AudioEncoding(value)The encoding of the audio data sent in the request.
All encodings support only 1 channel (mono) audio, unless the
audio_channel_count and
enable_separate_recognition_per_channel fields are set.
For best results, the audio source should be captured and
transmitted using a lossless encoding (FLAC or LINEAR16).
The accuracy of the speech recognition can be reduced if lossy
codecs are used to capture or transmit audio, particularly if
background noise is present. Lossy codecs include MULAW,
AMR, AMR_WB, OGG_OPUS, SPEEX_WITH_HEADER_BYTE,
MP3, and WEBM_OPUS.
The FLAC and WAV audio file formats include a header that
describes the included audio content. You can request recognition
for WAV files that contain either LINEAR16 or MULAW
encoded audio. If you send FLAC or WAV audio file format in
your request, you do not need to specify an AudioEncoding; the
audio encoding format is determined from the file header. If you
specify an AudioEncoding when you send send FLAC or WAV
audio, the encoding configuration must match the encoding described
in the audio header; otherwise the request returns an
google.rpc.Code.INVALID_ARGUMENT][google.rpc.Code.INVALID_ARGUMENT]
error code.
Enums |
|
|---|---|
| Name | Description |
ENCODING_UNSPECIFIED |
Not specified. |
LINEAR16 |
Uncompressed 16-bit signed little-endian samples (Linear PCM). |
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. |
MULAW |
8-bit samples that compand 14-bit audio samples using G.711 PCMU/mu-law. |
AMR |
Adaptive Multi-Rate Narrowband codec. `sample_rate_hertz` must be 8000. |
AMR_WB |
Adaptive Multi-Rate Wideband codec. `sample_rate_hertz` must be 16000. |
OGG_OPUS |
Opus encoded audio frames in Ogg container (`OggOpus |
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 |
MP3 |
MP3 audio. MP3 encoding is a Beta feature and only available in v1p1beta1. Support all standard MP3 bitrates (which range from 32-320 kbps). When using this encoding, `sample_rate_hertz` has to match the sample rate of the file being used. |
WEBM_OPUS |
Opus encoded audio frames in WebM container (`WebM |
ALAW |
8-bit samples that compand 13-bit audio samples using G.711 PCMU/a-law. |