1. class
  2. Google
  3. \
  4. Cloud
  5. \
  6. Speech
  7. \
  8. V1
  9. \
  10. RecognitionConfig_AudioEncoding

RecognitionConfig_AudioEncoding

class RecognitionConfig_AudioEncoding

Audio encoding of the data sent in the audio message. All encodings support only 1 channel (mono) audio. Only FLAC includes a header that describes the bytes of audio that follow the header. The other encodings are raw audio bytes with no header.

For best results, the audio source should be captured and transmitted using a lossless encoding (FLAC or LINEAR16). Recognition accuracy may be reduced if lossy codecs, which include the other codecs listed in this section, are used to capture or transmit the audio, particularly if background noise is present.

Protobuf enum Google\Cloud\Speech\V1\RecognitionConfig\AudioEncoding

Constants

ENCODING_UNSPECIFIED

Not specified. Will return result [google.rpc.Code.INVALID_ARGUMENT][].

Generated from protobuf enum ENCODING_UNSPECIFIED = 0;
LINEAR16

Uncompressed 16-bit signed little-endian samples (Linear PCM).

Generated from protobuf enum LINEAR16 = 1;
FLAC

FLAC (Free Lossless Audio Codec) is the recommended encoding because it is lossless--therefore recognition is not compromised--and requires only about half the bandwidth of LINEAR16. FLAC stream encoding supports 16-bit and 24-bit samples, however, not all fields in STREAMINFO are supported.

Generated from protobuf enum FLAC = 2;
MULAW

8-bit samples that compand 14-bit audio samples using G.711 PCMU/mu-law.

Generated from protobuf enum MULAW = 3;
AMR

Adaptive Multi-Rate Narrowband codec. sample_rate_hertz must be 8000.

Generated from protobuf enum AMR = 4;
AMR_WB

Adaptive Multi-Rate Wideband codec. sample_rate_hertz must be 16000.

Generated from protobuf enum AMR_WB = 5;
OGG_OPUS

Opus encoded audio frames in Ogg container (OggOpus).

sample_rate_hertz must be 16000.

Generated from protobuf enum OGG_OPUS = 6;
SPEEX_WITH_HEADER_BYTE

Although the use of lossy encodings is not recommended, if a very low bitrate encoding is required, OGG_OPUS is highly preferred over Speex encoding. The Speex encoding supported by Cloud Speech API has a header byte in each block, as in MIME type audio/x-speex-with-header-byte.

It is a variant of the RTP Speex encoding defined in RFC 5574. The stream is a sequence of blocks, one block per RTP packet. Each block starts with a byte containing the length of the block, in bytes, followed by one or more frames of Speex data, padded to an integral number of bytes (octets) as specified in RFC 5574. In other words, each RTP header is replaced with a single byte containing the block length. Only Speex wideband is supported. sample_rate_hertz must be 16000.

Generated from protobuf enum SPEEX_WITH_HEADER_BYTE = 7;