1,295
edits
MediaStreamAPI: Difference between revisions
→Stream mixing and processing
| Line 161: | Line 161: | ||
readonly attribute long audioSampleRate; | readonly attribute long audioSampleRate; | ||
readonly attribute short audioChannels; | readonly attribute short audioChannels; | ||
reaodnly attribute long audioLength; | |||
readonly attribute Float32Array audioSamples; | readonly attribute Float32Array audioSamples; | ||
// TODO something for video frames. | // TODO something for video frames. | ||
| Line 168: | Line 169: | ||
'audioSampleRate' and 'audioChannels' represent the format of the samples. 'audioSampleRate' is the number of samples per second. 'audioChannels' is the number of channels; the channel mapping is as defined in the Vorbis specification. | 'audioSampleRate' and 'audioChannels' represent the format of the samples. 'audioSampleRate' is the number of samples per second. 'audioChannels' is the number of channels; the channel mapping is as defined in the Vorbis specification. | ||
'audioLength' is the number of samples per channel. | |||
If 'variableAudioFormats' is false (the default) when the event handler fires, the UA will convert all the input audio to a single common format before presenting them to the event handler. Typically the UA would choose the highest-fidelity format to avoid lossy conversion. If variableAudioFormats was false for the previous invocation of the event handler, the UA also ensures that the format stays the same as the format used by the previous invocation of the handler. | If 'variableAudioFormats' is false (the default) when the event handler fires, the UA will convert all the input audio to a single common format before presenting them to the event handler. Typically the UA would choose the highest-fidelity format to avoid lossy conversion. If variableAudioFormats was false for the previous invocation of the event handler, the UA also ensures that the format stays the same as the format used by the previous invocation of the handler. | ||
'audioSamples' gives access to the audio samples for each input stream. The length | 'audioSamples' gives access to the audio samples for each input stream. The array length will be 'audioLength' multiplied by 'audioChannels'. The samples are floats ranging from -1 to 1, laid out non-interleaved, i.e. consecutive segments of 'audioLength' samples each. The durations of the input buffers for the input streams will be equal (or as equal as possible given varying sample rates). | ||
Streams not containing audio will have audioChannels set to zero, and the audioSamples array will be empty --- unless variableAudioFormats is false and some input stream has audio. | Streams not containing audio will have audioChannels set to zero, and the audioSamples array will be empty --- unless variableAudioFormats is false and some input stream has audio. | ||