从mp3 / ogg切下确切的时间范围 [英] cut exact time range from mp3/ogg

问题描述

我在CDN上有一堆音频文件。那些是mp3和ogg vorbises，并行。这些文件每个值约一小时播放。我需要从这些文件中提取任意部分：我给了一个文件名（我可以选择使用mp3或ogg版本）和两个时间戳，我需要在给定时间位置之间准确的音频。我不想下载整个文件，所以我想使用Range http标题。

I have a heap of audio files on a CDN. Those are mp3's and ogg vorbises, in parallel. Those files are each worth about one hour of playback. I need to extract arbitrary parts from those files: I am given a filename (I can choose if I use the mp3 or ogg version) and two timestamps and I need the audio exactly between the given time positions. I don't want to download the whole file, so I think of using the Range http header.

我完全控制了音频文件，因此我将它们编码为固定比特率，以便能够估计我应该达到的字节数。但是，两种格式都使用框架（或者vorbis的情况下的页面），必须以原子方式解码。

I have complete control over the audio files, so I encoded them in fixed bitrate, to be able to estimate which bytes I should reach for. However, both formats use frames (or pages in vorbis's case), which must be decoded atomically.

我编写的程序是Perl。我尝试下载文件的一部分，我相信要包含的给定窗口，然后使用Audio :: Mad和Ogg :: Vorbis :: Decoder来解析音频文件片段。但是，两者似乎都无法处理碎片，只有在我提供整数文件时才会成功。

The program I write is in Perl. I tried downloading a part of the file where I believe the given window to be contained, and then using Audio::Mad and Ogg::Vorbis::Decoder to parse the audio file fragments. However, both seem to fail to process the fragments, and only succeed when I serve an integral file.

所以我的问题是：我怎样才能获得精确的跨度音频文件没有下载整个东西？

So my question is: How can I get an exact span of an audio file without downloading the whole thing?

推荐答案

回答从mp3 / ogg切下确切的时间范围 - 你可以查看一下以下适合您的需求：

Answering "cut exact time range from mp3/ogg" - You can check out if the following fits Your needs:

ffmpeg -i InFile  -vn -acodec copy -ss 00:00:00 -t 00:01:32 -threads 0 OutFile

其中ss - 开始时间，t - 持续时间。它确实减少了 - 没有重新压缩。

where ss - start time, t - duration. It cuts indeed - no re-compressions.

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