13. A system for smoothed captioning of non-speech sounds in an audio stream, comprising: a content system coupled to a network and configured to: access an audio stream; input portions of the audio stream into one or more non-speech classifiers for classification; generating, by the non-speech classifiers, for one or more of the portions of the audio stream, a set of raw scores representing likelihoods that the respective portion of the audio stream includes an occurrence of a particular class of non-speech sounds associated with each of the non-speech classifiers; generate a set of binary scores for each of the sets of raw scores, each set of binary scores generated based on a smoothing of a respective set of raw scores, the smoothing of the respective set of raw scores determined based on the raw scores of the same class of non-speech sounds from neighboring portions of the audio stream in time, wherein for a portion of the portions, a first binary value indicates that a first class of the non-speech sounds occurs in the portion, and a second binary value indicates that the first class of the non-speech sounds does not occur in the portion, and wherein to generate the set of binary scores for each of the sets of raw scores comprises to: determine, using transition probabilities and a sequence of emission probabilities, a sequence of most likely binary scores for each set of raw scores, the sequence of binary scores corresponding to a sequence of on states and off states, the sequence of emission probabilities of the on states corresponding to the raw scores of the set of raw scores and the sequence of emission probabilities of the off states corresponding to a function of the raw scores, and the transition probabilities predefined such that a probability of a transition between different states is lower than a probability of transitioning between the same states; and apply a set of non-speech captions to portions of the audio stream in time, each of the sets of non-speech captions based on a different one of the set binary scores of the corresponding portion of the audio stream; and a client device coupled to the network and configured to: receive content from a content server; receive speech captions and non-speech captions; and present the content with the speech captions and non-speech captions to a user.
13. A system for smoothed captioning of non-speech sounds in an audio stream, comprising: a content system coupled to a network and configured to: access an audio stream; input portions of the audio stream into one or more non-speech classifiers for classification; generating, by the non-speech classifiers, for one or more of the portions of the audio stream, a set of raw scores representing likelihoods that the respective portion of the audio stream includes an occurrence of a particular class of non-speech sounds associated with each of the non-speech classifiers; generate a set of binary scores for each of the sets of raw scores, each set of binary scores generated based on a smoothing of a respective set of raw scores, the smoothing of the respective set of raw scores determined based on the raw scores of the same class of non-speech sounds from neighboring portions of the audio stream in time, wherein for a portion of the portions, a first binary value indicates that a first class of the non-speech sounds occurs in the portion, and a second binary value indicates that the first class of the non-speech sounds does not occur in the portion, and wherein to generate the set of binary scores for each of the sets of raw scores comprises to: determine, using transition probabilities and a sequence of emission probabilities, a sequence of most likely binary scores for each set of raw scores, the sequence of binary scores corresponding to a sequence of on states and off states, the sequence of emission probabilities of the on states corresponding to the raw scores of the set of raw scores and the sequence of emission probabilities of the off states corresponding to a function of the raw scores, and the transition probabilities predefined such that a probability of a transition between different states is lower than a probability of transitioning between the same states; and apply a set of non-speech captions to portions of the audio stream in time, each of the sets of non-speech captions based on a different one of the set binary scores of the corresponding portion of the audio stream; and a client device coupled to the network and configured to: receive content from a content server; receive speech captions and non-speech captions; and present the content with the speech captions and non-speech captions to a user. 15. The system of claim 13 , wherein the determination of the sequence of most likely binary scores uses Viterbi decoding.