Quicktime File Format (2012-08-14).pdf

Media Data Atom TypesMPEG-1 MediaMusic Sample DescriptionThe music sample description uses the standard sample description header, as described in the section “SampleDescription Atoms” (page 99).The data format field in the sample description is always set to 'musi'. The music media handler adds anadditional 32-bit integer field to the sample description containing flags. Currently no flags are defined, andthis field should be set to 0.Following the flags field, there may be appended data in the QuickTime music format. This data consists ofpart-to-instrument mappings in the form of General events containing note requests. One note request eventshould be present for each part that will be used in the sample data.Music Sample DataThe sample data for music samples consists entirely of data in the QuickTime music format. Typically, up to 30seconds of notes are grouped into a single sample.MPEG-1 MediaMPEG-1 media is used to store MPEG-1 video streams, MPEG-1, layer 2 audio streams, and multiplexed MPEG-1audio and video streams in QuickTime movies. It has a media type of 'MPEG'.MPEG-1 Sample DescriptionThe MPEG-1 sample description uses the standard sample description header, as described in “SampleDescription Atoms” (page 99).The data format field in the sample description is always set to 'MPEG'. The MPEG-1 media handler adds noadditional fields to the sample description.Note This data format is not used for MPEG-1, layer 3 audio, however (see “MPEG-1 Layer 3 (MP3)Codecs” (page 189)).MPEG-1 Sample DataEach sample in an MPEG-1 media is an entire MPEG-1 stream. This means that a single MPEG-1 sample maybe several hundred megabytes in size. The MPEG-1 encoding used by QuickTime corresponds to the ISOstandard, as described in ISO document CD 11172.2012-08-14 | © 2004, 2012 Apple Inc. All Rights Reserved.207