qgstutils.cpp

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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#include <common/qgstutils_p.h>
#include <common/qgst_p.h>
 
#include <QtMultimedia/qaudioformat.h>
 
#include <chrono>
 
QT_BEGIN_NAMESPACE
 
namespace {
 
const char *audioSampleFormatNames[QAudioFormat::NSampleFormats] = {
    nullptr,
#if Q_BYTE_ORDER == Q_LITTLE_ENDIAN
    "U8",
    "S16LE",
    "S32LE",
    "F32LE"
#else
    "U8",
    "S16BE",
    "S32BE",
    "F32BE"
#endif
};
 
QAudioFormat::SampleFormat gstSampleFormatToSampleFormat(const char *fmt)
{
    if (fmt) {
        for (int i = 1; i < QAudioFormat::NSampleFormats; ++i) {
            if (strcmp(fmt, audioSampleFormatNames[i]))
                continue;
            return QAudioFormat::SampleFormat(i);
        }
    }
    return QAudioFormat::Unknown;
}
 
} // namespace
 
/*
  Returns audio format for a sample \a sample.
  If the buffer doesn't have a valid audio format, an empty QAudioFormat is returned.
*/
QAudioFormat QGstUtils::audioFormatForSample(GstSample *sample)
{
    auto caps = QGstCaps(gst_sample_get_caps(sample), QGstCaps::NeedsRef);
    if (!caps)
        return {};
    return audioFormatForCaps(caps);
}
 
QAudioFormat QGstUtils::audioFormatForCaps(const QGstCaps &caps)
{
    QAudioFormat format;
    QGstStructureView s = caps.at(0);
    if (s.name() != "audio/x-raw")
        return format;
 
    auto rate = s["rate"].toInt();
    auto channels = s["channels"].toInt();
    QAudioFormat::SampleFormat fmt = gstSampleFormatToSampleFormat(s["format"].toString());
    if (!rate || !channels || fmt == QAudioFormat::Unknown)
        return format;
 
    format.setSampleRate(*rate);
    format.setChannelCount(*channels);
    format.setSampleFormat(fmt);
 
    return format;
}
 
/*
  Builds GstCaps for an audio format \a format.
  Returns 0 if the audio format is not valid.
 
  \note Caller must unreference GstCaps.
*/
 
QGstCaps QGstUtils::capsForAudioFormat(const QAudioFormat &format)
{
    if (!format.isValid())
        return {};
 
    auto sampleFormat = format.sampleFormat();
    auto caps = gst_caps_new_simple(
                "audio/x-raw",
                "format"  , G_TYPE_STRING, audioSampleFormatNames[sampleFormat],
                "rate"    , G_TYPE_INT   , format.sampleRate(),
                "channels", G_TYPE_INT   , format.channelCount(),
                "layout"  , G_TYPE_STRING, "interleaved",
                nullptr);
 
    return QGstCaps(caps, QGstCaps::HasRef);
}
 
QList<QAudioFormat::SampleFormat> QGValue::getSampleFormats() const
{
    if (!GST_VALUE_HOLDS_LIST(value))
        return {};
 
    QList<QAudioFormat::SampleFormat> formats;
    guint nFormats = gst_value_list_get_size(value);
    for (guint f = 0; f < nFormats; ++f) {
        QGValue v = QGValue{ gst_value_list_get_value(value, f) };
        auto *name = v.toString();
        QAudioFormat::SampleFormat fmt = gstSampleFormatToSampleFormat(name);
        if (fmt == QAudioFormat::Unknown)
            continue;
        formats.append(fmt);
    }
    return formats;
}
 
void QGstUtils::setFrameTimeStampsFromBuffer(QVideoFrame *frame, GstBuffer *buffer)
{
    using namespace std::chrono;
    using namespace std::chrono_literals;
 
    // GStreamer uses nanoseconds, Qt uses microseconds
    nanoseconds startTime{ GST_BUFFER_TIMESTAMP(buffer) };
    if (startTime >= 0ns) {
        frame->setStartTime(floor<microseconds>(startTime).count());
 
        nanoseconds duration{ GST_BUFFER_DURATION(buffer) };
        if (duration >= 0ns)
            frame->setEndTime(floor<microseconds>(startTime + duration).count());
    }
}
 
GList *qt_gst_video_sinks()
{
    return gst_element_factory_list_get_elements(GST_ELEMENT_FACTORY_TYPE_SINK
                                                         | GST_ELEMENT_FACTORY_TYPE_MEDIA_VIDEO,
                                                 GST_RANK_MARGINAL);
}
 
QLocale::Language QGstUtils::codeToLanguage(const gchar *lang)
{
    return QLocale::codeToLanguage(QString::fromUtf8(lang), QLocale::AnyLanguageCode);
}
 
// QTBUG-125249: gstreamer tries "to keep the input height (because of interlacing)". Can we align
// the behavior between GStreamer and FFmpeg?
QSize QGstUtils::qCalculateFrameSizeGStreamer(QSize resolution, Fraction par)
{
    if (!resolution.isValid()) {
        qWarning() << Q_FUNC_INFO << "invalid resolution when calculating frame size";
        return resolution;
    }
 
    if (par.numerator == par.denominator || par.numerator < 1 || par.denominator < 1)
        return resolution;
 
    return QSize{
        resolution.width() * par.numerator / par.denominator,
        resolution.height(),
    };
}
 
QT_END_NAMESPACE