使用（蟒蛇）的Gstreamer脱code音频（为PCM数据） [英] Use (Python) Gstreamer to decode audio (to PCM data)

问题描述

我正在写使用Python的Gstreamer绑定播放音频的应用，但现在我想也只是去code声音 - 那就是，我想用来读取数据的<一个href=\"http://gstreamer.freedesktop.org/data/doc/gstreamer/head/manual/html/section-components-de$c$cbin.html\"><$c$c>de$c$cbin并获得原始PCM缓冲区。具体而言，我想读取文件的块增量而不是读整个文件到内存中。

I'm writing an application that uses the Python Gstreamer bindings to play audio, but I'm now trying to also just decode audio -- that is, I'd like to read data using a decodebin and receive a raw PCM buffer. Specifically, I want to read chunks of the file incrementally rather than reading the whole file into memory.

一些具体的问题：我怎样才能做到这一点在GStreamer？随着pygst特别？是否有一个特定的汇元素我需要使用从流中读取数据？是否有一个preferred办法读取从 pygst 缓存对象？我该如何去控制在哪个我消耗数据（而不仅仅是进入一个主循环）率是多少？

Some specific questions: How can I accomplish this with Gstreamer? With pygst specifically? Is there a particular "sink" element I need to use to read data from the stream? Is there a preferred way to read data from a pygst Buffer object? How do I go about controlling the rate at which I consume data (rather than just entering a "main loop")?

推荐答案

要取回数据的应用程序时，推荐的方法是<一个href=\"http://gstreamer.org/data/doc/gstreamer/head/gst-plugins-base-libs/html/gst-plugins-base-libs-appsink.html\">appsink.

To get the data back in your application, the recommended way is appsink.

根据一个简单的音频播放器如这个（并更换oggdemux / vorbisdec由德codeBIN＆放大器; capsfilter与帽=音频/ X-RAW-INT），变更为autoaudiosink appsink，并连接<一个href=\"http://www.gstreamer.net/data/doc/gstreamer/head/gst-plugins-base-plugins/html/gst-plugins-base-plugins-appsink.html#GstAppSink-new-buffer\">\"new-buffer\"信号到蟒蛇功能+设置发出-信号为True。该函数将接收PCM / int数据的德codeD块。解码的速率将取决于在它可以解除code和消耗的速率。由于新的缓冲信号是GStreamer的线程上下文，你可能只是睡觉/等待该功能来控制或减缓解码速度。

Based on a simple audio player like this one (and replace the oggdemux/vorbisdec by decodebin & capsfilter with caps = "audio/x-raw-int"), change autoaudiosink to appsink, and connect "new-buffer" signal to a python function + set "emit-signals" to True. The function will receive decoded chunks of PCM/int data. The rate of the decoding will depend on the rate at which you can decode and consume. Since the new-buffer signal is in the Gstreamer thread context, you could just sleep/wait in that function to control or slow down the decoding speed.

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