int mpeg3audio_do_pcm(mpeg3audio_t *audio)
{
int i, j, k;
MPEG3_INT16 sample;
int frame_samples = (audio->framesize - 3) / audio->channels / 2;
if(mpeg3bits_read_buffer(audio->astream, audio->ac3_buffer, frame_samples * audio->channels * 2))
return 1;
/* Need more room */
if(audio->pcm_point / audio->channels >= audio->pcm_allocated - MPEG3AUDIO_PADDING * audio->channels)
{
mpeg3audio_replace_buffer(audio, audio->pcm_allocated + MPEG3AUDIO_PADDING * audio->channels);
}
k = 0;
for(i = 0; i < frame_samples; i++)
{
for(j = 0; j < audio->channels; j++)
{
sample = ((MPEG3_INT16)(audio->ac3_buffer[k++])) << 8;
sample |= audio->ac3_buffer[k++];
audio->pcm_sample[audio->pcm_point + i * audio->channels + j] =
(mpeg3_real_t)sample / 32767;
}
}
audio->pcm_point += frame_samples * audio->channels;
return 0;
}
int mpeg3audio_do_ac3(mpeg3audio_t *audio)
{
int result = 0, i;
/* Reset the coefficients and exponents */
mpeg3audio_ac3_reset_frame(audio);
for(i = 0; i < 6 && !result; i++)
{
memset(audio->ac3_samples, 0, sizeof(float) * 256 * (audio->ac3_bsi.nfchans + audio->ac3_bsi.lfeon));
/* Extract most of the audblk info from the bitstream
* (minus the mantissas */
result |= mpeg3audio_read_ac3_audblk(audio);
/* Take the differential exponent data and turn it into
* absolute exponents */
if(!result) result |= mpeg3audio_ac3_exponent_unpack(audio,
&(audio->ac3_bsi),
&(audio->ac3_audblk));
/* Figure out how many bits per mantissa */
if(!result) result |= mpeg3audio_ac3_bit_allocate(audio,
audio->sampling_frequency_code,
&(audio->ac3_bsi),
&(audio->ac3_audblk));
/* Extract the mantissas from the data stream */
if(!result) result |= mpeg3audio_ac3_coeff_unpack(audio,
&(audio->ac3_bsi),
&(audio->ac3_audblk),
audio->ac3_samples);
if(audio->ac3_bsi.acmod == 0x2)
if(!result) result |= mpeg3audio_ac3_rematrix(&(audio->ac3_audblk),
audio->ac3_samples);
/* Convert the frequency data into time samples */
if(!result) result |= mpeg3audio_ac3_imdct(audio,
&(audio->ac3_bsi),
&(audio->ac3_audblk),
audio->ac3_samples);
if(audio->pcm_point / audio->channels >= audio->pcm_allocated - MPEG3AUDIO_PADDING * audio->channels)
{
/* Need more room */
mpeg3audio_replace_buffer(audio, audio->pcm_allocated + MPEG3AUDIO_PADDING * audio->channels);
}
}
mpeg3bits_use_demuxer(audio->astream);
return result;
}
int mpeg3audio_dolayer2(mpeg3audio_t *audio)
{
int i, j, result = 0;
int channels = audio->channels;
float fraction[2][4][SBLIMIT]; /* pick_table clears unused subbands */
unsigned int bit_alloc[64];
int scale[192];
int single = audio->single;
if(audio->error_protection)
mpeg3bits_getbits(audio->astream, 16);
mpeg3audio_II_select_table(audio);
audio->jsbound = (audio->mode == MPG_MD_JOINT_STEREO) ?
(audio->mode_ext << 2) + 4 : audio->II_sblimit;
if(channels == 1 || single == 3)
single = 0;
result |= mpeg3audio_II_step_one(audio, bit_alloc, scale);
for(i = 0; i < SCALE_BLOCK && !result; i++)
{
result |= mpeg3audio_II_step_two(audio, bit_alloc, fraction, scale, i >> 2);
for(j = 0; j < 3; j++)
{
if(single >= 0)
{
/* Monaural */
mpeg3audio_synth_mono(audio, fraction[single][j], audio->pcm_sample, &(audio->pcm_point));
}
else
{
/* Stereo */
int p1 = audio->pcm_point;
mpeg3audio_synth_stereo(audio, fraction[0][j], 0, audio->pcm_sample, &p1);
mpeg3audio_synth_stereo(audio, fraction[1][j], 1, audio->pcm_sample, &(audio->pcm_point));
}
if(audio->pcm_point / audio->channels >= audio->pcm_allocated - MPEG3AUDIO_PADDING * audio->channels)
{
/* Need more room */
mpeg3audio_replace_buffer(audio, audio->pcm_allocated + MPEG3AUDIO_PADDING * audio->channels);
}
}
}
return result;
}