Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 1 | Encapsulation of FLAC in ISO Base Media File Format |
Ralph Giles | 55fba7e | 2016-10-27 08:47:09 -0700 | [diff] [blame] | 2 | Version 0.0.4 (draft) |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 3 | |
| 4 | Table of Contents |
| 5 | 1 Scope |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 6 | 2 Supporting Normative References |
Ralph Giles | 0925501 | 2016-10-04 09:46:26 -0700 | [diff] [blame] | 7 | 3 Design Rules of Encapsulation |
| 8 | 3.1 File Type Identification |
| 9 | 3.2 Overview of Track Structure |
| 10 | 3.3 Definition of FLAC sample |
| 11 | 3.3.1 Sample entry format |
| 12 | 3.3.2 FLAC Specific Box |
| 13 | 3.3.3 Sample format |
| 14 | 3.3.4 Duration of FLAC sample |
| 15 | 3.3.5 Sub-sample |
| 16 | 3.3.6 Random Access |
| 17 | 3.3.6.1 Random Access Point |
| 18 | 3.4 Basic Structure (informative) |
| 19 | 3.4.1 Initial Movie |
| 20 | 3.5 Example of Encapsulation (informative) |
| 21 | 4 Acknowledgements |
| 22 | 5 Author's Address |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 23 | |
| 24 | 1 Scope |
| 25 | |
| 26 | This document specifies the normative mapping for encapsulation of |
| 27 | FLAC coded audio bitstreams in ISO Base Media file format and its |
| 28 | derivatives. The encapsulation of FLAC coded bitstreams in |
| 29 | QuickTime file format is outside the scope of this specification. |
| 30 | |
| 31 | 2 Supporting Normative References |
| 32 | |
| 33 | [1] ISO/IEC 14496-12:2012 Corrected version |
| 34 | |
| 35 | Information technology — Coding of audio-visual objects — Part |
| 36 | 12: ISO base media file format |
| 37 | |
| 38 | [2] ISO/IEC 14496-12:2012/Amd.1:2013 |
| 39 | |
| 40 | Information technology — Coding of audio-visual objects — Part |
| 41 | 12: ISO base media file format AMENDMENT 1: Various |
| 42 | enhancements including support for large metadata |
| 43 | |
| 44 | [3] FLAC format specification |
| 45 | |
| 46 | https://xiph.org/flac/format.html |
| 47 | |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 48 | Definition of the FLAC Audio Codec stream format |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 49 | |
| 50 | [4] FLAC-in-Ogg mapping specification |
| 51 | |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 52 | https://xiph.org/flac/ogg_mapping.html |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 53 | |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 54 | Ogg Encapsulation for the FLAC Audio Codec |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 55 | |
| 56 | [5] Matroska specification |
| 57 | |
Ralph Giles | 0925501 | 2016-10-04 09:46:26 -0700 | [diff] [blame] | 58 | 3 Design Rules of Encapsulation |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 59 | |
Ralph Giles | 0925501 | 2016-10-04 09:46:26 -0700 | [diff] [blame] | 60 | 3.1 File Type Identification |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 61 | |
| 62 | This specification does not define any brand to declare files |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 63 | which conform to this specification. Files which conform to |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 64 | this specification shall contain at least one brand which |
| 65 | supports the requirements and the requirements described in |
| 66 | this clause without contradiction in the compatible brands |
| 67 | list of the File Type Box. The minimal support of the |
| 68 | encapsulation of FLAC bitstreams in ISO Base Media file format |
| 69 | requires the 'isom' brand. |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 70 | |
Ralph Giles | 0925501 | 2016-10-04 09:46:26 -0700 | [diff] [blame] | 71 | 3.2 Overview of Track Structure |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 72 | |
| 73 | FLAC coded audio shall be encapsulated into the ISO Base |
| 74 | Media File Format as media data within an audio track. |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 75 | |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 76 | + The handler_type field in the Handler Reference Box |
| 77 | shall be set to 'soun'. |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 78 | |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 79 | + The Media Information Box shall contain the Sound Media |
| 80 | Header Box. |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 81 | |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 82 | + The codingname of the sample entry is 'fLaC'. |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 83 | |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 84 | This specification does not define any encapsulation |
| 85 | using MP4AudioSampleEntry with objectTypeIndication |
| 86 | specified by the MPEG-4 Registration Authority |
| 87 | (http://www.mp4ra.org/). See section 'Sample entry |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 88 | format' for the definition of the sample entry. |
| 89 | |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 90 | + The 'dfLa' box is added to the sample entry to convey |
| 91 | initializing information for the decoder. |
| 92 | |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 93 | See section 'FLAC Specific Box' for the definition of |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 94 | the box contents. |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 95 | |
| 96 | + A FLAC sample is exactly one FLAC frame as described |
| 97 | in the format specification[3]. See section |
| 98 | 'Sample format' for details of the frame contents. |
| 99 | |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 100 | + Every FLAC sample is a sync sample. No pre-roll or |
| 101 | lapping is required. See section 'Random Access' for |
| 102 | further details. |
| 103 | |
Ralph Giles | 0925501 | 2016-10-04 09:46:26 -0700 | [diff] [blame] | 104 | 3.3 Definition of a FLAC sample |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 105 | |
Ralph Giles | 0925501 | 2016-10-04 09:46:26 -0700 | [diff] [blame] | 106 | 3.3.1 Sample entry format |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 107 | |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 108 | For any track containing one or more FLAC bitstreams, a |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 109 | sample entry describing the corresponding FLAC bitstream |
| 110 | shall be present inside the Sample Table Box. This version |
| 111 | of the specification defines only one sample entry format |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 112 | named FLACSampleEntry whose codingname is 'fLaC'. This |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 113 | sample entry includes exactly one FLAC Specific Box |
| 114 | defined in section 'FLAC specific box' as a mandatory box |
| 115 | and indicates that FLAC samples described by this sample |
| 116 | entry are stored by the sample format described in section |
| 117 | 'Sample format'. |
| 118 | |
| 119 | The syntax and semantics of the FLACSampleEntry is shown |
| 120 | as follows. The data fields of this box and native |
| 121 | FLAC[3] structures encoded within FLAC blocks are both |
| 122 | stored in big-endian format, though for purposes of the |
| 123 | ISO BMFF container, FLAC native metadata and data blocks |
| 124 | are treated as unstructured octet streams. |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 125 | |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 126 | class FLACSampleEntry() extends AudioSampleEntry ('fLaC'){ |
| 127 | FLACSpecificBox(); |
| 128 | } |
| 129 | |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 130 | The fields of the AudioSampleEntry portion shall be set as |
| 131 | follows: |
| 132 | |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 133 | + channelcount: |
| 134 | |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 135 | The channelcount field shall be set equal to the |
| 136 | channel count specified by the FLAC bitstream's native |
| 137 | METADATA_BLOCK_STREAMINFO header as described in [3]. |
| 138 | Note that the FLAC FRAME_HEADER structure that begins |
| 139 | each FLAC sample redundantly encodes channel number; |
| 140 | the number of channels declared in each FRAME_HEADER |
| 141 | MUST match the number of channels declared here and in |
| 142 | the METADATA_BLOCK_STREAMINFO header. |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 143 | |
| 144 | + samplesize: |
| 145 | |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 146 | The samplesize field shall be set equal to the bits |
| 147 | per sample specified by the FLAC bitstream's native |
| 148 | METADATA_BLOCK_STREAMINFO header as described in [3]. |
| 149 | Note that the FLAC FRAME_HEADER structure that begins |
| 150 | each FLAC sample redundantly encodes the number of |
| 151 | bits per sample; the bits per sample declared in each |
| 152 | FRAME_HEADER MUST match the samplesize declared here |
| 153 | and the bits per sample field declared in the |
| 154 | METADATA_BLOCK_STREAMINFO header. |
| 155 | |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 156 | + samplerate: |
| 157 | |
Ralph Giles | 0925501 | 2016-10-04 09:46:26 -0700 | [diff] [blame] | 158 | When possible, the samplerate field shall be set |
| 159 | equal to the sample rate specified by the FLAC |
| 160 | bitstream's native METADATA_BLOCK_STREAMINFO header |
| 161 | as described in [3], left-shifted by 16 bits to |
| 162 | create the appropriate 16.16 fixed-point |
| 163 | representation. |
| 164 | |
| 165 | When the bitstream's native sample rate is greater |
| 166 | than the maximum expressible value of 65535 Hz, |
| 167 | the samplerate field shall hold the greatest |
| 168 | expressible regular division of that rate. I.e. |
| 169 | the samplerate field shall hold 48000.0 for |
| 170 | native sample rates of 96 and 192 kHz. In the |
| 171 | case of unusual sample rates which do not have |
| 172 | an expressible regular division, the maximum value |
| 173 | of 65535.0 Hz should be used. |
| 174 | |
| 175 | High-rate FLAC bitstreams are common, and the native |
| 176 | value from the METADATA_BLOCK_STREAMINFO header in |
| 177 | the FLACSpecificBox MUST be read to determine the |
| 178 | correct sample rate of the bitstream. |
| 179 | |
| 180 | Note that the FLAC FRAME_HEADER structure that begins |
| 181 | each FLAC sample redundantly encodes the sample rate; |
| 182 | the sample rate declared in each FRAME_HEADER MUST |
| 183 | match the sample rate declared in the |
| 184 | METADATA_BLOCK_STREAMINFO header, and here in the |
| 185 | AudioSampleEntry portion of the FLACSampleEntry |
| 186 | as much as is allowed by the encoding restrictions |
| 187 | described above. |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 188 | |
| 189 | Finally, the FLACSpecificBox carries codec headers: |
| 190 | |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 191 | + FLACSpecificBox |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 192 | |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 193 | This box contains initializing information for the |
Ralph Giles | 0925501 | 2016-10-04 09:46:26 -0700 | [diff] [blame] | 194 | decoder as defined in section 'FLAC specific box'. |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 195 | |
Ralph Giles | 0925501 | 2016-10-04 09:46:26 -0700 | [diff] [blame] | 196 | 3.3.2 FLAC Specific Box |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 197 | |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 198 | Exactly one FLAC Specific Box shall be present in each |
Ralph Giles | 0925501 | 2016-10-04 09:46:26 -0700 | [diff] [blame] | 199 | FLACSampleEntry. This specification defines version 0 |
| 200 | of this box. If incompatible changes occur in future |
| 201 | versions of this specification, another version number |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 202 | will be defined. The data fields of this box and native |
| 203 | FLAC[3] structures encoded within FLAC blocks are both |
| 204 | stored in big-endian format, though for purposes of the |
| 205 | ISO BMFF container, FLAC native metadata and data blocks |
| 206 | are treated as unstructured octet streams. |
| 207 | |
| 208 | The syntax and semantics of the FLAC Specific Box is shown |
| 209 | as follows. |
| 210 | |
Ralph Giles | 0925501 | 2016-10-04 09:46:26 -0700 | [diff] [blame] | 211 | class FLACMetadataBlock { |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 212 | unsigned int(1) LastMetadataBlockFlag; |
| 213 | unsigned int(7) BlockType; |
| 214 | unsigned int(24) Length; |
| 215 | unsigned int(8) BlockData[Length]; |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 216 | } |
| 217 | |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 218 | aligned(8) class FLACSpecificBox |
| 219 | extends FullBox('dfLa', version=0, 0){ |
| 220 | for (i=0; ; i++) { // to end of box |
| 221 | FLACMetadataBlock(); |
| 222 | } |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 223 | } |
| 224 | |
| 225 | + Version: |
| 226 | |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 227 | The Version field shall be set to 0. |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 228 | |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 229 | In the future versions of this specification, this |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 230 | field may be set to other values. And without support |
| 231 | of those values, the reader shall not read the fields |
| 232 | after this within the FLACSpecificBox. |
| 233 | |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 234 | + Flags: |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 235 | |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 236 | The Flags field shall be set to 0. |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 237 | |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 238 | After the FullBox header, the box contains a sequence of |
| 239 | FLAC[3] native-metadata block structures that fill the |
| 240 | remainder of the box. |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 241 | |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 242 | Each FLACMetadataBlock structure consists of three fields |
| 243 | filling a total of four bytes that form a FLAC[3] native |
| 244 | METADATA_BLOCK_HEADER, followed by raw octet bytes that |
| 245 | comprise the FLAC[3] native METADATA_BLOCK_DATA. |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 246 | |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 247 | + LastMetadataBlockFlag: |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 248 | |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 249 | The LastMetadataBlockFlag field maps semantically to |
| 250 | the FLAC[3] native METADATA_BLOCK_HEADER |
| 251 | Last-metadata-block flag as defined in the FLAC[3] |
| 252 | file specification. |
| 253 | |
| 254 | The LastMetadataBlockFlag is set to 1 if this |
| 255 | MetadataBlock is the last metadata block in the |
| 256 | FLACSpecificBox. It is set to 0 otherwise. |
| 257 | |
| 258 | + BlockType: |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 259 | |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 260 | The BlockType field maps semantically to the FLAC[3] |
Ralph Giles | 55fba7e | 2016-10-27 08:47:09 -0700 | [diff] [blame] | 261 | native METADATA_BLOCK_HEADER BLOCK_TYPE field as |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 262 | defined in the FLAC[3] file specification. |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 263 | |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 264 | The BlockType is set to a valid FLAC[3] BLOCK_TYPE |
| 265 | value that identifies the type of this native metadata |
| 266 | block. The BlockType of the first FLACMetadataBlock |
| 267 | must be set to 0, signifying this is a FLAC[3] native |
| 268 | METADATA_BLOCK_STREAMINFO block. |
| 269 | |
| 270 | + Length: |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 271 | |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 272 | The Length field maps semantically to the FLAC[3] |
Ralph Giles | 55fba7e | 2016-10-27 08:47:09 -0700 | [diff] [blame] | 273 | native METADATA_BLOCK_HEADER Length field as |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 274 | defined in the FLAC[3] file specification. |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 275 | |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 276 | The length field specifies the number of bytes of |
| 277 | MetadataBlockData to follow. |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 278 | |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 279 | + BlockData |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 280 | |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 281 | The BlockData field maps semantically to the FLAC[3] |
Ralph Giles | 55fba7e | 2016-10-27 08:47:09 -0700 | [diff] [blame] | 282 | native METADATA_BLOCK_HEADER METADATA_BLOCK_DATA as |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 283 | defined in the FLAC[3] file specification. |
| 284 | |
| 285 | Taken together, the bytes of the FLACMetadataBlock form a |
| 286 | complete FLAC[3] native METADATA_BLOCK structure. |
| 287 | |
| 288 | Note that a minimum of a single FLACMetadataBlock, |
| 289 | consisting of a FLAC[3] native METADATA_BLOCK_STREAMINFO |
| 290 | structure, is required. Should the FLACSpecificBox |
| 291 | contain more than a single FLACMetadataBlock structure, |
| 292 | the FLACMetadataBlock containing the FLAC[3] native |
| 293 | METADATA_BLOCK_STREAMINFO must occur first in the list. |
| 294 | |
| 295 | Other containers that package FLAC audio streams, such as |
| 296 | Ogg[4] and Matroska[5], wrap FLAC[3] native metadata without |
| 297 | modification similar to this specification. When |
| 298 | repackaging or remuxing FLAC[3] streams from another |
| 299 | format that contains FLAC[3] native metadata into an ISO |
| 300 | BMFF file, the complete FLAC[3] native metadata should be |
| 301 | preserved in the ISO BMFF stream as described above. It |
| 302 | is also allowed to parse this native metadata and include |
| 303 | contextually redundant ISO BMFF-native repackagings and/or |
| 304 | reparsings of FLAC[3] native metadata, so long as the |
| 305 | native metadata is also preserved. |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 306 | |
Ralph Giles | 0925501 | 2016-10-04 09:46:26 -0700 | [diff] [blame] | 307 | 3.3.3 Sample format |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 308 | |
| 309 | A FLAC sample is exactly one FLAC audio FRAME (as defined |
| 310 | in the FLAC[3] file specification) belonging to a FLAC |
| 311 | bitstreams. The FLAC sample data begins with a complete |
| 312 | FLAC FRAME_HEADER, followed by one FLAC SUBFRAME per |
| 313 | channel, any necessary bit padding, and ends with the |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 314 | usual FLAC FRAME_FOOTER. |
| 315 | |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 316 | Note that the FLAC native FRAME_HEADER structure that |
| 317 | begins each FLAC sample redundantly encodes channel count, |
| 318 | sample rate, and sample size. The values of these fields |
| 319 | must agree both with the values declared in the FLAC |
| 320 | METADATA_BLOCK_STREAMINFO structure as well as the |
| 321 | FLACSampleEntry box. |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 322 | |
Ralph Giles | 0925501 | 2016-10-04 09:46:26 -0700 | [diff] [blame] | 323 | 3.3.4 Duration of a FLAC sample |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 324 | |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 325 | The duration of any given FLAC sample is determined by |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 326 | dividing the decoded block size of a FLAC frame, as |
| 327 | encoded in the FLAC FRAME's FRAME_HEADER structure, by the |
| 328 | value of the timescale field in the Media Header Box. |
| 329 | FLAC samples are permitted to have variable durations |
| 330 | within a given audio stream. FLAC does not use padding |
| 331 | values. |
| 332 | |
Ralph Giles | 0925501 | 2016-10-04 09:46:26 -0700 | [diff] [blame] | 333 | 3.3.5 Sub-sample |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 334 | |
| 335 | Sub-samples are not defined for FLAC samples in this |
| 336 | specification. |
| 337 | |
Ralph Giles | 0925501 | 2016-10-04 09:46:26 -0700 | [diff] [blame] | 338 | 3.3.6 Random Access |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 339 | |
Ralph Giles | 0925501 | 2016-10-04 09:46:26 -0700 | [diff] [blame] | 340 | This subclause describes the nature of the random access |
| 341 | of FLAC sample. |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 342 | |
Ralph Giles | 0925501 | 2016-10-04 09:46:26 -0700 | [diff] [blame] | 343 | 3.3.6.1 Random Access Point |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 344 | |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 345 | All FLAC samples can be independently decoded |
| 346 | i.e. every FLAC sample is a sync sample. The Sync |
| 347 | Sample Box shall not be present as long as there are |
| 348 | no samples other than FLAC samples in the same |
| 349 | track. The sample_is_non_sync_sample field for FLAC |
| 350 | samples shall be set to 0. |
| 351 | |
Ralph Giles | 0925501 | 2016-10-04 09:46:26 -0700 | [diff] [blame] | 352 | 3.4 Basic Structure (informative) |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 353 | |
Ralph Giles | 0925501 | 2016-10-04 09:46:26 -0700 | [diff] [blame] | 354 | 3.4.1 Initial Movie |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 355 | |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 356 | This subclause shows a basic structure of the Movie Box as follows: |
| 357 | |
| 358 | +----+----+----+----+----+----+----+----+------------------------------+ |
| 359 | |moov| | | | | | | | Movie Box | |
| 360 | +----+----+----+----+----+----+----+----+------------------------------+ |
| 361 | | |mvhd| | | | | | | Movie Header Box | |
| 362 | +----+----+----+----+----+----+----+----+------------------------------+ |
| 363 | | |trak| | | | | | | Track Box | |
| 364 | +----+----+----+----+----+----+----+----+------------------------------+ |
| 365 | | | |tkhd| | | | | | Track Header Box | |
| 366 | +----+----+----+----+----+----+----+----+------------------------------+ |
| 367 | | | |edts|* | | | | | Edit Box | |
| 368 | +----+----+----+----+----+----+----+----+------------------------------+ |
| 369 | | | | |elst|* | | | | Edit List Box | |
| 370 | +----+----+----+----+----+----+----+----+------------------------------+ |
| 371 | | | |mdia| | | | | | Media Box | |
| 372 | +----+----+----+----+----+----+----+----+------------------------------+ |
| 373 | | | | |mdhd| | | | | Media Header Box | |
| 374 | +----+----+----+----+----+----+----+----+------------------------------+ |
| 375 | | | | |hdlr| | | | | Handler Reference Box | |
| 376 | +----+----+----+----+----+----+----+----+------------------------------+ |
| 377 | | | | |minf| | | | | Media Information Box | |
| 378 | +----+----+----+----+----+----+----+----+------------------------------+ |
| 379 | | | | | |smhd| | | | Sound Media Header Box | |
| 380 | +----+----+----+----+----+----+----+----+------------------------------+ |
| 381 | | | | | |dinf| | | | Data Information Box | |
| 382 | +----+----+----+----+----+----+----+----+------------------------------+ |
| 383 | | | | | | |dref| | | Data Reference Box | |
| 384 | +----+----+----+----+----+----+----+----+------------------------------+ |
| 385 | | | | | | | |url | | DataEntryUrlBox | |
| 386 | +----+----+----+----+----+----+ or +----+------------------------------+ |
| 387 | | | | | | | |urn | | DataEntryUrnBox | |
| 388 | +----+----+----+----+----+----+----+----+------------------------------+ |
| 389 | | | | | |stbl| | | | Sample Table | |
| 390 | +----+----+----+----+----+----+----+----+------------------------------+ |
| 391 | | | | | | |stsd| | | Sample Description Box | |
| 392 | +----+----+----+----+----+----+----+----+------------------------------+ |
| 393 | | | | | | | |fLaC| | FLACSampleEntry | |
| 394 | +----+----+----+----+----+----+----+----+------------------------------+ |
| 395 | | | | | | | | |dfLa| FLAC Specific Box | |
| 396 | +----+----+----+----+----+----+----+----+------------------------------+ |
| 397 | | | | | | |stts| | | Decoding Time to Sample Box | |
| 398 | +----+----+----+----+----+----+----+----+------------------------------+ |
| 399 | | | | | | |stsc| | | Sample To Chunk Box | |
| 400 | +----+----+----+----+----+----+----+----+------------------------------+ |
| 401 | | | | | | |stsz| | | Sample Size Box | |
| 402 | +----+----+----+----+----+ or +----+----+------------------------------+ |
| 403 | | | | | | |stz2| | | Compact Sample Size Box | |
| 404 | +----+----+----+----+----+----+----+----+------------------------------+ |
| 405 | | | | | | |stco| | | Chunk Offset Box | |
| 406 | +----+----+----+----+----+ or +----+----+------------------------------+ |
| 407 | | | | | | |co64| | | Chunk Large Offset Box | |
| 408 | +----+----+----+----+----+----+----+----+------------------------------+ |
| 409 | | |mvex|* | | | | | | Movie Extends Box | |
| 410 | +----+----+----+----+----+----+----+----+------------------------------+ |
| 411 | | | |trex|* | | | | | Track Extends Box | |
| 412 | +----+----+----+----+----+----+----+----+------------------------------+ |
| 413 | |
| 414 | Figure 1 - Basic structure of Movie Box |
| 415 | |
| 416 | It is strongly recommended that the order of boxes should |
| 417 | follow the above structure. Boxes marked with an asterisk |
Ralph Giles | 52df9c6 | 2016-10-04 08:46:00 -0700 | [diff] [blame] | 418 | (*) may or may not be present depending on context. For |
| 419 | most boxes listed above, the definition is as is defined |
| 420 | in ISO/IEC 14496-12 [1]. The additional boxes and the |
| 421 | additional requirements, restrictions and recommendations |
| 422 | to the other boxes are described in this specification. |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 423 | |
Ralph Giles | 0925501 | 2016-10-04 09:46:26 -0700 | [diff] [blame] | 424 | 3.5 Example of Encapsulation (informative) |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 425 | [File] |
| 426 | size = 17790 |
| 427 | [ftyp: File Type Box] |
| 428 | position = 0 |
| 429 | size = 24 |
| 430 | major_brand = mp42 : MP4 version 2 |
| 431 | minor_version = 0 |
| 432 | compatible_brands |
| 433 | brand[0] = mp42 : MP4 version 2 |
| 434 | brand[1] = isom : ISO Base Media file format |
| 435 | [moov: Movie Box] |
| 436 | position = 24 |
| 437 | size = 757 |
| 438 | [mvhd: Movie Header Box] |
| 439 | position = 32 |
| 440 | size = 108 |
| 441 | version = 0 |
| 442 | flags = 0x000000 |
| 443 | creation_time = UTC 2014/12/12, 18:41:19 |
| 444 | modification_time = UTC 2014/12/12, 18:41:19 |
| 445 | timescale = 48000 |
| 446 | duration = 33600 (00:00:00.700) |
| 447 | rate = 1.000000 |
| 448 | volume = 1.000000 |
| 449 | reserved = 0x0000 |
| 450 | reserved = 0x00000000 |
| 451 | reserved = 0x00000000 |
| 452 | transformation matrix |
| 453 | | a, b, u | | 1.000000, 0.000000, 0.000000 | |
| 454 | | c, d, v | = | 0.000000, 1.000000, 0.000000 | |
| 455 | | x, y, w | | 0.000000, 0.000000, 1.000000 | |
| 456 | pre_defined = 0x00000000 |
| 457 | pre_defined = 0x00000000 |
| 458 | pre_defined = 0x00000000 |
| 459 | pre_defined = 0x00000000 |
| 460 | pre_defined = 0x00000000 |
| 461 | pre_defined = 0x00000000 |
| 462 | next_track_ID = 2 |
| 463 | [iods: Object Descriptor Box] |
| 464 | position = 140 |
| 465 | size = 33 |
| 466 | version = 0 |
| 467 | flags = 0x000000 |
| 468 | [tag = 0x10: MP4_IOD] |
| 469 | expandableClassSize = 16 |
| 470 | ObjectDescriptorID = 1 |
| 471 | URL_Flag = 0 |
| 472 | includeInlineProfileLevelFlag = 0 |
| 473 | reserved = 0xf |
| 474 | ODProfileLevelIndication = 0xff |
| 475 | sceneProfileLevelIndication = 0xff |
| 476 | audioProfileLevelIndication = 0xfe |
| 477 | visualProfileLevelIndication = 0xff |
| 478 | graphicsProfileLevelIndication = 0xff |
| 479 | [tag = 0x0e: ES_ID_Inc] |
| 480 | expandableClassSize = 4 |
| 481 | Track_ID = 1 |
| 482 | [trak: Track Box] |
| 483 | position = 173 |
| 484 | size = 608 |
| 485 | [tkhd: Track Header Box] |
| 486 | position = 181 |
| 487 | size = 92 |
| 488 | version = 0 |
| 489 | flags = 0x000007 |
| 490 | Track enabled |
| 491 | Track in movie |
| 492 | Track in preview |
| 493 | creation_time = UTC 2014/12/12, 18:41:19 |
| 494 | modification_time = UTC 2014/12/12, 18:41:19 |
| 495 | track_ID = 1 |
| 496 | reserved = 0x00000000 |
| 497 | duration = 33600 (00:00:00.700) |
| 498 | reserved = 0x00000000 |
| 499 | reserved = 0x00000000 |
| 500 | layer = 0 |
| 501 | alternate_group = 0 |
| 502 | volume = 1.000000 |
| 503 | reserved = 0x0000 |
| 504 | transformation matrix |
| 505 | | a, b, u | | 1.000000, 0.000000, 0.000000 | |
| 506 | | c, d, v | = | 0.000000, 1.000000, 0.000000 | |
| 507 | | x, y, w | | 0.000000, 0.000000, 1.000000 | |
| 508 | width = 0.000000 |
| 509 | height = 0.000000 |
| 510 | [mdia: Media Box] |
| 511 | position = 273 |
| 512 | size = 472 |
| 513 | [mdhd: Media Header Box] |
| 514 | position = 281 |
| 515 | size = 32 |
| 516 | version = 0 |
| 517 | flags = 0x000000 |
| 518 | creation_time = UTC 2014/12/12, 18:41:19 |
| 519 | modification_time = UTC 2014/12/12, 18:41:19 |
| 520 | timescale = 48000 |
| 521 | duration = 34560 (00:00:00.720) |
| 522 | language = und |
| 523 | pre_defined = 0x0000 |
| 524 | [hdlr: Handler Reference Box] |
| 525 | position = 313 |
| 526 | size = 51 |
| 527 | version = 0 |
| 528 | flags = 0x000000 |
| 529 | pre_defined = 0x00000000 |
| 530 | handler_type = soun |
| 531 | reserved = 0x00000000 |
| 532 | reserved = 0x00000000 |
| 533 | reserved = 0x00000000 |
| 534 | name = Xiph Audio Handler |
| 535 | [minf: Media Information Box] |
| 536 | position = 364 |
| 537 | size = 381 |
| 538 | [smhd: Sound Media Header Box] |
| 539 | position = 372 |
| 540 | size = 16 |
| 541 | version = 0 |
| 542 | flags = 0x000000 |
| 543 | balance = 0.000000 |
| 544 | reserved = 0x0000 |
| 545 | [dinf: Data Information Box] |
| 546 | position = 388 |
| 547 | size = 36 |
| 548 | [dref: Data Reference Box] |
| 549 | position = 396 |
| 550 | size = 28 |
| 551 | version = 0 |
| 552 | flags = 0x000000 |
| 553 | entry_count = 1 |
| 554 | [url : Data Entry Url Box] |
| 555 | position = 412 |
| 556 | size = 12 |
| 557 | version = 0 |
| 558 | flags = 0x000001 |
| 559 | location = in the same file |
| 560 | [stbl: Sample Table Box] |
| 561 | position = 424 |
| 562 | size = 321 |
| 563 | [stsd: Sample Description Box] |
| 564 | position = 432 |
| 565 | size = 79 |
| 566 | version = 0 |
| 567 | flags = 0x000000 |
| 568 | entry_count = 1 |
| 569 | [fLaC: Audio Description] |
| 570 | position = 448 |
| 571 | size = 63 |
| 572 | reserved = 0x000000000000 |
| 573 | data_reference_index = 1 |
| 574 | reserved = 0x0000 |
| 575 | reserved = 0x0000 |
| 576 | reserved = 0x00000000 |
| 577 | channelcount = 2 |
| 578 | samplesize = 16 |
| 579 | pre_defined = 0 |
| 580 | reserved = 0 |
| 581 | samplerate = 48000.000000 |
| 582 | [dfLa: FLAC Specific Box] |
| 583 | position = 484 |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 584 | size = 50 |
| 585 | version = 0 |
| 586 | flags = 0x000000 |
Ralph Giles | 0925501 | 2016-10-04 09:46:26 -0700 | [diff] [blame] | 587 | [FLACMetadataBlock] |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 588 | LastMetadataBlockFlag = 1 |
| 589 | BlockType = 0 |
| 590 | Length = 34 |
| 591 | BlockData[34]; |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 592 | [stts: Decoding Time to Sample Box] |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 593 | position = 492 |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 594 | size = 24 |
| 595 | version = 0 |
| 596 | flags = 0x000000 |
| 597 | entry_count = 1 |
| 598 | entry[0] |
| 599 | sample_count = 18 |
| 600 | sample_delta = 1920 |
| 601 | [stsc: Sample To Chunk Box] |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 602 | position = 516 |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 603 | size = 40 |
| 604 | version = 0 |
| 605 | flags = 0x000000 |
| 606 | entry_count = 2 |
| 607 | entry[0] |
| 608 | first_chunk = 1 |
| 609 | samples_per_chunk = 13 |
| 610 | sample_description_index = 1 |
| 611 | entry[1] |
| 612 | first_chunk = 2 |
| 613 | samples_per_chunk = 5 |
| 614 | sample_description_index = 1 |
| 615 | [stsz: Sample Size Box] |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 616 | position = 556 |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 617 | size = 92 |
| 618 | version = 0 |
| 619 | flags = 0x000000 |
| 620 | sample_size = 0 (variable) |
| 621 | sample_count = 18 |
| 622 | entry_size[0] = 977 |
| 623 | entry_size[1] = 938 |
| 624 | entry_size[2] = 939 |
| 625 | entry_size[3] = 938 |
| 626 | entry_size[4] = 934 |
| 627 | entry_size[5] = 945 |
| 628 | entry_size[6] = 948 |
| 629 | entry_size[7] = 956 |
| 630 | entry_size[8] = 955 |
| 631 | entry_size[9] = 930 |
| 632 | entry_size[10] = 933 |
| 633 | entry_size[11] = 934 |
| 634 | entry_size[12] = 972 |
| 635 | entry_size[13] = 977 |
| 636 | entry_size[14] = 958 |
| 637 | entry_size[15] = 949 |
| 638 | entry_size[16] = 962 |
| 639 | entry_size[17] = 848 |
| 640 | [stco: Chunk Offset Box] |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 641 | position = 648 |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 642 | size = 24 |
| 643 | version = 0 |
| 644 | flags = 0x000000 |
| 645 | entry_count = 2 |
| 646 | chunk_offset[0] = 686 |
| 647 | chunk_offset[1] = 12985 |
| 648 | [free: Free Space Box] |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 649 | position = 672 |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 650 | size = 8 |
| 651 | [mdat: Media Data Box] |
Ralph Giles | 2fd3c22 | 2016-10-04 08:49:09 -0700 | [diff] [blame] | 652 | position = 680 |
Ralph Giles | 4bbd73a | 2016-10-04 08:41:07 -0700 | [diff] [blame] | 653 | size = 17001 |
| 654 | |
Ralph Giles | 0925501 | 2016-10-04 09:46:26 -0700 | [diff] [blame] | 655 | 4 Acknowledgements |
Ralph Giles | 52df9c6 | 2016-10-04 08:46:00 -0700 | [diff] [blame] | 656 | |
| 657 | This spec draws heavily from the Opus-in-ISOBMFF specification |
| 658 | work done by Yusuke Nakamura <muken.the.vfrmaniac |at| gmail.com> |
| 659 | |
Ralph Giles | 0925501 | 2016-10-04 09:46:26 -0700 | [diff] [blame] | 660 | Thank you to Tim Terriberry, David Evans, and Yusuke Nakamura |
| 661 | for valuable feedback. Thank you to Ralph Giles for editorial |
| 662 | help. |
| 663 | |
| 664 | 5 Author Address |
Ralph Giles | 52df9c6 | 2016-10-04 08:46:00 -0700 | [diff] [blame] | 665 | |
| 666 | Monty Montgomery <cmontgomery@mozilla.com> |