mixengine.cpp

著名的 helix realplayer 基于手机 symbian 系统的 播放器全套源代码

        7, 7, 6, 6, 5, 5, 4, 4, 3, 3, 2, 2,
        1, 1, 0, 0
    } ;

    if (vol > HX_MAX_VOLUME)
      return 0 ;
    else if (vol <= 0)
      return VOLUME_SILENT ;
    else
      return -(INT32)vol2TenthOfDb[vol] ;
}
#endif

HX_RESULT HXAudioSvcMixEngine::MixIntoBuffer(void* pPlayerbuf0, UINT32 ulBufSizeInBytes_4, BOOL &bIsMixBufferDirty)
{
    // our caller's sense of "dirty" is inverted
    bIsMixBufferDirty = !bIsMixBufferDirty ;

    char *pPlayerbuf = (char*)pPlayerbuf0 ; // keep the original around
    BOOL bHadInput = FALSE ;

    // optimization lazy-init of buffers.
    // We only allocate the sample buffers when we really need them (the first
    // time MixIntoBuffer() is called)

    if (!m_pBuffer_1)
    {
        // allocate both buffers
        m_pBuffer_1 = new tAudioSample[m_ulChunkSize_1] ;
        if (!m_pBuffer_1)
            return HXR_OUTOFMEMORY ;

        if (m_pResampler)
        {
            m_pBuffer_3 = new tAudioSample[m_ulBufferSize_3] ;
            if (!m_pBuffer_3)
                return HXR_OUTOFMEMORY ;
        }
    }

    UINT32 nSamplesOutput_4 = ulBufSizeInBytes_4 / m_ulBytesPerSample ;

    // make sure we are being handed right-sized buffers.
    if (nSamplesOutput_4 / m_nChannels_4 * (m_ulBytesPerSample * m_nChannels_4) != ulBufSizeInBytes_4)
    {
        HX_ASSERT(0) ;
        return HXR_FAIL ;
    }

    // tile output into chunks
    while (nSamplesOutput_4)
    {
        // Figure out how many samples we need on the resampler output.
        // If we have left-overs from last time, adjust the tile size
        UINT32 nSamples_3 = MIN(nSamplesOutput_4 / m_nChannels_4 * m_nChannels_2_3, m_ulChunkSize_3) ;

        // how many samples in do we need on input?
        UINT32 nSamples_2 ;
#ifdef HELIX_FEATURE_RESAMPLER
        if (m_pResampler)
            nSamples_2 = m_pResampler->GetMinInput(nSamples_3 - m_nOutputSamplesLeft_3) ;
        else
#endif
        nSamples_2 = (nSamples_3 - m_nOutputSamplesLeft_3) ;
        UINT32 nSamples_1 = nSamples_2 * m_nChannels_1 / m_nChannels_2_3 ;

        // make sure that we don't overflow the input buffer (if we did, that would
        // be a design error)
        HX_ASSERT(nSamples_1 <= m_ulChunkSize_1) ;

        //
        // Phase 1: Get the input
        //

        // get input
        BOOL bHaveInput = m_pCvt->ConvertIntoBuffer(m_pBuffer_1, nSamples_1, m_llTimestamp_1);

        // update the time stamp.
        m_llTimestamp_1 += nSamples_1 ;

        //
        // Phase 2: Downmix if necessary. This might need headroom and create overgain
        // (not implemented yet)
        //

        // downmix if necessary (creates nSamples_2 samples)
        if (bHaveInput && m_nChannels_2_3 != m_nChannels_1)
            (*this.*m_pfDownmix)(m_pBuffer_1, nSamples_1) ;

        //
        // apply any volume changes
        //

#ifdef HELIX_FEATURE_GAINTOOL
        if (bHaveInput)
            gainFeed(m_pBuffer_1, nSamples_2, m_pGaintool) ;
#endif

        //
        // Phase 3: Resample
        //

        // resample, but only if we have data. This is a hack -- it ignores
        // the buffers in the resamplers, and thus looses some data, and time-
        // shifts other data. This needs to be worked out.

        tAudioSample *pResampOutput_3 ;
        if (m_pResampler && bHaveInput)
        {
#ifdef HELIX_FEATURE_RESAMPLER
            // compiler should optimize one of these branches away.
            if (NBITS_PER_AUDIOSAMPLE == 32)
                m_nOutputSamplesLeft_3 += m_pResampler->Resample(m_pBuffer_1, nSamples_2, (signed int*)(m_pBuffer_3 + m_nOutputSamplesLeft_3) ) ;
            else
                m_nOutputSamplesLeft_3 += m_pResampler->Resample(m_pBuffer_1, nSamples_2, (signed short*)(m_pBuffer_3 + m_nOutputSamplesLeft_3) ) ;

            // assert that the resampler did not write out-of-bounds
            HX_ASSERT(m_nOutputSamplesLeft_3 <= m_ulBufferSize_3) ;

            // assert that we got at least nSamples_3 samples
            HX_ASSERT(m_nOutputSamplesLeft_3 >= nSamples_3) ;

            pResampOutput_3 = m_pBuffer_3 ;
#endif
        }
        else // estimate the resampler output.
        {
            m_ulResamplerPhase += (nSamples_2 / m_nChannels_2_3) * m_ulSampleRate_3_4 ;
            int sampleFramesOut = m_ulResamplerPhase / m_ulSampleRate_1_2 ;
            m_ulResamplerPhase -= sampleFramesOut * m_ulSampleRate_1_2 ;

            m_nOutputSamplesLeft_3 += sampleFramesOut * m_nChannels_2_3 ;
            pResampOutput_3 = m_pResampler ? m_pBuffer_3 : m_pBuffer_1 ; // pass-through
        }

        // m_nOutputSamplesLeft_3 is the total number of resampled samples (including leftovers
        // from the last time around). Do all further DSP only on nSamples_3 samples, leaving
        // any leftovers for the next time.

#ifdef HELIX_FEATURE_CROSSFADE
        // We apply the crossfade even if we won't use the data, in order to
        // kick its timestamp keeping forward.
        // The performance impact should be negligible, though, since we won't be
        // in crossfades most of the time.

        //
        // if we are at the start of a fade, notify the xfader
        //

        //
        // m_llTimestamp                         ts+nsamples
        // +-------------------------------------+ incoming
        //                  XFade
        //                   |
        // nSamplesBeforeFade nSamplesInFade

        //
        //       m_llTimestamp                         ts+nsamples
        //       +-------------------------------------+ incoming
        // XFade
        //   |------V----------------------------------|
        //       nSamplesInFade
        //  nSamplesBeforeFade  < 0

        INT64 nSamplesBeforeFade = m_llFadeStart - m_llTimestamp_3 ;
        INT64 nSamplesInFade     = nSamples_3 - nSamplesBeforeFade ;

        if (nSamplesBeforeFade >= 0 // fade starts after this segment start
            && nSamplesInFade > 0) // fade starts before this segment end
        {
            // time to start an XFade
            m_bPastXFade = TRUE ;
            XFader_start(m_ulXFadeSamples, m_pXFader) ;
        }

        // if we have passed the X-Fade point, we always run the signal through
        // the XFader. Since it has a fast path when the XFade is done, this is
        // not a resource drain.

        if (m_bPastXFade)
        {
            if (nSamplesBeforeFade < 0) // fade was started earlier
            {
                nSamplesInFade += nSamplesBeforeFade ; // == nSamples_3
                nSamplesBeforeFade = 0 ;
            }
            HX_ASSERT( nSamplesInFade > 0 );

            if (XFader_active(m_pXFader))
                Fader_feed(pResampOutput_3 + nSamplesBeforeFade, (INT32)nSamplesInFade, m_eCrossFadeDirection == FADE_OUT, m_pXFader) ;
        }
#endif

        //
        // Phase 3.5: Run the limiter if needed
        //

#ifdef HELIX_FEATURE_LIMITER
        if (m_pLimiter && NBITS_PER_AUDIOSAMPLE == 32)
        {
            LimiterProcess((int*)pResampOutput_3, nSamples_3, m_pLimiter);
        }
        else
#endif
        {
            // TODO: insert clipping code
        }

        //
        // Phase 4: Mix into the output buffer.
        //

        UINT32 nSamples_4 = nSamples_3 / m_nChannels_2_3 * m_nChannels_4 ;

        if (bHaveInput)
        {
            if (!bHadInput && bIsMixBufferDirty)
            {
                // if we did not have input earlier, but we now receive data, we need to clean out
                // the parts that have not been touched so far.
                memset(pPlayerbuf0,0,pPlayerbuf - (char*)pPlayerbuf0) ;
            }

            // and mix into output (mix) buffer
            switch (m_ulBytesPerSample)
            {
            case 2:
                upmix(pResampOutput_3, (INT16*)pPlayerbuf, m_upmixMachine, nSamples_3, bIsMixBufferDirty) ;
                break ;
            case 4:
                upmix(pResampOutput_3, (INT32*)pPlayerbuf, m_upmixMachine, nSamples_3, bIsMixBufferDirty) ;
                break ;
            }

            // if we have input anywhere, the buffer is not "dirty" anymore.
            bHadInput = TRUE ;
        }
        else
        {
            if (bHadInput && bIsMixBufferDirty)
            {
                // if we did have input earlier, but do not now, we need to clean the output
                // buffer (because it will not be marked "dirty" anymore).
                memset(pPlayerbuf, 0, nSamples_4 * m_ulBytesPerSample) ;
            }
        }

        // save left-over samples
        m_nOutputSamplesLeft_3 -= nSamples_3 ;
        m_llTimestamp_3        += nSamples_3 ;

        // if there is no resampler, there should be no left-over samples
        if (!m_pResampler) HX_ASSERT(m_nOutputSamplesLeft_3 == 0) ;

        // if left-over samples
        if (m_nOutputSamplesLeft_3)
            memcpy(m_pBuffer_3, m_pBuffer_3 + nSamples_3, m_nOutputSamplesLeft_3 * sizeof(*m_pBuffer_3)) ;

        nSamplesOutput_4 -= nSamples_4 ;
        pPlayerbuf += nSamples_4 * m_ulBytesPerSample ;
    }

    // if we had input anywhere within this function, the buffer is not dirty anymore.

    bIsMixBufferDirty &= !bHadInput ;

    bIsMixBufferDirty = !bIsMixBufferDirty ;

    return HXR_OK ;
}

HX_RESULT HXAudioSvcMixEngine::SetCrossFade(
    enum eCrossfadeDirection inOut, // FADE_IN and FADE_OUT
    INT64 llStarttimeInSamples, // output side!
    INT64 llEndtimeInSamples
)
{
#if defined(HELIX_FEATURE_CROSSFADE)
    m_eCrossFadeDirection = inOut ;

    HX_ASSERT(llStarttimeInSamples % m_nChannels_4 == 0 &&
              llEndtimeInSamples   % m_nChannels_4 == 0 ) ;

    m_llFadeStart = llStarttimeInSamples ; // both are pre-resampler

    if (llEndtimeInSamples - llStarttimeInSamples > INT_MAX ||
        llEndtimeInSamples - llStarttimeInSamples < 0)
    {
        // we don't support such long fades
        return HXR_FAIL ;
    }
    // duration is in part 3 samples
    m_ulXFadeSamples = (INT32)(llEndtimeInSamples - llStarttimeInSamples) / m_nChannels_4 * m_nChannels_2_3 ;

    m_bPastXFade = FALSE ;

    return HXR_OK ;
#else
    return HXR_NOTIMPL ;
#endif
}