技术背景
在Android上实现RTSP服务器确实是一个不太常见的需求,因为Android平台主要是为客户端应用设计的。在一些内网场景下,我们更希望把安卓终端或开发板,作为一个IPC(网络摄像机)一样,对外提供个拉流的rtsp url,然后把摄像头麦克风甚至屏幕采集的数据,共享出去,轻量级RTSP的设计理念脱颖而出。
轻量级RTSP服务设计初衷,就是避免用户单独部署RTSP或者RTMP服务,实现本地的音视频数据(如摄像头、麦克风),编码后,汇聚到内置RTSP服务,对外提供可供拉流的RTSP URL,轻量级RTSP服务,适用于内网环境下,对并发要求不高的场景,支持H.264/H.265,支持RTSP鉴权、单播、组播模式,考虑到单个服务承载能力,我们支持同时创建多个RTSP服务,并支持获取当前RTSP服务会话连接数。
如何实现RTSP服务器
如果你找不到合适的库,或者需要更高级的功能,你可以考虑编写自己的RTSP服务器:
- 了解RTSP协议:首先,你需要深入了解RTSP协议的工作原理,包括其消息格式、会话管理和流控制机制。
- 网络编程:在Android上,你可以使用Java的Socket API来处理网络通信,也可以直接底层实现,然后对上提供jni的接口。你需要编写代码来监听端口、接收RTSP请求、解析请求并发送响应。
- 媒体处理:RTSP服务器需要能够捕获、编码和传输媒体数据。你可以使用Android的Camera或Camera2的API来捕获视频,并使用FFmpeg或Android的MediaCodec API来实现音视频数据编码。
- 多线程和并发:RTSP服务器需要处理多个并发客户端连接。你可以使用Java的线程或并发API来管理这些连接。
功能设计
一个完整的RTSP服务,需要设计的功能如下:
- [视频格式]H.264/H.265(Android H.265硬编码);
- [音频格式]G.711 A律、AAC;
- 协议:RTSP;
- [音量调节]Android平台采集端支持实时音量调节;
- [H.264硬编码]支持H.264特定机型硬编码;
- [H.265硬编码]支持H.265特定机型硬编码;
- [音视频]支持纯音频/纯视频/音视频;
- [摄像头]支持采集过程中,前后摄像头实时切换;
- 支持帧率、关键帧间隔(GOP)、码率(bit-rate)设置;
- [实时水印]支持动态文字水印、png水印;
- [实时快照]支持实时快照;
- [降噪]支持环境音、手机干扰等引起的噪音降噪处理、自动增益、VAD检测;
- [外部编码前视频数据对接]支持YUV数据对接;
- [外部编码前音频数据对接]支持PCM对接;
- [外部编码后视频数据对接]支持外部H.264、H.265数据对接;
- [外部编码后音频数据对接]外部AAC数据对接;
- [扩展录像功能]支持和录像SDK组合使用,录像相关功能。
- 支持RTSP端口设置;
- 支持RTSP鉴权用户名、密码设置;
- 支持获取当前RTSP服务会话连接数;
- 支持Android 5.1及以上版本。
接口设计
Android内置轻量级RTSP服务SDK接口详解 | ||
调用描述 | 接口 | 接口描述 |
SmartRTSPServerSDK | ||
初始化RTSP Server | InitRtspServer | Init rtsp server(和UnInitRtspServer配对使用,即便是启动多个RTSP服务,也只需调用一次InitRtspServer,请确保在OpenRtspServer之前调用) |
创建一个rtsp server | OpenRtspServer | 创建一个rtsp server,返回rtsp server句柄 |
设置端口 | SetRtspServerPort | 设置rtsp server 监听端口, 在StartRtspServer之前必须要设置端口 |
设置鉴权用户名、密码 | SetRtspServerUserNamePassword | 设置rtsp server 鉴权用户名和密码, 这个可以不设置,只有需要鉴权的再设置 |
获取rtsp server当前会话数 | GetRtspServerClientSessionNumbers | 获取rtsp server当前的客户会话数, 这个接口必须在StartRtspServer之后再调用 |
启动rtsp server | StartRtspServer | 启动rtsp server |
停止rtsp server | StopRtspServer | 停止rtsp server |
关闭rtsp server | CloseRtspServer | 关闭rtsp server |
UnInit rtsp server | UnInitRtspServer | UnInit rtsp server(和InitRtspServer配对使用,即便是启动多个RTSP服务,也只需调用一次UnInitRtspServer) |
SmartRTSPServerSDK供Publisher调用的接口 | ||
设置rtsp的流名称 | SetRtspStreamName | 设置rtsp的流名称 |
给要发布的rtsp流设置rtsp server | AddRtspStreamServer | 给要发布的rtsp流设置rtsp server, 一个流可以发布到多个rtsp server上,rtsp server的创建启动请参考OpenRtspServer和StartRtspServer接口 |
清除设置的rtsp server | ClearRtspStreamServer | 清除设置的rtsp server |
启动rtsp流 | StartRtspStream | 启动rtsp流 |
停止rtsp流 | StopRtspStream | 停止rtsp流 |
调用逻辑
以大牛直播SDK的Android平台Camera2对接为例,先初始化RTSP Server,启动RTSP服务,然后发布RTSP流即可,如果需要停止RTSP服务,那么先停止RTSP流,再停止RTSP服务即可:
/** MainActivity.java* Author: daniusdk.com* WeChat: xinsheng120*/
@Override
protected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);...context_ = this.getApplicationContext();libPublisher = new SmartPublisherJniV2();libPublisher.InitRtspServer(context_); //和UnInitRtspServer配对使用,即便是启动多个RTSP服务,也只需调用一次InitRtspServer,请确保在OpenRtspServer之前调用
}
启动、停止RTSP服务:
//启动/停止RTSP服务
class ButtonRtspServiceListener implements View.OnClickListener {public void onClick(View v) {if (isRTSPServiceRunning) {stopRtspService();btnRtspService.setText("启动RTSP服务");btnRtspPublisher.setEnabled(false);isRTSPServiceRunning = false;return;}Log.i(TAG, "onClick start rtsp service..");rtsp_handle_ = libPublisher.OpenRtspServer(0);if (rtsp_handle_ == 0) {Log.e(TAG, "创建rtsp server实例失败! 请检查SDK有效性");} else {int port = 8554;if (libPublisher.SetRtspServerPort(rtsp_handle_, port) != 0) {libPublisher.CloseRtspServer(rtsp_handle_);rtsp_handle_ = 0;Log.e(TAG, "创建rtsp server端口失败! 请检查端口是否重复或者端口不在范围内!");}if (libPublisher.StartRtspServer(rtsp_handle_, 0) == 0) {Log.i(TAG, "启动rtsp server 成功!");} else {libPublisher.CloseRtspServer(rtsp_handle_);rtsp_handle_ = 0;Log.e(TAG, "启动rtsp server失败! 请检查设置的端口是否被占用!");}btnRtspService.setText("停止RTSP服务");btnRtspPublisher.setEnabled(true);isRTSPServiceRunning = true;}}
}
stopRtspService()实现如下:
//停止RTSP服务
private void stopRtspService() {if(!isRTSPServiceRunning){return;}if (libPublisher != null && rtsp_handle_ != 0) {libPublisher.StopRtspServer(rtsp_handle_);libPublisher.CloseRtspServer(rtsp_handle_);rtsp_handle_ = 0;}
}
发布、停止RTSP流:
//发布/停止RTSP流
class ButtonRtspPublisherListener implements View.OnClickListener {public void onClick(View v) {if (stream_publisher_.is_rtsp_publishing()) {stopRtspPublisher();btnRtspPublisher.setText("发布RTSP流");btnGetRtspSessionNumbers.setEnabled(false);btnRtspService.setEnabled(true);return;}Log.i(TAG, "onClick start rtsp publisher..");InitAndSetConfig();String rtsp_stream_name = "stream1";stream_publisher_.SetRtspStreamName(rtsp_stream_name);stream_publisher_.ClearRtspStreamServer();stream_publisher_.AddRtspStreamServer(rtsp_handle_);if (!stream_publisher_.StartRtspStream()) {stream_publisher_.try_release();Log.e(TAG, "调用发布rtsp流接口失败!");return;}startAudioRecorder();startLayerPostThread();btnRtspPublisher.setText("停止RTSP流");btnGetRtspSessionNumbers.setEnabled(true);btnRtspService.setEnabled(false);}
}
stopRtspPublisher()实现如下:
//停止发布RTSP流
private void stopRtspPublisher() {stream_publisher_.StopRtspStream();stream_publisher_.try_release();if (!stream_publisher_.is_publishing())stopAudioRecorder();
}
其中,InitAndSetConfig()实现如下,通过调研SmartPublisherOpen()接口,生成推送实例句柄。
/** MainActivity.java* Author: daniusdk.com*/
private void InitAndSetConfig() {if (null == libPublisher)return;if (!stream_publisher_.empty())return;Log.i(TAG, "InitAndSetConfig video width: " + video_width_ + ", height" + video_height_ + " imageRotationDegree:" + cameraImageRotationDegree_);int audio_opt = 1;long handle = libPublisher.SmartPublisherOpen(context_, audio_opt, 3, video_width_, video_height_);if (0==handle) {Log.e(TAG, "sdk open failed!");return;}Log.i(TAG, "publisherHandle=" + handle);int fps = 25;int gop = fps * 3;initialize_publisher(libPublisher, handle, video_width_, video_height_, fps, gop);stream_publisher_.set(libPublisher, handle);
}
对应的initialize_publisher()实现如下,设置软硬编码、帧率、关键帧间隔等。
private boolean initialize_publisher(SmartPublisherJniV2 lib_publisher, long handle, int width, int height, int fps, int gop) {if (null == lib_publisher) {Log.e(TAG, "initialize_publisher lib_publisher is null");return false;}if (0 == handle) {Log.e(TAG, "initialize_publisher handle is 0");return false;}if (videoEncodeType == 1) {int kbps = LibPublisherWrapper.estimate_video_hardware_kbps(width, height, fps, true);Log.i(TAG, "h264HWKbps: " + kbps);int isSupportH264HWEncoder = lib_publisher.SetSmartPublisherVideoHWEncoder(handle, kbps);if (isSupportH264HWEncoder == 0) {lib_publisher.SetNativeMediaNDK(handle, 0);lib_publisher.SetVideoHWEncoderBitrateMode(handle, 1); // 0:CQ, 1:VBR, 2:CBRlib_publisher.SetVideoHWEncoderQuality(handle, 39);lib_publisher.SetAVCHWEncoderProfile(handle, 0x08); // 0x01: Baseline, 0x02: Main, 0x08: High// lib_publisher.SetAVCHWEncoderLevel(handle, 0x200); // Level 3.1// lib_publisher.SetAVCHWEncoderLevel(handle, 0x400); // Level 3.2// lib_publisher.SetAVCHWEncoderLevel(handle, 0x800); // Level 4lib_publisher.SetAVCHWEncoderLevel(handle, 0x1000); // Level 4.1 多数情况下,这个够用了//lib_publisher.SetAVCHWEncoderLevel(handle, 0x2000); // Level 4.2// lib_publisher.SetVideoHWEncoderMaxBitrate(handle, ((long)h264HWKbps)*1300);Log.i(TAG, "Great, it supports h.264 hardware encoder!");}} else if (videoEncodeType == 2) {int kbps = LibPublisherWrapper.estimate_video_hardware_kbps(width, height, fps, false);Log.i(TAG, "hevcHWKbps: " + kbps);int isSupportHevcHWEncoder = lib_publisher.SetSmartPublisherVideoHevcHWEncoder(handle, kbps);if (isSupportHevcHWEncoder == 0) {lib_publisher.SetNativeMediaNDK(handle, 0);lib_publisher.SetVideoHWEncoderBitrateMode(handle, 1); // 0:CQ, 1:VBR, 2:CBRlib_publisher.SetVideoHWEncoderQuality(handle, 39);// libPublisher.SetVideoHWEncoderMaxBitrate(handle, ((long)hevcHWKbps)*1200);Log.i(TAG, "Great, it supports hevc hardware encoder!");}}boolean is_sw_vbr_mode = true;//H.264 software encoderif (is_sw_vbr_mode) {int is_enable_vbr = 1;int video_quality = LibPublisherWrapper.estimate_video_software_quality(width, height, true);int vbr_max_kbps = LibPublisherWrapper.estimate_video_vbr_max_kbps(width, height, fps);lib_publisher.SmartPublisherSetSwVBRMode(handle, is_enable_vbr, video_quality, vbr_max_kbps);}if (is_pcma_) {lib_publisher.SmartPublisherSetAudioCodecType(handle, 3);} else {lib_publisher.SmartPublisherSetAudioCodecType(handle, 1);}lib_publisher.SetSmartPublisherEventCallbackV2(handle, new EventHandlerPublisherV2().set(handler_, record_executor_));lib_publisher.SmartPublisherSetSWVideoEncoderProfile(handle, 3);lib_publisher.SmartPublisherSetSWVideoEncoderSpeed(handle, 2);lib_publisher.SmartPublisherSetGopInterval(handle, gop);lib_publisher.SmartPublisherSetFPS(handle, fps);// lib_publisher.SmartPublisherSetSWVideoBitRate(handle, 600, 1200);boolean is_noise_suppression = true;lib_publisher.SmartPublisherSetNoiseSuppression(handle, is_noise_suppression ? 1 : 0);boolean is_agc = false;lib_publisher.SmartPublisherSetAGC(handle, is_agc ? 1 : 0);int echo_cancel_delay = 0;lib_publisher.SmartPublisherSetEchoCancellation(handle, 1, echo_cancel_delay);return true;
}
发布RTSP流成功后,会回调上来可供拉流的RTSP URL:
private static class EventHandlerPublisherV2 implements NTSmartEventCallbackV2 {@Overridepublic void onNTSmartEventCallbackV2(long handle, int id, long param1, long param2, String param3, String param4, Object param5) {switch (id) {...case NTSmartEventID.EVENT_DANIULIVE_ERC_PUBLISHER_RTSP_URL:publisher_event = "RTSP服务URL: " + param3;break;}}
}
获取RTSP Session会话数:
//获取RTSP会话数
class ButtonGetRtspSessionNumbersListener implements View.OnClickListener {public void onClick(View v) {if (libPublisher != null && rtsp_handle_ != 0) {int session_numbers = libPublisher.GetRtspServerClientSessionNumbers(rtsp_handle_);Log.i(TAG, "GetRtspSessionNumbers: " + session_numbers);PopRtspSessionNumberDialog(session_numbers);}}
}//当前RTSP会话数弹出框
private void PopRtspSessionNumberDialog(int session_numbers) {final EditText inputUrlTxt = new EditText(this);inputUrlTxt.setFocusable(true);inputUrlTxt.setEnabled(false);String session_numbers_tag = "RTSP服务当前客户会话数: " + session_numbers;inputUrlTxt.setText(session_numbers_tag);AlertDialog.Builder builderUrl = new AlertDialog.Builder(this);builderUrl.setTitle("内置RTSP服务").setView(inputUrlTxt).setNegativeButton("确定", null);builderUrl.show();
}
onDestroy() 的时候,调研UnInitRtspServer()即可:
@Override
protected void onDestroy() {Log.i(TAG, "activity destory!");stopAudioRecorder();stopRtspPublisher();stopRtspService();isRTSPServiceRunning = false;stream_publisher_.release();if (libPublisher != null)libPublisher.UnInitRtspServer(); //如已启用内置服务功能(InitRtspServer),调用UnInitRtspServer, 注意,即便是启动多个RTSP服务,也只需调用UnInitRtspServer一次stopLayerPostThread();if (camera2Helper != null) {camera2Helper.release();}super.onDestroy();
}
总结
Android上实现RTSP服务器是一个极具挑战的任务,功能设计这块,除了需要支持接编码前音视频数据外,还需要支持对接编码后音视频数据,并实现本地录像、快照等功能组合使用。需要注意的是,就像海康、大华的摄像头一样,对外的并发,一般限于4-8个,Android设备的性能一般来说,可能不足以处理高负载的RTSP服务器,但是小并发模式下,能稳定的运行,就达到设计初衷了,感兴趣的开发者,可以单独跟单独探讨。