diff options
Diffstat (limited to 'src/base/QXmppCodec.cpp')
| -rw-r--r-- | src/base/QXmppCodec.cpp | 30 |
1 files changed, 26 insertions, 4 deletions
diff --git a/src/base/QXmppCodec.cpp b/src/base/QXmppCodec.cpp index ed346764..0e47de63 100644 --- a/src/base/QXmppCodec.cpp +++ b/src/base/QXmppCodec.cpp @@ -398,12 +398,11 @@ QXmppOpusCodec::QXmppOpusCodec(int clockrate, int channels): sampleRate(clockrate), nChannels(channels) { - // https://tools.ietf.org/html/draft-ietf-payload-rtp-opus-04 - int error; encoder = opus_encoder_create(clockrate, channels, OPUS_APPLICATION_VOIP, &error); if (encoder || error == OPUS_OK) { + // Add some options for error correction. opus_encoder_ctl(encoder, OPUS_SET_INBAND_FEC(1)); opus_encoder_ctl(encoder, OPUS_SET_PACKET_LOSS_PERC(20)); opus_encoder_ctl(encoder, OPUS_SET_DTX(1)); @@ -417,11 +416,19 @@ QXmppOpusCodec::QXmppOpusCodec(int clockrate, int channels): if (!encoder || error != OPUS_OK) qCritical() << "Opus decoder initialization error:" << opus_strerror(error); + // Opus only supports fixed frame durations from 2.5ms to 60ms. + // + // NOTE: https://mf4.xiph.org/jenkins/view/opus/job/opus/ws/doc/html/group__opus__encoder.html validFrameSize << 2.5e-3 << 5e-3 << 10e-3 << 20e-3 << 40e-3 << 60e-3; + // so now, calculate the equivalent number of samples to process in each + // frame. + // + // nSamples = t * frameRate for (int i = 0; i < validFrameSize.size(); i++) validFrameSize[i] *= clockrate; + // Maxmimum number of samples for the audio buffer. nSamples = validFrameSize.last(); } @@ -440,14 +447,21 @@ QXmppOpusCodec::~QXmppOpusCodec() qint64 QXmppOpusCodec::encode(QDataStream &input, QDataStream &output) { + // Read an audio frame. QByteArray pcm_buffer(input.device()->bytesAvailable(), 0); int length = input.readRawData(pcm_buffer.data(), pcm_buffer.size()); + + // and append it to the sample buffer. sampleBuffer.append(pcm_buffer.left(length)); + + // Get the maximum number of samples to encode. It must be a number + // accepted by the Opus encoder int samples = readWindow(sampleBuffer.size()); if (samples < 1) return 0; + // The encoded stream is supposed to be smaller than the raw stream, so QByteArray opus_buffer(sampleBuffer.size(), 0); length = opus_encode(encoder, @@ -459,8 +473,10 @@ qint64 QXmppOpusCodec::encode(QDataStream &input, QDataStream &output) if (length < 1) qWarning() << "Opus encoding error:" << opus_strerror(length); else + // Write the encoded stream to the output. output.writeRawData(opus_buffer.constData(), length); + // Remove the frame from the sample buffer. sampleBuffer.remove(0, samples * nChannels * 2); if (length < 1) @@ -477,8 +493,11 @@ qint64 QXmppOpusCodec::decode(QDataStream &input, QDataStream &output) if (length < 1) return 0; + // Audio frame is nSamples at maximum, so QByteArray pcm_buffer(nSamples * nChannels * 2, 0); + // The last argumment must be 1 to enable FEC, but I don't why it results + // in a SIGSEV. int samples = opus_decode(decoder, (uchar *) opus_buffer.constData(), length, @@ -492,6 +511,7 @@ qint64 QXmppOpusCodec::decode(QDataStream &input, QDataStream &output) return 0; } + // Write the audio frame to the output. output.writeRawData(pcm_buffer.constData(), samples * nChannels * 2); return samples; @@ -502,10 +522,12 @@ int QXmppOpusCodec::readWindow(int bufferSize) // WARNING: We are expecting 2 bytes signed samples, but this is wrong since // input stream can have a different sample formats. - int nFrames = bufferSize / nChannels / 2; + // Get the number of frames in the buffer. + int samples = bufferSize / nChannels / 2; + // Find an appropiate number of samples to read, according to Opus specs. for (int i = validFrameSize.size() - 1; i >= 0; i--) - if (validFrameSize[i] <= nFrames) + if (validFrameSize[i] <= samples) return validFrameSize[i]; return 0; |