Ticket #2265: audiooutputca.cpp.v2.diff

File audiooutputca.cpp.v2.diff, 2.9 KB (added by awk@…, 14 years ago)

revised patch to audiooutputca.cpp

  • audiooutputca.cpp

     
    226226    return bufferedBytes;
    227227}
    228228
     229int AudioOutputCA::GetAudiotime(void)
     230{
     231    /* Returns the current timecode of audio leaving the soundcard, based
     232       on the 'audiotime' computed earlier, and the delay since it was computed.
     233
     234       This is a little roundabout...
     235
     236       The reason is that computing 'audiotime' requires acquiring the audio
     237       lock, which the video thread should not do. So, we call 'SetAudioTime()'
     238       from the audio thread, and then call this from the video thread. */
     239    int ret;
     240
     241    if (GetBaseAudioTime() == 0)
     242        return 0;
     243
     244        UInt64 hostNanos = AudioConvertHostTimeToNanos(AudioGetCurrentHostTime());
     245        ret = (hostNanos / 1000000) - CA_audiotime_updated;
     246       
     247    ret += GetBaseAudioTime();
     248
     249    return ret;
     250}
     251
     252void AudioOutputCA::SetAudiotime(void)
     253{
     254    if (GetBaseAudBufTimeCode() == 0)
     255        return;
     256
     257    int soundcard_buffer = 0;
     258    int totalbuffer;
     259
     260    /* We want to calculate 'audiotime', which is the timestamp of the audio
     261       which is leaving the sound card at this instant.
     262
     263       We use these variables:
     264
     265       'effdsp' is samples/sec, multiplied by 100.
     266       Bytes per sample is assumed to be 4.
     267
     268       'audiotimecode' is the timecode of the audio that has just been
     269       written into the buffer.
     270
     271       'totalbuffer' is the total # of bytes in our audio buffer, and the
     272       sound card's buffer.
     273
     274       'ms/byte' is given by '25000/effdsp'...
     275     */
     276
     277    soundcard_buffer = getBufferedOnSoundcard(); // bytes
     278    totalbuffer = audiolen(false) + soundcard_buffer;
     279 
     280    // include algorithmic latencies
     281    if (GetSoundStretch())
     282    {
     283        // add the effect of unprocessed samples in time stretch algo
     284        totalbuffer += (int)((GetSoundStretch()->numUnprocessedSamples() *
     285                              audio_bytes_per_sample) / audio_stretchfactor);
     286    }
     287               
     288    SetBaseAudioTime(GetBaseAudBufTimeCode() - (int)(totalbuffer * 100000.0 /
     289                                   (audio_bytes_per_sample * effdspstretched)));
     290 
     291        // We also store here the host time stamp of when the update occurred. 
     292        // That way when asked later for the audio time we can use the sum of
     293        // the output time code info calculated here and the delta since when it
     294        // was calculated and when we asked.
     295       
     296        // Note that since we're using a single 32bit variable here there is no need to
     297        // use a lock or similar since the 32 bit accesses are atomic. Also we use
     298        // AudioHost time here so that we're all referring to the same clock.
     299        UInt64 hostNanos = AudioConvertHostTimeToNanos(AudioGetCurrentHostTime());
     300        CA_audiotime_updated = hostNanos / 1000000;
     301
     302}
     303
    229304void AudioOutputCA::StartOutputThread(void)
    230305{
    231306    return;     // no thread for CA