Python3/vlc：如何获取媒体统计信息（函数get_stats）

Question

我正在尝试在媒体上调用 get_stats() 函数：

>>> instance = vlc.Instance()
>>> media = instance.media_new('song.mp3')
>>> media.get_stats()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: get_stats() missing 1 required positional argument: 'p_stats'
>>> media.get_stats('input_bitrate')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/alain/Audio/vlc.py", line 2517, in get_stats
    return libvlc_media_get_stats(self, p_stats)
  File "/home/alain/Audio/vlc.py", line 5349, in libvlc_media_get_stats
    return f(p_md, p_stats)
ctypes.ArgumentError: argument 2: <class 'TypeError'>: expected LP_MediaStats instance instead of str

预期的参数类型 LP_MediaStats 在 vlc.py 中不存在，但我发现了这个：

class MediaStats(_Cstruct):
    _fields_ = [
        ('read_bytes',          ctypes.c_int  ),
        ('input_bitrate',       ctypes.c_float),
        ('demux_read_bytes',    ctypes.c_int  ),
        ('demux_bitrate',       ctypes.c_float),
        ('demux_corrupted',     ctypes.c_int  ),
        ('demux_discontinuity', ctypes.c_int  ),
        ('decoded_video',       ctypes.c_int  ),
        ('decoded_audio',       ctypes.c_int  ),
        ('displayed_pictures',  ctypes.c_int  ),
        ('lost_pictures',       ctypes.c_int  ),
        ('played_abuffers',     ctypes.c_int  ),
        ('lost_abuffers',       ctypes.c_int  ),
        ('sent_packets',        ctypes.c_int  ),
        ('sent_bytes',          ctypes.c_int  ),
        ('send_bitrate',        ctypes.c_float),
    ]

有人知道这个功能怎么用吗？

Answer 1

从文档开始 here。它说：

libvlc_media_get_stats(p_md, p_stats) Get the current statistics about the media.

Parameters: p_md - : media descriptor object. p_stats - : structure that contain the statistics about the media (this structure must be allocated by the caller). Returns: true if the statistics are available, false otherwise \libvlc_return_bool.

根据文档，您应该使用 media descriptor 作为参数。现在我们必须弄清楚如何获取媒体描述符。