场景
当一个音视频房间中同时有多路音视频流时，可能就需要用到混流转码，把多条音视频流转成一路，这样既便于录制存储，也便于旁路推流到直播 CDN 上。目前TXLiteAVSDK_TRTC的方案是：
1、在控制台实时音视频服务下功能配置启用自动旁路直播，如果混流画面需要录制存储还需要启用旁路直播自动录制，参考：https://cloud.tencent.com/document/product/647/16826#.E5.A6.82.E4.BD.95.E5.BC.80.E5.90.AF.E6.97.81.E8.B7.AF.E6.9C.8D.E5.8A.A1；
2、当需要混流的时候客户端直接调用setMixTranscodingConfig，并传入对应参数，这个时候SDK内部会组装请求并请求腾讯云后台；
3、混流成功后可以通过获取旁路地址播放：https://cloud.tencent.com/document/product/647/16826#.E5.A6.82.E4.BD.95.E8.8E.B7.E5.8F.96.E6.92.AD.E6.94.BE.E5.9C.B0.E5.9D.80。
流程图
代码示例
- Objective-C
//云端混流转码的示例代码
- (void)enableTranscoding
{
TRTCTranscodingConfig *config = [[TRTCTranscodingConfig alloc] init];
config.appId = xxxxxxxxxx; //appid和bizid可以在腾讯云控制台账号信息里面查到
config.bizId = xxxx;
config.videoWidth = 540;
config.videoHeight = 960;
config.videoBitrate = 1200;
config.videoFramerate = 20;
config.videoGOP = 2;
config.audioSampleRate = 48000;
config.audioBitrate = 64;
config.audioChannels = 2;
TRTCMixUser *user1 = [[TRTCMixUser alloc] init];
user1.userId = @"Web_trtc_03";
user1.zOrder = 0;
user1.rect = CGRectMake(0, 0, 540, 960);
// user1.streamType = TRTCVideoStreamTypeBig;
TRTCMixUser *user2 = [[TRTCMixUser alloc] init];
user2.userId = @"Web_trtc_04";
user2.zOrder = 1;
user2.rect = CGRectMake(380, 630, 160, 240);
// user2.streamType = TRTCVideoStreamTypeBig;
config.mixUsers = @[user1,user2];
[_trtc setMixTranscodingConfig:config]; //启动混流
}
- Android
//开启云端混流转码
public void enableTranscoding() {
TRTCCloudDef.TRTCTranscodingConfig config = new TRTCCloudDef.TRTCTranscodingConfig();
// 设置分辨率为 1280x720, 码率为 1500kbps
config.appId = xxxxxxxxxx;
config.bizId = xxxx;
config.videoWidth = 368;
config.videoHeight = 640;
config.videoBitrate = 1500;
config.videoGOP = 2;
config.videoFramerate = 30;
config.audioSampleRate = 48000;
config.audioBitrate = 64;
config.audioChannels = 2;
// 设置混流后主播的画面位置
TRTCCloudDef.TRTCMixUser broadCaster = new TRTCCloudDef.TRTCMixUser();
broadCaster.userId = "Web_trtc_01"; // 以主播uid为broadcaster为例
// 铺满屏幕并放到最下面
broadCaster.zOrder = 0;
broadCaster.x = 0;
broadCaster.y = 0;
broadCaster.width = 368;
broadCaster.height = 640;
TRTCCloudDef.TRTCMixUser audience = new TRTCCloudDef.TRTCMixUser();
audience.userId = "Web_trtc_02"; // 以观众uid为audience为例
// 放到左下角，置于主播画面之上
audience.zOrder = 1;
audience.x = 178;
audience.y = 310;
audience.width = 180;
audience.height = 320;
config.mixUsers = new ArrayList<>();
config.mixUsers.add(broadCaster);
config.mixUsers.add(audience);
trtcCloud.setMixTranscodingConfig(config);
}
- C++
// 开启云端混流转码
void enableTranscoding()
{
TRTCTranscodingConfig config;
config.appId = xxxxxxxxxx; //appid和bizid可以在腾讯云控制台账号信息里面查到
config.bizId = xxxx;
// 设置分辨率为 1280x720, 码率为 1500kbps
config.videoWidth = 1080;
config.videoHeight = 720;
config.videoBitrate = 1500;
config.audioSampleRate = 48000;
config.audioBitrate = 64;
config.audioChannels = 2;
std::vector mixUsers;
// 设置混流后主播的画面位置
TRTCMixUser broadCaster;
broadCaster.userId = "broadcaster"; // 以主播uid为broadcaster为例
broadCaster.zOrder = 0; // 铺满屏幕并放到最下面
broadCaster.rect.left = 0;
broadCaster.rect.top = 0;
broadCaster.rect.right = 1280;
broadCaster.rect.bottom = 720;
// 设置观众位置, 以一个观众放到左下角为例, 左下角边距10个象素
TRTCMixUser audience;
audience.userId = "audience"; // 以观众uid为audience为例
audience.zOrder = 1; // 放到左下角，置于主播画面之上
audience.rect.left = 920;
audience.rect.top = 480;
audience.rect.right = 1080;
audience.rect.bottom = 720;
mixUsers.push_back(std::move(broadCaster));
mixUsers.push_back(std::move(audience));
config.mixUsersArray = &mixUsers[0]; // 要求 mixUsers 非空
config.mixUsersArraySize = mixUsers.size();
trtcCloud->setMixTranscodingConfig(config);
}
原理解释
这里以iOS端为例，参考上述代码调用setMixTranscodingConfig接口后，SDK内部会转化成如下请求，实际上开发者也可以使用下面这种方式自己请求，这样更加灵活，SDK出于降低复杂度做了这一层处理。混流接口文档参考：https://cloud.tencent.com/document/product/267/8832#.E6.8E.A5.E5.8F.A3.E6.8F.8F.E8.BF.B0
请求url
http://fcgi.video.qcloud.com/common_access?appid=1252500000&interface=Mix_StreamV2&t=t&sign=sign请求体
{
"domain":"2157.live.push.com",
"interface":"set_live_mix_transcoding",
"session_id":"2157_bf49b24917d4f42543ef886f601134da",
"event_id":1551428085,
"output_param":{
"output_audio_channels":2,
"output_stream_gop":2,
"output_sei":"{}",
"output_stream_type":0,
"output_stream_id":"2157_bf49b24917d4f42543ef886f601134da",
"output_audio_sample_rate":48000,
"output_audio_bitrate":64,
"output_stream_frame_rate":20,
"output_stream_bitrate":1200
},
"path":"live",
"timestamp":1551428085,
"appid":1251783440,
"input_stream_list":[
{
"input_stream_id":"canvas1",
"layout_params":{
"image_layer":1,
"color":"0x000000",
"input_type":3,
"image_width":540,
"location_x":0,
"image_height":960,
"location_y":0
}
},
{
"input_stream_id":"2157_bf49b24917d4f42543ef886f601134da",
"layout_params":{
"location_y":0,
"image_layer":2,
"image_width":540,
"image_height":960,
"location_x":0
}
},
{
"input_stream_id":"2157_1ec16ae5326160affe9f6e3117e5b918",
"layout_params":{
"location_y":630,
"image_layer":3,
"image_width":160,
"image_height":240,
"location_x":380
}
}
]
}
- 响应结果，code返回0代表成功，返回其它状态码说明混流失败，可以参考文档里面常见错误码说明：https://cloud.tencent.com/document/product/267/8832#.E6.8E.A5.E5.8F.A3.E6.8F.8F.E8.BF.B0
混流成功响应示例：
{"code":0,"event_id":"1551428085","message":"","timestamp":1551428085}
混流失败响应示例：
{"code":256,"event_id":"1551430294","message":"upload report get usr info failed, dal_config.GetLiveUserInfoByAppid ret: config no exist, appid: 1251783441","timestamp":1551430295}
- 旁路播放效果
混流效果示例