hvirtual/libmpeg3/audio/pcm.c

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#include "mpeg3private.h"
#include "mpeg3protos.h"

#include <stdlib.h>


mpeg3_pcm_t* mpeg3_new_pcm()
{
        mpeg3_pcm_t *result = calloc(1, sizeof(mpeg3_pcm_t));
        return result;
}



void mpeg3_delete_pcm(mpeg3_pcm_t *audio)
{
        free(audio);
}


int mpeg3_pcm_check(unsigned char *header)
{
        if(header[0] == ((MPEG3_PCM_START_CODE & 0xff000000) >> 24) &&
                header[1] == ((MPEG3_PCM_START_CODE & 0xff0000) >> 16) &&
                header[2] == ((MPEG3_PCM_START_CODE & 0xff00) >> 8) &&
                header[3] == (MPEG3_PCM_START_CODE & 0xff))
                return 0;
        else
                return 1;
}




int mpeg3_pcm_header(mpeg3_pcm_t *audio, unsigned char *data)
{
        if(mpeg3_pcm_check(data)) return 0;

/* Custom header generated by the demuxer */
        audio->samplerate = *(int32_t*)(data + 4);
        audio->bits = *(int32_t*)(data + 8);
        audio->channels = *(int32_t*)(data + 12);
        audio->framesize = *(int32_t*)(data + 16);

        return audio->framesize;
}

int mpeg3audio_dopcm(mpeg3_pcm_t *audio, 
        char *frame, 
        int frame_size, 
        float **output,
        int render)
{
        int bytes_per_sample = audio->bits / 8 * audio->channels;
        int output_size = (frame_size - PCM_HEADERSIZE) / bytes_per_sample;
        int i, j;
//printf("mpeg3audio_dopcm 2 %d\n", frame_size);

        if(render)
        {
                for(i = 0; i < audio->channels; i++)
                {
//printf("mpeg3audio_dopcm 3\n");
                        float *output_channel = output[i];
//printf("mpeg3audio_dopcm 4\n");
                        switch(audio->bits)
                        {
                                case 16:
                                {
//printf("mpeg3audio_dopcm 5\n");
                                        unsigned char *input = frame + 
                                                PCM_HEADERSIZE + 
                                                audio->bits / 8 * i;
                                                int16_t sample;
//printf("mpeg3audio_dopcm 6\n");
                                        for(j = 0; j < output_size; j++)
                                        {
                                                sample = ((int16_t)(input[0])) << 8;
                                                sample |= input[1];
                                                *output_channel = (float)sample / 32767.0;
                                                input += bytes_per_sample;
                                                output_channel++;
                                        }
//printf("mpeg3audio_dopcm 7\n");
                                }
                                        break;
                        }
                }
        }

/*
 * printf("mpeg3audio_dopcm 2 %02x%02x%02x%02x\n", 
 * *(unsigned char*)(frame + PCM_HEADERSIZE + 0),
 * *(unsigned char*)(frame + PCM_HEADERSIZE + 1),
 * *(unsigned char*)(frame + PCM_HEADERSIZE + 2),
 * *(unsigned char*)(frame + PCM_HEADERSIZE + 3));
 */

        return output_size;
}

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