[英]How to convert in-memory WebM audio file to mp3 audio file in Python?
I am trying to convert the audio file in WebM format into MP3 file.我正在尝试将 WebM 格式的音频文件转换为 MP3 文件。 I need to keep both files in memory due to server limitations.
由于服务器限制,我需要将这两个文件都保存在内存中。 I tried to do it using PyAv, but I can't manage to receive Python file-like object after processing stream.
我尝试使用 PyAv 来做到这一点,但在处理流后我无法接收 Python 文件类对象。 My attempt:
我的尝试:
with av.open(webm_file, 'r') as inp:
f = SpooledTemporaryFile(mode="w+b")
with av.open(f, 'w', format="mpeg") as out:
out_stream = out.add_stream("mp3")
for frame in inp.decode(audio=0):
frame.pts = None
for packets in out_stream.encode(frame):
out.mux(packets)
for packets in out_stream.encode(None):
out.mux(packets)
webm_file is of SpooledTemporaryFile type, but I can`t get outfile as file-like, can anyone help? webm_file 是 SpooledTemporaryFile 类型,但我不能像文件一样获得 outfile,有人可以帮忙吗?
Replace format="mpeg"
with format="mp3"
.将
format="mpeg"
替换为format="mp3"
。
mpeg
applies MPEG-1 program stream, and we want to create mp3
container format. mpeg
应用 MPEG-1 节目流,我们要创建mp3
容器格式。
mpeg
container supports mp3 codec as audio stream, but it's not the container we are looking for... mpeg
容器支持 mp3 编解码器作为音频流,但它不是我们要寻找的容器...
I suppose replacing "mpeg"
with "mp3"
is going to solve the issue.我想用
"mp3"
替换"mpeg"
可以解决这个问题。
I don't know how to test f = SpooledTemporaryFile(mode="w+b")
, so I used input and output files instead.我不知道如何测试
f = SpooledTemporaryFile(mode="w+b")
,所以我使用了输入和输出文件。
Start by creating WebM file with synthetic audio and video (using FFmpeg CLI) for testing:首先创建带有合成音频和视频的 WebM 文件(使用 FFmpeg CLI)进行测试:
ffmpeg -y -f lavfi -i testsrc=size=192x108:rate=1 -f lavfi -i sine=frequency=100 -f lavfi -i sine=frequency=500 -map_channel 1.0.0 -map_channel 2.0.0 -vcodec libvpx-vp9 -crf 32 -acodec libopus -b:a 96K -ar 48000 -ac 2 -t 10s input.webm
Transcoding the audio channel from opus codec to mp3 codec in output.mp3
file using PyAV:使用 PyAV 在
output.mp3
文件中将音频通道从 opus 编解码器转码为 mp3 编解码器:
import av
#from tempfile import SpooledTemporaryFile
# Build input file for testing:
# ffmpeg -y -f lavfi -i testsrc=size=192x108:rate=1 -f lavfi -i sine=frequency=500 -f lavfi -i sine=frequency=800 -map_channel 1.0.0 -map_channel 2.0.0 -vcodec libvpx-vp9 -crf 32 -acodec libopus -b:a 96K -ar 48000 -ac 2 -t 10s input.webm
webm_file = "input.webm"
mp3_file = "output.mp3"
with av.open(webm_file, 'r') as inp:
#f = SpooledTemporaryFile(mode="w+b")
f = mp3_file
with av.open(f, 'w', format="mp3") as out: # Open file, setting format to mp3
out_stream = out.add_stream("mp3")
for frame in inp.decode(audio=0):
frame.pts = None
for packets in out_stream.encode(frame):
out.mux(packets)
for packets in out_stream.encode(None):
out.mux(packets)
Output of MediaInfo tool: MediaInfo 工具的输出:
General
Complete name : C:\Tmp\output.mp3
Format : MPEG Audio
File size : 157 KiB
Duration : 10 s 32 ms
Overall bit rate mode : Variable
Overall bit rate : 128 kb/s
Writing library : LAME3.100
Audio
Format : MPEG Audio
Format version : Version 1
Format profile : Layer 3
Format settings : Joint stereo / MS Stereo
Duration : 10 s 32 ms
Bit rate mode : Variable
Bit rate : 128 kb/s
Channel(s) : 2 channels
Sampling rate : 48.0 kHz
Frame rate : 41.667 FPS (1152 SPF)
Compression mode : Lossy
Stream size : 157 KiB (100%)
Writing library : LAME3.100
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