MPEG Audio Byte Stream Format

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Do not attempt to implement this version of the specification. Do not reference this version as authoritative in any way. Instead, see https://w3c.github.io/mse-byte-stream-format-mpeg-audio/ for the Editor's draft.

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This specification defines segment formats for implementations of Media Source Extensions™ [ MEDIA-SOURCE ] that choose to support MPEG audio streams specified in [ ISO11172-3 ], [ ISO13818-3 ], and [ ISO14496-3 ].

It defines the MIME-types (see 2. MIME-types ) used to signal codecs, and provides the necessary format specific definitions for initialization segments , media segments , and random access points required by the Byte Stream Formats section of the Media Source Extensions™ specification. This document also defines extra behaviors and state that only apply to this byte stream format.

This section specifies the MIME-types that may be passed to isTypeSupported () or addSourceBuffer () for byte streams that conform to this specification.

"audio/aac" for sequences of ADTS frames, as specified in [ ISO14496-3 ].
"audio/mpeg" for MPEG-1/2/2.5 Layer I/II/III streams, as specified in [ RFC3003 ].

The "codecs" MIME-type parameter MUST NOT be used with these MIME-types.

The format of an MPEG Audio Frame depends on the MIME type used (see 2. MIME-types ).

If the "audio/aac" MIME-type is used, an MPEG Audio Frame is a sequence of bytes that conform to the adts_frame() syntax specified in Table 1.A.5 of [ ISO14496-3 ].
If the "audio/mpeg" MIME-type is used, an MPEG Audio Frame is a sequence of bytes that conform to the frame() syntax element specified in Section 2.4.1.2 of [ ISO11172-3 ] or the corresponding definition in [ ISO13818-3 ].

Since [ ID3v1 ], [ ID3v2 ] metadata frames, and Icecast headers are common in existing MPEG audio streams, implementations SHOULD gracefully handle such frames. Zero or more of these metadata frames are allowed to occur before, after, or between MPEG Audio Frame . Minimal implementations MUST accept, consume, and ignore these frames. More advanced implementations MAY choose to expose the metadata information via an inband TextTrack or some other mechanism.

There is no normative spec for Icecast / SHOUTcast headers, just examples . For the purpose of this specification, an Icecast header is defined as beginning with the 4 character sequence "ICY "(U+0049 I, U+0043 C, U+0059 Y, U+0020 SPACE) and ending with a pair of carriage-return line-feed sequences (U+000D CARRIAGE RETURN, U+000A LINE FEED, U+000D CARRIAGE RETURN, U+000A LINE FEED).

Note

Icecast headers are allowed in the byte streams because some Icecast and SHOUTcast servers return a status line that looks like "ICY OK 200" instead of a standard HTTP status line. User-agent network stacks typically interpret this as an HTTP 0.9 response and include the header in the response body. Allowing these headers to appear provides a simple way to interoperate with these servers.

As well as sections marked as non-normative, all authoring guidelines, diagrams, examples, and notes in this specification are non-normative. Everything else in this specification is normative.

The key words MAY , MUST , MUST NOT , and SHOULD in this document are to be interpreted as described in BCP 14 [ RFC2119 ] [ RFC8174 ] when, and only when, they appear in all capitals, as shown here.

MPEG Audio Byte Stream Format

Abstract

Status of This Document

1. Introduction

2. MIME-types

3. MPEG Audio Frames

4. Metadata Frames

4.1 Icecast headers

5. Segment Definitions

6. Conformance

A. References

A.1 Normative references