将 Shoutcast 流延迟 12 小时 (Linux/bash)
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19-08-2019 - |
题
我住在世界的另一端(现在是 GMT+1,GMT+13 是家),我想念我以前的地面广播电台。它有一个 Shoutcast 流,我想简单地将其延迟 12 小时,以便当我想听它时它始终可用,从而使其时区与我的时区同步。
我设想这是在我的服务器主机上运行的脚本。
一种简单的方法就是在环形缓冲区中分配足够的内存来存储整个 12 小时的延迟,并通过管道输入 Streamripper 的输出。但该流是 128kbps mp3,这意味着 (128/8) * 60 * 60 = 每小时约 56MB,或者整个 12 小时缓冲区为 675MB,这实际上不太实用。另外,我可能必须处理我的服务器主机,只是在一定的超时后终止进程。
那么,有哪些策略可能真正实用呢?
解决方案
流开膛手将是简单的方法,也可能是正确的方法,但如果你想用程序员的方式来做......
- 大多数开发机器都有相当多的 RAM。您确定不能腾出 675 MB 空间吗?
- 除了将输出存储在缓冲区中之外,您不能将其存储在一个或多个文件中(例如一次一个小时)吗?(本质上,您将编写自己的流开膛手)
- 如果您可以忍受质量损失,请将流转换为较低的比特率
其他提示
为什么你不只是一个流开膛手像Ripshout或东西下载呢?
要回答我的问题,下面是作为cron作业启动后,每30分钟的脚本。它转储在5分钟的组块的输入流(或由FILE _设定秒),以特定的目录中。块边界被同步到时钟,并且它不开始写入,直到当前时间块的端,所以运行cronjobs可以没有数据翻倍或离开间隙重叠。文件命名(在24小时内的秒信号出现时间%数)名为.str。
我还没有做出一个球员还没有,但计划是设置输出目录某处网络访问,并写入到本地运行一个脚本,使用相同的时间戳的计算代码这里按顺序访问(时间戳2小时前)名为.str,钉它们重新结合在一起,然后设置为Shoutcast的本地服务器。然后我可能只是在指向http我的音乐播放器://本地主机:端口并把它
编辑:有超时和更好的错误条件检查,加上不错的日志文件的新版。这是当前运行的牵引 - 免费我的(便宜的)共享的虚拟主机,没有任何问题。
#!/usr/bin/python
import time
import urllib
import datetime
import os
import socket
# number of seconds for each file
FILE_SECONDS = 300
# run for 30 minutes
RUN_TIME = 60*30
# size in bytes of each read block
# 16384 = 1 second
BLOCK_SIZE = 16384
MAX_TIMEOUTS = 10
# where to save the files
OUTPUT_DIRECTORY = "dir/"
# URL for original stream
URL = "http://url/path:port"
debug = True
log = None
socket.setdefaulttimeout(10)
class DatestampedWriter:
# output_path MUST have trailing '/'
def __init__(self, output_path, run_seconds ):
self.path = output_path
self.file = None
# needs to be -1 to avoid issue when 0 is a real timestamp
self.curr_timestamp = -1
self.running = False
# don't start until the _end_ of the current time block
# so calculate an initial timestamp as (now+FILE_SECONDS)
self.initial_timestamp = self.CalcTimestamp( FILE_SECONDS )
self.final_timestamp = self.CalcTimestamp( run_seconds )
if debug:
log = open(OUTPUT_DIRECTORY+"log_"+str(self.initial_timestamp)+".txt","w")
log.write("initial timestamp "+str(self.initial_timestamp)+", final "+str(self.final_timestamp)+" (diff "+str(self.final_timestamp-self.initial_timestamp)+")\n")
self.log = log
def Shutdown(self):
if self.file != None:
self.file.close()
# write out buf
# returns True when we should stop
def Write(self, buf):
# check that we have the correct file open
# get timestamp
timestamp = self.CalcTimestamp()
if not self.running :
# should we start?
if timestamp == self.initial_timestamp:
if debug:
self.log.write( "starting running now\n" )
self.log.flush()
self.running = True
# should we open a new file?
if self.running and timestamp != self.curr_timestamp:
if debug:
self.log.write( "new timestamp "+str(timestamp)+"\n" )
self.log.flush()
# close old file
if ( self.file != None ):
self.file.close()
# time to stop?
if ( self.curr_timestamp == self.final_timestamp ):
if debug:
self.log.write( " -- time to stop\n" )
self.log.flush()
self.running = False
return True
# open new file
filename = self.path+str(timestamp)+".str"
#if not os.path.exists(filename):
self.file = open(filename, "w")
self.curr_timestamp = int(timestamp)
#else:
# uh-oh
# if debug:
# self.log.write(" tried to open but failed, already there\n")
# self.running = False
# now write bytes
if self.running:
#print("writing "+str(len(buf)))
self.file.write( buf )
return False
def CalcTimestamp(self, seconds_offset=0):
t = datetime.datetime.now()
seconds = time.mktime(t.timetuple())+seconds_offset
# FILE_SECONDS intervals, 24 hour days
timestamp = seconds - ( seconds % FILE_SECONDS )
timestamp = timestamp % 86400
return int(timestamp)
writer = DatestampedWriter(OUTPUT_DIRECTORY, RUN_TIME)
writer_finished = False
# while been running for < (RUN_TIME + 5 minutes)
now = time.mktime(datetime.datetime.now().timetuple())
stop_time = now + RUN_TIME + 5*60
while not writer_finished and time.mktime(datetime.datetime.now().timetuple())<stop_time:
now = time.mktime(datetime.datetime.now().timetuple())
# open the stream
if debug:
writer.log.write("opening stream... "+str(now)+"/"+str(stop_time)+"\n")
writer.log.flush()
try:
u = urllib.urlopen(URL)
except socket.timeout:
if debug:
writer.log.write("timed out, sleeping 60 seconds\n")
writer.log.flush()
time.sleep(60)
continue
except IOError:
if debug:
writer.log.write("IOError, sleeping 60 seconds\n")
writer.log.flush()
time.sleep(60)
continue
# read 1 block of input
buf = u.read(BLOCK_SIZE)
timeouts = 0
while len(buf) > 0 and not writer_finished and now<stop_time and timeouts<MAX_TIMEOUTS:
# write to disc
writer_finished = writer.Write(buf)
# read 1 block of input
try:
buf = u.read(BLOCK_SIZE)
except socket.timeout:
# catch exception but do nothing about it
if debug:
writer.log.write("read timed out ("+str(timeouts)+")\n")
writer.log.flush()
timeouts = timeouts+1
now = time.mktime(datetime.datetime.now().timetuple())
# stream has closed,
if debug:
writer.log.write("read loop bailed out: timeouts "+str(timeouts)+", time "+str(now)+"\n")
writer.log.flush()
u.close();
# sleep 1 second before trying to open the stream again
time.sleep(1)
now = time.mktime(datetime.datetime.now().timetuple())
writer.Shutdown()