mirror of
https://github.com/mpv-player/mpv
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f331f54b26
git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@5482 b3059339-0415-0410-9bf9-f77b7e298cf2
204 lines
5.1 KiB
C
204 lines
5.1 KiB
C
/*
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MS ADPCM Decoder for MPlayer
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by Mike Melanson
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This file is responsible for decoding Microsoft ADPCM data.
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Details about the data format can be found here:
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http://www.pcisys.net/~melanson/codecs/
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include "config.h"
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#include "bswap.h"
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#include "ad_internal.h"
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static ad_info_t info =
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{
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"MS ADPCM audio decoder",
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"msadpcm",
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AFM_MSADPCM,
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"Nick Kurshev",
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"Mike Melanson",
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""
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};
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LIBAD_EXTERN(msadpcm)
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static int ms_adapt_table[] =
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{
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230, 230, 230, 230, 307, 409, 512, 614,
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768, 614, 512, 409, 307, 230, 230, 230
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};
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static int ms_adapt_coeff1[] =
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{
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256, 512, 0, 192, 240, 460, 392
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};
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static int ms_adapt_coeff2[] =
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{
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0, -256, 0, 64, 0, -208, -232
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};
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#define MS_ADPCM_PREAMBLE_SIZE 7
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#define LE_16(x) (le2me_16(*(unsigned short *)(x)))
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#define LE_32(x) (le2me_32(*(unsigned int *)(x)))
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// useful macros
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// clamp a number between 0 and 88
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#define CLAMP_0_TO_88(x) if (x < 0) x = 0; else if (x > 88) x = 88;
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// clamp a number within a signed 16-bit range
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#define CLAMP_S16(x) if (x < -32768) x = -32768; \
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else if (x > 32767) x = 32767;
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// clamp a number above 16
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#define CLAMP_ABOVE_16(x) if (x < 16) x = 16;
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// sign extend a 16-bit value
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#define SE_16BIT(x) if (x & 0x8000) x -= 0x10000;
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// sign extend a 4-bit value
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#define SE_4BIT(x) if (x & 0x8) x -= 0x10;
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static int preinit(sh_audio_t *sh_audio)
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{
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sh_audio->audio_out_minsize = sh_audio->wf->nBlockAlign * 4;
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sh_audio->ds->ss_div =
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(sh_audio->wf->nBlockAlign - MS_ADPCM_PREAMBLE_SIZE) * 2;
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sh_audio->audio_in_minsize =
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sh_audio->ds->ss_mul = sh_audio->wf->nBlockAlign;
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return 1;
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}
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static int init(sh_audio_t *sh_audio)
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{
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sh_audio->channels=sh_audio->wf->nChannels;
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sh_audio->samplerate=sh_audio->wf->nSamplesPerSec;
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sh_audio->i_bps = sh_audio->wf->nBlockAlign *
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(sh_audio->channels*sh_audio->samplerate) / sh_audio->ds->ss_div;
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return 1;
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}
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static void uninit(sh_audio_t *sh_audio)
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{
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}
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static int control(sh_audio_t *sh_audio,int cmd,void* arg, ...)
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{
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if(cmd==ADCTRL_SKIP_FRAME){
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demux_read_data(sh_audio->ds, sh_audio->a_in_buffer,sh_audio->ds->ss_mul);
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return CONTROL_TRUE;
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}
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return CONTROL_UNKNOWN;
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}
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static int ms_adpcm_decode_block(unsigned short *output, unsigned char *input,
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int channels, int block_size)
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{
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int current_channel = 0;
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int idelta[2];
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int sample1[2];
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int sample2[2];
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int coeff1[2];
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int coeff2[2];
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int stream_ptr = 0;
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int out_ptr = 0;
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int upper_nibble = 1;
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int nibble;
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int snibble; // signed nibble
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int predictor;
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// fetch the header information, in stereo if both channels are present
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if (input[stream_ptr] > 6)
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mp_msg(MSGT_DECAUDIO, MSGL_WARN,
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"MS ADPCM: coefficient (%d) out of range (should be [0..6])\n",
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input[stream_ptr]);
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coeff1[0] = ms_adapt_coeff1[input[stream_ptr]];
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coeff2[0] = ms_adapt_coeff2[input[stream_ptr]];
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stream_ptr++;
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if (channels == 2)
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{
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if (input[stream_ptr] > 6)
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mp_msg(MSGT_DECAUDIO, MSGL_WARN,
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"MS ADPCM: coefficient (%d) out of range (should be [0..6])\n",
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input[stream_ptr]);
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coeff1[1] = ms_adapt_coeff1[input[stream_ptr]];
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coeff2[1] = ms_adapt_coeff2[input[stream_ptr]];
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stream_ptr++;
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}
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idelta[0] = LE_16(&input[stream_ptr]);
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stream_ptr += 2;
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SE_16BIT(idelta[0]);
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if (channels == 2)
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{
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idelta[1] = LE_16(&input[stream_ptr]);
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stream_ptr += 2;
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SE_16BIT(idelta[1]);
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}
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sample1[0] = LE_16(&input[stream_ptr]);
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stream_ptr += 2;
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SE_16BIT(sample1[0]);
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if (channels == 2)
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{
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sample1[1] = LE_16(&input[stream_ptr]);
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stream_ptr += 2;
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SE_16BIT(sample1[1]);
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}
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sample2[0] = LE_16(&input[stream_ptr]);
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stream_ptr += 2;
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SE_16BIT(sample2[0]);
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if (channels == 2)
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{
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sample2[1] = LE_16(&input[stream_ptr]);
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stream_ptr += 2;
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SE_16BIT(sample2[1]);
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}
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while (stream_ptr < block_size)
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{
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// get the next nibble
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if (upper_nibble)
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nibble = snibble = input[stream_ptr] >> 4;
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else
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nibble = snibble = input[stream_ptr++] & 0x0F;
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upper_nibble ^= 1;
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SE_4BIT(snibble);
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predictor = (
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((sample1[current_channel] * coeff1[current_channel]) +
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(sample2[current_channel] * coeff2[current_channel])) / 256) +
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(snibble * idelta[current_channel]);
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CLAMP_S16(predictor);
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sample2[current_channel] = sample1[current_channel];
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sample1[current_channel] = predictor;
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output[out_ptr++] = predictor;
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// compute the next adaptive scale factor (a.k.a. the variable idelta)
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idelta[current_channel] =
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(ms_adapt_table[nibble] * idelta[current_channel]) / 256;
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CLAMP_ABOVE_16(idelta[current_channel]);
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// toggle the channel
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current_channel ^= channels - 1;
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}
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return (block_size - (MS_ADPCM_PREAMBLE_SIZE * channels)) * 2;
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}
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static int decode_audio(sh_audio_t *sh_audio,unsigned char *buf,int minlen,int maxlen)
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{
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if (demux_read_data(sh_audio->ds, sh_audio->a_in_buffer,
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sh_audio->ds->ss_mul) !=
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sh_audio->ds->ss_mul)
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return -1; /* EOF */
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return 2 * ms_adpcm_decode_block(
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(unsigned short*)buf, sh_audio->a_in_buffer,
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sh_audio->wf->nChannels, sh_audio->wf->nBlockAlign);
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}
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