
    .name           = "nellymoser",
    .type           = AVMEDIA_TYPE_AUDIO,
    .id             = AV_CODEC_ID_NELLYMOSER,
    .priv_data_size = sizeof(NellyMoserDecodeContext),
    .init           = decode_init,
    .close          = decode_end,
    .decode         = decode_tag,
    .capabilities   = CODEC_CAP_DR1 | CODEC_CAP_PARAM_CHANGE,
    .long_name      = NULL_IF_CONFIG_SMALL("Nellymoser Asao"),
    .sample_fmts    = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_FLT,
                                                      AV_SAMPLE_FMT_NONE },
};