1. 多媒体相关模块

"Wot? No quote?" - Guido van Rossum

1.1. 概览

Python 提供了一些用于处理图片和音频文件的模块.

另请参阅 Pythonware Image Library ( PIL , http://www.pythonware.com/products/pil/ ), 以及 PythonWare Sound Toolkit (PST , http://www.pythonware.com/products/pst/ ).

译注: 别参阅 PST 了, 废了, 用 pymedia 代替吧.

1.2. imghdr 模块

imghdr 模块可识别不同格式的图片文件. 当前版本可以识别 bmp , gif , jpeg , pbm , pgm , png , ppm , rast (Sun raster), rgb (SGI), tiff , 以及 xbm 图像. 如 Example 9-1 所示.

1.2.0.1. Example 9-1. 使用 imghdr 模块

File: imghdr-example-1.py

import imghdr

result = imghdr.what("samples/sample.jpg")

if result:
    print "file format:", result
else:
    print "cannot identify file"

*B*file format: jpeg*b*

# 使用 PIL 
import Image

im = Image.open("samples/sample.jpg")
print im.format, im.mode, im.size

1.3. sndhdr 模块

sndhdr 模块, 可来识别不同的音频文件格式, 并提取文件内容相关信息. 如 Example 9-2 所示.

执行成功后, what 函数将返回一个由文件类型, 采样频率, 声道数, 音轨数和每个采样点位数组成的元组. 具体含义请参考 help(sndhdr) .

1.3.0.1. Example 9-2. 使用 sndhdr 模块

File: sndhdr-example-1.py

import sndhdr

result = sndhdr.what("samples/sample.wav")

if result:
    print "file format:", result
else:
    print "cannot identify file"

*B*file format: ('wav', 44100, 1, -1, 16)*b*

1.4. whatsound 模块

(已废弃) whatsound 是 sndhdr 模块的一个别名. 如 Example 9-3 所示.

1.4.0.1. Example 9-3. 使用 whatsound 模块

File: whatsound-example-1.py

import whatsound # same as sndhdr

result = whatsound.what("samples/sample.wav")

if result:
    print "file format:", result
else:
    print "cannot identify file"

*B*file format: ('wav', 44100, 1, -1, 16)*b*

1.5. aifc 模块

aifc 模块用于读写 AIFF 和 AIFC 音频文件(在 SGI 和 Macintosh 的计算机上使用). 如 Example 9-4 所示.

1.5.0.1. Example 9-4. 使用 aifc 模块

File: SimpleAsyncHTTP.py

import asyncore
import string, socket
import StringIO
import mimetools, urlparse

class AsyncHTTP(asyncore.dispatcher_with_send):
    # HTTP requestor

    def _ _init_ _(self, uri, consumer):
        asyncore.dispatcher_with_send._ _init_ _(self)

        self.uri = uri
        self.consumer = consumer

        # turn the uri into a valid request
        scheme, host, path, params, query, fragment = urlparse.urlparse(uri)
        assert scheme == "http", "only supports HTTP requests"
        try:
            host, port = string.split(host, ":", 1)
            port = int(port)
        except (TypeError, ValueError):
            port = 80 # default port
        if not path:
            path = "/"
        if params:
            path = path + ";" + params
        if query:
            path = path + "?" + query

        self.request = "GET %s HTTP/1.0\r\nHost: %s\r\n\r\n" % (path, host)

        self.host = host
        self.port = port

        self.status = None
        self.header = None

        self.data = ""

        # get things going!
        self.create_socket(socket.AF_INET, socket.SOCK_STREAM)
        self.connect((host, port))

    def handle_connect(self):
        # connection succeeded
        self.send(self.request)

    def handle_expt(self):
        # connection failed; notify consumer (status is None)
        self.close()
        try:
            http_header = self.consumer.http_header
        except AttributeError:
            pass
        else:
            http_header(self)

    def handle_read(self):
        data = self.recv(2048)
        if not self.header:
            self.data = self.data + data
            try:
                i = string.index(self.data, "\r\n\r\n")
            except ValueError:
                return # continue
            else:
                # parse header
                fp = StringIO.StringIO(self.data[:i+4])
                # status line is "HTTP/version status message"
                status = fp.readline()
                self.status = string.split(status, " ", 2)
                # followed by a rfc822-style message header
                self.header = mimetools.Message(fp)
                # followed by a newline, and the payload (if any)
                data = self.data[i+4:]
                self.data = ""
                # notify consumer (status is non-zero)
                try:
                    http_header = self.consumer.http_header
                except AttributeError:
                    pass
                else:
                    http_header(self)
                if not self.connected:
                    return # channel was closed by consumer

        self.consumer.feed(data)

    def handle_close(self):
        self.consumer.close()
        self.close()

1.6. sunau 模块

sunau 模块用于读写 Sun AU 音频文件. 如 Example 9-5 所示.

1.6.0.1. Example 9-5. 使用 sunau 模块

File: sunau-example-1.py

import sunau

w = sunau.open("samples/sample.au", "r")

if w.getnchannels() == 1:
    print "mono,",
else:
    print "stereo,",

print w.getsampwidth()*8, "bits,",
print w.getframerate(), "Hz sampling rate"

*B*mono, 16 bits, 8012 Hz sampling rate*b*

1.7. sunaudio 模块

sunaudio 模块用于识别 Sun AU 音频文件, 并提取其基本信息. sunau 模块为 Sun AU 文件提供了更完成的支持. 如 Example 9-6 所示

1.7.0.1. Example 9-6. 使用 sunaudio 模块

File: sunaudio-example-1.py

import sunaudio

file = "samples/sample.au"

print sunaudio.gethdr(open(file, "rb"))

*B*(6761, 1, 8012, 1, 'sample.au')*b*

1.8. wave 模块

wave 模块用于读写 Microsoft WAV 音频文件, 如 Example 9-7 所示.

1.8.0.1. Example 9-7. 使用 wave 模块

File: wave-example-1.py

import wave

w = wave.open("samples/sample.wav", "r")

if w.getnchannels() == 1:
    print "mono,",
else:
    print "stereo,",

print w.getsampwidth()*8, "bits,",
print w.getframerate(), "Hz sampling rate"

*B*mono, 16 bits, 44100 Hz sampling rate*b*

1.9. audiodev 模块

(只用于 Unix) audiodev 为 Sun 和 SGI 计算机提供了音频播放支持. 如 Example 9-8 所示.

1.9.0.1. Example 9-8. 使用 audiodev 模块

File: audiodev-example-1.py

import audiodev
import aifc

sound = aifc.open("samples/sample.aiff", "r")

player = audiodev.AudioDev()

player.setoutrate(sound.getframerate())
player.setsampwidth(sound.getsampwidth())
player.setnchannels(sound.getnchannels())

bytes_per_frame = sound.getsampwidth() * sound.getnchannels()
bytes_per_second = sound.getframerate() * bytes_per_frame

while 1:
    data = sound.readframes(bytes_per_second)
    if not data:
        break
    player.writeframes(data)

player.wait()

1.10. winsound 模块

(只用于 Windows ) winsound 模块允许你在 Winodws 平台上播放 Wave 文件. 如 Example 9-9 所示.

1.10.0.1. Example 9-9. 使用 winsound 模块

File: winsound-example-1.py

import winsound

file = "samples/sample.wav"

winsound.PlaySound(
    file,
    winsound.SND_FILENAME|winsound.SND_NOWAIT,
    )

flag 变量说明:

SND_FILENAME - sound 是一个 wav 文件名
SND_ALIAS - sound 是一个注册表中指定的别名
SND_LOOP - 重复播放直到下一次 PlaySound ; 必须指定 SND_ASYNC
SND_MEMORY - sound 是一个 wav 文件的内存映像
SND_PURGE - 停止指定 sound 的所有实例
SND_ASYNC - 异步播放声音, 声音开始播放后函数立即返回
SND_NODEFAULT - 找不到 sound 时不播放默认的 beep 声音
SND_NOSTOP - 不打断当前播放中的任何 sound
SND_NOWAIT - sound 驱动忙时立即返回

PythonStandardLib/chpt9_多媒体相关模块 (last edited 2009-12-25 07:15:47 by localhost)