hvirtual/libmpeg3/audio/ac3.c

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#include <stdint.h>
#include <stdio.h>

#include <a52dec/a52.h>
#include "mpeg3private.h"
#include "mpeg3protos.h"

#include <string.h>


mpeg3_ac3_t* mpeg3_new_ac3()
{
        mpeg3_ac3_t *result = calloc(1, sizeof(mpeg3_ac3_t));
        result->stream = mpeg3bits_new_stream(0, 0);
        result->state = a52_init(0);
        result->output = a52_samples(result->state);
        return result;
}

void mpeg3_delete_ac3(mpeg3_ac3_t *audio)
{
        mpeg3bits_delete_stream(audio->stream);
        a52_free(audio->state);
        free(audio);
}


/* Return 1 if it isn't an AC3 header */
int mpeg3_ac3_check(unsigned char *header)
{
        int flags, samplerate, bitrate;
        return !a52_syncinfo(header,
                &flags,
                &samplerate,
                &bitrate);
}

/* Decode AC3 header */
int mpeg3_ac3_header(mpeg3_ac3_t *audio, unsigned char *header)
{
        int result = 0;
        audio->flags = 0;

//printf("mpeg3_ac3_header %02x%02x%02x%02x%02x%02x%02x%02x\n", header[0], header[1], header[2], header[3], header[4], header[5], header[6], header[7]);
        result = a52_syncinfo(header, 
                &audio->flags,
        &audio->samplerate, 
                &audio->bitrate);


        if(result)
        {
//printf("%d\n", result);
                audio->framesize = result;
                audio->channels = 0;

                if(audio->flags & A52_LFE)
                        audio->channels++;
/*
 * printf("mpeg3_ac3_header %08x %08x\n", 
 * audio->flags & A52_LFE, 
 * audio->flags & A52_CHANNEL_MASK);
 */
                switch(audio->flags & A52_CHANNEL_MASK)
                {
                        case A52_CHANNEL:
                                audio->channels++;
                                break;
                        case A52_MONO:
                                audio->channels++;
                                break;
                        case A52_STEREO:
                                audio->channels += 2;
                                break;
                        case A52_3F:
                                audio->channels += 3;
                                break;
                        case A52_2F1R:
                                audio->channels += 3;
                                break;
                        case A52_3F1R:
                                audio->channels += 4;
                                break;
                        case A52_2F2R:
                                audio->channels += 4;
                                break;
                        case A52_3F2R:
                                audio->channels += 5;
                                break;
                        case A52_DOLBY:
                                audio->channels += 2;
                                break;
                        default:
                                printf("mpeg3_ac3_header: unknown channel code: %p\n", audio->flags & A52_CHANNEL_MASK);
                                break;
                }
        }
//printf("mpeg3_ac3_header 1 %d\n", audio->channels);
        return result;
}


int mpeg3audio_doac3(mpeg3_ac3_t *audio, 
        char *frame, 
        int frame_size, 
        float **output,
        int render)
{
        int output_position = 0;
        sample_t level = 1;
        int i, j, k, l;

//printf("mpeg3audio_doac3 1\n");
        a52_frame(audio->state, 
                frame, 
                &audio->flags,
                &level, 
                0);
//printf("mpeg3audio_doac3 2\n");
        a52_dynrng(audio->state, NULL, NULL);
//printf("mpeg3audio_doac3 3\n");
        for(i = 0; i < 6; i++)
        {
                if(!a52_block(audio->state))
                {
                        l = 0;
                        if(render)
                        {
// Remap the channels to conform to encoders.
                                for(j = 0; j < audio->channels; j++)
                                {
                                        int dst_channel = j;

// Make LFE last channel.
// Shift all other channels down 1.
                                        if((audio->flags & A52_LFE))
                                        {
                                                if(j == 0)
                                                        dst_channel = audio->channels - 1;
                                                else
                                                        dst_channel--;
                                        }

// Swap front left and center for certain configurations
                                        switch(audio->flags & A52_CHANNEL_MASK)
                                        {
                                                case A52_3F:
                                                case A52_3F1R:
                                                case A52_3F2R:
                                                        if(dst_channel == 0) dst_channel = 1;
                                                        else
                                                        if(dst_channel == 1) dst_channel = 0;
                                                        break;
                                        }

                                        for(k = 0; k < 256; k++)
                                        {
                                                output[dst_channel][output_position + k] = ((sample_t*)audio->output)[l];
                                                l++;
                                        }
                                }
                        }
                        output_position += 256;
                }
        }


        return output_position;
}

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