Exemple #1
0
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;
}
Exemple #2
0
int mpeg3audio_read_ac3_header(mpeg3audio_t *audio)
{
	unsigned int code, crc;
	unsigned int i;
	mpeg3_ac3bsi_t *bsi = &(audio->ac3_bsi);

/* Get the sync code */
	code = mpeg3bits_getbits(audio->astream, 16);
	while(!mpeg3bits_eof(audio->astream) && code != MPEG3_AC3_START_CODE)
	{
		code <<= 8;
		code &= 0xffff;
		code |= mpeg3bits_getbits(audio->astream, 8);
	}

	if(mpeg3bits_eof(audio->astream)) return 1;

/* Get crc1 - we don't actually use this data though */
/* The crc can be the same as the sync code or come after a sync code repeated twice */
	crc = mpeg3bits_getbits(audio->astream, 16);

/* Got the sync code.  Read the entire frame into a buffer if possible. */
	if(audio->avg_framesize > 0)
	{
		if(mpeg3bits_read_buffer(audio->astream, audio->ac3_buffer, audio->framesize - 4))
			return 1;
		mpeg3bits_use_ptr(audio->astream, audio->ac3_buffer);	
	}

/* Get the sampling rate code */
	audio->sampling_frequency_code  = mpeg3bits_getbits(audio->astream, 2);

/* Get the frame size code */
	audio->ac3_framesize_code = mpeg3bits_getbits(audio->astream, 6);

	audio->bitrate = framesize_codes[audio->ac3_framesize_code].bit_rate;
	audio->avg_framesize = audio->framesize = 2 * framesize_codes[audio->ac3_framesize_code].frm_size[audio->sampling_frequency_code];

/* Check the AC-3 version number */
	bsi->bsid = mpeg3bits_getbits(audio->astream, 5);

/* Get the audio service provided by the steram */
	bsi->bsmod = mpeg3bits_getbits(audio->astream, 3);

/* Get the audio coding mode (ie how many channels)*/
	bsi->acmod = mpeg3bits_getbits(audio->astream, 3);
	
/* Predecode the number of full bandwidth channels as we use this
 * number a lot */
	bsi->nfchans = mpeg3_ac3_acmodes[bsi->acmod];
	audio->channels = bsi->nfchans;

/* If it is in use, get the centre channel mix level */
	if((bsi->acmod & 0x1) && (bsi->acmod != 0x1))
		bsi->cmixlev = mpeg3bits_getbits(audio->astream, 2);

/* If it is in use, get the surround channel mix level */
	if(bsi->acmod & 0x4)
		bsi->surmixlev = mpeg3bits_getbits(audio->astream, 2);

/* Get the dolby surround mode if in 2/0 mode */
	if(bsi->acmod == 0x2)
		bsi->dsurmod= mpeg3bits_getbits(audio->astream, 2);

/* Is the low frequency effects channel on? */
	bsi->lfeon = mpeg3bits_getbits(audio->astream, 1);

/* Get the dialogue normalization level */
	bsi->dialnorm = mpeg3bits_getbits(audio->astream, 5);

/* Does compression gain exist? */
	bsi->compre = mpeg3bits_getbits(audio->astream, 1);
	if (bsi->compre)
	{
/* Get compression gain */
		bsi->compr = mpeg3bits_getbits(audio->astream, 8);
	}

/* Does language code exist? */
	bsi->langcode = mpeg3bits_getbits(audio->astream, 1);
	if (bsi->langcode)
	{
/* Get langauge code */
		bsi->langcod = mpeg3bits_getbits(audio->astream, 8);
	}

/* Does audio production info exist? */
	bsi->audprodie = mpeg3bits_getbits(audio->astream, 1);
	if (bsi->audprodie)
	{
/* Get mix level */
		bsi->mixlevel = mpeg3bits_getbits(audio->astream, 5);

/* Get room type */
		bsi->roomtyp = mpeg3bits_getbits(audio->astream, 2);
	}

/* If we're in dual mono mode then get some extra info */
	if (bsi->acmod == 0)
	{
/* Get the dialogue normalization level two */
		bsi->dialnorm2 = mpeg3bits_getbits(audio->astream, 5);

/* Does compression gain two exist? */
		bsi->compr2e = mpeg3bits_getbits(audio->astream, 1);
		if (bsi->compr2e)
		{
/* Get compression gain two */
			bsi->compr2 = mpeg3bits_getbits(audio->astream, 8);
		}

/* Does language code two exist? */
		bsi->langcod2e = mpeg3bits_getbits(audio->astream, 1);
		if (bsi->langcod2e)
		{
/* Get langauge code two */
			bsi->langcod2 = mpeg3bits_getbits(audio->astream, 8);
		}

/* Does audio production info two exist? */
		bsi->audprodi2e = mpeg3bits_getbits(audio->astream, 1);
		if (bsi->audprodi2e)
		{
/* Get mix level two */
			bsi->mixlevel2 = mpeg3bits_getbits(audio->astream, 5);

/* Get room type two */
			bsi->roomtyp2 = mpeg3bits_getbits(audio->astream, 2);
		}
	}

/* Get the copyright bit */
	bsi->copyrightb = mpeg3bits_getbits(audio->astream, 1);

/* Get the original bit */
	bsi->origbs = mpeg3bits_getbits(audio->astream, 1);
	
/* Does timecode one exist? */
	bsi->timecod1e = mpeg3bits_getbits(audio->astream, 1);

	if(bsi->timecod1e)
		bsi->timecod1 = mpeg3bits_getbits(audio->astream, 14);

/* Does timecode two exist? */
	bsi->timecod2e = mpeg3bits_getbits(audio->astream, 1);

	if(bsi->timecod2e)
		bsi->timecod2 = mpeg3bits_getbits(audio->astream, 14);

/* Does addition info exist? */
	bsi->addbsie = mpeg3bits_getbits(audio->astream, 1);

	if(bsi->addbsie)
	{
/* Get how much info is there */
		bsi->addbsil = mpeg3bits_getbits(audio->astream, 6);

/* Get the additional info */
		for(i = 0; i < (bsi->addbsil + 1); i++)
			bsi->addbsi[i] = mpeg3bits_getbits(audio->astream, 8);
	}

	if(mpeg3bits_eof(audio->astream))
	{
		mpeg3bits_use_demuxer(audio->astream);
		return 1;
	}
	return 0;
//	return mpeg3bits_error(audio->astream);
}