如何将 rtp 数据包有效载荷字节转换为任何音频数据? [英] How to convert rtp packet payload bytes to any audio data?

问题描述

我正在用 Java 制作一个项目，而不使用任何第三方库.我已经使用 DatagramSocket 成功建立了 udp 连接.然后我开始使用 sip 协议进行通信.我已成功通过注册和邀请阶段.这就是我获得音频数据流将传输到的主机和端口的方式.然后我使用 DatagramSocket 成功建立了到新地址的连接.我开始以 rtp 数据包的形式接收数据.我成功地从包中获取了以下数据:有效载荷类型(在我的情况下为 8 或 PCMA)、时间戳、序列号和有效载荷数据(字节数组).现在我想处理接收到的数据，以便我将来可以使用它.即保存到磁盘，随意转换为任何其他音频格式，播放音频等等.我无法弄清楚从数据包中收到的字节数组到底需要做什么.

I am making a project in java without using any third party libraries. I have successfully established an udp connection using the DatagramSocket. Then I started communicating using the sip protocol. I have successfully passed the registration and invitation stage. This is how I got the host and port to which the audio data stream will be transmitted. Then I successfully established a connection to the new address using DatagramSocket. And i began to receive data in the form of rtp packets. I managed to successfully get the following data from the package: Payload type (in my case 8 or PCMA), Timestamp, Sequence number and payload data (byte array). Now I want to process the received data so that I can use it in the future. That is, save to disk, convert to any other audio format at will, play audio, and so on. I can't figure out what exactly needs to be done with the byte array received from the packet.

假设首先我想将接收到的数据保存到 AudioFormat.Encoding.PCM_FLOAT 8000.0 Hz、8 位、单声道、160 字节/帧格式的文件中.我需要为此做什么?

Let's say for a start I want to save the received data to a file in the AudioFormat.Encoding.PCM_FLOAT 8000.0 Hz, 8 bit, mono, 160 bytes / frame format. What do I need to do for this?

推荐答案

使用 示例 来自 Aaron Clauson 我解决了我的问题.数据包中的字节数组必须根据建议的方案进行转换.我做了一个有效的示例，说明这在 Kotlin 中的表现.

Using the example by Aaron Clauson I solved my problem. The byte array from the packet must be converted according to the proposed scheme. I made a working example of how this might look in Kotlin.

关于如何从原始 rtp 包获取数据的示例.

An example of how to get data from a raw rtp package.

如果您以正确的顺序(按 sequenceNumber)粘合结果数组并且没有重复，那么您可以，例如，使用 javax.sound.sampled 将其写入 WAV 文件.AudioInputStream，如示例.

If you glue the resulting arrays in the correct order (by sequenceNumber) and no duplicates, then you can, for example, write this to a WAV file using javax.sound.sampled.AudioInputStream, as in the example.

一个简化的示例，说明如何在安卓.还有一个简化的示例，说明如何将声音从麦克风发送到服务器.

A simplified example of how you can play a stream of sound in real time on an Android. And a simplified example of how you can send sound from a microphone to a server.

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