如何使用pyglet播放流式音频？
作者：互联网
这个问题的目标是试图弄清楚如何使用pyglet播放流式音频.第一个是确保你能够使用pyglet播放mp3文件,这就是第一个片段的目的：
import sys
import inspect
import requests
import pyglet
from pyglet.media import *
pyglet.lib.load_library('avbin')
pyglet.have_avbin = True
def url_to_filename(url):
return url.split('/')[-1]
def download_file(url, filename=None):
filename = filename or url_to_filename(url)
with open(filename, "wb") as f:
print("Downloading %s" % filename)
response = requests.get(url, stream=True)
total_length = response.headers.get('content-length')
if total_length is None:
f.write(response.content)
else:
dl = 0
total_length = int(total_length)
for data in response.iter_content(chunk_size=4096):
dl += len(data)
f.write(data)
done = int(50 * dl / total_length)
sys.stdout.write("\r[%s%s]" % ('=' * done, ' ' * (50 - done)))
sys.stdout.flush()
url = "https://freemusicarchive.org/file/music/ccCommunity/DASK/Abiogenesis/DASK_-_08_-_Protocell.mp3"
filename = "mcve.mp3"
download_file(url, filename)
music = pyglet.media.load(filename)
music.play()
pyglet.app.run()
如果您已安装了库pip install pyglet requests并且此时还安装了AVBin,那么一旦下载了mp3,您就应该能够收听它.
一旦我们达到这一点,我想弄清楚如何玩和使用pyglet请求以与大多数现有Web视频/音频播放器类似的方式缓冲文件.这意味着播放文件时无需等待文件完全下载.
阅读pyglet媒体docs后,您可以看到这些类可用：
media
sources
base
AudioData
AudioFormat
Source
SourceGroup
SourceInfo
StaticSource
StreamingSource
VideoFormat
player
Player
PlayerGroup
我已经看到有另外类似的SO问题,但它们没有得到妥善解决,其内容没有提供很多相关细节：
> Play streaming audio using pyglet
> How can I play audio stream without saving it into the file with pyglet?
这就是我创造一个新问题的原因.你如何使用pyglet播放流音频？你能用上面的mcve作为基础提供一些例子吗？
解决方法:
假设您不想导入新包来为您执行此操作 – 这可以通过一些努力来完成.
首先,让我们转到Pyglet源代码并查看media / __ init__.py中的media.load.
"""Load a Source from a file.
All decoders that are registered for the filename extension are tried.
If none succeed, the exception from the first decoder is raised.
You can also specifically pass a decoder to use.
:Parameters:
`filename` : str
Used to guess the media format, and to load the file if `file` is
unspecified.
`file` : file-like object or None
Source of media data in any supported format.
`streaming` : bool
If `False`, a :class:`StaticSource` will be returned; otherwise
(default) a :class:`~pyglet.media.StreamingSource` is created.
`decoder` : MediaDecoder or None
A specific decoder you wish to use, rather than relying on
automatic detection. If specified, no other decoders are tried.
:rtype: StreamingSource or Source
"""
if decoder:
return decoder.decode(file, filename, streaming)
else:
first_exception = None
for decoder in get_decoders(filename):
try:
loaded_source = decoder.decode(file, filename, streaming)
return loaded_source
except MediaDecodeException as e:
if not first_exception or first_exception.exception_priority < e.exception_priority:
first_exception = e
# TODO: Review this:
# The FFmpeg codec attempts to decode anything, so this codepath won't be reached.
if not first_exception:
raise MediaDecodeException('No decoders are available for this media format.')
raise first_exception
add_default_media_codecs()
这里的关键线是loaded_source = decoder.decode(…).从本质上讲,加载音频Pyglet需要一个文件并将其传递给媒体解码器(例如FFMPEG),媒体解码器然后返回Pyglet可以使用内置Player类播放的“帧”或数据包列表.如果音频格式是压缩的(例如mp3或aac),Pyglet将使用外部库(目前仅支持AVBin)将其转换为原始的解压缩音频.你可能已经知道了一些.
因此,如果我们想看看如何将字节流填充到Pyglet的音频引擎而不是文件中,我们需要看看其中一个解码器.对于这个例子,让我们使用FFMPEG,因为它是最容易访问的.
在media / codecs / ffmpeg.py中：
class FFmpegDecoder(object):
def get_file_extensions(self):
return ['.mp3', '.ogg']
def decode(self, file, filename, streaming):
if streaming:
return FFmpegSource(filename, file)
else:
return StaticSource(FFmpegSource(filename, file))
它继承的’对象’是MediaDecoder,可在media / codecs / __ init__.py中找到.回到media / __ init__.py中的load函数,你会看到pyglet会根据文件扩展名选择一个MediaDecoder,然后返回它的解码函数,并以文件作为参数来获取数据包流形式的音频.该数据包流是一个Source对象;每个解码器都有自己的风格,以StaticSource或StreamingSource的形式.前者用于在内存中存储音频,后者用于立即播放. FFmpeg的解码器仅支持StreamingSource.
我们可以看到FFMPEG是FFmpegSource,也位于media / codecs / ffmpeg.py中.我们发现这个类的歌利亚：
class FFmpegSource(StreamingSource):
# Max increase/decrease of original sample size
SAMPLE_CORRECTION_PERCENT_MAX = 10
def __init__(self, filename, file=None):
if file is not None:
raise NotImplementedError('Loading from file stream is not supported')
self._file = ffmpeg_open_filename(asbytes_filename(filename))
if not self._file:
raise FFmpegException('Could not open "{0}"'.format(filename))
self._video_stream = None
self._video_stream_index = None
self._audio_stream = None
self._audio_stream_index = None
self._audio_format = None
self.img_convert_ctx = POINTER(SwsContext)()
self.audio_convert_ctx = POINTER(SwrContext)()
file_info = ffmpeg_file_info(self._file)
self.info = SourceInfo()
self.info.title = file_info.title
self.info.author = file_info.author
self.info.copyright = file_info.copyright
self.info.comment = file_info.comment
self.info.album = file_info.album
self.info.year = file_info.year
self.info.track = file_info.track
self.info.genre = file_info.genre
# Pick the first video and audio streams found, ignore others.
for i in range(file_info.n_streams):
info = ffmpeg_stream_info(self._file, i)
if isinstance(info, StreamVideoInfo) and self._video_stream is None:
stream = ffmpeg_open_stream(self._file, i)
self.video_format = VideoFormat(
width=info.width,
height=info.height)
if info.sample_aspect_num != 0:
self.video_format.sample_aspect = (
float(info.sample_aspect_num) /
info.sample_aspect_den)
self.video_format.frame_rate = (
float(info.frame_rate_num) /
info.frame_rate_den)
self._video_stream = stream
self._video_stream_index = i
elif (isinstance(info, StreamAudioInfo) and
info.sample_bits in (8, 16) and
self._audio_stream is None):
stream = ffmpeg_open_stream(self._file, i)
self.audio_format = AudioFormat(
channels=min(2, info.channels),
sample_size=info.sample_bits,
sample_rate=info.sample_rate)
self._audio_stream = stream
self._audio_stream_index = i
channel_input = avutil.av_get_default_channel_layout(info.channels)
channels_out = min(2, info.channels)
channel_output = avutil.av_get_default_channel_layout(channels_out)
sample_rate = stream.codec_context.contents.sample_rate
sample_format = stream.codec_context.contents.sample_fmt
if sample_format in (AV_SAMPLE_FMT_U8, AV_SAMPLE_FMT_U8P):
self.tgt_format = AV_SAMPLE_FMT_U8
elif sample_format in (AV_SAMPLE_FMT_S16, AV_SAMPLE_FMT_S16P):
self.tgt_format = AV_SAMPLE_FMT_S16
elif sample_format in (AV_SAMPLE_FMT_S32, AV_SAMPLE_FMT_S32P):
self.tgt_format = AV_SAMPLE_FMT_S32
elif sample_format in (AV_SAMPLE_FMT_FLT, AV_SAMPLE_FMT_FLTP):
self.tgt_format = AV_SAMPLE_FMT_S16
else:
raise FFmpegException('Audio format not supported.')
self.audio_convert_ctx = swresample.swr_alloc_set_opts(None,
channel_output,
self.tgt_format, sample_rate,
channel_input, sample_format,
sample_rate,
0, None)
if (not self.audio_convert_ctx or
swresample.swr_init(self.audio_convert_ctx) < 0):
swresample.swr_free(self.audio_convert_ctx)
raise FFmpegException('Cannot create sample rate converter.')
self._packet = ffmpeg_init_packet()
self._events = [] # They don't seem to be used!
self.audioq = deque()
# Make queue big enough to accomodate 1.2 sec?
self._max_len_audioq = 50 # Need to figure out a correct amount
if self.audio_format:
# Buffer 1 sec worth of audio
self._audio_buffer = \
(c_uint8 * ffmpeg_get_audio_buffer_size(self.audio_format))()
self.videoq = deque()
self._max_len_videoq = 50 # Need to figure out a correct amount
self.start_time = self._get_start_time()
self._duration = timestamp_from_ffmpeg(file_info.duration)
self._duration -= self.start_time
# Flag to determine if the _fillq method was already scheduled
self._fillq_scheduled = False
self._fillq()
# Don't understand why, but some files show that seeking without
# reading the first few packets results in a seeking where we lose
# many packets at the beginning.
# We only seek back to 0 for media which have a start_time > 0
if self.start_time > 0:
self.seek(0.0)
---
[A few hundred lines more...]
---
def get_next_video_timestamp(self):
if not self.video_format:
return
if self.videoq:
while True:
# We skip video packets which are not video frames
# This happens in mkv files for the first few frames.
video_packet = self.videoq[0]
if video_packet.image == 0:
self._decode_video_packet(video_packet)
if video_packet.image is not None:
break
self._get_video_packet()
ts = video_packet.timestamp
else:
ts = None
if _debug:
print('Next video timestamp is', ts)
return ts
def get_next_video_frame(self, skip_empty_frame=True):
if not self.video_format:
return
while True:
# We skip video packets which are not video frames
# This happens in mkv files for the first few frames.
video_packet = self._get_video_packet()
if video_packet.image == 0:
self._decode_video_packet(video_packet)
if video_packet.image is not None or not skip_empty_frame:
break
if _debug:
print('Returning', video_packet)
return video_packet.image
def _get_start_time(self):
def streams():
format_context = self._file.context
for idx in (self._video_stream_index, self._audio_stream_index):
if idx is None:
continue
stream = format_context.contents.streams[idx].contents
yield stream
def start_times(streams):
yield 0
for stream in streams:
start = stream.start_time
if start == AV_NOPTS_VALUE:
yield 0
start_time = avutil.av_rescale_q(start,
stream.time_base,
AV_TIME_BASE_Q)
start_time = timestamp_from_ffmpeg(start_time)
yield start_time
return max(start_times(streams()))
@property
def audio_format(self):
return self._audio_format
@audio_format.setter
def audio_format(self, value):
self._audio_format = value
if value is None:
self.audioq.clear()
您在这里感兴趣的行是self._file = ffmpeg_open_filename(asbytes_filename(filename)).这再次在media / codecs / ffmpeg.py中将我们带到这里：
def ffmpeg_open_filename(filename):
"""Open the media file.
:rtype: FFmpegFile
:return: The structure containing all the information for the media.
"""
file = FFmpegFile() # TODO: delete this structure and use directly AVFormatContext
result = avformat.avformat_open_input(byref(file.context),
filename,
None,
None)
if result != 0:
raise FFmpegException('Error opening file ' + filename.decode("utf8"))
result = avformat.avformat_find_stream_info(file.context, None)
if result < 0:
raise FFmpegException('Could not find stream info')
return file
这就是事情变得混乱的地方：它调用了一个ctypes函数(avformat_open_input),当给定一个文件时,它会获取它的详细信息并填写FFmpegSource类所需的所有信息.通过一些工作,您应该能够获得avformat_open_input以获取字节对象而不是文件的路径,该文件将打开以获取相同的信息.我喜欢这样做并包含一个有效的例子,但我现在没有时间.然后,您需要使用新的avformat_open_input函数创建一个新的ffmpeg_open_filename函数,然后使用新的ffmpeg_open_filename函数创建一个新的FFmpegSource类.您现在需要的是一个新的FFmpegDecoder类,它使用新的FFmpegSource类.
然后,您可以通过直接将其添加到pyglet包来实现它.之后,您需要在load()函数中添加对byte对象参数的支持(位于media / __ init__.py中,并将解码器覆盖到新的.)现在,您可以在不保存的情况下流式传输音频它.
或者,您可以简单地使用已经支持它的包. Python-vlc呢.您可以使用示例here从链接播放您想要的任何音频.如果您不是为了挑战而这样做,我强烈建议您使用另一个包.否则：祝你好运.
标签：python,audio,audio-streaming,pyglet,streaming 来源： https://codeday.me/bug/20190910/1800064.html