decoder.c

the mpeg2/4 aac decoder

                        for (i = ch1; i < ch; i+=2)
                        {
                            hInfo->channel_position[i] = BACK_CHANNEL_LEFT;
                            hInfo->channel_position[i+1] = BACK_CHANNEL_RIGHT;
                        }
                    }
                }
                hInfo->num_lfe_channels = hDecoder->has_lfe;
                for (i = ch; i < hDecoder->fr_channels; i++)
                {
                    hInfo->channel_position[i] = LFE_CHANNEL;
                }
            }
            break;
        }
    }
}

void* NEAACDECAPI NeAACDecDecode(NeAACDecHandle hDecoder,
                                 NeAACDecFrameInfo *hInfo,
                                 uint8_t *buffer, uint32_t buffer_size)
{
    return aac_frame_decode(hDecoder, hInfo, buffer, buffer_size, NULL, 0);
}

void* NEAACDECAPI NeAACDecDecode2(NeAACDecHandle hDecoder,
                                  NeAACDecFrameInfo *hInfo,
                                  uint8_t *buffer, uint32_t buffer_size,
                                  void **sample_buffer, uint32_t sample_buffer_size)
{
    if ((sample_buffer == NULL) || (sample_buffer_size == 0))
    {
        hInfo->error = 27;
        return NULL;
    }

    return aac_frame_decode(hDecoder, hInfo, buffer, buffer_size,
        sample_buffer, sample_buffer_size);
}

static void* aac_frame_decode(NeAACDecHandle hDecoder, NeAACDecFrameInfo *hInfo,
                              uint8_t *buffer, uint32_t buffer_size,
                              void **sample_buffer2, uint32_t sample_buffer_size)
{
    uint8_t channels = 0;
    uint8_t output_channels = 0;
    bitfile ld;
    uint32_t bitsconsumed;
    uint16_t frame_len;
    void *sample_buffer;

#ifdef PROFILE
    int64_t count = faad_get_ts();
#endif

    /* safety checks */
    if ((hDecoder == NULL) || (hInfo == NULL) || (buffer == NULL))
    {
        return NULL;
    }

#if 0
    printf("%d\n", buffer_size*8);
#endif

    frame_len = hDecoder->frameLength;


    memset(hInfo, 0, sizeof(NeAACDecFrameInfo));
    memset(hDecoder->internal_channel, 0, MAX_CHANNELS*sizeof(hDecoder->internal_channel[0]));

    /* initialize the bitstream */
    faad_initbits(&ld, buffer, buffer_size);

#if 0
    {
        int i;
        for (i = 0; i < ((buffer_size+3)>>2); i++)
        {
            uint8_t *buf;
            uint32_t temp = 0;
            buf = faad_getbitbuffer(&ld, 32);
            //temp = getdword((void*)buf);
            temp = *((uint32_t*)buf);
            printf("0x%.8X\n", temp);
            free(buf);
        }
        faad_endbits(&ld);
        faad_initbits(&ld, buffer, buffer_size);
    }
#endif

#ifdef DRM
    if (hDecoder->object_type == DRM_ER_LC)
    {
        /* We do not support stereo right now */
        if (0) //(hDecoder->channelConfiguration == 2)
        {
            hInfo->error = 8; // Throw CRC error
            goto error;
        }

        faad_getbits(&ld, 8
            DEBUGVAR(1,1,"NeAACDecDecode(): skip CRC"));
    }
#endif

    if (hDecoder->adts_header_present)
    {
        adts_header adts;

        adts.old_format = hDecoder->config.useOldADTSFormat;
        if ((hInfo->error = adts_frame(&adts, &ld)) > 0)
            goto error;

        /* MPEG2 does byte_alignment() here,
         * but ADTS header is always multiple of 8 bits in MPEG2
         * so not needed to actually do it.
         */
    }

#ifdef ANALYSIS
    dbg_count = 0;
#endif

    /* decode the complete bitstream */
#ifdef SCALABLE_DEC
    if ((hDecoder->object_type == 6) || (hDecoder->object_type == DRM_ER_LC))
    {
        aac_scalable_main_element(hDecoder, hInfo, &ld, &hDecoder->pce, hDecoder->drc);
    } else {
#endif
        raw_data_block(hDecoder, hInfo, &ld, &hDecoder->pce, hDecoder->drc);
#ifdef SCALABLE_DEC
    }
#endif

    channels = hDecoder->fr_channels;

    if (hInfo->error > 0)
        goto error;

    /* safety check */
    if (channels == 0 || channels > MAX_CHANNELS)
    {
        /* invalid number of channels */
        hInfo->error = 12;
        goto error;
    }

    /* no more bit reading after this */
    bitsconsumed = faad_get_processed_bits(&ld);
    hInfo->bytesconsumed = bit2byte(bitsconsumed);
    if (ld.error)
    {
        hInfo->error = 14;
        goto error;
    }
    faad_endbits(&ld);


    if (!hDecoder->adts_header_present && !hDecoder->adif_header_present)
    {
        if (hDecoder->channelConfiguration == 0)
            hDecoder->channelConfiguration = channels;

        if (channels == 8) /* 7.1 */
            hDecoder->channelConfiguration = 7;
        if (channels == 7) /* not a standard channelConfiguration */
            hDecoder->channelConfiguration = 0;
    }

    if ((channels == 5 || channels == 6) && hDecoder->config.downMatrix)
    {
        hDecoder->downMatrix = 1;
        output_channels = 2;
    } else {
        output_channels = channels;
    }

#if (defined(PS_DEC) || defined(DRM_PS))
    hDecoder->upMatrix = 0;
    /* check if we have a mono file */
    if (output_channels == 1)
    {
        /* upMatrix to 2 channels for implicit signalling of PS */
        hDecoder->upMatrix = 1;
        output_channels = 2;
    }
#endif

    /* Make a channel configuration based on either a PCE or a channelConfiguration */
    create_channel_config(hDecoder, hInfo);

    /* number of samples in this frame */
    hInfo->samples = frame_len*output_channels;
    /* number of channels in this frame */
    hInfo->channels = output_channels;
    /* samplerate */
    hInfo->samplerate = get_sample_rate(hDecoder->sf_index);
    /* object type */
    hInfo->object_type = hDecoder->object_type;
    /* sbr */
    hInfo->sbr = NO_SBR;
    /* header type */
    hInfo->header_type = RAW;
    if (hDecoder->adif_header_present)
        hInfo->header_type = ADIF;
    if (hDecoder->adts_header_present)
        hInfo->header_type = ADTS;
#if (defined(PS_DEC) || defined(DRM_PS))
    hInfo->ps = hDecoder->ps_used_global;
#endif

    /* check if frame has channel elements */
    if (channels == 0)
    {
        hDecoder->frame++;
        return NULL;
    }

    /* allocate the buffer for the final samples */
    if ((hDecoder->sample_buffer == NULL) ||
        (hDecoder->alloced_channels != output_channels))
    {
        static const uint8_t str[] = { sizeof(int16_t), sizeof(int32_t), sizeof(int32_t),
            sizeof(float32_t), sizeof(double), sizeof(int16_t), sizeof(int16_t),
            sizeof(int16_t), sizeof(int16_t), 0, 0, 0
        };
        uint8_t stride = str[hDecoder->config.outputFormat-1];
#ifdef SBR_DEC
        if (((hDecoder->sbr_present_flag == 1)&&(!hDecoder->downSampledSBR)) || (hDecoder->forceUpSampling == 1))
        {
            stride = 2 * stride;
        }
#endif
        /* check if we want to use internal sample_buffer */
        if (sample_buffer_size == 0)
        {
            if (hDecoder->sample_buffer)
                faad_free(hDecoder->sample_buffer);
            hDecoder->sample_buffer = NULL;
            hDecoder->sample_buffer = faad_malloc(frame_len*output_channels*stride);
        } else if (sample_buffer_size < frame_len*output_channels*stride) {
            /* provided sample buffer is not big enough */
            hInfo->error = 27;
            return NULL;
        }
        hDecoder->alloced_channels = output_channels;
    }

    if (sample_buffer_size == 0)
    {
        sample_buffer = hDecoder->sample_buffer;
    } else {
        sample_buffer = *sample_buffer2;
    }

#ifdef SBR_DEC
    if ((hDecoder->sbr_present_flag == 1) || (hDecoder->forceUpSampling == 1))
    {
        uint8_t ele;

        /* this data is different when SBR is used or when the data is upsampled */
        if (!hDecoder->downSampledSBR)
        {
            frame_len *= 2;
            hInfo->samples *= 2;
            hInfo->samplerate *= 2;
        }

        /* check if every element was provided with SBR data */
        for (ele = 0; ele < hDecoder->fr_ch_ele; ele++)
        {
            if (hDecoder->sbr[ele] == NULL)
            {
                hInfo->error = 25;
                goto error;
            }
        }

        /* sbr */
        if (hDecoder->sbr_present_flag == 1)
        {
            hInfo->object_type = HE_AAC;
            hInfo->sbr = SBR_UPSAMPLED;
        } else {
            hInfo->sbr = NO_SBR_UPSAMPLED;
        }
        if (hDecoder->downSampledSBR)
        {
            hInfo->sbr = SBR_DOWNSAMPLED;
        }
    }
#endif

    sample_buffer = output_to_PCM(hDecoder, hDecoder->time_out, sample_buffer,
        output_channels, frame_len, hDecoder->config.outputFormat);


    hDecoder->postSeekResetFlag = 0;

    hDecoder->frame++;
#ifdef LD_DEC
    if (hDecoder->object_type != LD)
    {
#endif
        if (hDecoder->frame <= 1)
            hInfo->samples = 0;
#ifdef LD_DEC
    } else {
        /* LD encoders will give lower delay */
        if (hDecoder->frame <= 0)
            hInfo->samples = 0;
    }
#endif

    /* cleanup */
#ifdef ANALYSIS
    fflush(stdout);
#endif

#ifdef PROFILE
    count = faad_get_ts() - count;
    hDecoder->cycles += count;
#endif

    return sample_buffer;

error:

    faad_endbits(&ld);

    /* cleanup */
#ifdef ANALYSIS
    fflush(stdout);
#endif

    return NULL;
}