Libav 0.7.1
libavcodec/nellymoserdec.c
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00001 /*
00002  * NellyMoser audio decoder
00003  * Copyright (c) 2007 a840bda5870ba11f19698ff6eb9581dfb0f95fa5,
00004  *                    539459aeb7d425140b62a3ec7dbf6dc8e408a306, and
00005  *                    520e17cd55896441042b14df2566a6eb610ed444
00006  * Copyright (c) 2007 Loic Minier <lool at dooz.org>
00007  *                    Benjamin Larsson
00008  *
00009  * Permission is hereby granted, free of charge, to any person obtaining a
00010  * copy of this software and associated documentation files (the "Software"),
00011  * to deal in the Software without restriction, including without limitation
00012  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
00013  * and/or sell copies of the Software, and to permit persons to whom the
00014  * Software is furnished to do so, subject to the following conditions:
00015  *
00016  * The above copyright notice and this permission notice shall be included in
00017  * all copies or substantial portions of the Software.
00018  *
00019  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
00020  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
00021  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
00022  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
00023  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
00024  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
00025  * DEALINGS IN THE SOFTWARE.
00026  */
00027 
00034 #include "nellymoser.h"
00035 #include "libavutil/lfg.h"
00036 #include "libavutil/random_seed.h"
00037 #include "libavutil/audioconvert.h"
00038 #include "avcodec.h"
00039 #include "dsputil.h"
00040 #include "fft.h"
00041 #include "fmtconvert.h"
00042 #include "sinewin.h"
00043 
00044 #define ALT_BITSTREAM_READER_LE
00045 #include "get_bits.h"
00046 
00047 
00048 typedef struct NellyMoserDecodeContext {
00049     AVCodecContext* avctx;
00050     DECLARE_ALIGNED(32, float, float_buf)[NELLY_SAMPLES];
00051     float           state[128];
00052     AVLFG           random_state;
00053     GetBitContext   gb;
00054     float           scale_bias;
00055     DSPContext      dsp;
00056     FFTContext      imdct_ctx;
00057     FmtConvertContext fmt_conv;
00058     DECLARE_ALIGNED(32, float, imdct_out)[NELLY_BUF_LEN * 2];
00059 } NellyMoserDecodeContext;
00060 
00061 static void overlap_and_window(NellyMoserDecodeContext *s, float *state, float *audio, float *a_in)
00062 {
00063     int bot, top;
00064 
00065     bot = 0;
00066     top = NELLY_BUF_LEN-1;
00067 
00068     while (bot < NELLY_BUF_LEN) {
00069         audio[bot] = a_in [bot]*ff_sine_128[bot]
00070                     +state[bot]*ff_sine_128[top];
00071 
00072         bot++;
00073         top--;
00074     }
00075     memcpy(state, a_in + NELLY_BUF_LEN, sizeof(float)*NELLY_BUF_LEN);
00076 }
00077 
00078 static void nelly_decode_block(NellyMoserDecodeContext *s,
00079                                const unsigned char block[NELLY_BLOCK_LEN],
00080                                float audio[NELLY_SAMPLES])
00081 {
00082     int i,j;
00083     float buf[NELLY_FILL_LEN], pows[NELLY_FILL_LEN];
00084     float *aptr, *bptr, *pptr, val, pval;
00085     int bits[NELLY_BUF_LEN];
00086     unsigned char v;
00087 
00088     init_get_bits(&s->gb, block, NELLY_BLOCK_LEN * 8);
00089 
00090     bptr = buf;
00091     pptr = pows;
00092     val = ff_nelly_init_table[get_bits(&s->gb, 6)];
00093     for (i=0 ; i<NELLY_BANDS ; i++) {
00094         if (i > 0)
00095             val += ff_nelly_delta_table[get_bits(&s->gb, 5)];
00096         pval = -pow(2, val/2048) * s->scale_bias;
00097         for (j = 0; j < ff_nelly_band_sizes_table[i]; j++) {
00098             *bptr++ = val;
00099             *pptr++ = pval;
00100         }
00101 
00102     }
00103 
00104     ff_nelly_get_sample_bits(buf, bits);
00105 
00106     for (i = 0; i < 2; i++) {
00107         aptr = audio + i * NELLY_BUF_LEN;
00108 
00109         init_get_bits(&s->gb, block, NELLY_BLOCK_LEN * 8);
00110         skip_bits_long(&s->gb, NELLY_HEADER_BITS + i*NELLY_DETAIL_BITS);
00111 
00112         for (j = 0; j < NELLY_FILL_LEN; j++) {
00113             if (bits[j] <= 0) {
00114                 aptr[j] = M_SQRT1_2*pows[j];
00115                 if (av_lfg_get(&s->random_state) & 1)
00116                     aptr[j] *= -1.0;
00117             } else {
00118                 v = get_bits(&s->gb, bits[j]);
00119                 aptr[j] = ff_nelly_dequantization_table[(1<<bits[j])-1+v]*pows[j];
00120             }
00121         }
00122         memset(&aptr[NELLY_FILL_LEN], 0,
00123                (NELLY_BUF_LEN - NELLY_FILL_LEN) * sizeof(float));
00124 
00125         s->imdct_ctx.imdct_calc(&s->imdct_ctx, s->imdct_out, aptr);
00126         /* XXX: overlapping and windowing should be part of a more
00127            generic imdct function */
00128         overlap_and_window(s, s->state, aptr, s->imdct_out);
00129     }
00130 }
00131 
00132 static av_cold int decode_init(AVCodecContext * avctx) {
00133     NellyMoserDecodeContext *s = avctx->priv_data;
00134 
00135     s->avctx = avctx;
00136     av_lfg_init(&s->random_state, 0);
00137     ff_mdct_init(&s->imdct_ctx, 8, 1, 1.0);
00138 
00139     dsputil_init(&s->dsp, avctx);
00140     ff_fmt_convert_init(&s->fmt_conv, avctx);
00141 
00142     s->scale_bias = 1.0/(1*8);
00143 
00144     /* Generate overlap window */
00145     if (!ff_sine_128[127])
00146         ff_init_ff_sine_windows(7);
00147 
00148     avctx->sample_fmt = AV_SAMPLE_FMT_S16;
00149     avctx->channel_layout = AV_CH_LAYOUT_MONO;
00150     return 0;
00151 }
00152 
00153 static int decode_tag(AVCodecContext * avctx,
00154                       void *data, int *data_size,
00155                       AVPacket *avpkt) {
00156     const uint8_t *buf = avpkt->data;
00157     int buf_size = avpkt->size;
00158     NellyMoserDecodeContext *s = avctx->priv_data;
00159     int blocks, i, block_size;
00160     int16_t* samples;
00161     samples = (int16_t*)data;
00162 
00163     if (buf_size < avctx->block_align) {
00164         *data_size = 0;
00165         return buf_size;
00166     }
00167 
00168     if (buf_size % 64) {
00169         av_log(avctx, AV_LOG_ERROR, "Tag size %d.\n", buf_size);
00170         *data_size = 0;
00171         return buf_size;
00172     }
00173     block_size = NELLY_SAMPLES * av_get_bytes_per_sample(avctx->sample_fmt);
00174     blocks     = FFMIN(buf_size / 64, *data_size / block_size);
00175     if (blocks <= 0) {
00176         av_log(avctx, AV_LOG_ERROR, "Output buffer is too small\n");
00177         return AVERROR(EINVAL);
00178     }
00179     /* Normal numbers of blocks for sample rates:
00180      *  8000 Hz - 1
00181      * 11025 Hz - 2
00182      * 16000 Hz - 3
00183      * 22050 Hz - 4
00184      * 44100 Hz - 8
00185      */
00186 
00187     for (i=0 ; i<blocks ; i++) {
00188         nelly_decode_block(s, &buf[i*NELLY_BLOCK_LEN], s->float_buf);
00189         s->fmt_conv.float_to_int16(&samples[i*NELLY_SAMPLES], s->float_buf, NELLY_SAMPLES);
00190     }
00191     *data_size = blocks * block_size;
00192 
00193     return buf_size;
00194 }
00195 
00196 static av_cold int decode_end(AVCodecContext * avctx) {
00197     NellyMoserDecodeContext *s = avctx->priv_data;
00198 
00199     ff_mdct_end(&s->imdct_ctx);
00200     return 0;
00201 }
00202 
00203 AVCodec ff_nellymoser_decoder = {
00204     "nellymoser",
00205     AVMEDIA_TYPE_AUDIO,
00206     CODEC_ID_NELLYMOSER,
00207     sizeof(NellyMoserDecodeContext),
00208     decode_init,
00209     NULL,
00210     decode_end,
00211     decode_tag,
00212     .long_name = NULL_IF_CONFIG_SMALL("Nellymoser Asao"),
00213 };
00214