A number of environment variables can be used to configure the behavior of the library. There are also functions to configure this behavior in code. The environment variables are convenient when troubleshooting problems.
Endpoint Overrides
GOOGLE_CLOUD_CPP_TEXT_TO_SPEECH_ENDPOINT=...overrides theEndpointOption(which defaults to "texttospeech.googleapis.com") used byMakeTextToSpeechConnection().
GOOGLE_CLOUD_CPP_ENABLE_TRACING=rpc: turns on tracing for most gRPC calls. The library injects an additional Stub decorator that prints each gRPC request and response. Unless you have configured your own logging backend, you should also setGOOGLE_CLOUD_CPP_ENABLE_CLOGto produce any output on the program's console.
See Also
google::cloud::TracingComponentsOptionGOOGLE_CLOUD_CPP_TRACING_OPTIONS=...: modifies the behavior of gRPC tracing, including whether messages will be output on multiple lines, or whether string/bytes fields will be truncated.
See Also
google::cloud::GrpcTracingOptionsOptionGOOGLE_CLOUD_CPP_ENABLE_CLOG=yes: turns on logging in the library, basically the library always "logs" but the logging infrastructure has no backend to actually print anything until the application sets a backend or they set this environment variable.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-09-04 UTC."],[[["\u003cp\u003eThe latest release candidate version for the C++ Text-to-Speech library is 2.37.0-rc, with version 2.23.0 being the starting point of the versions listed on the document.\u003c/p\u003e\n"],["\u003cp\u003eThe library's behavior can be configured using various environment variables, which is particularly helpful when debugging issues.\u003c/p\u003e\n"],["\u003cp\u003e\u003ccode\u003eGOOGLE_CLOUD_CPP_TEXT_TO_SPEECH_ENDPOINT\u003c/code\u003e is used to override the default endpoint for the Text-to-Speech service.\u003c/p\u003e\n"],["\u003cp\u003eEnabling gRPC tracing is done by setting the \u003ccode\u003eGOOGLE_CLOUD_CPP_ENABLE_TRACING\u003c/code\u003e environment variable to "rpc", which will print all gRPC requests and responses to help in logging and tracking.\u003c/p\u003e\n"],["\u003cp\u003eUsing \u003ccode\u003eGOOGLE_CLOUD_CPP_ENABLE_CLOG=yes\u003c/code\u003e will turn on logging in the library which will utilize the log infrastructure to print to the program console.\u003c/p\u003e\n"]]],[],null,["Version 2.23.0keyboard_arrow_down\n\n- [2.42.0-rc (latest)](/cpp/docs/reference/texttospeech/latest/texttospeech-env)\n- [2.41.0](/cpp/docs/reference/texttospeech/2.41.0/texttospeech-env)\n- [2.40.0](/cpp/docs/reference/texttospeech/2.40.0/texttospeech-env)\n- [2.39.0](/cpp/docs/reference/texttospeech/2.39.0/texttospeech-env)\n- [2.38.0](/cpp/docs/reference/texttospeech/2.38.0/texttospeech-env)\n- [2.37.0](/cpp/docs/reference/texttospeech/2.37.0/texttospeech-env)\n- [2.36.0](/cpp/docs/reference/texttospeech/2.36.0/texttospeech-env)\n- [2.35.0](/cpp/docs/reference/texttospeech/2.35.0/texttospeech-env)\n- [2.34.0](/cpp/docs/reference/texttospeech/2.34.0/texttospeech-env)\n- [2.33.0](/cpp/docs/reference/texttospeech/2.33.0/texttospeech-env)\n- [2.32.0](/cpp/docs/reference/texttospeech/2.32.0/texttospeech-env)\n- [2.31.0](/cpp/docs/reference/texttospeech/2.31.0/texttospeech-env)\n- [2.30.0](/cpp/docs/reference/texttospeech/2.30.0/texttospeech-env)\n- [2.29.0](/cpp/docs/reference/texttospeech/2.29.0/texttospeech-env)\n- [2.28.0](/cpp/docs/reference/texttospeech/2.28.0/texttospeech-env)\n- [2.27.0](/cpp/docs/reference/texttospeech/2.27.0/texttospeech-env)\n- [2.26.0](/cpp/docs/reference/texttospeech/2.26.0/texttospeech-env)\n- [2.25.1](/cpp/docs/reference/texttospeech/2.25.1/texttospeech-env)\n- [2.24.0](/cpp/docs/reference/texttospeech/2.24.0/texttospeech-env)\n- [2.23.0](/cpp/docs/reference/texttospeech/2.23.0/texttospeech-env)\n- [2.22.1](/cpp/docs/reference/texttospeech/2.22.1/texttospeech-env)\n- [2.21.0](/cpp/docs/reference/texttospeech/2.21.0/texttospeech-env)\n- [2.20.0](/cpp/docs/reference/texttospeech/2.20.0/texttospeech-env)\n- [2.19.0](/cpp/docs/reference/texttospeech/2.19.0/texttospeech-env)\n- [2.18.0](/cpp/docs/reference/texttospeech/2.18.0/texttospeech-env)\n- [2.17.0](/cpp/docs/reference/texttospeech/2.17.0/texttospeech-env)\n- [2.16.0](/cpp/docs/reference/texttospeech/2.16.0/texttospeech-env)\n- [2.15.1](/cpp/docs/reference/texttospeech/2.15.1/texttospeech-env)\n- [2.14.0](/cpp/docs/reference/texttospeech/2.14.0/texttospeech-env)\n- [2.13.0](/cpp/docs/reference/texttospeech/2.13.0/texttospeech-env)\n- [2.12.0](/cpp/docs/reference/texttospeech/2.12.0/texttospeech-env)\n- [2.11.0](/cpp/docs/reference/texttospeech/2.11.0/texttospeech-env) \n\nEnvironment Variables\n=====================\n\nA number of environment variables can be used to configure the behavior of the library. There are also functions to configure this behavior in code. The environment variables are convenient when troubleshooting problems.\n\nEndpoint Overrides\n------------------\n\n- `GOOGLE_CLOUD_CPP_TEXT_TO_SPEECH_ENDPOINT=...` overrides the `EndpointOption` (which defaults to \"texttospeech.googleapis.com\") used by `MakeTextToSpeechConnection()`.\n\n###### See Also\n\n[`google::cloud::EndpointOption`](https://cloud.google.com/cpp/docs/reference/common/latest/structgoogle_1_1cloud_1_1EndpointOption.html)\n\nLogging\n-------\n\n`GOOGLE_CLOUD_CPP_ENABLE_TRACING=rpc`: turns on tracing for most gRPC calls. The library injects an additional Stub decorator that prints each gRPC request and response. Unless you have configured your own logging backend, you should also set `GOOGLE_CLOUD_CPP_ENABLE_CLOG` to produce any output on the program's console.\n\n###### See Also\n\n[`google::cloud::TracingComponentsOption`](about:invalid#zCSafez)`GOOGLE_CLOUD_CPP_TRACING_OPTIONS=...`: modifies the behavior of gRPC tracing, including whether messages will be output on multiple lines, or whether string/bytes fields will be truncated.\n\n###### See Also\n\n[`google::cloud::GrpcTracingOptionsOption`](https://cloud.google.com/cpp/docs/reference/common/latest/structgoogle_1_1cloud_1_1GrpcTracingOptionsOption.html)`GOOGLE_CLOUD_CPP_ENABLE_CLOG=yes`: turns on logging in the library, basically the library always \"logs\" but the logging infrastructure has no backend to actually print anything until the application sets a backend or they set this environment variable.\n\n###### See Also\n\n[`google::cloud::LogBackend`](https://cloud.google.com/cpp/docs/reference/common/latest/classgoogle_1_1cloud_1_1LogBackend.html)\n\n###### See Also\n\n[`google::cloud::LogSink`](https://cloud.google.com/cpp/docs/reference/common/latest/classgoogle_1_1cloud_1_1LogSink.html)\n\nSetting the Default Project\n---------------------------\n\n`GOOGLE_CLOUD_PROJECT=...`: is used in examples and integration tests to configure the GCP project. This has no effect in the library."]]
