Re: In-band track metadata attribute

On Tue, Mar 11, 2014 at 7:15 AM, Brendan Long <B.Long@cablelabs.com> wrote:

>  On Tue, 2014-03-11 at 06:41 +1100, Silvia Pfeiffer wrote:
>
> Could you provide some examples of the data that goes there for mp2-ts?
>
> The same data that's currently listed for inBandMetadataTrackDispatchType
> would work, except without base64 encoding:
>
> Let stream type be the value of the "stream_type" field describing the
> text track's type in the file's program map section, interpreted as an
> 8-bit unsigned integer. Let length be the value of the "ES_info_length"
> field for the track in the same part of the program map section,
> interpreted as an integer as defined by the MPEG-2 specification. Let descriptor
> bytes be the length bytes following the "ES_info_length" field. The text
> track in-band metadata track dispatch type<http://www.w3.org/html/wg/drafts/html/CR/embedded-content-0.html#text-track-in-band-metadata-track-dispatch-type>must be set to the concatenation of the stream
> type byte and the zero or more descriptor bytes bytes, expressed in
> hexadecimal using uppercase ASCII hex digits<http://www.w3.org/html/wg/drafts/html/CR/infrastructure.html#uppercase-ascii-hex-digits>.
> [MPEG2]<http://www.w3.org/html/wg/drafts/html/CR/references.html#refsMPEG2>
>
> Even better might be including the entire "elementary stream info data"<http://en.wikipedia.org/wiki/Program-specific_information>
> :
>
>   *Name* *Number*
> *of bits* *Description*  stream type 8 This defines the structure of the
> data contained within the elementary packet identifier.  Reserved bits 3 Set
> to 0x07 (all bits on)  Elementary PID 13 The packet identifier that
> contains the stream type data.  Reserved bits 4 Set to 0x0f (all bits on)  ES
> Info length unused bits 2 Set to 0 (all bits off)  ES Info length length 10
> The number of bytes that follow for the elementary stream descriptors.  Elementary
> stream descriptors N*8 When the ES info length is non-zero, this is the
> ES info length number of elementary stream descriptor bytes.
>
>
Is this once-off information or does it repeat? I was under the impression
that, e.g. PID can repeat and change during the course of the video.

Regards,
Silvia.