Metadata: Difference between revisions

From XiphWiki
Jump to navigation Jump to search
No edit summary
(Changed tense of M3F + tidy)
 
(67 intermediate revisions by 18 users not shown)
Line 1: Line 1:
==Motivation==
This page aims to give an overview of the current state of metadata in Ogg and the ongoing projects towards improving it. The different components work in concert; for example [[Ogg Skeleton]] provides important infrastructure for [[CMML]], [[VorbisComment]] is simple to use and program, while the draft [[M3F|Multimedia Metadata Format (M3F)]] provides more sophisticated information.
 
== [[VorbisComment]]s ==


All the Xiph.org codecs have some internal mechanism for including metadata about the current stream.
All the Xiph.org codecs have some internal mechanism for including metadata about the current stream.
Generally, this is one of the codec headers, and in the words of the [http://www.xiph.org/ogg/vorbis/doc/v-comment.html vorbis spec],  
Generally, this is one of the codec headers, and in the words of the [http://www.xiph.org/vorbis/doc/v-comment.html vorbis spec],  
"It is meant for short, text comments...much like someone jotting a quick note on the bottom of a CDR."
"It is meant for short, text comments ... much like someone jotting a quick note on the bottom of a CDR." A single VorbisComment can store upto 2^64 bytes (16 exabytes).
 
VorbisComments store metadata describing the stream in key=value pairs, such as "ARTIST=Elvis", "TITLE=Blue Suede Shoes". Multiple copies of any given key are allowed (for example you can specify ARTIST several times for multiple performers). The specification has several suggested keys: TITLE, VERSION, ALBUM, TRACKNUMBER, ARTIST, PERFORMER, COPYRIGHT, LICENSE, ORGANIZATION, DESCRIPTION, GENRE, DATE, LOCATION, CONTACT, ISRC. See the [http://www.xiph.org/vorbis/doc/v-comment.html specification] for the intent of each one.
 
The [[VorbisComment]] page contains improvements to the suggested comment set.
 
== [[FLAC]] metadata blocks ==
 
Metadata is included in the FLAC codec as METADATA_BLOCK_DATA. Seven types of metadata block are defined: 
#''METADATA_BLOCK_STREAMINFO'': Sample rate, number of channels, etc.
#''METADATA_BLOCK_PADDING'': Nul padding.
#''METADATA_BLOCK_APPLICATION'': Third-party applications can register an ID. Metadata is typically 32-bit integers, but any datatypes can be specified.
#''METADATA_BLOCK_SEEKTABLE'': For one or more seek points.
#''METADATA_BLOCK_VORBIS_COMMENT'': Also known as FLAC tags, the contents of a VorbisComment packet. Note that the 32-bit field lengths are little-endian coded according to the Vorbis spec, as opposed to the usual big-endian coding of fixed-length integers in the rest of FLAC. FLAC metadata blocks are limited to 2^24 bytes (16 megabytes) and a VorbisComment packet in FLAC must fit within that limit.
#''METADATA_BLOCK_CUESHEET'': Typically, but not necessarily, for CD-DA (Red Book) cuesheets.
#''METADATA_BLOCK_PICTURE'': For binary picture data.
 
== [[Ogg Skeleton]] ==
 
[[Ogg Skeleton]] provides metadata useful for handling Ogg streams. This includes information like mime-types and mapping for granulepos which allows seeking streams without the need for the demuxer to understand them. The latest version, [[Ogg Skeleton 4]], also provides a keyframe index to enable faster seeking over high latency networks.
 
Ogg Skeleton allows for attachment of message header fields, given as name-value pairs, that contain some sort of protocol messages about the logical bitstream. This is intended for decode related stuff, such as the screen size for a video bitstream or the number of channels for an audio bitstream.
 
== [[OggKate]] ==
 
[[OggKate]] was originally designed for karaoke and text. The stream can carry text and images, and these can be animated.
 
== [[CMML]] (deprecated) ==
 
CMML is not used anymore; use [[OggKate]] instead. The [[CMML|Continuous Media Markup Language]] allowed time-based marking up of media streams, at its simplest this allowed you to divide media files into clips and provide information about each clip.
 
== [[M3F]] (unused draft) ==
 
[[M3F|Multimedia Metadata Format]] is not being developed anymore; use [[VorbisComment]] instead.
 
The format was intended to replace VorbisComments for the use of ''structured'' metadata, allowing VorbisComments to revert to its orginally intended use of "short, text comments ... much like someone jotting a quick note on the bottom of a CDR."
 
[[M3F]] for the Ogg container was a draft specification which aimed to provide metadata for media streams. The exact aims of this project were still under development, but they included being able to describe artist relationships to a piece more accurately as well as providing the structure to encourage more reliable metadata.


This works well enough for most things, and can be overloaded/abused (depending on your point of view)
== [[XMLEmbedding]] (unused draft) ==
for most other things. But there are three major requirements that point to the design of an external
metadata format; one that can be interleaved with the other streams in a container.


* ''Machinability'' There are a number of items of metadata that a player will want to parse and take action on. While there are usually 'convention' schemes for doing this with the embedded comment headers, this is much easier if there is a separate metadata stream designed for such use, instead of having to do best-effort parsing of natural language comments. For example, a video file with multiple audio tracks can specify the language of each one; a player than can parse these reliably can match them against a language preference list configured by the user to automatically select and begin playback of the best option.
To implement XML metadata in Ogg (as for [[M3F]]), a mapping to Ogg streams is needed. The use of XML metadata will also open the way for the inclusion of technologies such as:
* RDF + dublin core
* [http://www.adobe.com/products/xmp/ XMP]
* [http://wiki.musicbrainz.org/MusicBrainzXMLMetaData MusicBrainz]
* [http://www.w3.org/Graphics/SVG/ SVG]
This specification is still not past the discussion stage.


* ''Kitchen Sink'' There are a minority of people who care passionately about having every detail about a track available. In the sense of conserving such information, and providing an equivalent to liner notes for online distribution, this is a goal worth supporting. However, the simple unstructured key-value pairs offered by the inline metadata are unwieldy for this level of detail. How do you tell the 2nd unit Assistant Director from the USA unit Assistant Director? How do you indicate which artist played tenor sax in the solo?
== Aims of advanced metadata ==


* ''Addressability'' The internal comment metadata headers are by necessity attached to a single content stream. This is useful for some appication, but a limitation in others. In a multiplexed stream, which set of comments refers to the collection as a whole? (By convention, in Ogg, it's the first logical bitstream occuring, but we can do better.) A separate metadata stream type must address this issue of collective metadata while still allowing description of individual streams. It should also allow temporal addressability, so that changes can be described. Because the in-stream comment metadata are part of the codec headers, it cannot change over the course of the stream, and allowing additional comment packets elsewhere in the stream presents seeking challenges. In the Ogg container this can be resolved by inserting a chain boundary, but this is a poor option for very-low-bitrate streams and unreliable transports such as RTP.
VorbisComments work well enough for most things, and can be overloaded/abused (depending on your point of view) for most other things. But there are three major requirements that point to the design of an external metadata format; one that can be interleaved with the other streams in a container.


==Proposed Solutions==
* '''Machinability:''' There are a number of items of metadata that a player will want to parse and take action on. While there are usually 'convention' schemes for doing this with the embedded comment headers, this is much easier if there is a separate metadata stream designed for such use, instead of having to do best-effort parsing of natural language comments. For example, a video file with multiple audio tracks can specify the language of each one; a player than can parse these reliably can match them against a language preference list configured by the user to automatically select and begin playback of the best option.


RDF + dublin core
* '''Kitchen Sink:''' There are a minority of people who care passionately about having every detail about a track available. In the sense of conserving such information, and providing an equivalent to liner notes for online distribution, this is a goal worth supporting. However, the simple unstructured key-value pairs offered by the inline metadata are unwieldy for this level of detail. How do you tell the 2nd unit Assistant Director from the USA unit Assistant Director? How do you indicate which artist played tenor sax in the solo?


XML-encoding (generic rdf or CMML?)
* '''Addressability:''' The internal comment metadata headers are by necessity attached to a single content stream. This is useful for some appication, but a limitation in others. In a multiplexed stream, which set of comments refers to the collection as a whole? (By convention, in Ogg, it's the first logical bitstream occuring, but we can do better.) A separate metadata stream type must address this issue of collective metadata while still allowing description of individual streams. It should also allow temporal addressability, so that changes can be described. Because the in-stream comment metadata are part of the codec headers, it cannot change over the course of the stream, and allowing additional comment packets elsewhere in the stream presents seeking challenges. In the Ogg container this can be resolved by inserting a chain boundary, but this is a poor option for very-low-bitrate streams and unreliable transports such as RTP.
[http://www.shop263.com/i-48/649.htm 分子生物学产品]
[http://www.shop263.com/i-48/650.htm 分子蒸馏]
[http://www.shop263.com/i-48/651.htm 粉末涂料生产成套设备]
[http://www.shop263.com/i-48/652.htm 粉末涂装设备]
[http://www.shop263.com/i-48/653.htm 粉碎机]
[http://www.shop263.com/i-48/654.htm 粉体表面改性机械]
[http://www.shop263.com/i-48/655.htm 粉体混合工程设备]
[http://www.shop263.com/i-48/656.htm 风冷式热油泵]
[http://www.shop263.com/i-48/657.htm 氟表面活性剂]
[http://www.shop263.com/i-48/658.htm 氟合金液下泵]
[http://www.shop263.com/i-48/659.htm 氟化铵]
[http://www.shop263.com/i-48/660.htm 氟化氢铵]
[http://www.shop263.com/i-48/661.htm 氟树脂]
[http://www.shop263.com/i-48/662.htm 氟塑料衬里泵]
[http://www.shop263.com/i-48/663.htm 氟塑料衬里阀门]
[http://www.shop263.com/i-48/664.htm 氟塑料衬里隔膜阀]
[http://www.shop263.com/i-48/665.htm 氟塑料衬里截止阀]
[http://www.shop263.com/i-48/666.htm 氟塑料衬里球阀]
[http://www.shop263.com/i-48/667.htm 氟塑料衬里旋塞阀]
[http://www.shop263.com/i-48/668.htm 氟塑料衬里止回阀]
[http://www.shop263.com/i-48/669.htm 氟塑料合金材料]
[http://www.shop263.com/i-48/670.htm 氟塑料合金液下泵]
[http://www.shop263.com/i-48/671.htm 氟塑料喷涂]
[http://www.shop263.com/i-48/672.htm 氟塑料增强合金泵]
[http://www.shop263.com/i-48/673.htm 浮水泵]
[http://www.shop263.com/i-48/674.htm 浮头列管式石墨换热器]
[http://www.shop263.com/i-48/675.htm 釜外循环系统设置]
[http://www.shop263.com/i-48/676.htm 复合机]
[http://www.shop263.com/i-48/677.htm 复合喷丝板]
[http://www.shop263.com/i-48/678.htm 复合橡胶板]
[http://www.shop263.com/i-48/679.htm 干湿纺喷丝头]
[http://www.shop263.com/i-48/680.htm 干式真空泵]
[http://www.shop263.com/i-48/681.htm 干燥机]
[http://www.shop263.com/i-48/682.htm 干燥器]
[http://www.shop263.com/i-48/683.htm 干燥设备]
[http://www.shop263.com/i-48/684.htm 甘油]
[http://www.shop263.com/i-48/685.htm 钢衬复合管]
[http://www.shop263.com/i-48/686.htm 钢衬聚乙烯管道]
[http://www.shop263.com/i-48/687.htm 钢衬塑管道]
[http://www.shop263.com/i-48/688.htm 钢筘]
[http://www.shop263.com/i-48/689.htm 钢瓶]
[http://www.shop263.com/i-48/690.htm 钢丝缠绕胶管]
[http://www.shop263.com/i-48/691.htm 钢丝螺套]
[http://www.shop263.com/i-48/692.htm 钢塑复合管]
[http://www.shop263.com/i-48/693.htm 钢质焊接气瓶]
[http://www.shop263.com/i-48/694.htm 高纯化学品酸]
[http://www.shop263.com/i-48/695.htm 高档挤出复合机]
[http://www.shop263.com/i-48/696.htm 高档塑料制品]
[http://www.shop263.com/i-48/697.htm 高低密度聚乙烯]
[http://www.shop263.com/i-48/698.htm 高低压空温式汽化器]
[http://www.shop263.com/i-48/699.htm 高剪刀混合乳化机]
[http://www.shop263.com/i-48/700.htm 高剪切乳化设备]
[http://www.shop263.com/i-48/701.htm 高精度金属丝]
[http://www.shop263.com/i-48/702.htm 高岭土]
[http://www.shop263.com/i-48/703.htm 高频塑料热合机]
[http://www.shop263.com/i-48/704.htm 高强度聚乙稀PE储运罐]
[http://www.shop263.com/i-48/705.htm 高速分散机]
[http://www.shop263.com/i-48/706.htm 高速离心喷雾干燥机]
[http://www.shop263.com/i-48/707.htm 高速离心造粒干燥机]
[http://www.shop263.com/i-48/708.htm 高速升降搅拌机]
[http://www.shop263.com/i-48/709.htm 高速枕式全自动包装机]
[http://www.shop263.com/i-48/710.htm 高速制管机]
[http://www.shop263.com/i-48/711.htm 高温泵]
[http://www.shop263.com/i-48/712.htm 高温耐腐蚀离心泵]
[http://www.shop263.com/i-48/713.htm 高温液下泵]
[http://www.shop263.com/i-48/714.htm 高效板式密闭过滤机]
[http://www.shop263.com/i-48/715.htm 高效多管除尘器]
[http://www.shop263.com/i-48/716.htm 高效沸腾干燥机]
[http://www.shop263.com/i-48/717.htm 高效粉碎机]
[http://www.shop263.com/i-48/718.htm 高效过滤器]
[http://www.shop263.com/i-48/719.htm 高效换热器]
[http://www.shop263.com/i-48/720.htm 高效活性聚合物驱油剂]
[http://www.shop263.com/i-48/721.htm 高效节能聚四氟乙烯离心泵]
[http://www.shop263.com/i-48/722.htm 高效四氟换热器]
[http://www.shop263.com/i-48/723.htm 高效细粉分离器]
[http://www.shop263.com/i-48/724.htm 高压泵]
[http://www.shop263.com/i-48/725.htm 高压反应釜]
[http://www.shop263.com/i-48/726.htm 高压胶管]
[http://www.shop263.com/i-48/727.htm 高压静电除尘器]
[http://www.shop263.com/i-48/728.htm 高压绝缘子]
[http://www.shop263.com/i-48/729.htm 高压清洗机]
[http://www.shop263.com/i-48/730.htm 高压探测器]
[http://www.shop263.com/i-48/731.htm 高压无缝钢瓶]
[http://www.shop263.com/i-48/732.htm 高真空连续分离成套装置]
[http://www.shop263.com/i-48/733.htm 隔膜泵]
[http://www.shop263.com/i-48/734.htm 隔直流电容器]
[http://www.shop263.com/i-48/735.htm 各类塔器]
[http://www.shop263.com/i-48/736.htm 给排水泵]
[http://www.shop263.com/i-48/737.htm 工程爆破]
[http://www.shop263.com/i-48/738.htm 工程塑料泵]
[http://www.shop263.com/i-48/739.htm 工程塑料阀门]
[http://www.shop263.com/i-48/740.htm 工程陶瓷]
[http://www.shop263.com/i-48/741.htm 工程液压设备]
[http://www.shop263.com/i-48/742.htm 工民建筑]
[http://www.shop263.com/i-48/743.htm 工业泵]
[http://www.shop263.com/i-48/744.htm 工业除尘]
[http://www.shop263.com/i-48/745.htm 工业阀门]
[http://www.shop263.com/i-48/746.htm 工业锅炉]
[http://www.shop263.com/i-48/747.htm 工业级磷酸一铵]
[http://www.shop263.com/i-48/748.htm 工业加湿机]
[http://www.shop263.com/i-48/749.htm 工业冷水机]
[http://www.shop263.com/i-48/750.htm 工业炉]
[http://www.shop263.com/i-48/751.htm 工业热风炉]
[http://www.shop263.com/i-48/752.htm 工业消耗品]
[http://www.shop263.com/i-48/753.htm 工业氧气]
[http://www.shop263.com/i-48/754.htm 工业用离心泵]
[http://www.shop263.com/i-48/755.htm 工业噪音治理]
[http://www.shop263.com/i-48/756.htm 工艺蜡烛]
[http://www.shop263.com/i-48/757.htm 工作梯]
[http://www.shop263.com/i-48/758.htm 供氧装置]
[http://www.shop263.com/i-48/759.htm 固定式沸腾床干燥机]
[http://www.shop263.com/i-48/760.htm 固定箱体式调速型液力偶合器]
[http://www.shop263.com/i-48/761.htm 刮板薄膜蒸发器喷雾干燥机]
[http://www.shop263.com/i-48/762.htm 刮板式薄膜蒸发器]
[http://www.shop263.com/i-48/763.htm 刮刀下卸料离心机]
[http://www.shop263.com/i-48/764.htm 观片灯]
[http://www.shop263.com/i-48/765.htm 观片灯X射线胶片]
[http://www.shop263.com/i-48/766.htm 管道]
[http://www.shop263.com/i-48/767.htm 管道泵]
[http://www.shop263.com/i-48/768.htm 管道附件]
[http://www.shop263.com/i-48/769.htm 管道过滤器]
[http://www.shop263.com/i-48/770.htm 管道配件]
[http://www.shop263.com/i-48/771.htm 管道式无堵塞排污泵]
[http://www.shop263.com/i-48/772.htm 管道式自动增压泵]
[http://www.shop263.com/i-48/773.htm 管道特殊件]
[http://www.shop263.com/i-48/774.htm 管件]
[http://www.shop263.com/i-48/775.htm 管配件]
[http://www.shop263.com/i-48/776.htm 管式热交换器]
[http://www.shop263.com/i-48/777.htm 管束干燥机]
[http://www.shop263.com/i-48/778.htm 灌装机械]
[http://www.shop263.com/i-48/779.htm 罐内封闭阀门]
[http://www.shop263.com/i-48/780.htm 硅胶]
[http://www.shop263.com/i-48/781.htm 硅藻土精滤机]
[http://www.shop263.com/i-48/782.htm 癸二酸铵]
[http://www.shop263.com/i-48/783.htm 辊式破碎机]
[http://www.shop263.com/i-48/784.htm 辊式压力机]
[http://www.shop263.com/i-48/785.htm 滚滴浸绝缘处理设备]
[http://www.shop263.com/i-48/786.htm 滚筒干燥机]
[http://www.shop263.com/i-48/787.htm 滚筒干燥器]
[http://www.shop263.com/i-48/788.htm 锅炉]
[http://www.shop263.com/i-48/789.htm 国标储气桶]
[http://www.shop263.com/i-48/790.htm 过滤分离设备]
[http://www.shop263.com/i-48/791.htm 过滤机]
[http://www.shop263.com/i-48/792.htm 过滤器]
[http://www.shop263.com/i-48/793.htm 过滤器材设备]
[http://www.shop263.com/i-48/794.htm 过滤网]
[http://www.shop263.com/i-48/795.htm 含氮化合物]
[http://www.shop263.com/i-48/796.htm 含氟农药产品]
[http://www.shop263.com/i-48/797.htm 含氟新农药]
[http://www.shop263.com/i-48/798.htm 焊管]
[http://www.shop263.com/i-48/799.htm 焊管生产线]
[http://www.shop263.com/i-48/800.htm 焊接绝热气瓶]
[http://www.shop263.com/i-48/801.htm 合成氨]
[http://www.shop263.com/i-48/802.htm 黑液提取设备]
[http://www.shop263.com/i-48/803.htm 恒压变量自动给水控制设备]
[http://www.shop263.com/i-48/804.htm 喉管]
[http://www.shop263.com/i-48/805.htm 后整理设备]
[http://www.shop263.com/i-48/806.htm 呼吸阀]
[http://www.shop263.com/i-48/807.htm 呼吸人孔]
[http://www.shop263.com/i-48/808.htm 护栏网]
[http://www.shop263.com/i-48/809.htm 滑阀真空泵]
[http://www.shop263.com/i-48/800.htm 滑片式管道泵]
[http://www.shop263.com/i-48/811.htm 化成箔]
[http://www.shop263.com/i-48/812.htm 化工泵]
[http://www.shop263.com/i-48/813.htm 化工泵阀]
[http://www.shop263.com/i-48/814.htm 化工反应釜]
[http://www.shop263.com/i-48/815.htm 化工防腐]
[http://www.shop263.com/i-48/816.htm 化工防腐成套设备]
[http://www.shop263.com/i-48/817.htm 化工管道]
[http://www.shop263.com/i-48/818.htm 化工机械]
[http://www.shop263.com/i-48/819.htm 化工离心泵]
[http://www.shop263.com/i-48/820.htm 化工设备]
[http://www.shop263.com/i-48/821.htm 化工试剂]
[http://www.shop263.com/i-48/822.htm 化工行业筛分机]
[http://www.shop263.com/i-48/823.htm 化工液体]
[http://www.shop263.com/i-48/824.htm 化纤备件]
[http://www.shop263.com/i-48/825.htm 化纤纺丝配件]
[http://www.shop263.com/i-48/826.htm 化纤专件]
[http://www.shop263.com/i-48/827.htm 化学加药装置]
[http://www.shop263.com/i-48/828.htm 化学纤维]
[http://www.shop263.com/i-48/829.htm 化妆品]
[http://www.shop263.com/i-48/830.htm 环保工业用途的真空系统]
[http://www.shop263.com/i-48/831.htm 环保三废治理设备]
[http://www.shop263.com/i-48/832.htm 环保脱硫除尘设备]
[http://www.shop263.com/i-48/833.htm 环保型热熔胶]
[http://www.shop263.com/i-48/834.htm 环保用品]
[http://www.shop263.com/i-48/835.htm 环氧树脂真空浇注设备]
[http://www.shop263.com/i-48/836.htm 缓蚀剂]
[http://www.shop263.com/i-48/837.htm 换热]
[http://www.shop263.com/i-48/838.htm 换热器]
[http://www.shop263.com/i-48/839.htm 换热容器]
[http://www.shop263.com/i-48/840.htm 换热设备]
[http://www.shop263.com/i-48/841.htm 磺化设备]
[http://www.shop263.com/i-48/842.htm 回收净化]
[http://www.shop263.com/i-48/843.htm 混合机]
[http://www.shop263.com/i-48/844.htm 混料机]
[http://www.shop263.com/i-48/845.htm 混流式喷雾干燥机]
[http://www.shop263.com/i-48/846.htm 活塞推料离心机]
[http://www.shop263.com/i-48/847.htm 活性磷酸钙]
[http://www.shop263.com/i-48/848.htm 活性炭]
[http://www.shop263.com/i-48/849.htm 活性炭过滤器]
[http://www.shop263.com/i-48/850.htm 活性碳过滤网]
[http://www.shop263.com/i-48/851.htm 活性碳口罩]
[http://www.shop263.com/i-48/852.htm 活性碳酸钙]
[http://www.shop263.com/i-48/853.htm 活性氧化铝]
[http://www.shop263.com/i-48/854.htm 活性氧化铝球]
[http://www.shop263.com/i-48/855.htm 火灾逃生面具]
[http://www.shop263.com/i-48/856.htm 机械粉碎机]
[http://www.shop263.com/i-48/857.htm 机械过滤器]
[http://www.shop263.com/i-48/858.htm 机械密封件]
[http://www.shop263.com/i-48/859.htm 机械式单缸热熔釜]
[http://www.shop263.com/i-48/860.htm 机械式双缸热熔釜]
[http://www.shop263.com/i-48/861.htm 机械式无级变速器]
[http://www.shop263.com/i-48/862.htm 基因扩增仪]
[http://www.shop263.com/i-48/863.htm 集智能阀门]
[http://www.shop263.com/i-48/864.htm 己二酸]
[http://www.shop263.com/i-48/865.htm 挤出机]
[http://www.shop263.com/i-48/866.htm 挤水机]
[http://www.shop263.com/i-48/867.htm 挤压机]
[http://www.shop263.com/i-48/868.htm 计量泵]
[http://www.shop263.com/i-48/869.htm 加弹机]
[http://www.shop263.com/i-48/870.htm 加氢脱氧纯化装置]
[http://www.shop263.com/i-48/871.htm 加压叶滤机]
[http://www.shop263.com/i-48/872.htm 甲醇]
[http://www.shop263.com/i-48/873.htm 甲醇催化剂]
[http://www.shop263.com/i-48/874.htm 甲醇废水回收甲醇装置]
[http://www.shop263.com/i-48/875.htm 甲醇重整制氢装置]
[http://www.shop263.com/i-48/876.htm 甲醛]
[http://www.shop263.com/i-48/877.htm 甲醛尾气废热锅炉]
[http://www.shop263.com/i-48/878.htm 甲酸铵]
[http://www.shop263.com/i-48/879.htm 钾盐]
[http://www.shop263.com/i-48/880.htm 尖嘴式造粒机]
[http://www.shop263.com/i-48/881.htm 减速器]
[http://www.shop263.com/i-48/882.htm 剪板机]
[http://www.shop263.com/i-48/883.htm 检漏仪]
[http://www.shop263.com/i-48/884.htm 碱回收苛化工段成套设备]
[http://www.shop263.com/i-48/885.htm 建材机械]
[http://www.shop263.com/i-48/886.htm 剑杆织机]
[http://www.shop263.com/i-48/887.htm 浆叶干燥机]
[http://www.shop263.com/i-48/888.htm 降膜式吸收器]
[http://www.shop263.com/i-48/889.htm 降膜吸收器]
[http://www.shop263.com/i-48/890.htm 降膜蒸发器]
[http://www.shop263.com/i-48/891.htm 降凝干加剂]
[http://www.shop263.com/i-48/892.htm 胶带机]
[http://www.shop263.com/i-48/893.htm 胶囊填充设备]
[http://www.shop263.com/i-48/894.htm 胶体磨]
[http://www.shop263.com/i-48/895.htm 胶粘剂]
[http://www.shop263.com/i-48/896.htm 搅拌机]
[http://www.shop263.com/i-48/897.htm 搅拌容器]
[http://www.shop263.com/i-48/898.htm 酵母]
[http://www.shop263.com/i-48/899.htm 接地]
[http://www.shop263.com/i-48/900.htm 接口波纹管]
[http://www.shop263.com/i-48/901.htm 接头]
[http://www.shop263.com/i-48/902.htm 节能浓缩器]
[http://www.shop263.com/i-48/903.htm 洁净地漏]
[http://www.shop263.com/i-48/904.htm 洁净阀门]
[http://www.shop263.com/i-48/905.htm 结晶罐]
[http://www.shop263.com/i-48/906.htm 截止阀]
[http://www.shop263.com/i-48/907.htm 金刚石砂轮]
[http://www.shop263.com/i-48/908.htm 金属表面粗糙度测量仪]
[http://www.shop263.com/i-48/909.htm 金属波纹填料]
[http://www.shop263.com/i-48/910.htm 金属管接头总成]
[http://www.shop263.com/i-48/911.htm 金属检出机]
[http://www.shop263.com/i-48/912.htm 金属筛网]
[http://www.shop263.com/i-48/913.htm 金属压铸机床]
[http://www.shop263.com/i-48/914.htm 金属毡]
[http://www.shop263.com/i-48/915.htm 锦纶]
[http://www.shop263.com/i-48/916.htm 锦纶滤布]
[http://www.shop263.com/i-48/917.htm 腈纶]
[http://www.shop263.com/i-48/918.htm 精馏塔成套装置]
[http://www.shop263.com/i-48/919.htm 精馏塔配套设备]
[http://www.shop263.com/i-48/920.htm 精密阀门]
[http://www.shop263.com/i-48/921.htm 精密过滤器]
[http://www.shop263.com/i-48/922.htm 精密模具]
[http://www.shop263.com/i-48/923.htm 精细过滤器]
[http://www.shop263.com/i-48/924.htm 精细化学品]
[http://www.shop263.com/i-48/925.htm 井用潜水泵]
[http://www.shop263.com/i-48/926.htm 净水设备]
[http://www.shop263.com/i-48/927.htm 静电粉末涂装设备及回收系统]
[http://www.shop263.com/i-48/928.htm 酒精回收塔]
[http://www.shop263.com/i-48/929.htm 酒精蒸馏装置]
[http://www.shop263.com/i-48/930.htm 矩形块孔式石墨换热器]
[http://www.shop263.com/i-48/931.htm 聚氨酯发泡机]
[http://www.shop263.com/i-48/932.htm 聚氨酯连帮成型机]
[http://www.shop263.com/i-48/933.htm 聚氨酯设备]
[http://www.shop263.com/i-48/934.htm 聚丙烯]
[http://www.shop263.com/i-48/935.htm 聚丙烯换热器]
[http://www.shop263.com/i-48/936.htm 聚丙烯聚氯乙烯贮槽]
[http://www.shop263.com/i-48/937.htm 聚丙烯填料塔]
[http://www.shop263.com/i-48/938.htm 聚丙烯真空计量罐]
[http://www.shop263.com/i-48/939.htm 聚磷酸铵]
[http://www.shop263.com/i-48/940.htm 聚氯乙烯绝缘电线电缆]
[http://www.shop263.com/i-48/941.htm 聚偏二氟乙烯]
[http://www.shop263.com/i-48/942.htm 聚四氟乙烯]
[http://www.shop263.com/i-48/943.htm 聚四氟乙烯衬里防腐设备]
[http://www.shop263.com/i-48/944.htm 真空炉]
[http://www.shop263.com/i-48/945.htm 真空浓缩罐]
[http://www.shop263.com/i-48/946.htm 真空浓缩设备]
[http://www.shop263.com/i-48/947.htm 真空排气设备]
[http://www.shop263.com/i-48/948.htm 真空热缩膜机]
[http://www.shop263.com/i-48/949.htm 真空吸滤器]
[http://www.shop263.com/i-48/950.htm 真空压封机]
[http://www.shop263.com/i-48/951.htm 真空压力凝胶设备]
[http://www.shop263.com/i-48/952.htm 真空应用设备]
[http://www.shop263.com/i-48/953.htm 真空制膏机]
[http://www.shop263.com/i-48/954.htm 真石漆专用搅拌机]
[http://www.shop263.com/i-48/955.htm 振动干燥机]
[http://www.shop263.com/i-48/956.htm 振动给料设备]
[http://www.shop263.com/i-48/957.htm 振动机械]
[http://www.shop263.com/i-48/958.htm 振动流化床干燥机]
[http://www.shop263.com/i-48/959.htm 振动螺旋上料机]
[http://www.shop263.com/i-48/960.htm 振动筛]
[http://www.shop263.com/i-48/961.htm 振动筛分设备]
[http://www.shop263.com/i-48/962.htm 振动设备]
[http://www.shop263.com/i-48/963.htm 振动式流动床干燥机]
[http://www.shop263.com/i-48/964.htm 振动输送设备]
[http://www.shop263.com/i-48/965.htm 蒸发浓缩]
[http://www.shop263.com/i-48/966.htm 蒸发器]
[http://www.shop263.com/i-48/967.htm 蒸发式冷凝器]
[http://www.shop263.com/i-48/968.htm 蒸气电加热反应釜]
[http://www.shop263.com/i-48/969.htm 蒸汽电磁阀门]
[http://www.shop263.com/i-48/970.htm 蒸汽加热不锈钢反应锅]
[http://www.shop263.com/i-48/971.htm 蒸汽热油阀]
[http://www.shop263.com/i-48/972.htm 整体PE一次成型无缝无焊储罐]
[http://www.shop263.com/i-48/973.htm 脂肪族]
[http://www.shop263.com/i-48/974.htm 脂环族]
[http://www.shop263.com/i-48/975.htm 轴承]
http://www.shop263.com/i-48/649.htm
http://www.shop263.com/i-48/650.htm
http://www.shop263.com/i-48/651.htm
http://www.shop263.com/i-48/652.htm
http://www.shop263.com/i-48/653.htm
http://www.shop263.com/i-48/654.htm
http://www.shop263.com/i-48/655.htm
http://www.shop263.com/i-48/656.htm
http://www.shop263.com/i-48/657.htm
http://www.shop263.com/i-48/658.htm
http://www.shop263.com/i-48/659.htm
http://www.shop263.com/i-48/660.htm
http://www.shop263.com/i-48/661.htm
http://www.shop263.com/i-48/662.htm
http://www.shop263.com/i-48/663.htm
http://www.shop263.com/i-48/664.htm
http://www.shop263.com/i-48/665.htm
http://www.shop263.com/i-48/666.htm
http://www.shop263.com/i-48/667.htm
http://www.shop263.com/i-48/668.htm
http://www.shop263.com/i-48/669.htm
http://www.shop263.com/i-48/670.htm
http://www.shop263.com/i-48/671.htm
http://www.shop263.com/i-48/672.htm
http://www.shop263.com/i-48/673.htm
http://www.shop263.com/i-48/674.htm
http://www.shop263.com/i-48/675.htm
http://www.shop263.com/i-48/676.htm
http://www.shop263.com/i-48/677.htm
http://www.shop263.com/i-48/678.htm
http://www.shop263.com/i-48/679.htm
http://www.shop263.com/i-48/680.htm
http://www.shop263.com/i-48/681.htm
http://www.shop263.com/i-48/682.htm
http://www.shop263.com/i-48/683.htm
http://www.shop263.com/i-48/684.htm
http://www.shop263.com/i-48/685.htm
http://www.shop263.com/i-48/686.htm
http://www.shop263.com/i-48/687.htm
http://www.shop263.com/i-48/688.htm
http://www.shop263.com/i-48/689.htm
http://www.shop263.com/i-48/690.htm
http://www.shop263.com/i-48/691.htm
http://www.shop263.com/i-48/692.htm
http://www.shop263.com/i-48/693.htm
http://www.shop263.com/i-48/694.htm
http://www.shop263.com/i-48/695.htm
http://www.shop263.com/i-48/696.htm
http://www.shop263.com/i-48/697.htm
http://www.shop263.com/i-48/698.htm
http://www.shop263.com/i-48/699.htm
http://www.shop263.com/i-48/700.htm
http://www.shop263.com/i-48/701.htm
http://www.shop263.com/i-48/702.htm
http://www.shop263.com/i-48/703.htm
http://www.shop263.com/i-48/704.htm
http://www.shop263.com/i-48/705.htm
http://www.shop263.com/i-48/706.htm
http://www.shop263.com/i-48/707.htm
http://www.shop263.com/i-48/708.htm
http://www.shop263.com/i-48/709.htm
http://www.shop263.com/i-48/710.htm
http://www.shop263.com/i-48/711.htm
http://www.shop263.com/i-48/712.htm
http://www.shop263.com/i-48/713.htm
http://www.shop263.com/i-48/714.htm
http://www.shop263.com/i-48/715.htm
http://www.shop263.com/i-48/716.htm
http://www.shop263.com/i-48/717.htm
http://www.shop263.com/i-48/718.htm
http://www.shop263.com/i-48/719.htm
http://www.shop263.com/i-48/720.htm
http://www.shop263.com/i-48/721.htm
http://www.shop263.com/i-48/722.htm
http://www.shop263.com/i-48/723.htm
http://www.shop263.com/i-48/724.htm
http://www.shop263.com/i-48/725.htm
http://www.shop263.com/i-48/726.htm
http://www.shop263.com/i-48/727.htm
http://www.shop263.com/i-48/728.htm
http://www.shop263.com/i-48/729.htm
http://www.shop263.com/i-48/730.htm
http://www.shop263.com/i-48/731.htm
http://www.shop263.com/i-48/732.htm
http://www.shop263.com/i-48/733.htm
http://www.shop263.com/i-48/734.htm
http://www.shop263.com/i-48/735.htm
http://www.shop263.com/i-48/736.htm
http://www.shop263.com/i-48/737.htm
http://www.shop263.com/i-48/738.htm
http://www.shop263.com/i-48/739.htm
http://www.shop263.com/i-48/740.htm
http://www.shop263.com/i-48/741.htm
http://www.shop263.com/i-48/742.htm
http://www.shop263.com/i-48/743.htm
http://www.shop263.com/i-48/744.htm
http://www.shop263.com/i-48/745.htm
http://www.shop263.com/i-48/746.htm
http://www.shop263.com/i-48/747.htm
http://www.shop263.com/i-48/748.htm
http://www.shop263.com/i-48/749.htm
http://www.shop263.com/i-48/750.htm
http://www.shop263.com/i-48/751.htm
http://www.shop263.com/i-48/752.htm
http://www.shop263.com/i-48/753.htm
http://www.shop263.com/i-48/754.htm
http://www.shop263.com/i-48/755.htm
http://www.shop263.com/i-48/756.htm
http://www.shop263.com/i-48/757.htm
http://www.shop263.com/i-48/758.htm
http://www.shop263.com/i-48/759.htm
http://www.shop263.com/i-48/760.htm
http://www.shop263.com/i-48/761.htm
http://www.shop263.com/i-48/762.htm
http://www.shop263.com/i-48/763.htm
http://www.shop263.com/i-48/764.htm
http://www.shop263.com/i-48/765.htm
http://www.shop263.com/i-48/766.htm
http://www.shop263.com/i-48/767.htm
http://www.shop263.com/i-48/768.htm
http://www.shop263.com/i-48/769.htm
http://www.shop263.com/i-48/770.htm
http://www.shop263.com/i-48/771.htm
http://www.shop263.com/i-48/772.htm
http://www.shop263.com/i-48/773.htm
http://www.shop263.com/i-48/774.htm
http://www.shop263.com/i-48/775.htm
http://www.shop263.com/i-48/776.htm
http://www.shop263.com/i-48/777.htm
http://www.shop263.com/i-48/778.htm
http://www.shop263.com/i-48/779.htm
http://www.shop263.com/i-48/780.htm
http://www.shop263.com/i-48/781.htm
http://www.shop263.com/i-48/782.htm
http://www.shop263.com/i-48/783.htm
http://www.shop263.com/i-48/784.htm
http://www.shop263.com/i-48/785.htm
http://www.shop263.com/i-48/786.htm
http://www.shop263.com/i-48/787.htm
http://www.shop263.com/i-48/788.htm
http://www.shop263.com/i-48/789.htm
http://www.shop263.com/i-48/790.htm
http://www.shop263.com/i-48/791.htm
http://www.shop263.com/i-48/792.htm
http://www.shop263.com/i-48/793.htm
http://www.shop263.com/i-48/794.htm
http://www.shop263.com/i-48/795.htm
http://www.shop263.com/i-48/796.htm
http://www.shop263.com/i-48/797.htm
http://www.shop263.com/i-48/798.htm
http://www.shop263.com/i-48/799.htm
http://www.shop263.com/i-48/800.htm
http://www.shop263.com/i-48/801.htm
http://www.shop263.com/i-48/802.htm
http://www.shop263.com/i-48/803.htm
http://www.shop263.com/i-48/804.htm
http://www.shop263.com/i-48/805.htm
http://www.shop263.com/i-48/806.htm
http://www.shop263.com/i-48/807.htm
http://www.shop263.com/i-48/808.htm
http://www.shop263.com/i-48/809.htm
http://www.shop263.com/i-48/800.htm
http://www.shop263.com/i-48/811.htm
http://www.shop263.com/i-48/812.htm
http://www.shop263.com/i-48/813.htm
http://www.shop263.com/i-48/814.htm
http://www.shop263.com/i-48/815.htm
http://www.shop263.com/i-48/816.htm
http://www.shop263.com/i-48/817.htm
http://www.shop263.com/i-48/818.htm
http://www.shop263.com/i-48/819.htm
http://www.shop263.com/i-48/820.htm
http://www.shop263.com/i-48/821.htm
http://www.shop263.com/i-48/822.htm
http://www.shop263.com/i-48/823.htm
http://www.shop263.com/i-48/824.htm
http://www.shop263.com/i-48/825.htm
http://www.shop263.com/i-48/826.htm
http://www.shop263.com/i-48/827.htm
http://www.shop263.com/i-48/828.htm
http://www.shop263.com/i-48/829.htm
http://www.shop263.com/i-48/830.htm
http://www.shop263.com/i-48/831.htm
http://www.shop263.com/i-48/832.htm
http://www.shop263.com/i-48/833.htm
http://www.shop263.com/i-48/834.htm
http://www.shop263.com/i-48/835.htm
http://www.shop263.com/i-48/836.htm
http://www.shop263.com/i-48/837.htm
http://www.shop263.com/i-48/838.htm
http://www.shop263.com/i-48/839.htm
http://www.shop263.com/i-48/840.htm
http://www.shop263.com/i-48/841.htm
http://www.shop263.com/i-48/842.htm
http://www.shop263.com/i-48/843.htm
http://www.shop263.com/i-48/844.htm
http://www.shop263.com/i-48/845.htm
http://www.shop263.com/i-48/846.htm
http://www.shop263.com/i-48/847.htm
http://www.shop263.com/i-48/848.htm
http://www.shop263.com/i-48/849.htm
http://www.shop263.com/i-48/850.htm
http://www.shop263.com/i-48/851.htm
http://www.shop263.com/i-48/852.htm
http://www.shop263.com/i-48/853.htm
http://www.shop263.com/i-48/854.htm
http://www.shop263.com/i-48/855.htm
http://www.shop263.com/i-48/856.htm
http://www.shop263.com/i-48/857.htm
http://www.shop263.com/i-48/858.htm
http://www.shop263.com/i-48/859.htm
http://www.shop263.com/i-48/860.htm
http://www.shop263.com/i-48/861.htm
http://www.shop263.com/i-48/862.htm
http://www.shop263.com/i-48/863.htm
http://www.shop263.com/i-48/864.htm
http://www.shop263.com/i-48/865.htm
http://www.shop263.com/i-48/866.htm
http://www.shop263.com/i-48/867.htm
http://www.shop263.com/i-48/868.htm
http://www.shop263.com/i-48/869.htm
http://www.shop263.com/i-48/870.htm
http://www.shop263.com/i-48/871.htm
http://www.shop263.com/i-48/872.htm
http://www.shop263.com/i-48/873.htm
http://www.shop263.com/i-48/874.htm
http://www.shop263.com/i-48/875.htm
http://www.shop263.com/i-48/876.htm
http://www.shop263.com/i-48/877.htm
http://www.shop263.com/i-48/878.htm
http://www.shop263.com/i-48/879.htm
http://www.shop263.com/i-48/880.htm
http://www.shop263.com/i-48/881.htm
http://www.shop263.com/i-48/882.htm
http://www.shop263.com/i-48/883.htm
http://www.shop263.com/i-48/884.htm
http://www.shop263.com/i-48/885.htm
http://www.shop263.com/i-48/886.htm
http://www.shop263.com/i-48/887.htm
http://www.shop263.com/i-48/888.htm
http://www.shop263.com/i-48/889.htm
http://www.shop263.com/i-48/890.htm
http://www.shop263.com/i-48/891.htm
http://www.shop263.com/i-48/892.htm
http://www.shop263.com/i-48/893.htm
http://www.shop263.com/i-48/894.htm
http://www.shop263.com/i-48/895.htm
http://www.shop263.com/i-48/896.htm
http://www.shop263.com/i-48/897.htm
http://www.shop263.com/i-48/898.htm
http://www.shop263.com/i-48/899.htm
http://www.shop263.com/i-48/900.htm
http://www.shop263.com/i-48/901.htm
http://www.shop263.com/i-48/902.htm
http://www.shop263.com/i-48/903.htm
http://www.shop263.com/i-48/904.htm
http://www.shop263.com/i-48/905.htm
http://www.shop263.com/i-48/906.htm
http://www.shop263.com/i-48/907.htm
http://www.shop263.com/i-48/908.htm
http://www.shop263.com/i-48/909.htm
http://www.shop263.com/i-48/910.htm
http://www.shop263.com/i-48/911.htm
http://www.shop263.com/i-48/912.htm
http://www.shop263.com/i-48/913.htm
http://www.shop263.com/i-48/914.htm
http://www.shop263.com/i-48/915.htm
http://www.shop263.com/i-48/916.htm
http://www.shop263.com/i-48/917.htm
http://www.shop263.com/i-48/918.htm
http://www.shop263.com/i-48/919.htm
http://www.shop263.com/i-48/920.htm
http://www.shop263.com/i-48/921.htm
http://www.shop263.com/i-48/922.htm
http://www.shop263.com/i-48/923.htm
http://www.shop263.com/i-48/924.htm
http://www.shop263.com/i-48/925.htm
http://www.shop263.com/i-48/926.htm
http://www.shop263.com/i-48/927.htm
http://www.shop263.com/i-48/928.htm
http://www.shop263.com/i-48/929.htm
http://www.shop263.com/i-48/930.htm
http://www.shop263.com/i-48/931.htm
http://www.shop263.com/i-48/932.htm
http://www.shop263.com/i-48/933.htm
http://www.shop263.com/i-48/934.htm
http://www.shop263.com/i-48/935.htm
http://www.shop263.com/i-48/936.htm
http://www.shop263.com/i-48/937.htm
http://www.shop263.com/i-48/938.htm
http://www.shop263.com/i-48/939.htm
http://www.shop263.com/i-48/940.htm
http://www.shop263.com/i-48/941.htm
http://www.shop263.com/i-48/942.htm
http://www.shop263.com/i-48/943.htm
http://www.shop263.com/i-48/944.htm
http://www.shop263.com/i-48/945.htm
http://www.shop263.com/i-48/946.htm
http://www.shop263.com/i-48/947.htm
http://www.shop263.com/i-48/948.htm
http://www.shop263.com/i-48/949.htm
http://www.shop263.com/i-48/950.htm
http://www.shop263.com/i-48/951.htm
http://www.shop263.com/i-48/952.htm
http://www.shop263.com/i-48/953.htm
http://www.shop263.com/i-48/954.htm
http://www.shop263.com/i-48/955.htm
http://www.shop263.com/i-48/956.htm
http://www.shop263.com/i-48/957.htm
http://www.shop263.com/i-48/958.htm
http://www.shop263.com/i-48/959.htm
http://www.shop263.com/i-48/960.htm
http://www.shop263.com/i-48/961.htm
http://www.shop263.com/i-48/962.htm
http://www.shop263.com/i-48/963.htm
http://www.shop263.com/i-48/964.htm
http://www.shop263.com/i-48/965.htm
http://www.shop263.com/i-48/966.htm
http://www.shop263.com/i-48/967.htm
http://www.shop263.com/i-48/968.htm
http://www.shop263.com/i-48/969.htm
http://www.shop263.com/i-48/970.htm
http://www.shop263.com/i-48/971.htm
http://www.shop263.com/i-48/972.htm
http://www.shop263.com/i-48/973.htm
http://www.shop263.com/i-48/974.htm
http://www.shop263.com/i-48/975.htm

Latest revision as of 12:44, 24 July 2013

This page aims to give an overview of the current state of metadata in Ogg and the ongoing projects towards improving it. The different components work in concert; for example Ogg Skeleton provides important infrastructure for CMML, VorbisComment is simple to use and program, while the draft Multimedia Metadata Format (M3F) provides more sophisticated information.

VorbisComments

All the Xiph.org codecs have some internal mechanism for including metadata about the current stream. Generally, this is one of the codec headers, and in the words of the vorbis spec, "It is meant for short, text comments ... much like someone jotting a quick note on the bottom of a CDR." A single VorbisComment can store upto 2^64 bytes (16 exabytes).

VorbisComments store metadata describing the stream in key=value pairs, such as "ARTIST=Elvis", "TITLE=Blue Suede Shoes". Multiple copies of any given key are allowed (for example you can specify ARTIST several times for multiple performers). The specification has several suggested keys: TITLE, VERSION, ALBUM, TRACKNUMBER, ARTIST, PERFORMER, COPYRIGHT, LICENSE, ORGANIZATION, DESCRIPTION, GENRE, DATE, LOCATION, CONTACT, ISRC. See the specification for the intent of each one.

The VorbisComment page contains improvements to the suggested comment set.

FLAC metadata blocks

Metadata is included in the FLAC codec as METADATA_BLOCK_DATA. Seven types of metadata block are defined:

  1. METADATA_BLOCK_STREAMINFO: Sample rate, number of channels, etc.
  2. METADATA_BLOCK_PADDING: Nul padding.
  3. METADATA_BLOCK_APPLICATION: Third-party applications can register an ID. Metadata is typically 32-bit integers, but any datatypes can be specified.
  4. METADATA_BLOCK_SEEKTABLE: For one or more seek points.
  5. METADATA_BLOCK_VORBIS_COMMENT: Also known as FLAC tags, the contents of a VorbisComment packet. Note that the 32-bit field lengths are little-endian coded according to the Vorbis spec, as opposed to the usual big-endian coding of fixed-length integers in the rest of FLAC. FLAC metadata blocks are limited to 2^24 bytes (16 megabytes) and a VorbisComment packet in FLAC must fit within that limit.
  6. METADATA_BLOCK_CUESHEET: Typically, but not necessarily, for CD-DA (Red Book) cuesheets.
  7. METADATA_BLOCK_PICTURE: For binary picture data.

Ogg Skeleton

Ogg Skeleton provides metadata useful for handling Ogg streams. This includes information like mime-types and mapping for granulepos which allows seeking streams without the need for the demuxer to understand them. The latest version, Ogg Skeleton 4, also provides a keyframe index to enable faster seeking over high latency networks.

Ogg Skeleton allows for attachment of message header fields, given as name-value pairs, that contain some sort of protocol messages about the logical bitstream. This is intended for decode related stuff, such as the screen size for a video bitstream or the number of channels for an audio bitstream.

OggKate

OggKate was originally designed for karaoke and text. The stream can carry text and images, and these can be animated.

CMML (deprecated)

CMML is not used anymore; use OggKate instead. The Continuous Media Markup Language allowed time-based marking up of media streams, at its simplest this allowed you to divide media files into clips and provide information about each clip.

M3F (unused draft)

Multimedia Metadata Format is not being developed anymore; use VorbisComment instead.

The format was intended to replace VorbisComments for the use of structured metadata, allowing VorbisComments to revert to its orginally intended use of "short, text comments ... much like someone jotting a quick note on the bottom of a CDR."

M3F for the Ogg container was a draft specification which aimed to provide metadata for media streams. The exact aims of this project were still under development, but they included being able to describe artist relationships to a piece more accurately as well as providing the structure to encourage more reliable metadata.

XMLEmbedding (unused draft)

To implement XML metadata in Ogg (as for M3F), a mapping to Ogg streams is needed. The use of XML metadata will also open the way for the inclusion of technologies such as:

This specification is still not past the discussion stage.

Aims of advanced metadata

VorbisComments work well enough for most things, and can be overloaded/abused (depending on your point of view) for most other things. But there are three major requirements that point to the design of an external metadata format; one that can be interleaved with the other streams in a container.

  • Machinability: There are a number of items of metadata that a player will want to parse and take action on. While there are usually 'convention' schemes for doing this with the embedded comment headers, this is much easier if there is a separate metadata stream designed for such use, instead of having to do best-effort parsing of natural language comments. For example, a video file with multiple audio tracks can specify the language of each one; a player than can parse these reliably can match them against a language preference list configured by the user to automatically select and begin playback of the best option.
  • Kitchen Sink: There are a minority of people who care passionately about having every detail about a track available. In the sense of conserving such information, and providing an equivalent to liner notes for online distribution, this is a goal worth supporting. However, the simple unstructured key-value pairs offered by the inline metadata are unwieldy for this level of detail. How do you tell the 2nd unit Assistant Director from the USA unit Assistant Director? How do you indicate which artist played tenor sax in the solo?
  • Addressability: The internal comment metadata headers are by necessity attached to a single content stream. This is useful for some appication, but a limitation in others. In a multiplexed stream, which set of comments refers to the collection as a whole? (By convention, in Ogg, it's the first logical bitstream occuring, but we can do better.) A separate metadata stream type must address this issue of collective metadata while still allowing description of individual streams. It should also allow temporal addressability, so that changes can be described. Because the in-stream comment metadata are part of the codec headers, it cannot change over the course of the stream, and allowing additional comment packets elsewhere in the stream presents seeking challenges. In the Ogg container this can be resolved by inserting a chain boundary, but this is a poor option for very-low-bitrate streams and unreliable transports such as RTP.