Using Gstreamer with Google speech API (Streaming Transcribe) in C++

Question

I am using the Google Speech API from cloud platform for getting speech-to-text of a streaming audio. I have already done the REST API calls using curl POST requests for a short audio file using GCP.

I have seen the documentation of the Google Streaming Recognize, which says "Streaming speech recognition is available via gRPC only."

I have gRPC (also protobuf) installed in my OpenSuse Leap 15.0. Here is the screenshot of the directory.

Next I am trying to run the streaming_transcribe example from this link, and I found that the sample program uses a local file as the input but simulate it as a microphone input (catching 64K chunks sequentially) and then send the data to Google server.

For initial tests to check the grpc is correctly set on my system I ran make run_tests. I have changed the Makefile as:

...
...Some text as original Makefile
...
.PHONY: all
all: streaming_transcribe
googleapis.ar: $(GOOGLEAPIS_CCS:.cc=.o) 
      ar r $@ $?
streaming_transcribe: streaming_transcribe.o parse_arguments.o googleapis.ar
      $(CXX) $^ $(LDFLAGS) -o $@
run_tests:
      ./streaming_transcribe -b 16000 resources/audio.raw
      ./streaming_transcribe --bitrate 16000 resources/audio2.raw
      ./streaming_transcribe resources/audio.flac
      ./streaming_transcribe resources/quit.raw
clean: rm -f *.o streaming_transcribe \
       googleapis.ar \
       $(GOOGLEAPIS_CCS:.cc=.o)

This do not work well (neither does the orignal Makefile). But the streaming_transcribe.o file is created after running the Makefile. So I manually ran the file and got the following responses

Any suggestions on how to run the test and use gstreamer instead of the function used for simulating the mic-phone audio?

You can't execute plain object files. They need to be linked (which is what the line starting with sreaming_transcribe: is for) - but make is picky. The $(CXX) $^ $(LDFLAGS) -o $@ line for linking streaming_transcribe must start with a tab character. — Ted Lyngmo
Hi @TedLyngmo The suggestions given above are already taken care of. But I am still getting the error. the LDFLAGS += -L/usr/local/lib 'pkg-config --libs grpc++ grpc' -Wl,--no-as-needed -lgrpc++_reflection -Wl,--no-as-needed -lprotobuf -lpthread -ldl — RC0993
Ok, then update your question and include the exact error you get (as text, not as an image). — Ted Lyngmo
I am trying to re-install everything. I will let you know the output — RC0993
Reinstalling from scratch really solved the problem. Apparently the shared objects were not set up correctly which stopped the the make run_tests to go through. Running *.o file was not correct anyway. The Makefile produces the executable which needs to be run. How do I mark this issue close? — RC0993

RC0993 RC0993 · Accepted Answer · 2019-02-22T04:50:41

how to run the test

Follow the instructions on cpp-docs-samples. Prerequisit - Install grpc, protobuf, and googleapis and setup the environment as said in the links above.

gstreamer instead of the function used for simulating the mic-phone audio

For this program I have created pipelines which are

gst-launch-1.0 filesrc location=/path/to/file/FOO.wav ! wavparse ! audioconvert ! audio/x-raw,channels=1,depth=16,width=16,rate=44100 ! rtpL16pay  ! udpsink host=xxx.xxx.xxx.xxx port=yyyy

The audio file can be changed to flac or mp3 with changing appropriate elemnets in pipeline

gst-launch-1.0 udpsrc port=yyyy ! "application/x-rtp,media=(string)audio, clock-rate=(int)44100, width=16, height=16, encoding-name=(string)L16, encoding-params=(string)1, channels=(int)1, channel-positions=(int)1, payload=(int)96" ! rtpL16depay ! audioconvert ! audio/x-raw,format=S16LE ! filesink location=/path/to/where/you/want/to/dump/the/rtp/payloads/ABC.raw

The process of taking payloads from rtp stream and writing it on file is done in another thread than sending the data to google and reading the response.

Using Gstreamer with Google speech API (Streaming Transcribe) in C++

2 Answers