Python 使用GStreamer的gnonlin和节奏变化

我的目标是将不同音频文件的各个部分编辑在一起，并将音调元素的单一时间拉伸效果节奏特性应用于这些部分中的每个部分。在最终混合中，每个片段应持续12秒，因此输出文件的长度为36秒。下面的代码对3个文件执行此操作，它可以通过使用循环并将所有内容存储到列表中进行扩展。[是的，有点长]

import gst, gobject
gobject.threads_init()
import numpy as np
import math

comp  = gst.element_factory_make("gnlcomposition", "composition")

gsrc1 = gst.element_factory_make("gnlfilesource")
gsrc1.props.location = "file1.mp3"
gsrc1.props.start          = 0
gsrc1.props.duration       = ?
gsrc1.props.media_start    = 0
gsrc1.props.priority       = 3
comp.add(gsrc1)

gsrc2 = gst.element_factory_make("gnlfilesource")
gsrc2.props.location = "file2.mp3"
gsrc2.props.start          = ?
gsrc2.props.duration       = ?
gsrc2.props.media_start    = 0
gsrc2.props.priority       = 4
comp.add(gsrc2)

gsrc3 = gst.element_factory_make("gnlfilesource")
gsrc3.props.location = "file3.mp3"
gsrc3.props.start          = ?
gsrc3.props.duration       = ?
gsrc3.props.media_start    = 0
gsrc3.props.priority       = 5
comp.add(gsrc3)

bin = gst.Bin()
audioconvertbin = gst.element_factory_make("audioconvert")
pitch1 = gst.element_factory_make("pitch")
pitch1.set_property("tempo", 1.05)
bin.add(audioconvertbin, pitch1)
audioconvertbin.link(pitch1)
bin.add_pad(gst.GhostPad("sink", audioconvertbin.get_pad("sink")))
bin.add_pad(gst.GhostPad("src", pitch1.get_pad("src")))

bin2 = gst.Bin()
audioconvertbin2 = gst.element_factory_make("audioconvert")
pitch2 = gst.element_factory_make("pitch")
pitch2.set_property("tempo", 0.95)
bin2.add(audioconvertbin2, pitch2)
audioconvertbin2.link(pitch2)
bin2.add_pad(gst.GhostPad("sink", audioconvertbin2.get_pad("sink")))
bin2.add_pad(gst.GhostPad("src", pitch2.get_pad("src")))

bin3 = gst.Bin()
audioconvertbin3 = gst.element_factory_make("audioconvert")
pitch3 = gst.element_factory_make("pitch")
pitch3.set_property("tempo", 1.1)
bin3.add(audioconvertbin3, pitch3)
audioconvertbin3.link(pitch3)
bin3.add_pad(gst.GhostPad("sink", audioconvertbin3.get_pad("sink")))
bin3.add_pad(gst.GhostPad("src", pitch3.get_pad("src")))

op = gst.element_factory_make("gnloperation")
comp.add(op)

op2 = gst.element_factory_make("gnloperation", "op2")
comp.add(op2)

op3 = gst.element_factory_make("gnloperation", "op3")
comp.add(op3)

op.add(bin)
op.props.start          = 0 * gst.SECOND
op.props.duration       = ?
op.props.priority       = 1
op2.add(bin2)
op2.props.start          = ?
op2.props.duration       = ?
op2.props.priority       = 1
op3.add(bin3)
op3.props.start          = ?
op3.props.duration       = ?
op3.props.priority       = 1

pipeline = gst.Pipeline()
audioconvert = gst.element_factory_make("audioconvert")
encoder = gst.element_factory_make("vorbisenc")
mux = gst.element_factory_make("oggmux")
filesink = gst.element_factory_make("filesink")
filesink.set_property("location", "output.ogg")
pipeline.add(comp, audioconvert, encoder, mux, filesink)
gst.element_link_many(audioconvert, encoder, mux, filesink)

def on_pad(comp, pad, elements):
    convpad = elements.get_compatible_pad(pad, pad.get_caps())
    pad.link(convpad)
comp.connect("pad-added", on_pad, audioconvert)

loop = gobject.MainLoop(is_running=True)
bus = pipeline.get_bus()
bus.add_signal_watch()
def on_message(bus, message, loop):
    if message.type == gst.MESSAGE_EOS:
        loop.quit()
    elif message.type == gst.MESSAGE_ERROR:
        print message
        loop.quit()
bus.connect("message", on_message, loop)
pipeline.set_state(gst.STATE_PLAYING)
loop.run()
pipeline.set_state(gst.STATE_NULL)

---

我发现最好的价值观是什么？它们是：

gsrc1 = gst.element_factory_make("gnlfilesource")
gsrc1.props.location = "file1"
gsrc1.props.start          = 0
gsrc1.props.duration       = 12 * 1.05 * gst.SECOND
gsrc1.props.media_start    = 0
gsrc1.props.priority       = 3
comp.add(gsrc1)

gsrc2 = gst.element_factory_make("gnlfilesource")
gsrc2.props.location = "file2.mp3"
gsrc2.props.start          = int(12 * 1.05 * gst.SECOND)
gsrc2.props.duration       = int(12 * gst.SECOND)
gsrc2.props.media_start    = 36 * gst.SECOND
gsrc2.props.priority       = 4
comp.add(gsrc2)

gsrc3 = gst.element_factory_make("gnlfilesource")
gsrc3.props.location = "file3.mp3"
gsrc3.props.start          = int(12 * 1.05 * gst.SECOND + 12 * gst.SECOND)
gsrc3.props.duration       = int(12 * 1.1 * gst.SECOND)
gsrc3.props.media_start    = 60 * gst.SECOND
gsrc3.props.priority       = 4
comp.add(gsrc3)

op.add(bin)
op.props.start          = 0 * gst.SECOND
op.props.duration       = int(12 * 1.05 * gst.SECOND)
op.props.priority       = 1

op2.add(bin2)
op2.props.start          = int(12 * 1.05 * gst.SECOND)
op2.props.duration       = int(12 * gst.SECOND)
op2.props.priority       = 1

op3.add(bin3)
op3.props.start          = int(12 * 1.05 * gst.SECOND + 12 * gst.SECOND)
op3.props.duration       = int(12 * 1.1 * gst.SECOND)
op3.props.priority       = 1

简而言之，你不应该考虑节奏变化< 1有任何后果，但是你应该考虑节奏变化> 1。从用户的角度来看，这是一种奇怪的行为。 我将其与Audacity进行了比较，得出的结果大致相同，只是rougly 0.026s的两个摘录之间有一个很小的差距。我不认为这是由于舍入错误，可能我的持续时间/开始时间设置得不完全正确，请参见下图中的间隙

希望它能帮助一些人