Libav 0.7.1
libavcodec/ac3enc_fixed.c
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00001 /*
00002  * The simplest AC-3 encoder
00003  * Copyright (c) 2000 Fabrice Bellard
00004  * Copyright (c) 2006-2010 Justin Ruggles <justin.ruggles@gmail.com>
00005  * Copyright (c) 2006-2010 Prakash Punnoor <prakash@punnoor.de>
00006  *
00007  * This file is part of Libav.
00008  *
00009  * Libav is free software; you can redistribute it and/or
00010  * modify it under the terms of the GNU Lesser General Public
00011  * License as published by the Free Software Foundation; either
00012  * version 2.1 of the License, or (at your option) any later version.
00013  *
00014  * Libav is distributed in the hope that it will be useful,
00015  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00016  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00017  * Lesser General Public License for more details.
00018  *
00019  * You should have received a copy of the GNU Lesser General Public
00020  * License along with Libav; if not, write to the Free Software
00021  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00022  */
00023 
00029 #define CONFIG_FFT_FLOAT 0
00030 #undef CONFIG_AC3ENC_FLOAT
00031 #include "ac3enc.h"
00032 
00033 #define AC3ENC_TYPE AC3ENC_TYPE_AC3_FIXED
00034 #include "ac3enc_opts_template.c"
00035 static AVClass ac3enc_class = { "Fixed-Point AC-3 Encoder", av_default_item_name,
00036                                 ac3fixed_options, LIBAVUTIL_VERSION_INT };
00037 
00038 #include "ac3enc_template.c"
00039 
00040 
00044 av_cold void AC3_NAME(mdct_end)(AC3MDCTContext *mdct)
00045 {
00046     ff_mdct_end(&mdct->fft);
00047 }
00048 
00049 
00054 av_cold int AC3_NAME(mdct_init)(AVCodecContext *avctx, AC3MDCTContext *mdct,
00055                                 int nbits)
00056 {
00057     int ret = ff_mdct_init(&mdct->fft, nbits, 0, -1.0);
00058     mdct->window = ff_ac3_window;
00059     return ret;
00060 }
00061 
00062 
00066 void AC3_NAME(apply_window)(DSPContext *dsp, int16_t *output,
00067                             const int16_t *input, const int16_t *window,
00068                             unsigned int len)
00069 {
00070     dsp->apply_window_int16(output, input, window, len);
00071 }
00072 
00073 
00080 static int log2_tab(AC3EncodeContext *s, int16_t *src, int len)
00081 {
00082     int v = s->ac3dsp.ac3_max_msb_abs_int16(src, len);
00083     return av_log2(v);
00084 }
00085 
00086 
00093 int AC3_NAME(normalize_samples)(AC3EncodeContext *s)
00094 {
00095     int v = 14 - log2_tab(s, s->windowed_samples, AC3_WINDOW_SIZE);
00096     if (v > 0)
00097         s->ac3dsp.ac3_lshift_int16(s->windowed_samples, AC3_WINDOW_SIZE, v);
00098     /* +6 to right-shift from 31-bit to 25-bit */
00099     return v + 6;
00100 }
00101 
00102 
00106 void AC3_NAME(scale_coefficients)(AC3EncodeContext *s)
00107 {
00108     int blk, ch;
00109 
00110     for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
00111         AC3Block *block = &s->blocks[blk];
00112         for (ch = 1; ch <= s->channels; ch++) {
00113             s->ac3dsp.ac3_rshift_int32(block->mdct_coef[ch], AC3_MAX_COEFS,
00114                                        block->coeff_shift[ch]);
00115         }
00116     }
00117 }
00118 
00119 
00120 static av_cold int ac3_fixed_encode_init(AVCodecContext *avctx)
00121 {
00122     AC3EncodeContext *s = avctx->priv_data;
00123     s->fixed_point = 1;
00124     return ff_ac3_encode_init(avctx);
00125 }
00126 
00127 
00128 AVCodec ff_ac3_fixed_encoder = {
00129     "ac3_fixed",
00130     AVMEDIA_TYPE_AUDIO,
00131     CODEC_ID_AC3,
00132     sizeof(AC3EncodeContext),
00133     ac3_fixed_encode_init,
00134     ff_ac3_encode_frame,
00135     ff_ac3_encode_close,
00136     NULL,
00137     .sample_fmts = (const enum AVSampleFormat[]){AV_SAMPLE_FMT_S16,AV_SAMPLE_FMT_NONE},
00138     .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
00139     .priv_class = &ac3enc_class,
00140     .channel_layouts = ff_ac3_channel_layouts,
00141 };