多媒体技术第三讲课件.pptVIP

第三讲 音频媒体信息处理技术 基本概念 音频文件格式 音频信号编码 语音信号的处理、识别、理解 数字音乐 WAVe file format (Microsoft) RIFF A collection of data chunks. Each chunk has a 32-bit Id followed by a 32-bit chunk length followed by the chunk data. 0x00 chunk id RIFF 0x04 chunk size (32-bits) 0x08 wave chunk id WAVE 0x0C format chunk id fmt 0x10 format chunk size (32-bits) 0x14 format tag (currently pcm) 0x16 number of channels 1=mono, 2=stereo 0x18 sample rate in hz 0x1C average bytes per second 0x20 number of bytes per sample 1 = 8-bit mono 2 = 8-bit stereo or 16-bit mono 4 = 16-bit stereo 0x22 number of bits in a sample 0x24 data chunk id data 0x28 length of data chunk (32-bits) 0x2C Sample data Speech recognition, understanding and conversational interfaces Alexander Rudnicky School of Computer Science /~air Outline Speech Types of speech interfaces Speech systems and their structure Designing speech interfaces Some applications SpeechWear Communicator Speech as a signal The difference between speech and sound “CD” quality vs. intelligible quality high-quality is 44.1 / 48 kHz desirable speech bandwidth: 0-8kHz, 16bits at 16bits/sample: 256kbps (tethered mic) telephone: 64kbps (and lower) Compression: MPEG: 64kbps/channel and up (but not speech-optimal) CELP: 16kbps … 2.4kbps (optimized for speech) Speech for communication The difference between speech and language Speech recognition and speech understanding Computers and speech Transcription dictation, information retrieval Command and control data entry, device control, navigation Information access airline schedules, stock quotes Problem solving travel planning, logistics Speech system architecture SIGNAL PROCESSING